Blood Science: Principles and Pathology

 

Description:

An integrated textbook on Blood Science, haematology, clinical biochemistry and immunology, in accordance with the changing educational and training structure for Biomedical Scientists.

 

Table of Contents:

 

1 Introduction to Blood Science

Learning objectives

1.1 What is blood science?

An historical perspective

Table 1.1 The biomedical or life sciences

The reference range

The normal distribution

Figure 1.1 The normal distribution.

The non-normal distribution

Figure 1.2 The non-normal distribution.

Variation in reference ranges

Interpretation

Figure 1.3 Common biochemistry tests. Selected biochemistry results on a presumed healthy middle-aged male. The blood tests themselves are printed out in the first column on the left (headed by urea). The next column is the actual result (in this case, 4.1), and then the units (mmol/L), and finally the reference range on the right (3.0–8.3). Results which are outside the reference range are generally highlighted by an asterisk. The fact that there are no asterisks present means that all results are acceptable and no further testing is required.

Position statement

1.2 Biochemistry

Urea and electrolytes

Liver function tests

Lipids, glucose, diabetes and heart disease

Dyslipidaemia

Diabetes

Cardiovascular disease

Calcium, phosphate, magnesium and bone disease

Hormones and endocrine disorders

Other tests

Table 1.2 Common biochemistry tests

1.3 Blood transfusion

Blood groups

Table 1.3 ABO blood group factors.

The practice of blood transfusion

Blood group determination

Antibody screening

Cross-match

Blood components (previously blood products)

Clinical aspects of blood transfusion

Sources of error

Table 1.4 Some signs and symptoms of a transfusion reaction.

Responses to an incompatible transfusion

Repercussions

1.4 Genetics

Genetic disease in families

Penetrance

Genes, chromosomes and DNA

Chromosomal disorders

Table 1.5 Chromosome abnormalities.

Figure 1.4 A normal karyotype: 46 chromosomes arranged in 23 pairs, dependent on the length and the banding patterns, of 22 pairs of autosomes and two sex chromosomes.

Gene disorders

Deletions

Translocations

Oncogenes

Genetics as an independent blood science

Table 1.6 Molecular genetics across pathology.

Blood science angle: Haematology and molecular genetics

1.5 Haematology

The blood film

Figure 1.5 A blood film.

The full blood count

Red blood cells

Figure 1.6 The full blood count.

White blood cells

Platelets

Erythrocyte sedimentation rate

Haemostasis

Prothrombin time

Activated partial thromboplastin time

Fibrinogen

Pathology of thrombosis and haemostasis

Haematinics

Iron

Vitamin B12

The laboratory in micronutrient deficiency

Haematological disease

Table 1.7 Common routine haematology blood tests.

1.6 Immunology

Serology

Figure 1.7 An antibody molecule.

Cells

Immunopathology

An inappropriately excessive immune response

A weak or absent immune response

Table 1.8 Immunology

1.7 The role of blood science in modern healthcare

Blood science in human disease

Cancer

Connective tissue disease

Cardiovascular disease

Blood scientists: who are they?

Table 1.9 Blood science and human disease.

The role of the higher education institutions

Training in blood science

Figure 1.8 Training of blood scientists. (http://www.nhscareers.nhs.uk/explore-by-career/healthcare-science/modernising-scientific-careers/

1.8 What this book will achieve

Summary

References

Further reading

Web sites

2 Analytical Techniques in Blood Science

Learning objectives

2.1 Venepuncture

Figure 2.1 Venepuncture. The process of obtaining a sample of blood, generally from a vein near the surface of the skin on the inside of the elbow. Blood is being drawn into a vacutainer with a yellow top (right-hand side) that has no anticoagulant, but a small piece of gel at the bottom (left-hand side) to help the preparation of serum.

2.2 Anticoagulants

Figure 2.2 Vacutainers. Note the different coloured tops, indicating different anticoagulants (blue: sodium citrate; grey: fluoride oxalate) or no anticoagulant (beige). Note also that vacutainers come in different sizes.

Key anticoagulants

Ethylenediaminetetraacetic acid

Sodium citrate

Fluoride oxalate

Lithium heparin

2.3 Sample identification and tracking

2.4 Technical and analytical confidence

Assay performance

Confirming or refuting disease

Figure 2.3 Concentrations of substance X in the plasma of patients and controls. The thick bar represents the average (mean) value.

Value in predicting disease

Confidence in the result

Example 2.1: Value of a method

Interpretation

Figure 2.4 The accuracy and reproducibility of a test illustrated by an archery target. In the top figure, the results are spread out (poor reproducibility) but centre on the bull's eye (accurate). In the middle figure, the results are tightly clustered together (good reproducibility) but are far from the bull's eye (inaccurate). The bottom figure shows results that are both tightly clustered and accurate.

Quality control

Quality assurance

Example 2.2: Quality assurance

Audit

Figure 2.5 This Levey–Jennings plot shows sequential results for substance X, which are acceptably stable up to index point 10, then become highly variable, indicating a problem with the method.

2.5 Major techniques

An erratic analyser

The standard operating procedure

The standard curve

Figure 2.6 A standard curve. Analyser results from a series of five samples of known concentrations of the analyte (open circles) are plotted on a graph. The analyser result from the patient (perhaps 0.47 units on the vertical axis) drawn across the plot meets the standard curve at point ‘X’. Drawing down from this point to the horizontal axis gives a result of about 120 units.

Upper and lower limits of sensitivity

Centrifugation

Analysis of metals and nonmetals

Spectroscopy

The Beer–Lambert law

Colorimetry

Mass spectrometry

Immunoassay

Agglutination

Enzyme-linked immunosorbent assay

Figure 2.7 Five common steps in an ELISA, where the amount of an analyte in a sample is converted to colour for analysis. The amounts of the reagents are in excess so that the sole rate-limiting factor in determining the amount of colour being developed is the amount of the analyte.

Chemiluminesence immunoassay

Fluorescence immunoassay

Figure 2.8 A microtitre plate showing results of an ELISA procedure. Samples are loaded in groups of three (triplicates). The three columns (counting from the left: numbers 10–12) of the far right of the plate are the standard curve. The topmost triplet of wells have the highest concentration of a known amount of the analyte (perhaps 100 units/L), and triplets of wells below this have proportionately lower amounts of the known standard (80 units/L, 60 units/L and so on down to maybe 5 units/L). The rest of the plate, to the left of the standard curve, contains triplicates of samples of plasma from different patients. Note that some are highly coloured (such as the three wells in horizontal row F, vertical columns 1–3), and other less so (such as row B, columns 4–6). The standard curve (Figure 2.6) will translate these unknown colours to the concentration (units/L) of the analytes in the plasmas. Columns 7–9 are blank, and so have no colour.

Immunoturbidimetry and nephelometry

Immunoprecipitation

Radioisotopes

Chromatography

High-performance liquid chromatography

Gas–liquid chromatography

Figure 2.9 HPLC. This compact workstation consists of a series of enclosed units containing the columns, reservoirs for buffers, pumps and (on the far left) the sample area and controls. The Dionex HPLC-DAD offers the separating power of HPLC linked to a photodiode array detector (DAD) for clinical and forensic applications. The DAD records the absorbance spectra of compounds over a range of wavelengths (e.g. 200–595 nm) as they pass through the detector flow cell. This data can then be used to provide definitive identification of a compound, or to select the optimum wavelength for quantitation.

Electrophoresis

Counting cells and particles

Impedance

Flow cytometry

Fluorescence-activated cell scanning

Figure 2.10 Flow cytometry. This technique for counting white cell subpopulations makes use of the size of the nucleus and presence of intracellular granules. The colour coding defined by the analyser's software in this figure makes recognition of each type of cell easier; the cells themselves have no colour. Mono: monocytes; Lymph: lymphocytes; Neut: neutrophils; Baso: basophils; Eo: eosinophils. These cells are described in detail in Chapter 7.

Cytochemistry

Figure 2.11 FACS analysis of T lymphocyte subsets. In the upper figure, the scientist has put a ‘gate’ around that region of the plot where they expect lymphocytes to be, and the FACS machine software has coloured these in red. The lower figure shows analysis of those cells which have bound an antibody to CD4 (itself bound to the fluorochrome FITC, lower right (LR) quadrant), an antibody to CD8 (itself bound to fluorochrome phycoerythrin, upper left (UL) quadrant), both antibodies (lower left (LL) quadrant) and neither antibody (upper right (UR) panel).

Figure 2.12 Immunocytochemistry detecting an abnormal white cell (stained red). Unstained cells are counterstained light blue/grey. The enzyme is alkaline phosphatase.

Microscopy

Light microscopy

Figure 2.13 A simple bench light microscope. The top arrow indicates the eyepieces. The three objective lenses are highlighted by the arrow on the left; the stage, where the glass slide is placed, is indicated by the lower right arrow. The lowest arrow on the right points out the light source; the lowest on the left indicates the focusing apparatus.

Fluorescence microscopy

Other microscopy

Automation

Figure 2.14 A biochemistry analyser. This substantial item of capital equipment is capable of the simultaneous analysis of several different analytes. However, it still needs to be programmed by scientists, who also need to ensure reagents are kept topped up and that waste is being safely disposed of.

Figure 2.15 A haematology tracking system. A vacutainer is conducted along a track, and different machines are programmed to perform their own specific analyses as required.

2.6 Molecular genetics

Tools in molecular genetics

Purification and extraction of DNA

Analysis of DNA

Figure 2.16 Identification of mutated genes. Two different restriction endonucleases are mixed with the DNA (step 1). One enzyme cuts the DNA strand at nucleotides AB/AB, the other at XY/XY. In a normal situation, this generates two identical small fragments: AB=====XY. The same enzymes applied to the abnormal DNA, with abnormal nucleotides XY/OY but normal AB/AB sequences, which generate only one large fragment because the enzyme specific for XY/XY cannot cut the mutated sequence (step 2). Mixing the fragments with radiolabelled probe AB-----XY will see the probe binding both fragments as both the short normal and longer mutated fragments contain the matching DNA sequence (step 3). When this mixture is run through an electrophoresis gel, the smaller normal fragments will migrate faster than the larger abnormal fragments. The size of the patient's fragments can be assessed by running a series of fragments of known size.

The application of molecular genetics to human disease

Molecular genetics in biochemistry

Figure 2.17 Gene analysis. This is an amplification refractory mutation system PCR used for diagnosis of a β-thalassaemia mutation. Lane 1 (left-hand side) is molecular markers, lanes 2 and 3 patient 1 (normal and mutant primers respectively), lanes 4 and 5 patient 2 (normal and mutant) and lanes 6 and 7 patient 3 (normal and mutant primers). The arrowed bands represent internal control bands that identify a standard region of the DNA regardless of the thalassaemia mutation. This is very useful in confirming that the PCR reaction is optimized as the absence of the specific primer band (normal or mutant), and is diagnostic.

Molecular genetics in haematology

Molecular genetics in immunology

The place of molecular genetics in diagnosis and management

Pharmacogenomics

2.7 Point of care testing

Mini-analysers

Micro-analysers

The advantages of POCT

Table 2.1 Examples of POCT applications.

The disadvantages of POCT

Regulations and guidelines on POCT

2.8 Health and safety in the laboratory

Table 2.2 Laboratory hazards.

The Health and Safety at Work Act

Duties of employers

Duties of employees

The Control of Substances Hazardous to Health (COSHH)

Figure 2.18 Identification of hazards. All laboratory hazards must be identified. As far as chemicals are concerned, this can be marked on the labels. These include skull and crossbones with ‘toxic’ label on the left, the smaller orange marks on the label of the containers in the middle, and the diamonds on the propylene squeezy bottle on the right.

Summary

Further reading

Web sites

3 The Physiology of the Red Blood Cell

Learning objectives

3.1 Introduction

Table 3.1 Red cell aspects of the full blood count and allied tests.a

3.2 The development of blood cells

Bone marrow architecture and cellularity

Models of differentiation

Figure 3.1 Haemopoiesis. The pluripotent stem cell gives rise to two colony forming units (CFUs: myeloid and lymphoid) that in turn produce lineage-specific stems cells. These ultimately produce mature cells that leave the bone marrow and enter the blood.

