D immunization

The realization that D-negative women without anti-D who had just delivered a D-positive child could be protected from forming anti-D by the injection of IgG anti-D soon after delivery has been a powerful stimulus for experimental work on D-negative volunteers. About 90 of D-negative people will make anti-D after the transfusion of a large volume of D-positive cells, and 70 will respond to repeated small volumes. Res-ponders to D can usually be identified from survival curves after a single...

Diamond Blackfan anaemia

Have been reported but have not clarified the mechanism of in vivo erythroid failure. For many years, based on the typical selective deficiency in red cell precursors, many researchers believed that DBA is due to an intrinsic problem with erythroid proliferation differentiation. On the other hand, the observation of a wide range of somatic abnormalities in a significant proportion of patients and case reports of thrombocytopenia, neutropenia and AA, together with the recent evidence for a...

Pulmonary complications

Acute and chronic pulmonary complications are the leading cause of death in older patients. The acute chest syndrome is characterized by hypoxia, tachypnoea, fever, chest pain and pulmonary infiltrate on chest radiographs (Figure 7.4c). Acute chest syndrome often follows a painful event, particularly in adults (Table 7.3). The pathogenesis of acute chest syndrome involves vaso-occlusion, infection or both. Infections due to Mycoplasma, Table 7.3 Presenting symptoms of acute chest syndrome....

The origins of blood during development

Endothelium Developing haematopoietic cells Neural tube Somite Dorsal aorta Hindgut Neural tube Somite Dorsal aorta Hindgut Figure 2.1 An outline of the origin and development of erythropoiesis during embryogenesis. Although both primitive (blood islands) and definitive (AGM, liver and bone marrow) haemopoiesis are derived from mesoderm, probably via a haemangioblast, the true origin of these early cells is not yet clear. The figure shows the formation of embryonic blood islands in the...

Cell death apoptosis

The final stage in the life of a blood cell is death and disposal by apoptosis. Apoptotic cell death is a mechanism for disposing of unwanted or excess cells, and it occurs widely in biological systems. It ensures the destruction of cells without releasing any lysosomal or granule contents that would cause an inflammatory reaction. Apoptosis involves a complex series of events that culminate in the activation of the caspase proteases, fragmentation of DNA and phagocytosis of apoptotic bodies by...

Dangerous universal donors

Good practice in pretransfusion testing requires compatibility testing, which consists of incubating the patient's serum with the Table 15.5 Some properties of immune and naturally occurring anti-A and -B. Table 15.5 Some properties of immune and naturally occurring anti-A and -B. Inhibited by soluble A or B substances (e.g. saliva) *IgG ABO antibodies are usually inhibited only by large amounts of specific substance. 2-ME, 2-mercaptoethanol DTT, dithiothreitol. *IgG ABO antibodies are usually...

Minor red cell abnormalities

Donors with minor red cell abnormalities, such as thalassaemia trait, sickle cell trait and hereditary spherocytosis, are perfectly acceptable, providing that the haemoglobin (Hb) screening test excludes anaemia. Red cells containing HbS have a limited survival under conditions of reduced oxygen tension and so should not be transfused to newborn infants and patients with hypoxia or sickle cell disease. Red cells with HbS obstruct leucodepletion filters and it is therefore advisable, in the UK,...

Gene therapy

The self-renewal and expansion capacities of haemopoietic stem cells make them the ideal vehicle for gene therapy of genetic disorders. The transduced genes will be expressed for long periods of time in the stem cell population and in their differentiating and mature descendants (see Chapter 27). Almeida-Porada G, Porada CD, Chamberlain J et al. (2004) Formation of human hepatocytes by human hematopoietic stem cells in sheep. Blood 104 2582-90. Bacigalupo A (2004) Mesenchymal stem cells and...

Blood grouping reagents

To avoid potential fatalities due to errors in ABO and D grouping, it is essential that the chosen ABO typing reagents have suitable potency and comply with the European Directive on in vitro diagnostic devices and the associated Common Technical Specifications and carry the 'CE' mark to show they are in conformance. Blood grouping reagents prepared from polyclonal antisera should be free of unwanted antibodies and should have been exhaustively tested with an extensive panel of cells to exclude...

Cryoprecipitatepoor plasma cryosupernatant

This term is used for the remaining plasma after the removal of cryoprecipitate. The main and specific indication for cryosuper-natant is for plasma exchange in TTP. This is an immunemediated condition in which there is an autoantibody directed against a vWF cleaving metalloproteinase. The resulting accumulation of high-molecular-weight (HMV) vWF multimers contributes to the pathophysiology of the condition with thrombosis in the microvasculature. Cryosupernatant supplies both more of the...

Crossmatching for immunologically refractory patients

The major cause of immunological refractoriness to platelet transfusion is, by far, the presence of HLA-A and or HLA-B antibodies in multitransfused patients. Quite often, such antibodies are found to react with the lymphocytes from the majority (and sometimes all) of the donors included in the panel. Platelet-specific antibodies may occur in 3-9 or less of refractory patients. Implicated specificities have included anti-HPA-la and anti-HPA-lb, as well as anti-HPA-3a, anti-HPA-2b, HPA-15b, and...

Hazards of blood donation

The most common hazard of blood donation is fainting, reported in between 2 and 5 of all donors, but being especially common in young people and in those donating for the first time, particularly if they are nervous or apprehensive. A sympathetic approach by blood collection staff, enforcement of an adequate rest period, and constant vigilance to detect warning signs of an impending vasovagal attack can help to avert this problem. Once a faint occurs, the standard treatment of rest in a...

Newborn screening

Universal newborn screening is recommended to identify SCD in the neonatal period. The efficacy of penicillin prophylaxis in preventing death from early sepsis in SCD provided the rationale for development of screening programmes. Blood samples obtained by heel prick are spotted onto filter paper and tested by electrophoresis or chromatography. Neonates with HbSS disease and HbS P -thalassaemia have an FS pattern (the order of haemoglobins indicates their relative abundance in the sample). In...

