Hoffbrand's Essential Haematology This title is also available as an e-book. For more details, please see tioplacsubhesu.ml or scan this QR. Hoffbrand's Essential Haematology. Pages · The definitive haematology textbook of choice for medical studentsHoffbrand's Essential Haematology. Hoffbrand's Essential Haematology has built a reputation as the flagship haematology textbook for both students and junior doctors, providing an authoritative.
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Essential Haematology is established as the most authoritative introduction to haematology. Beautifully presented, it introduces the formation and function of. Essential. Haematology. A. V. Hoffbrand. MA DM FRCP FRCPath FRCP(Edin) DSc FMedSci. Emeritus Professor of Haematology. University College London. Essentials of tioplacsubhesu.ml - Ebook download as PDF File .pdf), Text File .txt) or read book online.
Foetal haemoglobin HbF. Haemoglobin MW The globin portion of the molecule consists of four or two pairs of polypeptide chains. Predominates in foetal life during foetal and adult life. One haem group is bound to each polypeptide chain. During embryonic life. Variants of haemoglobin: Haemoglobin is Box 1. Structure of globin genes: Basic structural properties of various red cell components haemoglobin. Genes are the base sequences. Open boxes represent pseudogenes while filled boxes represent active genes.
In humans. Splice junction sequences: These are sequences at the junction of exons and introns and are required for precise splicing or removal of introns during the formation of mRNA. Normal genotype is shown below each gene cluster Figure 1. The different functional areas of a globin gene are: Each globin gene contains three exons and two introns. Exons and introns: The regions of DNA strand which encode amino acids in the protein product are known as exons while non-coding regions which interrupt the coding sequences are known as introns or intervening sequences.
Binding of RNA polymerase to the promoter is essential for accurate initiation of transcription. Polyadenylation is required for stability of the transcript and its transport to the cytoplasm. Excision of Figure 1. Globin chain synthesis. The base sequence of RNA.
Steps in the synthesis of globin: Globin synthesis involves three steps—transcription. Processing of mRNA: In the next stage. Polyadenylation signal: Intron 1 is excised before intron 2. Translation always begins at a codon that specifies methionine AUG. This is followed by release of the completed polypeptide chain from the ribosomes. Amino acids are attached to each other by peptide bonds. The mRNA. Elongation of polypeptide chain occurs when successive amino acids are added after methionine according to the pattern provided by the genetic code.
The primary polypeptide chain is then organised into a secondary and a tertiary structure from interactions in its amino acids. The rRNA. Two different pairs of polypeptide chains with their attached haem moieties associate with each other to form a tetrameric haemoglobin molecule. This process. In activation. During this process. Hb Gower I. Termination of translation occurs when a chain-terminating or a stop codon is encountered UAA.
One molecule of haem is attached to each polypeptide chain. Hb Gower II. During splicing. The different steps of protein synthesis translation are activation. Haemoglobin variants with high oxygen affinity are methaemoglobin. Red Cell Enzymes The mature red cell requires energy to preserve the integrity of the cell membrane.
Biosynthesis of haem: Haem is a complex of protoporphyrin and iron. The function of haemoglobin is transport of oxygen from the lungs to the tissues. Small changes in oxygen tension allow significant amount of oxygen to be released or bound. There are eight helical segments designated A to H. As partial pressure of oxygen increases.
Low levels of 2. Low pH e. In this metabolic pathway. High temperature reduces the oxygen affinity while low temperature increases the oxygen affinity. When first oxygen binds to the haem group. Each polypeptide chain is arranged in a helical conformation. When the percent saturation of haemoglobin with oxygen is plotted against the partial pressure of oxygen.
The Bohr effect refers to the alteration in oxygen affinity due to alteration in pH. Charged or polar residues are arranged on the outer surface while the uncharged or nonpolar residues are arranged towards the inner part of the molecule.
The former is a stabilizing contact while the latter is the functional contact across which movement of chains occurs during oxygenation and deoxygenation. Factors affecting oxygen affinity of haemoglobin are pH. Biosynthesis of haem requires mitochondrial as well as cytosolic enzymes and therefore only erythroid precursors but not mature red cells can synthesize haem.
Iron of haem is covalently bound to histidine at the eighth position of the F helical segment. Structure and function of haemoglobin: The two dehydrogenase enzymes.