Growth factors

Bone marrow sampling and analysis

Figure 3.2 Top: A bone marrow aspirate spread on to a glass slide, dried, and stained as if a sample of peripheral blood. Middle: A trephine sample that retains the architecture of the bone marrow. Lower: For comparison, a sample of peripheral blood at the same low power magnification. Note the markedly fewer number of white cells in the latter.

Special investigations

Cytochemistry

Table 3.2 Commonly used CD markers.a

Flow cytometry

Blood science angle: Flow cytometry

3.3 Erythropoiesis

Figure 3.3 Erythropoiesis. Stages in the development of the red cell in the bone marrow. Early stages involve the derivation of the lineage-specific CFU for myeloid cells, which develop into proerythroblasts and erythroblasts under the influence of erythropoietin. The nucleated red blood cell loses its nucleus to become a reticulocyte, and then the mature red cell.

Blood science angle: Erythropoietin

3.4 The red cell membrane

Table 3.3 Glycoprotein components of the red cell membrane.

The organization of the membrane

Figure 3.4 The red blood cell membrane. Our current view of the red cell membrane can be explained in this cartoon. The ankyrin complex (left) includes transmembrane molecules Band 3 and GpA that span the lipid bilayer. The intracytoplasmic tails link to ankyrin and protein 4.2, and thus the internal cytoskeletom on alpha and beta spectrins. The 4.2 complex (right) also include Band 3, but also GpC. These molecules link to protein 4.1 and tropomyosin and also the spectrins. Not shown for clarity are molecules such as Duffy and Kell.

Cluster 1

Cluster 2

The cytoskeleton and cell volume

Consequences of membrane specialization

Blood science angle: Blood groups

3.5 The cytoplasm of the red cell

Haemoglobin

Haem

Figure 3.5 Major steps involved in the synthesis of haem in cells such as the erythroblast and nucleated red cell. On the left, within the mitochondrion, glycine and succinyl-coA form aminolevulinic acid, which leaves the mitochondrion and is converted into porphobilinogen, four of which form uroporphyrinogen. The latter enters the mitochondrion, and the enzyme ferrochelatase inserts iron, forming haem.

Blood science angle: Micronutrients

Iron

Table 3.4 Iron requirements.

Figure 3.6 Regulation of iron uptake, and its fate. Iron in the diet (1) passes through the enterocyte and is carried in the blood by transferrin (2). In the erythroblast in the bone marrow it is incorporated into haemoglobin (3); in other cells such as the hepatocyte or macrophage, it is stored in ferritin and haemosiderin (3). Tfr: transferrin receptor.

Blood science angle: Iron genetics

Vitamins

Globin

Embryonic and foetal haemoglobin

Adult haemoglobin

Table 3.5 Globin chains in haemoglobin variants.

Figure 3.7 Haemoglobin (Hb) development. Changes in species of Hb in different stages of development in the embryo (weeks 0–10) where zeta, epsilon and alpha globin molecules are synthesized. As the embryo grows into the foetus the zeta and epsilon chains give way to gamma globin, whilst close to birth the beta globin molecules take over from gamma globin. From perhaps 30 weeks, delta globin genes are active. The gamma globin genes slowly shut down so that after 30 or 40 weeks of age only a trace remains, the dominant molecules alpha and beta chains that form HbA.

Other haemoglobin species

Red cell enzymes and metabolism

Figure 3.8 Red cell metabolic pathways. The major pathway for the anaerobic generation of energy (in the form of adenosine triphosphate (ATP), nicotinamide adenine dinucleotide phosphate (NADH) and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH)) is the Embden–Meyerhof glycolytic pathway (central spine). See text for details.

Generating energy

Protection from oxygen

Clinical aspects of metabolism

3.6 Oxygen transport

Figure 3.9 The oxygen saturation curve. The normal relationship between the partial pressure of oxygen in the blood and the degree to which haemoglobin is saturated with oxygen is given by the solid line. It is convenient to refer to the degree of oxygen saturation where 50% of the haemoglobin is saturated (i.e. the P50, where in theory each molecule of haemoglobin carries two molecules of oxygen from a maximum of four molecules). This equates to a partial pressure of oxygen pO2 of approximately 26.8 mmHg.

Blood science angle: Blood gases

Factors influencing oxygen metabolism

Table 3.6 Factors influencing the oxygen dissociation curve.

3.7 Recycling the red cell

Figure 3.10 Red cell recycling. When the red cell comes to the end of its life, it is broken up and many of its components are recycled. An exception to this is bilirubin, which is excreted.

Blood science angle: Jaundice

3.8 Red cell indices in the full blood count

Figure 3.11 The RDW. Although both histograms show a roughly symmetrical distribution, values of the MCV in the normal (upper plot) vary from about 60 to 115, giving a mean of 84.9 and a standard deviation of 9.15, so that the RDW is (9.15/84.9) × 100 = 10.8%. Note that in the lower (abnormal) plot, although the mean MCV is a little higher, 86.7, the spread of results is much greater, ranging from 30 to 150, giving a larger standard deviation of 14.99. Hence, the RDW in the lower plot is 17.3%, outside the reference range of 10.3–15.3%.

Figure 3.12 The ESR. A series of eight ESR tubes, showing a column of cloudy plasma above the column of red cells. Clearly, there is variation in the level of the red cells. In numbers 1–3 and 7 the plasma is less than 10 mm, so the result is normal. In columns 5, 6 and 8 the column of plasma is much greater, being in the region of 70 mm, 80 mm and 105 mm respectively. All these are abnormal. However, in sample 4, the cutoff is not as clear cut, but many would report a result of 30 mm.

3.9 Morphology of the red cell

Figure 3.13 Normal red cells with a roughly uniform size and shape. Almost all of them have a small area of pallor right in the centre.

Figure 3.14 Anisocytosis. This photograph shows variety in the size of the cell; unlike Figure 3.15, there is a great variety in the size of the cells – some are clearly much larger than others; there are both macrocytes and microcytes. Many of the large cells are fully coloured, whereas many of the small cells are coloured only around the outside, with lack of staining in the middle. These small cells may therefore be hypochromic as well as microcytic.

Anisocytosis

Figure 3.15 Reticulocytes. This high-magnification photograph is dominated by two reticulocytes (arrowed). They have a more ‘blue’ colour than the other red cells.

Figure 3.16 The effect of storage. Samples taken into ethylenediaminetetraacetic acid and stored incorrectly or too long will undergo changes resulting in crenation (with lots of ‘spikes’) of the red cells and deterioration of the white cells.

Figure 3.17 The effect of poor fixation. Poor drying and fixation results in trapped water within the cells and poor morphology.

Macrocytes

Microcytes

Variation in colour

Other morphological changes

Inclusion bodies

Summary

Further reading

4 The Pathology of the Red Blood Cell

Learning objectives

4.1 Introduction: diseases of red cells

Table 4.1 The diverse aetiology of red cell pathology.

Anaemia

Definitions of anaemia

Table 4.2 Signs and symptoms of anaemia.a

A young woman with sickle cell disease

Classifications of anaemia

The size of the red cell

Symptoms

Haemolysis

Aetiology

4.2 Anaemia resulting from attack on, or stress to, the bone marrow

Reduction in red cells alone

Reduction in red cells and platelets

Reduction in all blood cells

Disease arising from the bone marrow itself

Disease caused by factors originating outside the bone marrow

Treatment of an anaemia resulting from disease of the bone marrow

The role of the laboratory in anaemia following bone marrow changes

Table 4.3 The bone marrow and anaemia.

4.3 Anaemia due to deficiency

Iron

Blood science angle: The liver

Figure 4.1 Perls' stain. This process stains iron a blue colour, as illustrated in these two samples of bone marrow: (a) complete lack of blue colour, is from a patient with profound iron deficiency; (b) from a subject with normal iron stores.

Vitamins B12, B6 and folate

The role of the laboratory in anaemia following lack of micronutrients

Microcytic anaemia

Figure 4.2 Marked microcytic anaemia, in this case due to gross iron deficiency. Almost all of the cells are ‘empty’ of colour, and so of haemoglobin, and almost all are microcytic. Compared with Figure 3.2 and Figure 3.13.

Macrocytic anaemia

Figure 4.3 Macrocytic anaemia. These red cells are much larger than those of Figure 4.2, and are also much more heavily stained, and so have more haemoglobin. This macrocytosis is due to deficiency in vitamin B12; an additional factor is the increased number of segments of the nucleus of the neutrophil, the so-called hypersegmented neutrophil, an example of which is shown in this figure. There is also a moderate degree of anisocytosis (variation in the sizes of the red cells).

Blood science angle: Immunology

Table 4.4 Deficiency of iron and vitamin B12.

Iron and vitamin B12 compared and contrasted

Endocrine disorders

4.4 Intrinsic defects in the red cell

Defects in iron metabolism

Defective synthesis of haem

Figure 4.4 Ring sideroblast. Perls' stain is also used to define a sideroblast, which in this figure has a large (blue) deposit in the cytoplasm, but there are also some deposits in the nucleus. Ring sideroblasts can be found in sideroblastic anaemia and lead poisoning.

Iron overload

The role of the laboratory in iron-related pathology

Figure 4.5 Basophilic stippling. These inclusion bodies, consisting of over a dozen very small blue or purple dots, can be very hard to detect. Notably, the red cell in which they occur is often larger than other cells.

Blood science angle: Micronutrients

Membrane defects

Hereditary spherocytosis

Hereditary elliptocytosis

Figure 4.6 Hereditary spherocytosis. This is manifest as cells which have lost their central pallor. There is also a modest degree of anisocytosis. The bar represents 10 μm.

Figure 4.7 Hereditary elliptocytosis. Few cells have retained their circular shape, the remainder varying from being slightly oval to grossly elliptical. The bar represents 10 μm.

Hereditary stomatocytosis

Paroxysmal nocturnal haemoglobinuria

Figure 4.8 Hereditary stomatocytosis. This condition is characterized by a slot-shaped area of central pallor, although smaller cells have retained their normal round area of central pallor. The bar represents 10 μm.

The laboratory in membrane defects

Other membrane defects

Figure 4.9 Paroxysmal nocturnal haemoglobinuria. This flow cytometry plot is the result of mixing red cells with one antibody to CD55 and another to CD59, both linked to different fluorescent probes (phycoerythrin and fluorescein isothiocyanate respectively). The machine counts the number of cells binding both antibodies (in the upper right (UR) quadrant), either antibody alone (upper left (UL) and lower right (LR)), or neither antibody (lower left (LL)). In health, all cells would express both CD55 and CD59, and so bind the antibodies, so that the UR quadrant should have almost 100% of the events. However, only 26.34% of the cells express neither CD55 nor CD59, making the diagnosis of PNH.

The RDW and membrane defects

Metabolic defects

G6PD deficiency

Pyruvate kinase deficiency

Table 4.5 Defects in the membrane and in enzymes.

Haemoglobinopathy

Sickle cell anaemia

Figure 4.10 The sickle cells are evident. Also present are a nucleated red blood cell and what is likely to be an extruded nucleus. There are also some target cells, so this may be from a patient with a mixed haemoglobinopathy.

Other qualitative beta globin gene disorders

Thalassaemia

Compound and other haemoglobinopathy

Laboratory definition of haemoglobinopathy

Table 4.6 Molecular genetics of the haemoglobinopathies.

Figure 4.11 A wet preparation of whole blood from a patient with sickle cell disease that has been incubated with a buffer to induce hypoxia, and this has resulted in many red cells adopting the sickle shape.

Figure 4.12 The solubility test. (a) Incubation of red cells in a lysing buffer will indicate those samples likely to come from a patient with sickle cell disease. Of the three tubes, that on the left is the negative control – the black line can easily be seen through the lysed cells. On the right is the positive control – the red cells have not been lysed and so the black line is almost completely obscured. In the middle is the test patient's sample, which clearly gives the same picture as the positive control, thus supporting the diagnosis of sickle cell disease. (b) After centrifugation, a positive result gives a dark red band at the top of clear plasma (middle and right tubes), whereas a negative result is a red column (left tube).