Naturally occurring and immune antibodies

Antibodies are naturally occurring when they are produced without any obvious immunizing stimulus such as pregnancy, transfusion or injection of blood. These antibodies are not present at birth and, in the case of anti-A and anti-B, start to appear in the serum of children with the appropriate ABO groups at about 3-6 months of age. ABO antibodies are probably produced in response to antigens of bacteria, viruses and other substances that are inhaled or ingested many Gram-negative organisms have...

Granulocyte concentrates

Granulocytes are extremely labile they must be separated from whole blood immediately after collection and transfused within hours of preparation. Granulocytes prepared from routine blood donations ('buffy coats') are heavily contaminated with red cells and platelets. Buffy coats from at least 10 donors are required to produce a therapeutic dose for an adult (at least 1 X 1010 granulocytes). Ten buffy coats also contain the equivalent of two units of red cells and 2.5 pools of platelets....

Other anticoagulants and additive solutions

Heparin is now rarely used, and it can only be useful for blood that is to be transfused within 12 h of collection. This is because heparin is gradually broken down in storage and the blood then clots. Heparinized blood for neonatal cardiac surgery and exchange transfusion has been replaced by citrate-phosphate-dextrose-adenine (CPD-AI) blood, less than 3-5 days old, with no untoward effects. Some neonatologists use SAGM red cells for newborn infants, with success. For intrauterine transfusion,...

Molecular pathology

The a0-thalassaemias result from deletions of both a-globin genes. There are many different-sized deletions however, one is particularly common in South-East Asia and another occurs mainly in Mediterranean populations (Figure 6.11). a0-Thalassaemia may also result from deletions about 40 kb upstream from the a-globin gene cluster, which involve the HS40 region. The molecular basis of the a+-thalassaemias is more complicated. In some cases, they result from deletions that remove one of the...

Selected bibliography

Chu X, Thompson D, Yee LJ, Sung LA (2000) Genomic organization of mouse and human erythrocyte tropomodulin genes encoding the pointed end capping protein for the actin filaments. Gene 256 271-81. Davies KA, Lux SE (1989) Hereditary disorders of the red cell membrane skeleton. Trends in Genetics 5 222-7. Delaunay J (2002) Molecular basis of red cell membrane disorders. Acta Haematologica 108 210-8. Delaunay J, Dhermy D (1993) Mutations involving the spectrin heterodimer contact site clinical...

Antenatal assessment of maternal blood

Rarely, anti-D may develop in a first pregnancy in a woman who has had no previous transfusions. However, it is not common for the antibody to reach high levels, and it is not usually detectable before 28 weeks most of such cases become apparent after delivery. Conversely, in women who have had previous pregnancies or transfusions with Rh-positive red cells, anti-D may be detected early in pregnancy regular monitoring of the level is necessary in order to plan the best type and timing of...

Deoxyuridine suppression test

In normal bone marrow, deoxyuridine (dU) considerably suppresses the uptake of radioactive thymidine into DNA. This is thought to be due to conversion of dU to thymidine triphosphate (dTTO) via dU monophosphate (dUMP), which inhibits thymidine kinase, on which thymidine uptake depends (Figure 5.1). Deoxyuridine suppresses radioactive thymidine incorporation less effectively in megaloblastic anaemia due to folate or cobalamin deficiency because of the block in dUMP methylation to dTMP. In...

Thrombopoietin

Thrombopoietin (TPO) is an essential growth factor for stem cell maintenance and proliferation, although its major role is to enhance platelet production and function. It is the ligand for the receptor c-mpl, which is a member of the cytokine receptor superfamily and is expressed on megakaryocytes, platelets and also on pluripotential stem cells. TPO is mainly synthesized in the liver, and its levels are regulated by clearance through platelet binding. The effect of TPO in culture is to...

Causes of iron deficiency Table

Renal tract Pulmonary tract Widespread bleeding disorders Self-inflicted Malabsorption Gluten-induced enteropathy (child or adult), gastrectomy, atrophic gastritis, chronic inflammation, clay eating, etc. Dietary Especially vegetarian diet Menorrhagia, post-menopausal bleeding, parturition Oesophageal varices, hiatus hernia, peptic ulcer, aspirin ingestion, hookworm, hereditary telangiectasia, carcinoma of the stomach, caecum or colon, ulcerative colitis,...

Diagnosis of folate deficiency Serum folate

This may be measured microbiologically with Lactobacillus casei, by radioassay or by an enzyme-linked immunosorbence assay (ELISA) technique. The serum folate level is low in all folate-deficient patients. In most laboratories, the normal range is quoted as from 2.0 g L (11 nmol L) to about 15 g L. The serum folate is markedly affected by recent diet inadequate intake for as little as 1 week may cause the level to become subnormal. Because of this, the serum folate assay is a very sensitive...

The transcription factor programme underlying erythropoiesis

Particularly relevant for erythropoiesis. Both are expressed in multipotent progenitors, although GATA-2 appears to be more important than GATA-1 at this stage, when GATA-2 plays an important role in the expansion and maintenance of haemopoi-etic progenitors. During erythroid differentiation the level of GATA-2 declines as GATA-1 increases. In mouse embryos lacking GATA-2, erythrocytes are present, but in severely reduced numbers. There appears to be some overlap and redundancy between the...

Hallervorden Spatz syndrome

This is an autosomal recessive neurodegenerative disorder associated with iron accumulation in the brain. Clinical features include extrapyramidal dysfunction, onset in childhood and a relentlessly progressive course. Histological study reveals iron deposits in the basal ganglia. Hallervorden-Spatz syndrome is caused by a defect in a novel pantothenate kinase gene that causes accumulation of cysteine. Iron binding by cysteine may cause iron accumulation and oxidative stress which is a likely...