The aerobic hexose monophosphate shunt pentose phosphate shunt is another metabolic pathway in red cells. Apart from ATP and 2. For simplicity. The net yield of ATP from glycolysis is dependent upon the amount of glucose utilised by this shunt.
In the middle of the glycolytic pathway. Metabolic pathways in red cell. Spectrin is the major cytoskeletal protein.
The membrane lipids include phospholipids. The distribution of phospholipids is asymmetrical with aminophospholipids and phosphatidyl inositols located preferentially in the inner part of the bilayer and choline phospholipids in the outer part. The important skeletal proteins are spectrin bands 1 and 2.
GSH along with glutathione peroxidase detoxifies hydrogen peroxide and protects haemoglobin from oxidant damage. Most of the methaemoglobin produced in the normal cell is reduced to haemoglobin by NAD-linked methaemoglobin reductase. The transmembranous and submembranous proteins constitute the red cell cytoskeleton. The red cell membrane proteins are embedded within the lipid bilayer transmembranous proteins and also form an extensive network beneath the bilayer submembranous proteins.
Red cell membrane proteins can be separated according to molecular size by sodium dodecyl sulphate polyacrylamide gel electrophoresis SDS-PAGE. The tail ends of spectrin tetramers interact with actin and this association is stabilised by protein 4. The phospholipids are arranged in the form of a bilayer.
The polar head groups are oriented both internally and externally while the fatty acid chains are oriented toward each other. Methaemoglobin reductase that is linked to NADP requires methylene blue for its activation and is more effective in druginduced methaemoglobinaemia Fig. Various metabolic pathways in the red cell are summarised in Box 1. On electron microscopy. Different bands can be visualised when stained with a protein stain such as Coomassie blue.
The head ends of the spectrin dimers interact with those of the other spectrin dimers to form spectrin tetramers and oligomers. Red Cell Membrane The red cell membrane Fig.
Synthesis of 2. The cell membrane also serves to maintain the red cell volume by the cation pump. Schematic illustration of red cell membrane a hexagonal lattice. The senile red cells are recognized by macrophages of reticuloendothelial system and are destroyed mainly in the spleen. Degradation of haem liberates iron and porphyrin. Globin is converted to amino acids. The porphyrin is converted to bilirubin.
The membrane provides mechanical strength and flexibility to the red cell to withstand the shearing forces in circulation. Red cell destruction: The life span of normal erythrocytes is about days. This process occurs within the marrow. The membrane ATPase also drives the calcium pump. The cation pump.
The anchorage of the cytoskeleton to the overlying lipid bilayer is achieved by two associations: Iron is stored as ferritin in macrophages or is released in circulation where it is taken up by transferrin and transported to erythroid precursors in bone marrow.
Nuclear chromatin pattern is coarse. The nucleus contains nucleoli as in myeloblast stage. Cytoplasm contains both primary and secondary granules. Azurophil granules. Myelocyte stage is characterised by the appearance of secondary or specific granules neutrophilic. The cytoplasm stains light pink and has small. Myelocyte is the last cell capable of mitotic division. Band stage stab form: This is characterised by band-like shape of the nucleus with constant diameter throughout and condensed nuclear chromatin.
The next stage in the maturation is promyelocyte which is slightly larger in size than myeloblast. Primary or azurophil granules appear at the promyelocyte stage.
Primary and secondary granules: The neutrophil granules are of two types: Stages in the formation of mature neutrophils Myeloblast: Myeloblast is the earliest recognizable cell in the granulocytic maturation process.
The nucleus contains 2 to 5 nucleoli and nuclear chromatin is fine and reticular. Myelocyte is a smaller cell with round to oval eccentrically placed nucleus. Cytoplasm is relatively greater in amount than in promyelocyte stage and contains both primary and secondary granules. In the metamyelocyte stage.
This is followed by escape of neutrophils from blood vessels to extravascular tissue emigration. Mature white blood cells Figure 1. Neutrophils have receptors for Fc portion of immunoglobulins and for complement.
In response to infection and inflammation. Specific granules contain lysozyme. Lysosomal Chemotactic factors for neutrophils include bacterial factors. Many organisms are identified by neutrophils after they are coated with opsonins IgG1. Phagocytosis follows which involves three steps—antigen recognition.