Figure 4.13 Electrophoresis. (a) At alkaline pH (8.5) together with a commercial control (AFSC) at lane 1. Haemoglobin is a negatively charged protein at alkaline pH and will migrate towards the anode (+) in an electrical field. According to their electrical charges, different Hb variants will separate into different bands. Hb variants can then be identified and compared with known control bands. The results from different patients were as follows: lane 1, AFSC control; lane 2, AS; lane 3, SS + F; lane 4, AC (or A/O-Arab, or A/E); lane 5, SC (or S/O-ARAB, or S/E); lane 6, A; lane 7, SC (or S/O-ARAB or S/E); lane 8, AC (or A/O-Arab or A/E). (b) Haemoglobin electrophoresis results on citrate agar at acidic pH (6.0) together with a commercial control (FASC). The corresponding mobility for the same patients at alkaline pH (8.5) were (from left to right) as follows: lane 1 AC; lane 2, SC + F; lane 3, AS; lane 4, AC; lane 5, A; lane 6, SC + F; lane 7, SS; lane 8, AS + F; lane 9, FASC control.

Laboratory findings in haemoglobinopathy

Figure 4.14 HPLC for different haemoglobin species. (a) Normal HPLC scan showing the major peaks of HbA (83.2%) and minor peaks (in red) of HbA2 (2.6%) and HbF (2.2%). (b) The major peak in the middle of the plot, at the HbA position, makes up only 49.3% of total haemoglobin. Note the new large peak to the right, making up 35.2% of all the haemoglobin, and this is HbS. Minor peaks are HbA2 (3.8%) and HbF (1.0%).

Figure 4.15 Gene analysis by polymerase chain reaction (PCR). BSu 36 I is a restriction enzyme with known restriction sites on the beta globin gene. In sickle cell disease some of these restriction sites disappear and therefore the enzyme cannot digest DNA from PCR products. Accordingly, larger PCR products can be viewed by electrophoresis in sickle cell disease (SS) compared with smaller (digested) bands in normal conditions. In heterozygous conditions (AS) both bands can be seen. Lane 1 is molecular marker, lanes 2 and 3 patient 1 (normal (N) and mutant (M) primers respectively), lanes 4 and 5 patient 2 (normal and mutant), lanes 6 and 7 patient 3 (normal and mutant primers), lane 8 is blank, the arrow points out the DNA variants.

Figure 4.16 Schistocytes. This figure is from a patient with hereditary pyropoikilocytosis, which leads to a haemolytic anaemia. There are numerous examples of damaged cells and also fragments. However, there are also spherocytes, the cells that are very darkly stained.

Figure 4.17 Target cells. There are many target cells present, but also microspherocytes, schistocytes, elliptocytes and a nucleated red blood cell. Consequently, the patient will have a complex and severe haemolytic anaemia.

Figure 4.18 Howell–Jolly bodies. These are small but distinct purple bodies inside six red cells composed of fragments of nuclear material, often found after splenectomy or splenic disease. There are also two white cells (a neutrophil and a lymphocyte).

Blood science angle: Thalassaemia

Clinical aspects

Prenatal diagnosis and prevention of haemoglobinopathy

4.5 External factors acting on healthy cells

Antibodies

Autoimmune haemolytic anaemias

Alloimmune haemolytic anaemia

The role of the laboratory in antibody-mediated haemolysis

Blood science angle: Antibodies

Physical damage

Drug-induced haemolytic anaemia

Infections

Figure 4.19 Malaria. A marked infection of the ring-form trophozoites of Plasmodium falciparum. Perhaps 20–25% of cells are carrying a parasite.

Haemorrhage

Other ‘external’ causes of anaemia

The anaemia of chronic diseases

4.6 Erythrocytosis and polycythaemia

Erythrocytosis

Pathology

The laboratory in erythrocytosis

Management of erythrocytosis

Chuvash polycythaemia

Polycythaemia

Pathology

The laboratory in polycythaemia

Blood science angle: Polycythaemia and erythrocytosis

Management

Table 4.7 Erythrocytosis and polycythaemia.

4.7 Molecular genetics and red cell disease

Table 4.8 Examples of molecular genetics in red cell pathology.

4.8 Inclusion bodies

4.9 Case studies

Case study 1

Discussion

Figure 4.20 Blood film for case study 1.

Case study 2

Figure 4.21 Blood film for case study 2.

Discussion

Summary

References

Further reading

5 White Blood Cells in Health and Disease

Learning objectives

5.1 Introduction

Table 5.1 Meaning of common terms.

CD molecules

Table 5.2 A white cell differential.

5.2 Leukopoiesis

Table 5.3 Selected leukocyte CD molecules

Lymphopoiesis

T lymphocytes (or T cells)

Figure 5.1 Lymphopoiesis. The process of the development of mature lymphocytes begins in the bone marrow. T lymphocytes must pass through the thymus to become fully functional, but the site of the transformation of pre-B lymphocytes into mature B lymphocytes is unknown.

B lymphocytes (or B cells)

Natural killer cells (NK cells)

Myelopoiesis

Monopoiesis

Granulocytopoiesis

Figure 5.2 Myelopoiesis. This process gives rise to red blood cells and platelets, as well as monocytes and granulocytes. As with lymphopoiesis, the key cell is the CFU, which generates the three granulocyte lineages, and the monocyte/macrophage lineage.

Granules

The role of growth factors

Blasts and malignancy

5.3 Neutrophils

Identification

Figure 5.3 Three neutrophils. Note the different number and layout of the three or four purple-stained lobes. The fine structure of the cytoplasm is not smooth but irregular, due to the presence of granules.

Function

5.4 Lymphocytes

Identification

Figure 5.4 The single lymphocyte is characterized by a single, roughly circular (purple) nucleus. Compare the fine details of the cytoplasm (which lacks granules) with the grainy nature of the cytoplasm on neutrophils.

Figure 5.5 Different lymphocyte groups can be enumerated by the presence of particular CD molecules. This example uses monoclonal antibodies to CD3 and CD19, both linked to different fluorochromes (Pac B and PC 5.5 respectively). Cells binding CD3, but not CD19 are defined as T cells (lower right quadrant), those binding CD19 but not CD3 (upper left quadrant) and B cells, whilst those binding neither antibodies are NK cells (lower left quadrant). There are almost no cells binding both antibodies (upper right quadrant).

Function

5.5 Monocytes

Figure 5.6 A monocyte. There are two cells in this figure; the monocyte is the upper cell. Note that about two-thirds to three-quarters of the cell is taken up by the purple nucleus, which has an indent. Contrast this with the lower cell, which is a three-lobed neutrophil.

Identification

Functions

5.6 Eosinophils

Identification

Figure 5.7 An eosinophil. The key features are a bilobed nucleus, and a cytoplasm dominated by reddish granules.

Function

5.7 Basophils

Identification

Figure 5.8 A basophil. The key features are a bilobed nucleus and a cytoplasm dominated by blue–black–purple granules. However, the granules may be so large and numerous that the nucleus becomes obscured.

Function

Blood science angle: Leukocyte physiology

5.8 Leukocytes in action

Inflammation

Recruitment of cells

Contact of cells with pathogens

Phagocytosis

Figure 5.9 Phagocytosis. (a) A monocyte (with its characteristic horseshoe-shaped nucleus) close by a colony of bacteria. The latter have strongly taken up a blue dye. (b) A monocyte that has ingested over a dozen bacteria it has absorbed by the process of phagocytosis. It is tempting to speculate that the bacteria are coated with antibodies and complement opsonins to increase the efficiency of this process.

Acute inflammation

Chronic inflammation

Table 5.4 Location and function of selected lymph nodes.

Immunity

Lymph nodes

Figure 5.10 Anatomy of the activated lymph node. Lymphatic vessels carry lymph fluid (possibly loaded with pathogens and cytokines) from the tissues to the lymph node. A germinal centre is primarily the focus of the activity of T helper cells and antigen-presenting cells in promoting antibody production. Each node is fed by an arterial blood vessel, whilst vein carries effluent blood back to the circulation. A lymphatic vessel may carry cells and lymph fluid to the next node in the chain.

B lymphocytes

Figure 5.11 Basic structure of an antibody molecule. Two heavy chains and two light chains come together to form a Y shaped molecule that binds antigens with its Fab sections. The other end of the molecule (the Fc section) has the capacity to dock into special receptors on certain leukocytes. The section of the heavy and light chains that find the antigen are called the variable region – the remainder is the constant region.

Antibodies

Antibody classes

Antibody class switch

Receptors for antibodies

T lymphocytes

Figure 5.12 Structure of major antibody classes. The standard ‘Y’-shaped molecule is the prototype, and is typified by IgG, consisting of two heavy chains and two light chains, each with a variable region and a constant region. Two such monomers form an IgA dimer, whilst IgM is composed of five monomers, both being stabilized by J chains.

Natural killer cells in action

Antigen recognition and genetics

5.9 White cells in clinical medicine

Neutrophilia

An excessive acute inflammation

Leukaemoid reaction

Chronic inflammation

Blood science angle: The acute-phase response

Lymphocytosis

Figure 5.13 Activated lymphocytes. The increased white cell count often found in IM is due largely to activated lymphocytes, which are larger than resting lymphocytes and have more cytoplasm. This figure shows four activated and one normal lymphocyte.

Monocytosis

Eosinophilia

Allergic disease

Chronic eosinophilic leukaemia

Hypereosinophilic syndrome

Other conditions

Basophilia

Leukopenia

Neutropenia

Lymphopenia

Myelodysplasia and myelofibrosis

Table 5.5 Principal functions of white blood cells.

5.10 Case studies

Case study 3

Interpretation

Case study 4

Interpretation

Summary

Further reading

6 White Blood Cell Malignancy

Learning objectives

6.1 The genetic basis of leukocyte malignancy

Figure 6.1 Deletions, inversions and translocations. Compared with a normal chromosome (a), a deletion is characterized by a missing nucleotide, gene or larger section of DNA, leading to a shorter chromosome (b). In an inversion (c) the chromosome is of the same length but a section of DNA or part of the chromosome is reversed (d). Most translocations see sections of DNA being reciprocally transferred between different chromosomes (e1 and e2), often resulting in new hybrid chromosomes of different lengths and containing different genes (e3 and e4).

Deletions

Inversions

Translocations

What this means

Blood science angle: Cancer genetics

Genes and chromosomes

Figure 6.2 Fluorescence in-situ hybridization. Red and green fluorochromes are linked to probes for different genes. Normally, the genes binding the two probes would be on different chromosomes. However, the arrows highlight two chromosomes with both colours, thus defining a reciprocal translocation. Some of the ‘red’ gene has moved to the ‘green’ chromosomes and vice versa.

Consequences

Figure 6.3 RNA microarray analysis. The upper panel shows (red colour) binding of patient's mRNA with genes consistent with a diagnosis of acute lymphocytic leukaemia, collected on the left of the array. In the lower panel, the patient's mRNA binds to a different pattern of genes, where the red colour is dominant on the right, suggesting a diagnosis of acute myeloid leukaemia.

Clinical presentation of white cell malignancies

6.2 Tissue techniques in haemato-oncology

Peripheral blood

Figure 6.4 Use of flow cytometry to quantify the proportion of CD34-bearing blast cells (16.4%; reference range <0.5%) in acute myeloid leukaemia.

Bone marrow

Table 6.1 Bone marrow cells in health and malignancy.

The lymph node

6.3 Leukaemia

Classification

Chronic myeloid leukaemia

The Philadelphia chromosome

Cellular basis of chronic myeloid leukaemia

Treatment of chronic myeloid leukaemia

Figure 6.5 Formation of BCR–ABL. This fused gene is generated by part of chromosome 22 joining with part of chromosome 9. The fused product is a variant of a tyrosine kinase that is effectively continuously active. The consequences of this are the activation of several genes involved in cell proliferation and signalling, so that the cell continues to generate abnormal ‘daughter’ progeny – that is, leukaemic cells.

Figure 6.6 Chronic myeloid leukaemia. This film shows granulocytes at several stages of differentiation. The larger cells are promyelocytes and myelocytes; the smaller cells are metamyelocytes. Note also the degree of granulation in the cytoplasm of the different cells. On the far right is a lymphocyte, with a darker nucleus that occupies almost all of the cell.

Chronic neutrophil leukaemia

Table 6.2 Partial FAB classification of AML.

Acute myeloid leukaemia

Classification

Molecular genetics of acute myeloid leukaemia

Table 6.3 Prognosis and cytogenetic abnormality.