Human immunodeficiency virus HIVl and HIV2

The classical descriptions and the vast majority of the literature on AIDS refer to HIV-1 a second retrovirus capable of causing AIDS, HIV-2, mainly occurs in West Africa. Human immunodeficiency virus (HIV) can be transmitted both in cellular and plasma components. Most of the patients infected by the transfusion of blood components were transfused before the introduction of the screening of blood donations for HIV antibodies. The majority of recipients of blood products who were infected in...

Cryoprecipitate

Cryoprecipitate is prepared from blood within 8 h of collection (Figure 16.1). Plasma is separated, frozen and allowed to thaw (classically at 4 C, overnight). After removal of the supernatant, the factor VIII C, vW factor, fibrinogen, fibronectin and FXIII are left as a precipitate, which is then refrozen in approximately 15 mL of plasma, and stored at -30 C or below for up to 24 months. Each unit should contain a minimum of 70 IU of factor VlII C and 140 mg of fibrinogen. Cryoprecipitate is...

Tn activation

Tn activation, unlike T and Tk, is a persistent abnormality caused by an abnormal clone of stem cells arising by somatic mutation. Tn is often associated with other haematological abnormalities, such as chronic haemolytic anaemia, leucopenia or thrombocy-topenia, but may be present in healthy individuals. Somatic mutation leads to a deficiency of the galactosyltransferase that elongates the O-linked oligosaccharides on GPA, so that many of the O-glycans consist of only N-acetylgalactosamine,...

Thrombocytosis

In the immediate postoperative period in uncomplicated splenectomy patients, the platelet count rises steeply to a maximum of usually 600-1000 X 109 L, with a peak at 7-12 days. In a number of patients, the thrombocytosis persists indefinitely after splenectomy. This usually appears to be a consequence of continuing anaemia with a hyperplastic marrow an inverse relationship exists between the severity of the anaemia and the height of the platelet counts. Although a reactive thrombocytosis is...

HLA nomenclature

The naming of HLA specificities falls under the remit of the WHO Nomenclature Committee for Factors of the HLA System. The Committee names HLA genes, alleles and serologically defined antigenic specificities. The names of the antigens, which were originally defined using either serological or cellular techniques, are a combination of letters that indicate the gene encoding the antigen and numbers assigned in chronological order of their description. An example of an individual's HLA type...

Immune responses

The previous sections have indicated that antigen-driven T- and B-cell activation leading to antibody production or the generation of effector T cells requires a complex series of interactions between cells. In most primary immune responses this will occur only within secondary lymphoid tissue. The lymph nodes, mucosal lymphoid tissues and spleen contain the bulk of secondary lymphoid tissue. The outward appearance of the various secondary lymphoid tissues is markedly different, but their fine...

Congenital intrinsic factor deficiency or functional abnormality

The affected child usually shows no demonstrable IF but has a normal gastric mucosa and normal secretion of acid. The inheritance is autosomally recessive. These patients usually present with megaloblastic anaemia in the first, second or third year of life when stores of cobalamin accumulated from the mother in utero are used up a few have presented as late as the second decade. Parietal cell and IF antibodies are absent. Variants have been described in which the child is born with IF that can...

Weak D Du

Cells that have the weak D phenotype (previously known as Du) should, for most transfusion purposes, be regarded as D-positive. Weak D red cells have fewer D sites per cell than normal D-positive red cells. In a white population, the gene for weak D is commonly accompanied by RHCE encoding C or E antigen (DuCe or DucE), and Duce is rare. Weak D is more common in Africans and is usually produced by Duce. It is important that anti-D typing reagents should detect most weak D phenotypes, especially...

T activation

T activation occurs transiently in some patients with an obvious microbial infection, especially Vibrio cholerae, Clostridium perfringens, Diplococcus pneumoniae, various streptococci and the influenza virus. These microbes produce sialidases, which remove sialic acid (N-acetylneuraminic acid, NANA) from the oligosaccharides of membrane sialoglycoproteins (Table 15.13) to expose the hidden T antigen (galactose linked to N-acetyl-galactosamine), with an accompanying loss of negative surface...

Transfusion haemosiderosis

Haemosiderosis is a very real complication of repeated blood transfusions, and is being seen more commonly as long-term blood transfusion therapy improves the survival of patients suffering from some chronic anaemias. It is most commonly seen in thalassaemic individuals, who commence transfusions in early childhood. Each unit of blood has approximately 200 mg of iron, whereas the daily excretion rate is about 1 mg the body has no way of excreting the excess. Unless a patient is actively...

Excess utilization or loss Pregnancy

Folate requirements are increased by 200-300 g to about 400 g daily in a normal pregnancy, partly because of transfer of the vitamin to the fetus, but mainly because of increased folate catabolism due to cleavage of folate coenzymes in rapidly proliferating tissues at the C-9-N-10 bond. Megaloblastic anaemia due to this deficiency is now largely prevented by prophylactic folic acid therapy. It occurred in 0.5 of pregnancies in the UK and other Western countries, but the incidence is much higher...

Reactions due to plasma protein antibodies

Mild urticarial reactions without other symptoms are not uncommon during blood transfusion they occur with an approximate incidence of 1 and are mediated by IgE antibodies, usually against plasma proteins or other allergens present in donor plasma. Mild urticarial reactions may be treated effectively with antihistamines, and do not always recur. There is no necessity to avoid transfusion of standard 'bank blood' unless symptoms are recurrent and severe. On the other hand, severe anaphylactic...

Blood grouping methods

American Association of Blood Banks (2002) American Association of Blood Banks Technical Manual, 14th edn. AABB, Bethesda, MD. BCSH Blood Transfusion Task Force (1996) Guidelines for pretrans-fusion compatibility procedures in blood transfusion laboratories. Transfusion Medicine 6 273-83. Guidelines for the Blood Transfusion Services in the United Kingdom (2002) The Stationery Office, London van der Schoot CE, Tax GHM, Rijnders RJP, de Haas M, Christaens GCML (2003) Prenatal typing of Rh and...