Cytoplasm of the neutrophil extends in the form of pseudopods around the microorganism. Neutrophil kinetics. Neutrophil compartments and kinetics is shown in Figure 1.
Neutrophils have a life span of only 1 to 2 days in circulation. Function of neutrophils: After their formation. The escape of neutrophils is guided by chemotactic factors present in the inflammatory zone. After release from the marrow. Crystalloids derived from eosinophil membrane form characteristic Charcot-Leyden crystals.
Another oxygen-dependent bactericidal mechanism is independent of myeloperoxidase and involves formation of superoxide radicals. The nucleus has condensed chromatin and is covered by granules. Tissue mast cells are of mesenchymal origin. Maturation time for eosinophils in bone marrow is 2 to 6 days and half-life in blood is less than 8 hours. The last step in phagocytosis is killing of micro-organism.
Eosinophils Eosinophil forms via same stages as the neutrophil and the specific granules first become evident at the myelocyte stage. Basophils Basophils are small. Mast cells in connective tissue or bone marrow differ morphologically from basophils in following respects: The granules contain major basic protein. Upon reaction of antigen with membrane-bound IgE. Oxygen-dependent mechanism involves conversion of oxygen to hydrogen peroxide by oxidase in phagolysosome.
The next cell is promonocyte which has an oval or clefted nucleus with fine chromatin pattern and 2 to 5 nucleoli.
The size of the eosinophil is slightly greater than that of neutrophil. In tissues. Oxygen independent bactericidal mechanism occurs in lysosomal granules and is mediated by substances such as lysozyme. Basophils are also involved in some cutaneous basophil hypersensitivity reactions. Monocytes The initial cell in development is monoblast.
Basophils bear surface membrane receptors for IgE. Eosinophilic peroxidase along with iodide and hydrogen peroxide may be responsible for some defense against helminthic parasites.
The nucleus is often bilobed and the cytoplasm contains numerous. Basophil granules contain histamine. The mononuclear phagocyte system with irregular shape. Macrophages also recognise and phagocytose some target substances by their surface characteristics. Activated macrophages secrete a variety of biologically active substances: Activated macrophages are larger and have enhanced metabolic and phagocytic activity.
Macrophages have receptors for Fc portion of IgG and C3b and cause phagocytosis of organisms that are coated with these substances. Monocytes circulate in blood for about 1 day and then enter and settle in tissues where they are called as macrophages or histiocytes.
Coagulation factors. Prostaglandins and leukotrienes which are chemical mediators in inflammation. Cytoplasm is abundant. Macrophage phagocytosis is slower as compared to neutrophils. Complement proteins. In some organs. Oxygen-derived free radicals—hydrogen peroxide. Differences between B and T lymphocytes are presented in Table 1. Table 1. The function of B lymphocytes is production of antibodies after differentiation to plasma cells. The cytoplasm is basophilic. Origin Lymphoid stem cell in bone marrow 2.
Lymphocytes These are of two types—small and large. Percentage in peripheral blood 5. Nuclear chromatin is dense and arranged in a radiating or cartwheel pattern. The nucleus is round or slightly clefted with coarse chromatin and occupies most of the cell.
Initial development occurs in primary lymphoid organ bone marrow from where B cells migrate to the secondary lymphoid organs lymph nodes and spleen where further differentiation occurs on antigenic stimulation.
B cells undergo differentiation and proliferation to form plasma cells and memory cells. Function CD Location in lymph node 6. Plasma cells secrete immunoglobulins while memory cells have a lifespan of many years and upon restimulation with the same antigen undergo proliferation and differentiation. B Lymphocytes B lymphocytes arise from the lymphoid stem cells in the bone marrow.
Surface receptor 4. Surface antigens 3. On activation by antigen. Plasma cell is a round to oval cell with eccentrically placed nucleus and deeply basophilic cytoplasm. Their nucleus is similar to that of small lymphocytes but their cytoplasm is relatively more and contains few azurophilic dark red granules. On immunophenotyping. Each immunoglobulin molecule consists of two heavy chains and two light chains.
Antigen-independent development occurs in bone marrow while antigen-dependent development occurs in peripheral lymphoid tissues. Light chain gene rearrangement: During light chain gene rearrangement. From the C region. Heavy chain gene rearrangement Fig. The VDJ thus formed codes for amino acid sequence in variable region. There are 5 classes of immunoglobulins: During development of B cells.