A wider view of acute myeloid leukaemia

Figure 6.7 A blood film in AML. This film shows four large blast cells. That of the top right has an Auer rod.

Chronic lymphocytic leukaemia

The blood film

Figure 6.8 A blood film in CLL. Note that the leukaemic cells in this film are markedly smaller than those of the AML or ALL blasts in Figure 6.7 and Figure 6.9, being only a little larger than the red cells.

Cytogenetics, prognosis and treatment

Other laboratory indices

B-cell chronic lymphocytic leukaemia

B-cell prolymphocytic leukaemia

Hairy cell leukaemia

Abnormal antibodies

T-cell and NK-cell leukaemias

Acute lymphoblastic leukaemia

Other types of leukaemia

Figure 6.9 A blood film in ALL. These blasts are clearly much larger than nearby red cells, and are also agranular, unlike the AML blasts in Figure 6.7. The presence of CD10 on these cells (as defined by flow cytometry) marks them as malignant B cells.

Figure 6.10 A blood film in chronic monocytic leukaemia. These blasts are relatively mature, with a low cytoplasm-to-nucleus ratio.

6.4 Lymphoma

The natural history of lymphoma

Aetiology and classification

Hodgkin lymphoma

Further classification

Advanced disease

Non-Hodgkin lymphoma

Classification

Burkitt's lymphoma

Lymphoplasmacytoid lymphoma

T-cell lymphomas

6.5 Myeloma and related conditions

Myeloma

The laboratory

Genetics and pathophysiology

Blood science angle: Cytogenetics of white cell malignancy

Myeloma as a systemic disease

Table 6.4 Protein subsets in health and myeloma.

Conditions allied to myeloma

Monoclonal gammopathy of undetermined significance

Amyloidosis

Hyperviscosity syndrome

Cryoglobulins

Lymphoplasmacytoid lymphoma

Blood science angle: B-cell malignancy

The paraprotein

Sub-typing the paraprotein

Light chain analysis

Figure 6.11 Immunofixation electrophoresis. Serum protein electrophoresis (SPE). On the left is the densitometer profile showing a large paraprotein peak in the gamma (γ) region. This will have been derived from the SPE trace at the top of the panel on the right. The second aspect of this analysis is the typing of the gamma-globulin band by IFE, which has produced a heavy band in the IgG and the lambda (λ) regions, thereby identifying the paraprotein as an IgGλ.

Urine analysis

Figure 6.12 Serum and urine electrophoresis. There are 12 sets of analyses. In each case the urine sample in on the left, and clearly has great deal less ‘blue’ than its paired serum sample to the right. The arrows on the left highlight the albumin band; the arrows on the right point to the gamma globulin region.

Table 6.5 Major aspects of white malignancies.

Blood science angle: Urine and serum electrophoresis

6.6 Myelofibrosis and myelodysplasia

6.7 Case studies

Case study 5

Interpretation

Figure 6.13 Blood film for case study 5. Two abnormal lymphocytes. Note the irregular border of the cytoplasm, best determined with high-magnification lenses.

Case study 6

Interpretation

Summary

Further reading

Guidelines

7 The Physiology and Pathology of Haemostasis

Learning objectives

Virchow's triad

Table 7.1 Major indices in haemostasis.

7.1 The blood vessel wall

Figure 7.1 Virchow's triad considers different roles for the blood vessel wall, blood flow and the constituents of the blood in the pathogenesis of thrombosis.

Table 7.2 Involvement of the endothelium in haemostasis.

Antithrombotics

Prothrombotics

Pathophysiology of the endothelium

7.2 Platelets

Thrombopoiesis and megakaryocytes

Figure 7.2 Thrombopoiesis. Platelets are the end cell of this process, intermediates being stem cells, and precursors the megakaryoblast and the megakaryocyte. The leading hormone promoting this process is thrombopoietin.

Platelets

Figure 7.3 Platelets in a blood film. This film shows two different white cells (each with a heavy purple nucleus), red cells (coloured pink) and platelets (several small light purple bodies, arrowed).

Table 7.3 The platelet membrane.

The platelet membrane

The platelet cytoplasm

Figure 7.4 Platelet metabolism. The primary metabolic pathway in the platelet is the generation of thromboxane via arachadonic acid and prostaglandin H2. They key enzyme in this pathway is cyclooxygenase. EC = endothelial cell.

7.3 The coagulation pathway

Coagulation factors

The coagulation pathway

Initiation

Table 7.4 Coagulation factors.

Amplification

Propagation

Figure 7.5 The coagulation pathway consists of three overlapping stages, initiation, amplification and propagation, and involves two complex super-enzymes, the tenase complex and the prothrombinase complex. These happen in close proximity to the endothelium and the platelet.

Table 7.5 Selected functions of thrombin.

Blood science angle: Anticoagulants

Inhibitors

Antithrombin

Tissue factor pathway inhibitor

Protein C system

Other inhibitors

7.4 Haemostasis as the balance between thrombus formation and removal

Activation of platelets

Thrombus formation

Figure 7.6 Platelet activation. A resting platelet undergoes shape change upon stimulation by agonists such as ADP. Further changes include the degranulation, the development of pseudopodia, and the expression of adhesion molecules and phospholipids.

Fibrinolysis

Figure 7.7 Fibrinolysis. Plasminogen is converted into plasmin by tissue plasminogen activator, itself regulated by an inhibitor. Plasmin, which can be regulated by TAFI, acts on fibrin, generating fragments called d-dimers.

The dynamics of haemostasis

Figure 7.8 The dynamics of haemostasis activation. When the forces of coagulation are balanced by those of inhibitors such as antithrombin, and of fibrinolysis, then haemostasis is in balance. However, if the coagulation is dominant then thrombosis is likely. Conversely, if inhibitors and fibrinolysis are stronger, then there is haemorrhage.

7.5 The haemostasis laboratory

Platelets

Platelet aggregation

Fluorescence flow cytometry

Platelet microparticles

Coagulation factors

Prothrombin time

Activated partial thromboplastin time

Thrombin time

Individual factor assays

Functional plasma haemostasis

7.6 The pathology of thrombosis

Loss of haemostasis

Arterial thrombosis

The risk factor hypothesis

Pathophysiology

Venous thrombosis

Risk factors

Table 7.6 Pathophysiology of arterial and venous thrombosis.

Pathophysiology

Contrasting arterial and venous thrombosis

Blood science angle: Inflammation and haemostasis

Summary

Further reading

8 The Diagnosis and Management of Disorders of Haemostasis

Learning objectives

8.1 Thrombosis 1: overactive platelets and thrombocytosis

Pathophysiology

Table 8.1 An overview of major aspects of thrombosis and haemorrhage.

Qualitative disease

Quantitative disease: thrombocytosis

Figure 8.1 The blood film in ET. This blood film shows a remarkably high platelet count, but also an eosinophil (on the left) and a monocyte (to the lower right). There is also a great variation in the size of the platelets (anisocytosis), suggestive of a malignancy, However, before a diagnosis of ET is made, causes of reactive thrombocytosis (e.g. infection, following surgery, post-splenectomy, inflammation, chronic blood loss), chronic myeloid leukaemia, PRV and idiopathic myelofibrosis should be excluded.

Assessment

Treatment

Metabolic inhibitors

Figure 8.2 Inhibition of platelet function. Platelets may be activated by the occupancy of various receptors (such as the ADP receptor and GpIIb/IIIa) by their particular ligands (ADP and fibrinogen respectively). This leads to the activation of the cyclooxygenase pathway, which in turn initiates platelet shape change, degranulation (releasing ADP, thromboxane and other mediators) and other features that result in the promotion of thrombosis. This includes binding to other platelets (linked by fibrinogen and vWf) and to the subendothelium (via endothelial-derived vWf, collagen, GpVI and GpI//IX/V).

Adenosine diphosphate receptor blockage

Preventing platelet–platelet interactions

Table 8.2 Mechanism for suppressing platelet function.

Other agents

8.2 Thrombosis 2: overactive coagulation

Pathophysiology

Increased coagulation factors

Lack of inhibition

Table 8.3 Stratification of the risk factor for VTE.

Thrombophilia

Table 8.4 Increase in the risk of VTE with multiple risk factors.

Blood science angle: Risk factors for VTE

Race

Assessment

Figure 8.3 The risk of a VTE is the sum of individual factors. Suppose that each factor has a particular numerical number: some factors are acquired, others natural. In this model, a score exceeding 15 arbitrary units puts the individual at high risk of a DVT or PE. This may be achieved by a combination of any factors: age 50 plus antithrombin deficiency (12 points plus 5 points equals 17 points) does, whereas age 30 plus hormone replacement therapy (HRT) or oral contraceptive pill (OCP; 3 points plus 9 points equals 12 points) does not. However, this simple model predicts that adding another 40 years (and so 4 points) at age 70 may well precipitate a thrombosis.

Inhibitors

Factor V Leiden and the prothrombin G20210A mutation

Antiphospholipid syndrome

Problems and pitfalls in antiphospholipid syndrome and lupus anticoagulant testing

Testing for thrombophilia

Treatment

Warfarin

The drug

Laboratory management of warfarin

Pros and cons of warfarin

Table 8.5 Target INRs and recommended duration of anticoagulation.

Table 8.6 Patient factors that influence the efficacy of warfarin.

Patient power – warfarin

Heparin

The drug

Blood science angle: Molecular genetics of antithrombotics and anticoagulants

Laboratory management of heparin

Pros and cons of heparin

Low molecular weight heparin

The drug

Laboratory management of low molecular weight heparin

Table 8.7 Differences between low molecular weight heparin (LMWH) and UFH.

Table 8.8 Risk factors for VTE for patients about to go on LMWH.

Table 8.9 Additional risk factors for surgical in-patients.

Table 8.10 Application of risk assessment for the use of LMWH.

Important point

Pros and cons of low molecular weight heparin

Patient power – low molecular weight heparin

Use of LMWHs

Fondaparinux (Arixtra)

Heparinoids, hirudins and other agents

New oral anticoagulants

Direct thrombin inhibition

Factor Xa inhibition

An ideal antithrombotic drug

8.3 Haemorrhage 1: platelet underactivity and thrombocytopenia

Table 8.11 Features of common anticoagulants.

Pathophysiology

The bone marrow

Intrinsic platelet defects

Destruction of platelets

Heparin-induced thrombocytopaenia

Assessment

Figure 8.4 A blood film showing microthrombi. To the left and right of the upper leukocyte (a neutrophil) are two microthrombi. The blood scientist needs to ask if these are genuine clots formed in the body by some pathogenic process (such as an autoantibody), or if they have formed in the vacutainer after the blood has been drawn (and so are an artefact of failed anticoagulation).

Flow cytometry

Table 8.12 Platelet CD molecules commonly used in flow cytometry.

Platelet aggregation

Figure 8.5 Light transmission aggregometry. (upper panel) Changes in light transmission (vertical axis) over 8 min (horizontal axis) when ADP (trace 1), epinephrine (2), collagen (3) and ristocetin (4) are added to platelet-rich plasma. After 4 min, the light transmission to all agonists is greater than 80% of a sample of the subject's platelet-free plasma, indicating the formation of thrombi. (lower panel) Changes in the response of platelet-rich plasma from a 15-year old female whose only symptom was prolonged bleeding from the gums. There were no abnormalities in her coagulation pathway. The aggregation plot shows a normal response to ristocetin (trace 4) of over 90% at 4 min. However, ADP, epinephrine and collagen (traces 1–3, the continuous lines at the top of the printout) have failed to induce any platelet aggregation. This profile supports the diagnosis of Glanzmann's thrombasthenia: the molecular lesion is lack of functioning GpIIb/IIIa.

Thromboelastography

The platelet function analyser (PFA-100)

Other tests of platelet function

Platelet function and near-patient testing

Treatment

8.4 Haemorrhage 2: coagulation underactivity

Pathophysiology of primary defects

Insufficient factor VIII

Insufficient von Willebrand factor

Insufficient factor IX

Deficiencies in other factors

Pathophysiology of secondary defects

Assessment

General screening tests

Factor-specific assays

Measurement of von Willebrand factor

Treatment

Treatment of primary deficiency

Figure 8.6 vWf multimer analysis. The plasma sample loaded onto the top of an SDS agarose gel, and staining of the resultant electrophoresis plot reveals a series of bands that equate to vWf of different sizes. The topmost are the high molecular weight species that fail to enter the gel, or fail to penetrate very far. Small multimers penetrate further, the smallest being at the bottom. The mass of each band can be estimated by densitometry.