Info

Figure 15.2 Diagrammatic representation of H and Lewis antigens. Lea requires the action of the Lewis a1,4-fucosyltransferase, H the action of the H a1,2-fucosyltransferase, Leb the action of both Lewis and H fucosyltransferases, and ALeb and BLeb the action of Lewis and H fucosyltransferases and the A or B glycosyltransferases. tions and in plasma. The Lewis antigens on red cells are adsorbed passively from the plasma, and the constant presence of plasma is needed to maintain Lewis antigen on...

Hereditary persistence of fetal haemoglobin

This is a heterogeneous group of conditions in which there is persistent fetal haemoglobin production in adult life in the absence of major haematological abnormalities. Although of little clinical importance, it may modify the phenotype of the P-haemoglobinopathies. Some forms of hereditary persistence of fetal haemoglobin (HPFH) result from long deletions of the P-globin gene cluster, similar to those that cause 8P-thalassaemia (Figure 6.8). Homozygotes, with 100 HbF, have a mild...

Paroxysmal cold haemoglobinuria

The rare syndrome usually occurs in children following acute viral infections. The original cases were described by Donath, Landsteiner and Ehrlich in congenital and tertiary syphilis but such cases are no longer encountered. A history of cold exposure is not always present and presentation is with sudden intravas-cular haemolysis, haemoglobinuria, abdominal pain, pallor and prostration. The cold antibody is IgG, which is biphasic, reacting with red cells below 20 C in the peripheral...

Effect on erythrocytes

Red cells acquire the sickle or elongated shape upon deoxy-genation as a result of intracellular polymerization of HbS, a phenomenon that is reversible upon reoxygenation. Even in the normally shaped red cells, however, the presence of HbS polymer reduces deformability, with consequent increase in blood viscosity. Repeated or prolonged sickling progressively damages the red cell membrane, which is a phenomenon of primary importance in the pathophysiology of SCD. Membrane damage causes movement...

Antibody screening and identification

Patients' sera should be screened against unpooled group O cells from selected individuals known to carry the following antigens between them D, C, E, c, e, M, N, S, s, P1, Lea, Leb, K, k, Fya, Fyb, Jka and Jkb. Ideally, one cell sample should be R1R1 (DCe DCe) and the other R2R2 (DcE DcE), and a minimum homozygous expression of Fya and Jka should be present on one of the red cell samples. It is generally possible to meet these requirements with two cells but, if more antigens are required with...

The polymorphism of major histocompatibility complex molecules

Mhc Class Molecules Diagram

There is extensive polymorphism of the major histocompatibility complex (MHC) class I and class II molecules (Figure 20.5). Figure 20.4 The aP T-cell receptor complex. The aP TCR is composed of two polypeptide chains, each with a variable (open ovoid) and constant (closed ovoid) domain. Peptide plus MHC is recognized by the combined variable regions. The TCR is surrounded by the CD3 complex of transmembrane signalling molecules. This is composed of four types of polypeptide chain, Y, S, e and Z...

Premature delivery

Modern neonatal intensive care has dramatically increased survival rates of very premature infants born at 24-30 weeks' gestation. Nevertheless, morbidity is high and premature delivery is now, due to the success of intrauterine transfusions, rarely performed. It is sometimes considered at 36 weeks for Figure 16.7 Middle cerebral artery Doppler. Peak velocity of systolic blood flow in the middle cerebral artery in 111 fetuses at risk for anaemia due to maternal red cell alloimmunization. Open...

Pyrimidine 5nucleotidase deficiency

Pyrimidine 5'-nucleotidase deficiency is not uncommon, although only some 40 or 50 families have been reported in the literature. It is probably the third most common enzyme deficiency causing haemolytic anaemia, perhaps equal to GPI deficiency. Nearly all reported cases have shown homozygosity for the mutation, and the mutation has been specific for individual families. There is, however, a suggestion that certain mutations (Del G576 and INS GG743) might be more prevalent in southern Italy or...

The white pulp immunological function

The spleen is the largest single accumulation of lymphoid tissue in the body. It contains 25 of the T-lymphocyte pool and 10-15 of the B-lymphocyte pool. T cells are found predominantly in periarteriolar lymphatic sheaths, and B cells in germinal centres in the white pulp. These cells do not appear to arise in the spleen but to have migrated there from other sites of origin, such as the bone marrow and thymus. There is a constant flow of both T and B cells through the spleen T cells are the...

Dietary and luminal factors

Much of dietary iron is non-haem iron derived from cereals Dietary factors Increased haem iron Increased animal foods Ferrous iron salts Luminal factors Acid pH (e.g. gastric HCl) Low-molecular-weight soluble chelates (e.g. vitamin C, sugars, amino acids) Ligand in meat (unidentified) Systemic factors Iron deficiency Increased erythropoiesis (e.g. after haemorrhage) Ineffective erythropoiesis Pregnancy Hypoxia (commonly fortified with additional iron in the UK), with a lesser component of haem...

Optimal additive solutions eg salineadenineglucosemannitol SAGM

Optimal additive plasma replacement solutions have been developed to improve viability of plasma-depleted red cells on storage, by maintaining both ATP and 2,3-DPG levels. SAGM (as well as ADSOL and Nutricel) medium provides good red cell storage conditions and is now the most usual preservative solution for red cells in the UK. A multiple 'top and bottom' blood collection pack is used (Figure 16.1). The blood donation is taken into the main pack, which contains standard CPD anticoagulant....

Acquired pure red cell aplasia

Casadevall N, Nataf J, Viron B et al. (2002) Pure red cell aplasia and Anti-erythropoietin antibodies in patients treated with recombinant erythropoietin. New England Journal of Medicine 346 469-75. Charles RJ, Sabo KM, Kidd PG etal (1996) The pathophysiology of pure red cell aplasia Implications for therapy. Blood 87 4831-8. Dessypris EN (2002) Pure red cell aplasia. In Hematology, Basic Principles and Practice, 3rd edn (R Hoffman, EJ Benz, SJ Shattil etal., eds). Successful treament of pure...