Both heavy and light chains have constant and variable regions. To react with a vast array of antigens. Second immunoglobulin gene rearrangement can occur in activated B cells in which switching to new C segment of heavy chain gene occurs.
The antigen-specificity of a particular immunoglobulin molecule depends upon amino acid sequence in the variable region antigen-binding site. There are several gene segments in V. In heavy chain genes. An immunoglobulin gene consists of V Variable and J Joining exons which code for amino acid sequences in variable region.
There are two stages of B cell development: The amino acid sequences in constant regions of heavy and light chains remain same for particular class and do not determine antigen specificity.
The heavy chain genes are located on chromosome Switching does not affect VDJ exon so that antigen specificity is not altered. Important features in B cell ontogeny are outlined below.
During B cell development. This causes change in the class of the immunoglobulin molecule. B cell ontogeny Fig. The unrearranged heavy and light chain genes are present in all the cells of the body germ-line configuration. V and D regions other than V3 and D2 are deleted. The mRNA formed is translated into a m heavy chain in cytoplasm ii. According to the fundamental theory of lymphoid neoplasms. T lymphocytes T lymphocytes originate from the progenitor cells in the bone marrow and undergo maturation in thymus.
In activated B cells. The rearranged gene is transcribed into mRNA and intervening sequences between J3 and Cm are spliced. In pre-B cell. Immunoglobulin heavy chain gene rearrangement. With development and maturation new antigens are expressed while some of the previous ones are lost.
Rearrangement of immunoglobulin genes and immunoglobulin expression: Initially there is rearrangement of heavy chain genes which is followed by rearrangement of light chain genes.
Cell surface antigens: After their release from thymus. There is a sequential appearance of antigens on developing B cells: Plasma cells do not have surface expression of immunoglobulin but synthesize and secrete large amounts of immunoglobulins of one class.
This is followed by rearrangement of light chain genes. Plasma cells express specific antigens such as CD38 Fig. Cytotoxic T cells recognize antigen in association with MHC class I molecules and play an important role in cell-mediated immunity.
As shown at the bottom. Helper-inducer T cells regulate the functions of B cells and cytotoxic T cells. T cell receptor TCR: The T cell receptor complex consists of seven polypeptide chains.
There are two major subsets of mature T cells: T helper-inducer cells and T cytotoxic cells. Normal stages of B cell development showing sequential expression of various antigens and heavy and light chain gene rearrangement.
Diffuse large B cell lymphoma. Mucosa associated lymphoid tissue. T helperinducer cells recognise antigen presented by antigen-presenting cells in association with MHC class II molecules. The rearranged gene is transcribed into mRNA. Progenitor T cells from the bone marrow are transported to thymus where they undergo maturation. As there are a number of V. T cell receptor complex In a minority of T cells. TCR gene rearrangement: The genetic structure of TCR bears resemblance to that of immunoglobulins.
T cell ontogeny Fig. Although all somatic cells contain T cell receptor gene in germ-line configuration. The mature T cells are released from thymus. One segment each from V. Rearrangement of other polypeptide chain occurs similarly. During maturation. These cells do not require previous exposure or sensitisation for their cytotoxic action.
Class II antigens: Class I antigens: Genes at HLA-A.
The antigens are called as HLA because they were first detected on white blood cells. Almost all nucleated cells possess class I antigens Fig. Types of HLA antigens: Class II antigens are present on monocytes. Stages of T cell development. There are numerous allelic genes at each locus which makes the HLA system extremely polymorphic. If particular antigen is present on lymphocytes. These lymphocytes are then added to known specific antisera in microwell plates and incubated to allow the antibodies to bind to target antigens.
A vital dye eosin Y or trypan blue is then added to differentiate living. In a given population. Class III genes encode certain complement components and cytokines tumour necrosis factor. Significance of HLA antigens: HLA antigens are responsible for alloimmunization against platelet antigens and refractoriness to platelet transfusions.
The HLA genes are closely linked and are inherited by an individual as a haplotype from each parent. Complement is added to the lymphocyte-antiserum mixture followed by further incubation. Tests for detection of HLA antigens: In this test.