Treatment of secondary deficiency

Table 8.13 Action in response to a high INR in an outpatient.

Table 8.14 Action in response to a high INR in an inpatient.

Tranexamic acid

8.5 Disseminated intravascular coagulation

Pathophysiology

Assessment

Treatment

Blood science angle: DIC

8.6 Molecular genetics in haemostasis

Coagulation factors

Platelets

Broader value of molecular genetics

Confirming diagnosis

8.7 Case studies

Case study 7

Interpretation and plan

Case study 8

Summary

References

Further reading

Guidelines

Web sites

9 Immunopathology

Cognosce te ipsum: Know thyself

Learning objectives

9.1 Introduction

Pathogens

Immunopathology

9.2 Basics of the immune system

Table 9.1 Principal physiological functions of white blood cells.

The anatomy of the immune system

Inflammation

The acute-phase response

Immunity

9.3 Humoral immunity

Antibodies

Figure 9.1 Simplified structure of an immunoglobulin molecule.

Complement

Table 9.2 Complement components.

Complement pathways

The regulation of complement

Blood science angle: Complement, coagulation and blood transfusion

Figure 9.2 The complement pathway consists of three initial pathways that come together to form different types of C3 convertase. The products of this enzyme, C3a and C3b, go on to have other functions – the former as an inflammatory mediator and the latter as the generator of C5a (another inflammatory mediator) and C5b, the latter coming together with C6–C9 to form the membrane attack complex. MBL = mannose binding lectin, MASP2 = MBL-associated serine protease-2.

Cooperation

9.4 Immunopathology 1: immunodeficiency

Quantitative deficiency in white cells

Bone marrow suppression

Genetic causes of neutropenia

Human immunodeficiency virus-1

DiGeorge syndrome

Severe combined immunodeficiency

Qualitative defects in white cells

Chronic granulomatous disease

Blood science angle: Leukopenia

Other neutrophil defects

Other white cell defects

Clinical aspects of defective cell-mediated immunity

Blood science angle: HIV/AIDS

Leukocyte malignancy

Defects in humoral immunity

Antibodies

Complement

Clinical aspects of defective humoral immunity

Table 9.3 Immunodeficiency.

9.5 Immunopathology 2: hypersensitivity

Type I hypersensitivity

Figure 9.3 Cellular basis of type I hypersensitivity. The basis of this process is the sensitization of resting mast cells and basophils by IgE, that itself then binds to the allergen. Cell degranulation releases inflammatory mediators (such as histamine and tryptase) that act on other cells such as smooth muscle cells and endothelial cells to produce the clinical symptoms such as respiratory distress and itching.

Table 9.4 Common allergens.

Type II hypersensitivity

Type III hypersensitivity

Figure 9.4 Cellular basis of type II hypersensitivity. There are two possible routes: resting cells may become sensitized by the location of IgG into their FcR. The leukocyte may then attack target cells that bear antigens specific for the particular antibody. Alternatively, a leukocyte may directly recognize the FcR of antibodies already bound to a target cell.

Figure 9.5 Cellular basis of type III hypersensitivity. Antibodies and antigens come together to form soluble or insoluble immune complexes which can bind nonspecifically to innocent cells and tissues. These bound complexes then attract the attention of leukocytes, which proceed to attack the underlying tissues and initiate a local inflammatory response.

Type IV hypersensitivity

9.6 Immunopathology 3: autoimmune disease

Connective tissue disease

Rheumatoid arthritis

Osteoarthritis

Figure 9.6 Synovial joint destruction in RA. The affected joint in RA exhibits a number of abnormalities. These include eroded bone and a reduced synovial space (detected by X-ray) and collagen, the presence of leukocytes and inflammatory mediators in the synovial fluid (detected by aspiration of the turbid fluid, and then biochemistry and microscopy), and swollen synovial tissues which have become infiltrated by leukocytes (as detected by histological examination of a biopsy).

Systemic lupus erythematosus

Sclerodema

Other inflammatory connective tissue disease

Table 9.5 Major inflammatory connective tissue diseases.

Blood science angle: Autoimmune connective tissue disease

Organ-specific disease

The endocrine system

The kidney

The liver

The intestines

Table 9.6 Other autoimmune diseases.

The spectrum of autoimmune disease

Blood science angle: The haematologist and autoimmunity

The complex nature of autoantibodies

Table 9.7 Extractable nuclear antigens.

Blood science angle: Autoimmune disease and leukaemia

9.7 Immunotherapy

Therapeutic antibodies

Haemolytic disease of the newborn

Polyclonal antibodies

Monoclonal antibodies

Vaccination

Cancer

Allergy desensitisation

9.8 The immunology laboratory

Cellular immunology

Neutrophils

Lymphocytes

Serology

Immunoglobulins

Laboratory assessment of complement

Table 9.8 Commonly requested autoantibodies.

Table 9.9 Levels of immunoglobulins.

Allergy testing

Clinical testing

Table 9.10 Defined protein analyses.

Immunoglobulin E

Leukocyte testing

Products of degranulation

The reference laboratory

9.9 Case studies

Case study 9

Interpretation

Flow cytometry

Case study 10

Figure 9.7 Flow cytometry of CD4 and CD8 subsets. The typical four-quadrant result showing 1075 events staining above background for CD8 in the upper left quadrant and 1285 events staining for CD4 in the lower right quadrant. These translate to a CD4/CD8 ratio of 1.2.

Interpretation

Summary

References

Further reading

Guidelines

Web sites

10 Immunogenetics and Histocompatibility

Cognosce te ipsum etiam meliores: Know thyself even better

Learning objectives

10.1 The genetics of antigen recognition

B lymphocyte responses to antigens

The B cell receptor

The genetics of antibody variability

T lymphocyte responses to antigens

Figure 10.1 Recombination of immunoglobulin genes. The variability in antibody responses resides in the combined variable regions of heavy and light chains that form the Fab. The VDJ recombinase enzyme selects a J region gene, a D region gene and any one of several variable region genes to form a single combined VDJ-constant gene. This is the template for the RNA polymerase, which generates messenger RNA and ultimately the production of the protein chain by the ribosomes. The inclusion of a membrane region gene traffics the molecule to the cell membrane; without this section it will be exported into the plasma as an antibody molecule.

The diversity of antigen recognition

Figure 10.2 Recombination of TcR genes. The antigen recognition site of the TcR is composed of two molecules: an alpha–beta dimer or a gamma–delta dimer, coded for by genes on different chromosomes. Like immunoglobulin genes, the recombination of germ-line V, D and J genes generates a new gene that in turn provides the protein.

Figure 10.3 The TcR and BcR. The TcR is composed of an alpha–beta dimer or a gamma–delta dimer, and a complex of five molecules that make up CD3. The BcR consists of an immunoglobulin molecule and two CD79 molecules.

Antigen-presenting cells

10.2 Human leukocyte antigens

Class I molecules

Figure 10.4 The structure of HLA molecules. HLA molecules bear similarities to immunoglobulins, with their globular domain structure. Class I molecules have three domains; each of the two class II molecules (alpha and beta) have two domains. A single-domain-sized molecule of beta-2-microglobulin is associated with the class I molecule. The variation in antigen binding resides in the terminal domains in a manner similar to that of the Fab of antibodies. In class I molecules, the antigen binding site is a groove between domains 1 and 2; in class II molecules, it is formed by the terminal domains of each chain.

Class II molecules

Class III molecules

Figure 10.5 The layout of HLA genes. The HLA genes are arranged in a sequence on chromosome 6 and span some 3600 kilobases. From the 3′ end these are the three class I genes, the class III genes and the three class II gene loci. Between these genes and the centromere is the gene for glyoxylase (GLO).

The generation of antibodies

Table 10.1 Molecular recognition systems between antigen presenting cells and T helper lymphocytes.

Other forms of antigen recognition

The B-cell co-receptor

Natural killer cells

Figure 10.6 T–B interactions generating antibodies. A summary of the interactions between an antigen-presenting cell and a T helper lymphocyte, which receives the antigenic peptide via its TcR. The T cell in turn presents the antigen to the BcR of the ‘early’ B lymphocyte. This is effectively the ‘go’ signal for the B cell to transform into a plasma cell, and so generate antibodies specific for the presented antigen.

CD1

The generation of cytotoxic T lymphocytes

Figure 10.7 The B-cell co-receptor. B-cells may be activated by the co-recognition of bacterial antigens by the BcR, and by C3d on the surface of the bacteria by CD21.

Figure 10.8 T cell–antigen-presenting cell interaction. An antigen-presenting cell and a naive T cell interact with HLA class I molecules and the TcR. The T cell CD8 molecule provides assurance that the presenting cell is self. The CD3 complex activates its zeta molecules, which initiates the final maturation of the cell and its clonal proliferation. The resultant cytotoxic T lymphocytes recognize and kill those cells presenting peptide and self-HLA class I molecules, which are therefore altered self.

10.3 Transplantation

Polymorphisms in human leukocyte antigen molecules

Human leukocyte antigen typing

Serological typing

Gene typing

Antibodies to human leukocyte antigen molecules

References

The practicalities of transplantation

Figure 10.9 Inheritance of HLA types. Each individual inherits one HLA haplotype from their mother and a second from their father. In this very simplified example, showing only three HLA loci, sibling A, on the left, requires a transplant. Sibling B, in the middle, has inherited the same maternal haplotype, but a different paternal haplotype, so is a part match. Sibling C, on the right, has inherited a different set of haplotypes, and so is a complete mismatch. All siblings are partially matched with each parent (by definition).

Solid organ transplantation

Bone marrow transplantation

Figure 10.10 Collection of peripheral blood stem cells. The donor undergoes a modified blood transfusion donation using a cell separator. Mononuclear cells are harvested, and red cells, granulocytes and platelets are returned to the donor.

Rejection

Figure 10.11 Peripheral blood counts in bone marrow transplantation. Red cell, platelet, total white cell and neutrophil counts before (on the left) and after (the right) transplantation. Note the white cell and neutophil counts fall to zero at conditioning (use of cyclophosphamide). Red cell and platelet numbers are maintained by standard transfusions. Success of the transplanted material is aided by the use of haemopoietic growth factors, such as granulocyte-macrophage colony-stimulating factor, and the use of post-transplant ciclosporin.

Blood science angle: Transplant rejection

The ultimate transplant

Blood science angle: Is transplanation a cure for HIV infection?

10.4 Autoimmunity and human leukocyte antigens

Aetiology

Loss of tolerance

Molecular mimicry

The scope of human leukocyte antigens and autoimmune disease

Table 10.2 Autoimmune disease linked with HLA types.

Blood science angle: HLA, rheumatoid arthritis and cardiovascular disease

Summary

Further reading

Guidelines

Web sites

11 Blood Transfusion

Learning objectives

Red Book

What can be transfused?

The basis of transfusion science

Blood science angle: Blood transfusion

11.1 Blood collection and processing

The blood donor

Blood processing

Pathogen screening

Specialized processing

Blood components

Fresh frozen plasma

Cryoprecipitate

Prothrombin complex concentrate

Platelets

Granulocytes

Albumin

Blood science angle: Blood components (previously blood products)

Other blood components

11.2 Blood groups

Red cell surface molecules

Table 11.1 Major red cell surface molecules.

The ABO system

Cell surface ABO molecules

Figure 11.1 Formation of A, B and H blood group structures. The base unit is the substrate for an enzyme coded for by the H gene that adds a molecule of fucose to the terminal galactose molecule. If active, the A enzyme, coded for by the A gene, adds a molecule of N-acetyl galactosamine to the terminal galactose. If active, the enzyme encoded for by the B gene adds another molecule of galactose to the terminal galactose. Whilst most ABH molecules are linked with Band 3 molecule, they are also found elsewhere.

Antibodies

Table 11.2 ABO blood group structures and antibodies.

Table 11.3 Racial distribution of ABO groups.