Cell and molecular biology

Cells from FA patients show an abnormally high frequency of spontaneous chromosomal breakage and hypersensitivity to the clastogenic effect of DNA cross-linking agents such as diepoxybutane (DEB) and mitomycin C (MMC). A laboratory test is available for FA. This is based on the increased chromosomal breakage seen in FA cells compared with normal control subjects after exposure to low concentrations of DEB or MMC ('DEB MMC stress test') (Figure 12.2). Other features of the FA cell phenotype...

The ability of the antibody to bind complement

Why some antibody molecules bind complement easily and others do not is not fully understood, but several factors seem to be important. 1 The immunoglobulin class and subclass of the antibody, as discussed later. 2 At least two Clq binding sites properly aligned and close together are necessary for complement fixation. One molecule of IgM antibody carries several Clq binding sites, whereas one molecule of IgG carries only one, and will therefore need another molecule of IgG alongside it (IgG...

Combined immunodeficiency

A number of rare inherited defects significantly compromise both humoral and cellular immunity but do not usually lead to early death from severe infection (Table 22.1). These include defects in CD40 ligand (HIM-1), ataxia telangiectasia (AT) and other defects in DNA repair systems, and the Wiskott-Aldrich syndrome (WAS). A predisposition to cancer, particularly lymphoma, occurs in many of these syndromes. In WAS, the clinical features range from thrombocytopenia alone to a severe disease...

Phagocytic killing antimicrobial proteins

Phagocytic cells such as neutrophils can kill micro-organisms using proteins present in various granules. The importance of such non-oxidative killing is evident in chronic granulomatous disease neutrophils that are still capable of killing many potent micro-organisms. Furthermore, this process is important for defence against organisms such as Escherichia coli and Salmonella typhimurium, which do not produce their own source of oxid-ants and are killed under anaerobic conditions. The contents...

The biological significance of blood group antigens

The functions of several red cell membrane protein structures bearing blood group antigenic determinants are known, or can be deduced from their structure (Table 14.1). Some are membrane transporters, facilitating the transport of biologically important molecules through the lipid bilayer band 3 membrane glycoprotein, the Diego antigen, provides an anion exchange channel for HCO- and Cl- ions the Kidd glycoprotein is a urea transporter the Colton glycoprotein is aquaporin 1, a water channel the...

Red cell antigens

In Alloimmune Disorders of Pregnancy (A Hadley, P Soothill, eds), pp. 121-39. Cambridge University Press, Cambridge. Avent ND, Reid ME (2000) The Rh blood group system a review. Blood 95 375-87. Cartron JP, Colin Y (2001) Structural and functional diversity of blood group antigens. Transfusion Clinical Biology 8 163-99. Chester MA, Olsson ML (2001) The ABO blood group gene a locus of considerable genetic diversity. Transfusion Medicine Reviews 15 177-200. Danek...

Measurement of splenic phagocytic and immunological function

Irreversible trapping of particulate matter is a function of the reticuloendothelial system. Colloid particles 1 im in size or less will be taken up by the liver, larger particles by the spleen. There is a well-established relationship between splenic reticuloendo-thelial function and the rate at which heat-damaged red cells are removed from the circulation. The half-clearance time in normal subjects is about 8-16 min. Post splenectomy, the time is increased to 60-120 min or longer and...

White cell and platelet antigens

Blanchette VS, Johnson J, Rand M (2000) The management of alloimmune neonatal thrombocytopenia. Bailli re's Clinical Haematology 13 365-90. Hurd C, Cavanagh G, Ouwehand WH et al. (2002) Genotyping for platelet-specific antigens - techniques for the detection of single nucleotide polymorphisms. Vox Sanguinis 83 1-12. International Forum (2003) Detection of platelet-reactive antibodies in patients who are refractory to platelet transfusions, and the selection of compatible donors. Vox Sanguinis...

Pathophysiology

The molecular defects in P-thalassaemia result in absent or reduced P-chain production. a-Chain synthesis is unaffected and hence there is imbalanced globin chain production, leading to an excess of a-chains. In the absence of their partners, they are unstable and precipitate in the red cell precursors, giving rise to large intracellular inclusions that interfere with red cell maturation. Hence there is a variable degree of intramedullary destruction of red cell precursors, i.e. ineffective...

Antigens with high or low frequency

There are many other antigens, of either very high or very low incidence, that have not been assigned to blood group systems. Anti-Vel, -Lan, -Ata, -AnWj and -MAM are examples of antibodies to high-frequency antigens (HFAs) that have caused HDN and or HTRs. For those rare individuals who have formed antibodies to HFAs, the provision of compatible blood can be a problem it is often necessary to approach the national or international panels of rare donors for compatible units. Antibodies to...

Other defects of the enzymes of the glycolytic system

Compared with PK deficiency, the other defects of the glycolytic pathway are very rare. The main features of these disorders are summarized in Table 9.1. Hexokinase (HK1) catalyses the phosphorylation of glucose to G6P, the first step in the glycolytic pathway. The enzyme in the red cell differs from that in nucleated cells, which have oxidative respiration, by lacking a porin-binding domain that links the enzyme to the mitochondrial membrane. The red cell enzyme is derived from alternative...

Lead poisoning

Chronic ingestion of lead in humans causes an anaemia that is usually normochromic or slightly hypochromic. Red cell lifespan is shortened and there is a mild rise in reticulocytes, but jaundice is rare. Basophilic stippling is a characteristic, although not universal, finding and it is thought to be due to precipitation of RNA, resulting from inhibition of the enzyme pyrimidine 5'-nucleotidase. Siderotic granules, and occasionally Cabot rings, are found in circulating red cells. The bone...