The secretor phenotype

The Bombay phenotype

Subgroups of A and B

Genetics and the racial distribution of ABO groups

Implications of ABO blood group

Blood science angle: von Willebrand factor

The Rh system

Molecules of the Rh system

Genetics of the Rh system

The Rh-associated glycoprotein

Table 11.4 Common combination of genotypes of the Rh system.

Antibodies of the Rh system

Haemolytic disease of the newborn

Other blood groups

Blood science angle: Malaria

Table 11.5 Human neutrophil antigen determinants.

White cell antigens

Platelets

Clinical consequence of platelet and granulocyte incompatibility

Table 11.6 Human platelet antigen determinants.

11.3 Laboratory practice of blood transfusion

Determination of blood group

Figure 11.2 Determination of blood group in a single multi-chamber gel agglutination cuvette. Each of the eight compartments is for a separate reaction between the cells and antibody reagents present in the gel. If there is no reaction between the two, the red cells fail to agglutinate and so move to the bottom of the reaction cuvette. However, if there is a reaction, agglutinated cells remain higher up the gel in the particular column. So in this case the cells fail to react with anti-A, anti-B but do react with anti-D and so are group O, RhD positive.

Antibody screening

Cross-match/compatibility testing

Figure 11.3 Principles of a cross-match. In this cross-match, samples of red cells from four packs of blood from potential donors are mixed with plasma from the patient. In three cases, there is no agglutination, so patient lacks antibodies to molecules on cells from the donor packs, which are therefore acceptable for transfusion. However, in one case the patient's plasma has antibodies that react with one of the potential donor cell, causing agglutination, and so these cells are incompatible and cannot be transfused.

Special investigations

Antiglobulin testing

Figure 11.4 Direct antiglobulin testing. Washed cells from the patient are mixed with an antiglobulin reagent to detect antibodies on the red cells. (a) If present, antibodies will be recognized by the antiglobulin reagent, and will cross-link the cells, giving a positive result. (b) In the absence of antibodies, the antiglobulin will have nothing to cross-link, so there will be no agglutination.

The direct antiglobulin test

The indirect antiglobulin test

Figure 11.5 Indirect antiglobulin testing. In step 1, washed cells from the donor are mixed with serum or plasma from the patient. If present, antibodies will bind to the red cells and sensitize them. In step 2, the cells are mixed with an antiglobulin reagent to detect antibodies on the red cells. As in the direct antiglobulin test, the anti-human reagent will cross-link the cells, so that agglutination will mark a positive result.

Figure 11.6 Antiglobulin testing. Testing for antibodies on red cells by the antiglobulin test can proceed in the same type of plastic cuvette with gel matrix as is used for blood group determination (Figure 11.2). In samples 1 and 2, cells have been agglutinated by the antiglobulin reagent and remain at the top of the column. Unagglutinated cells pass through to the bottom of the column, as in sample 3. The reagent shown here contains antibodies that recognize both IgG and complement component C3d, which may absorb passively onto the surface of the red cell. However, cuvettes are available that detect only the binding of IgG antibodies.

Immediate spin cross-match

Electronic issue

Special cases

Blood transfusion analysers

Figure 11.7 A blood transfusion autoanalyser.

11.4 Clinical practice of blood transfusion

Indications for transfusion

Red cell concentrates

Fresh frozen plasma

Cryoprecipitate

Platelet concentrates

Alternatives to blood transfusion

11.5 Hazards of blood transfusion

The hospital

Laboratory error

Post-laboratory error

Table 11.7 Key features of TRALI and TACO.

The responses of the body to an incompatible transfusion

Pathology

Early reactions

Table 11.8 Signs and symptoms of a transfusion reaction.

Late reactions

Allergic reactions

Repercussions

Summary

References

Further reading

Guidelines

Web sites

12 Waste Products, Electrolytes and Renal Disease

Learning objectives

12.1 Renal anatomy and physiology

Table 12.1 Major renal blood tests.

The nephron

12.2 Homeostasis

Ultrafiltration

Selective reabsorption

Figure 12.1 The nephron. An afferent blood vessel brings blood to the glomerulus, where ultrafiltration takes place. Filtrate passes into the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule and the collecting duct. The close association between the nephron and blood vessels allows the transfer of substances and water in selective reabsorption, which maintains homeostasis and mediates excretion.

Local hormones

Figure 12.2 Hormonal regulation of homeostasis. AVP from the posterior pituitary, and ANP and BNP from atrial cardiomyocytes act directly on the nephron. The juxta-glomerular apparatus secretes renin, which converts angiotensinogen to angiotensin I, which in turn is transformed into angiotensin II by angiotensin-converting enzyme. Angiotensin II acts on the adrenals to synthesize and release aldosterone, which acts on the nephron.

The electrolytes

The chemistry of electrolytes

Table 12.2 Key electrolytes.

Osmolality

Concentration, mass and volume

Water

Physiology

Pathology

Diabetes insipidus (N.B. unrelated to diabetes mellitus)

Fluid balance and insensible losses

Sodium

Hypernatraemia

Conn's syndrome

Hyponatraemia

Syndrome of inappropriate antidiuretic hormone (SIADH)

Potassium

Hyperkalaemia

Addison's disease

Hypokalaemia

Drugs

Intravenous fluids

Blood science angle: Hyperkalaemia and red blood cells

12.3 Excretion

Waste products

Tests of glomerular function

Albuminuria

Creatinine clearance

Estimated glomerular filtration rate

Urate/uric acid

12.4 Renal endocrinology

Hormones in homeostasis

Erythropoietin

Blood science angle: Erythropoietin

Calcium and vitamin D

Renal efficiency

Table 12.3 Constituents of blood, filtrate and urine in health.

12.5 Renal disease

Aetiology

Pre-renal disease

True renal disease

Post-renal disease

The perspective of the patient

Figure 12.3 An anatomical classification of renal disease. We can classify renal disease as being pre-renal, true renal, or post-renal, depending on the particular aetiology. In the first it is a problem with blood entering the kidney, and the last the problem is with urine leaving the kidney. True renal disease is where the nephrons themselves are damaged.

Acute kidney injury

Chronic kidney disease

Table 12.4 Stages of CKD.

Renal stones (calculi)

Metabolic renal disease

Blood science angle: Inflammatory renal disease

The genetics of renal disease

12.6 Case studies

Case study 11

Interpretation

Case study 12

Interpretation

Summary

Further reading

Guidelines

Web sites

13 Hydrogen Ions, pH, and Acid–Base Disorders

Learning objectives

13.1 Ions and molecules

Ionisation

Table 13.1 Major tests in pH and blood gases.

Water and pH

Acids and pH

Buffers

Bicarbonate

Other buffers

13.2 Blood gases

Measurement

Figure 13.1 Gases in the air, the lungs and the blood. Partial pressures of oxygen and carbon dioxide in the air, the alveoli, arterial blood, capillary blood and venous blood. As blood passes round the circulation in a clockwise manner, it gradually loses oxygen and gains carbon dioxide.

Figure 13.2 A blood gas analyser, as is present in an accident and emergency unit. The front left-hand side has two reagent reservoirs; on the right are three reservoirs. The touch-sensitive screen allows programming. Results are printed out on a strip of paper.

Interpretation

Regulation of blood gases and pH

At the lung

At the kidney

Figure 13.3 Gas exchange at the alveolus. Carbon dioxide generated in the tissues initially forms carbonic acid, which then ionizes to bicarbonate and a hydrogen ion. The latter can be carried by haemoglobin. The constituent parts reform at the alveolar surface, and water and carbon dioxide pass into the exhaled breath.

Figure 13.4 Regulation at the nephron. A cartoon of five tubule cells and the possible biochemical pathways that may be present. The top three are cells involved in the hormone-controlled regulation of sodium and water. Potassium moves to maintain electrical balance. The lower cells show potential regulation by passive movement of ions across the cell membrane, although some may be actively pumped. Note the sodium can also move passively, but this, like the potassium movement, is also to maintain the electrical balance.

Compensation

Total CO2

Chloride (Cl−)

Blood science angle: Blood gases and haemoglobin

13.3 Acidosis (pH <7.3)

Metabolic acidosis

The anion gap

Respiratory acidosis

13.4 Alkalosis (pH >7.5)

Metabolic alkalosis

Respiratory alkalosis

13.5 Mixed acid–base conditions

Table 13.2 A summary of acidosis and alkalosis.

13.6 Clinical interpretation

Management

13.7 Case studies

Case study 13

Interpretation

Case study 14

Interpretation

Summary

Further reading

Web site

14 Glucose, Lipids and Atherosclerosis

Learning objectives

14.1 Glucose

Table 14.1 Major blood tests in the pathophysiology of atherosclerosis.

The metabolism of glucose

Insulin

Glucagon

Table 14.2 The effects of insulin and glucagon.

Somatostatin and incretin hormones

Insulin resistance and sensitivity

Impaired lipoprotein regulation

The laboratory and glycaemia

Glucose

Glycated haemoglobin

Other laboratory tests in glucose pathology

Figure 14.1 The HPLC trace of a sample of blood. The vertical axis is the percentage of all results attributable to a particular peak, and the horizontal axis is the duration of the analysis. The peak P04 at 1.88 min makes up 11.1%, and is due to glycated haemoglobin, strongly suggestive of a diagnosis of diabetes mellitus.

Hypoglycaemia

The laboratory

Pathophysiology

‘Dad's gone all funny...’

Treatment

Impaired fasting glucose

Impaired glucose tolerance

The oral glucose tolerance test

Figure 14.2 In the OGTT, blood glucose concentrations rise, and then fall as insulin mediates the passage of the sugar into cells. The continuous line represents a typical normal profile, the dotted line the profile of IGT and the dashed line the profile as expected in diabetes. The latter two conditions may also have raised fasting glucose (5.6–7.0 mmol/L). N.B. The exact cut-off points vary; refer to your own local service.

Interpretation

Implications and treatment

The metabolic syndrome

Implications

Diabetes

Presentation of diabetes

Epidemiology and economics

The definition of diabetes

Type 1 diabetes

Pathophysiology

Clinical aspects

Type 2 diabetes

Pathophysiology

Mechanisms of beta cell dysfunction

Diabetes in pregnancy

The genetics of glycaemic disease

Clinical aspects of diabetes

Diabetic ketoacidosis

Hyperosmolar hyperglycaemic syndrome

Impaired lipoprotein regulation

Long-term complications of diabetes

Microvascular disease

Figure 14.3 The biochemistry and clinical aspects of diabetic ketoacidosis. Hyperglycaemia and low insulin lead to physiological changes (left), signs and symptoms (central box) and biochemical changes (right).

Macrovascular disease

Other disease

Treatment of diabetes

Beta cell stimulation

Insulin sensitizers

Insulin

Other treatments

Monitoring and management of diabetes

Diabetes and haematology

14.2 Dyslipidaemia

Lipid families

Fatty acids

Table 14.3 Common fatty acids.

Figure 14.4 Structure of fatty acids. The presence of a double bond allows two isomers of a particular molecule: the cis form, when the molecule is effectively straight, and the trans form, where it has a bend of 30° in the middle.

Triacylglycerols

Cholesterol

Figure 14.5 Metabolism of triacylglycerols. Each molecule is synthesized by linking fatty acids to a glycerol by transferase enzymes. If required as a source of energy, the triacylglycerol can be digested back to its component parts by lipase enzymes.

Figure 14.6 Synthesis of cholesterol. This complex molecule is constructed initially from acetyl groups, which are fused to form hydroxymethylglutatyl-coenzyme A (HMG-CoA). This is converted to mevalonate by the enzyme HMG-CoA reductase, which is inhibited by the statin group of lipid-lowering agents. Later steps see squalene being converted to cholesterol, which can then join with a fatty acid to form cholesterol ester.

Lipoproteins

Phospholipid, sphingolipids and glucolipids

Lipoproteins in the blood and tissues

Chylomicrons

Low, intermediate and very low density lipoproteins

High-density lipoprotein

Table 14.4 Major features of lipoproteins.

Lipoprotein (a)

Cell surface receptors

Enzymes, transporters and transfer molecules

Disorders of cholesterol

Dietary hypercholesterolaemia

Primary hypercholesterolaemia

Secondary hypercholesterolaemia

Increased HDL

Hypocholesterolaemia

Disorders of triacylglycerols

Dietary hypertriacylglycerolaemia

Primary hypertriacylglycerolaemia

Secondary hypertriacylglycerolaemia

Combined raised cholesterol and triacylglycerol

Clinical genetics and dyslipidaemia

The clinical consequences and treatment of dyslipidaemia

Treatment of hypercholesterolemia

Treatment of hypertriacylglycerolaemia

Treatment of combined hyperlipidaemia

Other treatments of dyslipidaemia

The laboratory and lipids

Total cholesterol

High-density lipoprotein cholesterol

Figure 14.7 The enzymatic method for each major lipid has a number of defined steps and requires several different reagents, and notably all conclude with the generation of hydrogen peroxide. Nevertheless, each is amenable to automation and has excellent reproducibility.

Triacylglycerols

Assay characteristics

Low-density lipoprotein cholesterol

Apoproteins

Blood science angle: Dyslipidaemia

14.3 Atherosclerosis

The risk factors for atherosclerosis

The pathogenesis of atherosclerosis

The initial phase

The development of atheroma

The late stages

The consequences of atherosclerosis

The heart

Pathophysiology of myocardial infarction

Cardiac enzymes

Muscle protein

The diagnosis and treatment of myocardial infarction

Table 14.5 Causes of a raised troponin.

Heart failure

Peripheral artery disease

14.4 Case studies

Case study 15

Interpretation

Case study 16

Interpretation

Summary

Further reading

Guidelines

Web sites

15 Calcium, Phosphate, Magnesium and Bone Disease

Learning objectives

Table 15.1 Major blood tests in the biology of bone.

15.1 Calcium

The biology of calcium

Figure 15.1 Distribution and turnover of calcium. Calcium in the diet passes through the intestines into the blood, where some binds to albumin. It may then pass into the bone or be excreted in the urine.

Parathyroid hormone

Figure 15.2 Role of PTH in regulating blood calcium. Falling concentrations of free calcium induce the release of PTH from the parathyroid glands, with three major consequences: (1) stimulation of cells within the bone, (2) reabsorption of calcium from urine by the renal tubules and (3) stimulation of the generation of active vitamin D that promotes the absorption of calcium in the intestines.

Calcitonin

Vitamin D

Figure 15.3 Synthesis of Vitamin D. Various isoforms of vitamin D are metabolized, often by hydroxylation, in the skin, liver and kidney. The most active form of vitamin D is the 1,25-dihydroxy species known as calcitriol.

15.2 Phosphates

The biology of phosphate

Regulation of plasma phosphate

15.3 Magnesium

Regulation of magnesium

15.4 The laboratory

Laboratory determination of calcium

The albumin issue

The effect of pH

Laboratory measurement of phosphate

Laboratory measurement of magnesium

Vitamin D isoforms

Parathyroid hormone and calcitonin

15.5 Disorders of calcium homeostasis

The causes of hypercalcaemia

The consequences of hypercalcaemia

Investigation and management of hypercalcaemia

The causes of hypocalcaemia

Investigation and management of hypocalcaemia

15.6 Disorders of phosphate homeostasis

Table 15.2 Causes of abnormal calcium.

Causes of hyperphosphataemia

Consequences of hyperphosphataemia

Hypophosphataemia

Table 15.3 Causes of abnormal phosphates.

15.7 Disorders of magnesium homeostasis

Hypermagnesaemia

Clinical consequences and management of hypermagnesaemia

Hypomagnesaemia

Clinical consequences and management of hypomagnesaemia

15.8 Bone physiology

The biology of bone

Figure 15.4 Structure of compact bone. An osteon consists of a series of concentric rings of canaliculi with a Haversian canal at the centre.

Markers of bone turnover

Point of nomenclature

Blood science angle: Bone

15.9 Bone disease

Osteoporosis

Osteomalacia and rickets

Paget's disease

Osteomyelitis

Figure 15.5 Pretty as a picture. The National Gallery in London has a portrait, perhaps unkindly titled ‘A Grotesque Old Woman’. Note the increased distance between the upper lip and the base of the nose, and the expanded bone of the front of the skull. The clavicles are also prominent, and it is likely that some fingers are misshapen. On reflection, these are all signs of bone deformity; and indeed, we now recognize that she is likely to have suffered from Paget's disease.

Osteoarthritis

Renal osteodystrophy

The scaffolding hypothesis

Figure 15.6 Bone as scaffolding. If we see bone as simple scaffolding, the long metal poles represent calcium and phosphates, but these poles need to be secured by clamps, which themselves must be place by scaffolders with special tools. The scaffolding will be unsafe if any of these components are defective.

The genetics of bone, calcium and phosphates

Familial hypocalciuric hypercalcaemia

Table 15.4 Blood tests in different bone diseases.

Familial tumoral calcinosis

Paget's disease

15.10 Case studies

Case study 17

Interpretation

Case study 18

Interpretation

Case study 19

Interpretation

Summary

Further reading

Guidelines

Web sites

16 Nutrients and Gastrointestinal Disorders

Learning objectives

16.1 Nutrients

Macronutrients

Carbohydrates

Proteins

Lipids

Table 16.1 Nutrients.

Micronutrients

Lipid-soluble vitamins

Water-soluble vitamins

Other requirements

Specific nutrients: inorganic micronutrients

Laboratory assessment of nutrients

Nutritional disorders

Table 16.2 Categories of BMI.

The pathology of underweight

The pathology of overweight

Nutritional intervention

Table 16.3 Components of a typical TPN infusion.

16.2 The intestines

Intestinal physiology

The upper intestines

The pancreas

The liver, gall bladder and bile

The small intestines

The large intestines

Other functions of the intestines

Intestinal disease

Disease of the mouth, throat and oesophagus

Diseases of the stomach

Disease of the biliary tree

Disease of the pancreas

Disease of the small Intestine

Bile acid metabolism

Disease of the large Intestine

Cancer of the large and small intestines

Blood science angle: Nutrition and intestinal disease

Diarrhoea

Figure 16.1 Key aspects of intestinal pathology. Different sections of the intestines are host to particular diseases, but some diseases are present in more than one location. Most diseases are inflammatory and neoplastic in nature.

Malabsorption

Table 16.4 Simple tests for initial investigation of malabsorption.

16.3 Case studies

Case study 20

Interpretation

Case study 21

Interpretation

Summary

Further reading

Guidelines

17 Liver Function Tests and Plasma Proteins

Learning objectives

Table 17.1 Major LFTs and plasma proteins.

17.1 Anatomy and physiology of the liver

Anatomy

Figure 17.1 The micro-architecture of the liver. (a) The major functional unit of the liver is the lobule, with branches of the hepatic portal vein, the hepatic artery and biliary tree at the periphery, and a branch of the hepatic vein at the centre. (b) Blood passes along sinusoids of merged venous and arterial blood, and perfuses tissues composed of hepatocytes and Kupffer cells, supported by fibroblasts and connective tissues. Bile is generated and passes into the biliary vessels that lead to the gall bladder and bile duct.

The gall bladder and biliary system

Physiology

Metabolism

The acute-phase response

Excretion of bilirubin and bile

Table 17.2 Acute-phase reactants.

Excretion of urea

Figure 17.2 The metabolism and excretion of bilirubin starts with bilirubin as a breakdown product of the red blood cell. In the plasma it is transported to the liver by albumin, where it is conjugated to glucuronide, becomes part of the bile and passes into the intestines. Some bile metabolites are acted upon by intestinal bacteria, and some may be reabsorbed. The remainder is excreted in the faeces.

Figure 17.3 The urea/ornithine cycle. This pathway operates partly in the cytoplasm and partly in the mitochondria of hepatocytes.

Storage

Figure 17.4 The liver stores carbohydrate as glycogen (glycogenesis). Glucose can be liberated from the glycogen stores (glycogenolysis) or can be generated from amino acids and glycerol from fatty acids (gluconeogenesis).

Detoxification

Blood science angle: The liver and the haematologist

17.2 Liver function tests

Aminotransferases

Bilirubin

Alkaline phosphatase

Gamma-glutamyl transpeptidase

Albumin

17.3 Diseases of the liver

Jaundice

Figure 17.5 Jaundice is the yellowing of the skin and mucous membranes due to the deposition of bilirubin. It is often most obvious in the eye, where the white sclera gives good contrast.

Pre-liver disease

Figure 17.6 Anatomical classification of liver disease. We can consider liver disease in terms of pre–, true– and post-factors. The principal pre-liver cause of jaundice is excessive haemolysis, whilst most post-liver disease is caused by partial or complete obstruction of the bile duct, leading to cholestasis. True liver disease is characterized by damage to hepatocytes by a defined toxin or condition such as cancer or cirrhosis.

True liver disease

Post-liver disease

Cholestasis

Acute liver disease

A cautionary tale: Acute liver failure

Chronic liver disease

Ascites

Autoimmune hepatitis

Cirrhosis

Fatty liver (steatosis)

Gilbert's syndrome

Blood science angle: Gilbert's syndrome

Primary liver cancer

Secondary liver cancer

Blood science angle: The genetics of liver disease

Other liver disease

Table 17.3 Some selected factors leading to liver disease.

Disease of the biliary tree

Primary sclerosing cholangitis

Primary biliary sclerosis

Cholangiocarcinoma

Other disease

Liver function tests in liver disease

Aminotransferases

Bilirubin

Alkaline phosphatase

Gamma-glutamyl transpeptidase

Comparing the liver function tests

The complexity of liver function tests

17.4 Plasma proteins

Table 17.4 A crude synopsis of LFTs.

Total proteins

Hyperproteinaemia

Hypoproteinaemia

Measurement of proteins

Protein electrophoresis

Figure 17.7 Protein electrophoresis. The separation of groups of proteins according to their overall electrical change. Dependent on the pH of the buffers, and their starting point, different molecules migrate towards the anode or cathode. The figure shows four samples of two patients in duplicate. The heavy blue band at the bottom is albumin, the different globulin bands being easily characterized. Note that samples 3 and 4 have a much heavier staining of the gamma-globulin region. This is because of an abnormality, and is called a paraprotein, the origin of which may be malignant.

Figure 17.8 Quantification of proteins by electrophoresis. These figures are screenshots of densitometer plots. A beam of light passes over the electrophoresis gel (Figure 17.7) and plots the density of the stain, which is proportional to the concentration of protein present in the gel.

The scope of plasma proteins

Albumin

Table 17.5 Major plasma proteins.

Transport

Osmosis

Albumin as a disease marker

The consequences of hypoalbuminaemia

Alpha-1-antitrypsin

Caeruloplasmin

Wilson's disease

Menkes syndrome

C-reactive protein

Ferritin

Fibrinogen

Haptoglobin

Thyroxine-binding globulin

Transferrin

Other plasma proteins

Blood science angle: Plasma proteins

Analysis of urine

Bence–Jones protein

Albumin

Other analyses

17.5 Case studies

Case study 22

Interpretation

Case study 23

Interpretation

Summary

Further reading

Web sites

18 Hormones and Endocrine Disorders

Learning objectives

18.1 Endocrine physiology

Hormones

Lipid-soluble hormones

Table 18.1 The endocrine system.

Water-soluble hormones

Control of hormone secretion

The anterior pituitary

Adrenocorticotrophic hormone

Figure 18.1 The location of endocrine organs, variously positioned in the skull, then neck, the abdomen and at the base of the trunk.

Figure 18.2 Feedback inhibition. In almost all cases, the hypothalamus secretes a releasing hormone that stimulates the pituitary, which then releases a second hormone which acts on a target organ. The products of the latter feed back to the hypothalamus and pituitary to suppress this pathway. The target organ may act on a second target organ which itself may release a factor or factors that have a physiological effect.

Table 18.2 Reference ranges for hormones of the anterior pituitary.

Growth hormone

Prolactin

Thyroid stimulating hormone

Luteinizing hormone and follicle-stimulating hormone

The posterior pituitary

Oxytocin

Table 18.3 Reference ranges for hormones of the posterior pituitary.

Arginine vasopressin

The thyroid

Table 18.4 Reference ranges for thyroid hormones.

Thyroid hormones

Regulation of tri- and tetra-iodothyronine

Function of thyroid hormones

Table 18.5 Reference range for parathyroid hormone.

The parathyroids

The adrenals

Table 18.6 The adrenal gland and its hormones.