Clinical effects of human immunodeficiency virus

The outcome of HIV infection is divided into four stages (or groups) according to the Centers for Disease Control (CDC) (Table 23.1), and it is not yet clear what factors determine whether (or how rapidly) movement occurs from one stage to the other. After the initial seroconversion, which is often associated with a febrile mononucleosis-like illness, patients who are HIV antibody-positive enter either group 2 (chronic asymptomatic infection) or group 3 (persistent generalized lymphadenopathy)....

CDA type I

Type I has been identified far less frequently than CDA II. It has an autosomally recessive inheritance no method is available to identify heterozygous subjects. Clinical features are similar to those of CDAII. Most patients present with splenomegaly and mild to moderate macrocytic anaemia. Two cases have been reported with skeletal defects in fingers and toes resembling the features seen in congenital aplastic anaemias. Haematologically, it differs from type II by its bone marrow morphological...

Differential diagnosis of primary and secondary antibody deficiency

Figure 22.3 shows the procedures for investigating patients with suspected antibody deficiency. The family history may suggest an inherited defect. The pattern of the serum immunoglobulin deficiency can be helpful, with complete agammaglobulinaemia and absence of circulating B lymphocytes suggesting a B-cell maturation differentiation defect. The presence of a normal or raised serum IgM, with very low IgG and IgA, suggests one of the HIM syndromes, whereas low IgG, unrecordable IgA and very low...

The follicles of secondary lymphoid tissues and germinal centres

These B-cell-rich areas are permeated by a dense network of follicular dendritic cells (FDCs). In follicles where no antigen-dependent activation is taking place, small recirculating B cells fill the spaces in the FDC network. In the first 3 weeks of T-dependent antibody responses, there is massive clonal expansion of B cells in follicles. This is associated with germinal centre formation. In the later stages of responses to protein antigens, small numbers of memory B blasts continue to...

Hyposplenism

Hyposplenism (excluding that induced by medical or surgical intervention) occurs in a wide range of conditions. In some disorders such as sickle cell disease, gluten-induced enteropathy (coeliac syndrome) and dermatitis herpetiformis, hyposplenism occurs frequently it is seen less frequently in Crohn's disease, ulcerative colitis and essential thrombocy-thaemia, and it occurs only occasionally in the other conditions listed in Table 21.2. Congenital absence of the spleen is rare and may be...

Microcolumn tests gel and beads

The principle of microcolumn tests is the separation of agglutinated from non-agglutinated red cells by centrifugation through a miniature filtration column. For blood grouping, red cells are layered on microcolumns impregnated with blood grouping sera for antibody screening and identification, phenotyped panel red cells are mixed with patients' sera within the incubation chamber of the microcolumn. After centrifugation, agglutinated red cells are retained towards the top of the microcolumn...

Therapy

Effective treatment of lysosomal storage disorders self-evidently involves reduction of the stored compound and prevention of its reaccumulation. This has been achieved by replacement of the missing protein by stem cell transplantation and by infusion of the missing enzyme (enzyme replacement therapy, ERT). Many patients with Gaucher's disease, metachromatic leucodystrophy, Krabbe's disease and mucopolysaccharidosis type I have undergone stem cell transplantation. Donation of stem cells has...

Shwachman Diamond syndrome Clinical features

Shwachman and Bodian and their colleagues first reported this disease independently in 1964. It is now recognized as an autosomal recessive disorder characterized by exocrine pancreatic insufficiency (100 ), bone marrow dysfunction (100 ) and other somatic abnormalities (particularly involving the skeletal system). Signs of pancreatic insufficiency (malabsorption, failure to thrive) are apparent early in infancy (note that the pancreatic function can improve in a subset of Shwachman-Diamond...

The integral proteins and vertical interaction

The two major integral proteins that span the lipid bilayer are band 3 (the anion channel protein) and the glycophorins A, B and C. Band 3 and associated molecules, 4.2 (pallidin) and ankyrin (2.1), form one major vertical interactive pathway with binding to the P-chain of the spectrin tetramer through ankyrin. Glycophorin C and protein 4.1 also provide a vertical interaction but the association with spectrin is through a link with actin, which is a key part of the horizontal network. The band...

Granulocyte and granulocytemacrophage colonystimulating factors

G-CSF and GM-CSF are both glycosylated polypeptides in their natural form, which are the main regulators of granulocyte production. The gene for G-CSF is located on chromosome 17q, whereas that of GM-CSF is located on chromosome 5q. Both of these CSFs can be secreted by a variety of cell types, including monocytes macrophages, T cells, endothelial cells and fibroblasts when appropriately stimulated in vitro. The levels of endogenous G-CSF can increase to detectable levels when there is a demand...

CDA type II

Type II will be described first as it is the most common type of CDA. It is transmitted as an autosomal recessive disease the geographical distribution of the earlier recorded cases suggests a particularly high frequency in north-west Europe, in Italy and in North Africa. It is usually diagnosed in the first few years of life. Some cases have presented with anaemia and or jaundice at birth, and this should be considered in the evaluation of nonimmune hydrops fetalis. The clinical manifestations...

Cobalamin

Cobalamin (vitamin B12) exists in a number of different chemical forms. The molecule consists of two halves a 'planar group' and 'nucleotide' set at right angles to it (Figure 5.5). The planar group is a corrin ring and the nucleotide consists of the base, 5,6-dimethylbenziminazole, and a phosphorylated sugar, ribose-s-phosphate. In nature, the vitamin is mainly in the Figure 5.5 The structure of vitamin B12 (cyanocobalamin). Figure 5.5 The structure of vitamin B12 (cyanocobalamin)....

Hydroxyurea

Hydroxyurea (HU) is a tremendously important drug in the management of patients with SCD who have severe clinical manifestations. HU inhibits ribonucleotide reductase, leading to S-phase arrest of replicating cells, and is used in SCD because of its ability to stimulate production of HbF. HU increases HbF as a result of stress erythropoiesis induced by its myelosuppress-ive effect. Patients show variable response in the degree of rise in HbF, and some experience no change from the baseline...

Optimum temperature and pH for complement lysis

Many of the active complement components are enzymes and as such are very sensitive to changes in pH and temperature. The optimum pH for haemolysis to occur is 6.8 and the optimum temperature is 32-37 C. At temperatures below 15 C, the red cell cannot be haemolysed by complement and it is assumed that the last stages of complement fixation do not occur. However, the early stages of complement fixation can occur at 15 C and the components can be detected on the red cell surface with...

Diagnosis Peripheral blood findings

The peripheral blood picture depends upon the type of sickle cell syndrome. The haemoglobin level is normal in the newborn period, but anaemia develops and sickle or cigar-shaped ISCs can be observed in the peripheral blood by 3-4 months of age as HbF declines. In HbSS disease, the red cells are normocytic and normochromic, with polychromasia, many ISCs and fewer target cells (Figure 7.5a). The average reticulocyte count is 10 (4-20 ) and normoblasts may be observed. Red cells are microcytic in...

Regulation

The globin gene clusters contain several types of regulatory elements that interact to promote erythroid-specific gene expression and to coordinate changes in globin gene activity during development. They include promoter elements, enhancers, i.e. regulatory elements that increase gene expression despite being located at a variable distance from the genes, and, in the case of the P-globin gene cluster, a master sequence called the 'locus control region' (LCR), or 'locus activating region'...

Neonatal topup transfusion

Premature infants are amongst the most widely transfused patients, with 'top-up' transfusions being very frequent. Only the first pretransfusion sample needs to be tested, with no further sample testing until 4 months of age, as infants are not cap able of making clinically significant antibodies in the first months of life. Ideally, the unit of red cells used for the first transfusion should be aliquoted into several (six to eight) satellite packs and used for the same infant until expiry, to...

Anticoagulants and solutions for red cell preservation

The addition of 'rejuvenating' agents or purine nucleosides (adenosine, inosine) to standard anticoagulant solutions has been shown to improve significantly the viability of red cells (e.g. CPD-AI). Adenosine is effective in restoring the ATP content of stored red cells, whereas inosine restores the 2,3-DPG content. Adenosine is potentially toxic, although rapidly deaminated to inosine in the circulation. Inosine catabolism can raise serum uric acid levels. Hence, neither compound is used in...

Dyserythropoiesis

Fukada MN, Papayannopoulou T, Gordon-Smith EC etal. (1984) Defect in glycosylation of erythrocyte membrane proteins in congenital dyserythropoietic anaemia type II (HEMPAS). British Journal of Haematology 56 55-68. Marks PW, Mitus AJ (1996) Congenital dyserythropoietic anemias. American Journal of Haematology 51 55-63. Tomita A, Parker CJ (1994) Aberrant regulation of complement by the erythrocytes of hereditary erythroblastic multinuclearity with a positive acidified serum lysis test (HEMPAS)....

Subclassification of severe combined immunodeficiency

Infants and young children with SCID can be conveniently sub-classified into those patients who lack both T and B lymphocytes (T- B- SCID) and those who retain B lymphocytes (T- B+ SCID). Additional clues to the molecular diagnosis can be provided by the presence or absence of natural killer (NK) cells (Figure 22.1). This is only a guide to a molecular defect, and is less reliable in patients presenting later in life. The most common molecular defects involve the recombinase-activating genes...

P blood groups

P1 was discovered by Landsteiner and Levine, who used suitably absorbed sera of rabbits injected with human red cells. About 75 of subjects tested were positive for P1, which is inherited as a mendelian dominant character. P1 frequency varies in different populations and the P1-negative phenotype is called P2. P1 is weakly expressed at birth and its strength varies considerably in adults. For this reason, identification of anti-P1 can be difficult, as panel cells will have varying expression of...

AThalassaemia traits

A0-Thalassaemia trait is characterized by a mild hypochromic anaemia with red cell indices similar to those of the P-thalassaemia trait the HbA2 level is normal. There are no diagnostic tests with which to identify this condition with certainty except DNA analysis. Deletional a+-thalassaemia carriers have near-normal haematological findings. The heterozygous states for the non-deletion forms of a+-thalassaemia are sometimes associated with very mild hypochromic anaemia the type associated with...

Pharmacological alternatives

Aprotinin in cardiac and liver surgery. Tranexamic acid infusion intra- or post-operatively. Appropriate use of blood and alternatives to allogeneic blood transfusion DDAVP preoperatively in mild haemophiliacs. Intravenous iron, with or without recombinant erythropoietin (rEPO) preoperatively, especially in patients intolerant or unresponsive to oral iron. In the future Oxygen carriers such as fluorocarbons. Haemolytic disease of the newborn (HDN) is a condition in which the lifespan of the...

Alloimmune haemolytic anaemia

Drug-induced immune haemolytic anaemia Immune haemolytic anaemia produced by drugs is rare but, in some cases, it may be very severe and even life-threatening. There are three main mechanisms by which red cell destruction is increased by antibodies bound to the red cell surface. Autoimmune haemolytic anaemia induced by methyldopa has been described in the previous section. Immune antibodies which require the presence of the drug to produce a positive DAT may react with red cells when the drug...

Classification

Because of the unique structural and functional specialization of the mature red cell, the impact on it of a wide range of exogenous or endogenous changes is relatively uniform the cell will be destroyed prematurely. According to the site of the primary change, haemolytic disorders have been traditionally classified as being due either to intracorpuscular or to extracorpuscular causes. According to the nature of the primary change, haemolytic disorders have also been classified as inherited or...