Figure 18.3 Functional anatomy of the adrenal gland. The adrenal consists of three areas: the innermost medulla, the cortex and the outer zona glomerulosma. Each has specific functions. CRF: corticotrophin releasing factor; ACTH: adrenocorticotrophic hormone.

Adrenaline, noradrenaline and dopamine

Table 18.7 Reference ranges for adrenal hormones.

Cortisol

Adrenal androgens

Aldosterone

Table 18.8 Reference ranges for testosterone.

The gonads

Sex-hormone-binding globulin

Male sexual development

Figure 18.4 Fluctuations in concentrations of oestradiol, FSH and testosterone in the life cycle. Concentrations rise in puberty, and change again at the menopause and andropause.

Female sexual development

The menstrual cycle

Table 18.9 Reference ranges for LH, FSH, oestradiol and progesterone according to the menstrual cycle.

Pregnancy

Lactation

The menopause

Laboratory issues

Steroid chemistry

18.2 The pathology of the endocrine system

Figure 18.5 Pathways of steroid metabolism. The synthesis of cortisol, aldosterone, testosterone and oestrogens begins with cholesterol, with many complex intermediates which are the substrate for a host of enzymes: (1) desmolase; (2) 17-hydroxylase; (3) 21-hydroxylase; (4) 3-β-hydroxysteroid dehydrogenase; (5) 11-hydroxylase; (6) 17,20-lyase; (7) aldosterone synthase; (8) 17-β-hydroxysteroid dehydrogenase; (9) aromatase; (10) 5-α-reductase. The activity of the enzyme aldosterone synthase is promoted by angiotensin, the end product of a pathway initiated by the kidney, involving angiotensin-converting enzyme and the enzyme renin (Chapter 12). The aromatase enzyme is the objective of inhibitors used to treat breast and ovarian cancer, and also gynaecomastia.

Figure 18.6 Steroid structure. Very minor differences in the structures of cholesterol and five steroid hormones. N.B. This is very simplified, and with apologies to card-carrying steroid biochemists.

Abnormalities in adrenocorticotrophic hormone and cortisol

Cushing's syndrome

Figure 18.7 Pathogenesis of Cushing's syndrome. On the left, ACTH arising from the pituitary acts on the adrenals, which secrete cortisol. The latter in turn feeds back to the pituitary to regulate ACTH production. In the middle, a pituitary adenoma secretes high levels of ACTH that flood the adrenal, which responds by secreting high concentrations of cortisol. On the right, an adrenal tumour secretes excess cortisol, which feeds back to a normal pituitary so concentrations of ACTH fall. Ectopic production of ACTH and clinical disease caused by steroid therapy are not shown.

Figure 18.8 Clinical features of Cushing's syndrome. (a) The patient exhibits the round (‘moon’) face characteristic of this disease, a consequence of the high concentrations of cortisol secreted by her adrenocortical adenoma. (b) The same patient 6 months after removal of the tumour.

Addison's disease

Investigation of abnormalities in adrenocorticotrophic hormone and cortisol

Management of Cushing's syndrome

Abnormalities in growth hormone

Investigation of acromegaly

Management of acromegaly

Low concentrations of growth hormone

Abnormalities in prolactin

Hyperprolactinaemia

Investigation of hyperprolactinaemia

Table 18.10 Increased concentrations of prolactin.

Hypoprolactinaemia

Thyroid disease

Hyperthyroidism

Figure 18.9 Goitre. An exceptionally large goitre due to profound and chronic iodine deficiency in rural Africa. This case would never develop to such an extent in the UK.

Pathophysiology of hyperthyroidism

Clinical features of hyperthyroidism

Table 18.11 General features of thyroid disease.

Management of hyperthyroidism

Hypothyroidism

Pathophysiology of primary hypothyroidism

Clinical features of hypothyroidism

Investigation and diagnosis of hypothyroidism

Management of hypothyroidism

The laboratory and thyroid disease

The thyroid and pregnancy

Thyroid cancer

Blood science angle: The thyroid

Anterior pituitary hypofunction

Posterior pituitary dysfunction

Decreased levels of arginine vasopressin

The laboratory in diabetes insipidus

Increased concentrations of arginine vasopressin

Parathyroid dysfunction

Hyperparathyroidism

Hypoparathyroidism

Adrenal pathology

Congenital adrenal hyperplasia

The laboratory in congenital adrenal hyperplasia

Conn's syndrome

Catecholamine abnormalities

Treatment of adrenal disease

Abnormalities in male reproductive endocrinology

Spermatogenesis

Blood science angle: Testosterone

Testicular cancer

Male endocrinology as target for therapy

Abnormalities in female reproductive endocrinology

Pathophysiology

Endometriosis

Polycystic ovary syndrome

Investigations in female reproductive endocrinology

Limitations in assays for steroid and protein hormones

Multiple endocrine neoplasia

MEN 1

MEN 2

The laboratory in multiple endocrine neoplasia

Molecular genetics of endocrine disease

Chromosomal abnormalities

Genetic mutations

Figure 18.10 Male precocious puberty. Molecular genetic techniques discovered a gain-of-function mutation in the gene encoding the LH receptor in this patient. The consequences of this are the hyper-reactivity to high testosterone from Leydig cells, and so the development of pubic hair and genitals. The patient is 2 years old but is the size of a 4-year-old.

The genetics of multiple endocrine neoplasia

Genetics of steroid production

18.3 Case studies

Case study 24

Interpretation

Case study 25

Interpretation

Summary

Further reading

Web sites

19 Cancer and Tumour Markers

Learning objectives

19.1 General concepts in cancer biology

Nomenclature and classification

Tumour biology

Table 19.1 Cancer deaths in 2010.

Clinical oncology

Tumour markers

Sensitivity

Specificity

Clinical value

Figure 19.1 Use of a cancer marker in diagnosis and in monitoring the effect of treatment.

19.2 Blood science and cancer

Markers with no clear biological effect

Blood science angle: Paraproteins

Markers with a biological effect

Table 19.2 Bowel cancer.

Combining markers

Haemato-oncology

Table 19.3 Selected cancer markers.

Interpretation

19.3 Molecular genetics

Pharmacogenomics

Blood science angle: Cancer

19.4 Case studies

Case study 26

Interpretation

Case study 27

Interpretation

Summary

Further reading

Guidelines

Web sites

20 Inherited Metabolic Disorders

Learning objectives

20.1 The genetics of inheritance

Table 20.1 Examples of IMDs.

Inherited metabolic disorders

Figure 20.1 Consequences of an enzyme deficiency in a metabolic pathway. An enzyme deficiency causes reduction of product, together with accumulation of substrate, and minor products of metabolic pathway.

20.2 Molecular inherited metabolic disorders

Amino acid disorders

Methionine and homocysteine

Figure 20.2 Metabolism of methionine and homocysteine. This grossly simplified metabolic pathway serves as a useful illustration of the interrelationships of certain amino acids, their linked enzymes and vitamin cofactors. The numbers refer to enzymes: (1) methionine synthase (requires vitamin B12), (2) adenosyl transferase, (3) methyl transferase, (4) cystathionine synthase (requires vitamin B6), (5) methylene tetrahydrofolate reductase (MTHFr).

Ornithine and citrulline

Phenylalanine and phenylketones

Figure 20.3 Metabolism of phenylalanine and tyrosine. Phenylalanine is the substrate for phenylalanine hydroxlase, the product being tyrosine, which is the substrate for at least three pathways.

Tyrosine

Organic acid disorders

Purine and pyrimidine disorders

Lipid disorders

Carbohydrate disorders

Disorders of galactose metabolism

Disorders of fructose metabolism

Disorders in glycogen metabolism

Figure 20.4 Glucose and glycogen metabolism. Maintenance of fasting blood glucose concentrations by glycogenolysis and gluconeogenesis in the liver. Deficiency of the enzyme glucose-6-phosphatase blocks the conversion of glucose-6-phosphate to glucose.

Cystic fibrosis

20.3 Organelle inherited metabolic disorders

Lysosomes

Peroxisomes

Mitochondria

20.4 Antenatal diagnosis and neonatal screening

The laboratory

20.5 Case studies

Case study 28

Interpretation

Figure 20.5 Blood film from case study 29. There is marked anisocytosis with microcytes (possibly some microspherocytes) and many reticulocytes (leading to polychromasia) and some schistocytes. Chapters 3 and 4 have parallel figures of red cell morpohology.

Case study 29

Interpretation

Summary

Further Reading

21 Drugs and Poisons

Learning objectives

21.1 Toxicology

General biochemical features of poisoning

The kidney

Figure 21.1 Outline of drug metabolism and clinical effect at target sites. This is far from the case that the amount of drug interfacing with cells and tissues is that which is prescribed. Factors such as compliance, absorption, metabolism and excretion all influence drug activity.

The liver

Pharmacokinetics and pharmacodynamics

21.2 Toxicology of specific compounds

Carbon monoxide

Table 21.1 Common causes of fatal toxic events.

Paracetamol

Salicylate

Drugs of abuse

Figure 21.2 Pathways involved in the metabolism of paracetamol. Conjugation to glucuronide, sulphate or glutathione renders the drug nontoxic. However, in their absence, paracetamol causes hepatic and renal cell damage. NAPQI: N-acetyl-p-benzo-quinoneimine.

Ethanol

Figure 21.3 Metabolism of acetylsalicylic acid. The liver converts acetylsalicylic acid to its active salicylic acid (salicylate) by hydrolysis and deacetylation, and so the generation of a molecule of acetic acid.

Amphetamines

Cocaine

Opiates

Barbiturates and benzodiazapines

Cannabis

Heavy metals

Lead

Aluminium

Arsenic

Cadmium

21.3 Therapeutic drug monitoring

General concepts

Which drugs to monitor?

Anticoagulants

Anticonvulsant drugs

Antimicrobial drugs

Cancer chemotherapy

Blood science angle: Chemotherapy

Cardiovascular drugs

Psychoactive drugs

Table 21.2 Common TDM target ranges.

Blood science angle: TDM

21.4 Case studies

Case study 30

Interpretation

Case study 31

Interpretation

Summary

References

Further reading

22 Case Reports in Blood Science

Abbreviations

Case report 1

History

Table 22.1 Case report 1.

Interpretation

Additional analyses

Discussion and diagnosis

Case report 2

History

Table 22.2 Case report 2.

Interpretation

Discussion and diagnosis

Risk factor management

Case report 3

History

Interpretation

Discussion and diagnosis

Table 22.3 Case report 3.

Case report 4

Part 1

History

Table 22.4 Case report 4: part 1.

Interpretation

Discussion and diagnosis

Part 2

Interpretation

Table 22.5 Case report 4: part 2.

Discussion and diagnosis

Case report 5

Part 1

History

Interpretation

Discussion and diagnosis

Table 22.6 Case report 5: part 1.

Part 2

Interpretation

Table 22.7 Case report 5: part 2.

Part 3

History

Interpretation

Table 22.8 Case report 5: part 3.

Discussion and diagnosis

Case report 6

History

Table 22.9 Case report 6.

Interpretation, discussion and diagnosis

Case report 7

History

Table 22.10 Case report 7.

Interpretation and discussion

Diagnosis

Case report 8

Table 22.11 Case report 8.

Interpretation

Discussion and diagnosis

Case report 9

Day 1

Interpretation

Day 2

Table 22.12 Case report 9.

Day 3

Interpretation

Day 4

Interpretation

Day 5

Interpretation

Case report 10

Day 1

Table 22.13 Case report 10.

Interpretation and discussion

Day 2

Interpretation and discussion

Day 3

Interpretation and discussion

Case report 11

Interpretation

Table 22.14 Case report 11.

Diagnosis

Case report 12

Interpretation

Table 22.15 Case report 12.

Discussion and diagnosis

Figure 22.1 Blood film from case report 12

Case report 13

Table 22.16 Case report 13.

Interpretation

Discussion and diagnosis

Case report 14

Table 22.17 Case report 14.

Interpretation

Discussion and diagnosis

References

Back Matter

Appendix Reference Ranges

Further Reading

Glossary

Index

 

An aparitie	2014
Autor	Andrew Blann, Nessar Ahmed
Dimensiuni	19.05 x 2.34 x 24.64 cm
Editura	John Wiley & Sons
Format	Paperback
ISBN	9781118351468
Limba	Engleza
Nr pag	556