Agents that enhance agglutination

Various agents may be added to serological mixtures to enhance the agglutinability of red cells. These include albumin and LISS, as described above, as well as polybrene and polyethylene glycol (PEG). Whereas albumin and LISS work by reducing interfacial red cell surface tension and increasing electrostatic attraction, respectively, the mode of action of polybrene and PEG is not so clear. Polybrene is the bromide salt of polymerized hexadime-thrine and, as a quaternary amine, is thought to...

Hereditary spherocytosis

As the name implies, hereditary spherocytosis (HS) is a genetically determined haemolytic anaemia characterized by the spherical shape of the affected red cells. The spherical shape produces a characteristic appearance in the stained blood film of round cells with smaller than normal diameter, which lack the area of central pallor of the normal biconcave discs (Figure 8.4). The Figure 8.4 Hereditary spherocytosis, peripheral blood. Small spherocytic red cells lack area of central pallor. Large...

Sensing hypoxia

Tissue hypoxia induces a variety of physiological responses in addition to activation of the Epo-EpoR pathway (see below). Parallel responses include the stimulation of new blood vessels by vascular endothelial growth factor (VEGF) and metabolic changes (e.g. in glycolytic pathway enzymes) that enable continued energy production despite inadequate oxygen availability. In addition, expression of the transferrin receptor is upregulated. Over the past few years the mechanisms by which cells sense...

Electronic crossmatch

A number of hospitals with suitable blood bank computing systems now use a so-called 'electronic cross-match' or 'electronic issue'. A patient has group and screen performed on two separate occasions. If both screen results on the laboratory's computer system are negative, and if no blood has been transfused during this period, ABO and Rh compatible blood is issued directly via the computer with no further wet testing being performed. This makes it possible to reduce the number of operations...

Haemoglobin estimation

A test to exclude anaemia is performed before donation. A convenient and widely used method depends upon the specific gravity of a drop of blood, obtained by means of a finger prick. An estimate of the Hb value can be made, depending upon whether the drop of blood sinks in a copper sulphate solution of known specific gravity. The standard for male donors is generally a solution of specific gravity 1.055, approximating to a Hb level of 13.0 g dL. The equivalent for females is 1.053 (Hb of 12.0 g...

Neuroferritinopathy

A previously unknown, dominantly inherited, late-onset basal ganglia disease, variably presenting with extrapyramidal features similar to those of Huntington's disease or Parkinsonism also shows iron accumulation in the forebrain and cerebellum. The disorder was mapped 19q13.3, which contains the gene for ferritin light-chain polypeptide (FTL). An adenine insertion at position 460-461 was found that was predicted to alter carboxy-terminal residues of the gene product. Abnormal aggregates of...

Erythropoiesis in clinical practice

Erythropoiesis is disturbed to a greater or lesser extent in almost all multisystem diseases and so the reader is referred to other chapters and references for specific examples. The aim of this chapter is to provide a framework for thinking about the process of erythropoiesis in clinical practice. The first stage involves the production of committed erythroid progenitors. The second involves controlling red cell production, which is mainly achieved via the oxygen sensor influencing the level...

Antibodies of the ABO system AntiA B and AB

Sera taken from people over the age of about 6 months which do not contain the expected A and B antibodies (Table 15.3) are very rare. They should always be investigated thoroughly often, some interesting explanation will be found, for example a rare subgroup of A, a blood group chimera or congenital absence of IgM. It is likely that ABO antibodies arise in response to A- and B-like antigens present on bacterial, viral or animal molecules. Titres of ABO antibodies vary considerably with age,...

Bone marrow failure and relationship between paroxysmal nocturnal haemoglobinuria and acquired aplastic anaemia AAA

PNH has an intimate link with AAA, for several reasons. As stated above, sometimes a patient with PNH becomes 'less haemolytic' and more pancytopenic and ultimately evolves to frank AAA. In terms of pathogenesis, it is believed that AAA is essentially an organ-specific autoimmune disease that is mediated by 'activated' cytotoxic (CD8+) T lymphocytes, which are able to inhibit haemopoietic stem cells. Recently, skewing of the T-cell repertoire indicating the presence of abnormally expanded...

Fabrys disease

Fabry's disease (or Anderson-Fabry disease) is an X-linked lysosomal storage disorder due to mutation within the gene for a-galactosidase A (aGal A) (Figure 19.2). The resulting inability to catabolize glycosphingolipids leads to progressive accumulation of the substrate globotriasylceramide (Gb3) in a range of tissues. In contrast to GD, the lipid accumulation in Fabry's disease affects a range of cells (e.g. endothelial cells, epithelial cells, myocytes) within a broad range of tissues and...

Factors that affect the second stage of agglutination

These include the degree of contact of the antibody-coated red cells with each other, the span of the antibody molecules, the electrical charge of the red cells, the location and density of the antigen sites on the red cells and the capacity of the antibody to bind complement after reacting with the antigen. The degree of contact of antibody coated cells It is obvious that the antibody molecules cannot form bridges between individual cells until the cells are close together. This contact can be...

HLA function

Table 24.1 Complete listing of recognized serological and cellular HLA specificities. Table 24.1 Complete listing of recognized serological and cellular HLA specificities. B54(22) B55(22) B56(22) B57(17) B58(17) B59 B60(40) B61(40) B62(15) B63(15) B64(14) B65(14) B67 Broad specificities are indicated in parentheses. Figure 24.3 The increase in number of HLA alleles identified by year. Figure 24.3 The increase in number of HLA alleles identified by year. For example, the A*24020101 and...

Factors affecting the first stage of agglutination

Factors that affect the equilibrium constant include pH, ionic strength and temperature. Most antibodies are not affected by changes in pH within the range 5.5-8.5. However, this is not true for all antibodies, and, in order to make one day's work similar to the next, routine serology should be carried out with saline buffered to pH 7.07.4. Below pH 4 and above pH 9, antigen-antibody complexes are largely dissociated and the antibody can be recovered in the supernatant. This is the basis of...