Lymphocytotoxicity test: Class I HLA antigens are detected by lymphocytotoxicity test. During incubation in culture. As these responder cells have been primed i. This is because class II antigens are present on B lymphocytes and not on unstimulated T cells. It is based on mixed lymphocyte culture. DNA analysis: Allelic genes at HLA-D loci can be identified by allele-specific oligonucleotide probe analysis.
This test is used for detection of class II antigens. Lymphocytes from two different individuals are cultured together. Primed lymphocyte typing PLT test: Lymphocytes from one individual are inactivated by irradiation or by mitomycin C before the test to suppress their division. Damaged cells take up the dye due to the increased permeability of injured cell membrane while living cells remain unstained. After 5 to 7 days 3H-thymidine is added to the culture and radioactive material incorporated into the dividing responder cells is quantitated.
Neutrophil-specific antigens play an important role in immune neutropaenias and in febrile nonhaemolytic transfusion reactions. In this method the culture of lymphocytes is extended for 2 weeks during which death of stimulator cells occurs and proliferation of responder cells halts.
Separation of B lymphocytes is usually achieved by magnetic beads. With the advent of polymerase chain reaction technology. These are NA1. The amount of radioactive thymidine incorporated into the dividing cells is proportional to DNA synthesis. The area J of the heavy chains in the constant regions between CH1 and CH2 domains is flexible and is called hinge region.
The H and L chains are linked together by disulfide s-s bonds. Each Fab fragment antigen binding fragment contains amino terminal portion of H chain and complete light chain and has the antigen-combining site Fig. Five classes of immunoglobulins are recognised based on the type of H chain: Amino acid composition in the carboxy terminal region of heavy chain and light chain is the constant region.
Kappa and lambda chains are present in 2: Structure of Immunoglobulins The immunoglobulin molecule consists of two identical heavy H chains and two identical light L chains. Broken line indicates site of papain digestion. Each immunoglobulin molecule can be digested by a proteolytic enzyme papain just above the disulphide bond joining the two heavy chains into three parts: They are produced by plasma cells.
Structure of immunoglobulin molecule. The fragment. The variable region of the molecule VL and VH is the specific antigen-binding site and is in the amino-terminal part of the molecule. Each chain has a constant and a variable region Fig. IgG1 and IgG2. IgD and IgE: Both are present in trace amounts in serum and are monomeric. This has high molecular weight and is also called as macroglobulin due to its large size.
There are four subclasses of IgG: IgA is present mostly in body secretions such as gastrointestinal and respiratory mucosal secretions. Alloantibodies vs autoantibodies: Alloantibodies are those which are produced by an individual against antigens present in another individual of the same species. Autoantibodies are those. Most IgG antibodies are of warm type while most IgM antibodies are of cold type.
IgG is capable of fixing complement with order of efficacy being IgG3. NO YES. Hoffbrand's Essential Haematology, 7th Edition.
Selected type: Added to Your Shopping Cart. Evaluation Copy Request an Evaluation Copy. Moss ISBN: British Medical Association Book Award Winner - Student Textbook of the Year The definitive haematology textbook of choice for medical students Hoffbrand's Essential Haematology has built a reputation as the flagship haematology textbook for both students and junior doctors, providing an authoritative introduction to the subject. Antifungals often interact with other drugs, so ask your pharmacist.
Knowing everything about haematology is not needed but seize every opportunity to attend clinics and the lab. Haematology nurse specialists have vast knowledge; listen and learn. If they bleep with concerns about a patient, run to the ward. Many day-unit attenders will be expert patients; get to know and learn from them.
Often they will be there for hours. It can be quite the social hub! Good communication skills involve active listening. Be proactive: talk to patients and relatives. Communication can prevent angst so never assume they know everything about the disease, especially prognosis. Document all discussions. Know your patients inside and out and recognise any deterioration.
The governance issues around blood products are very important. Familiarise yourself with the transfusion policies for both the unit and hospital. For further information about blood components, transfusions, and their complications, including the reporting of serious adverse events or reactions, see the Serious Hazards Of Transfusion SHOT website.
You may encounter patients with bleeding disorders such as haemophilia and Von Willebrand disease. Familiarise yourself with local policies and know how to administer treatment. Patients requiring irradiated blood products include those treated with purine analogue drugs fludarabine, cladribine, and deoxycoformycin , adults and children with Hodgkin lymphoma, and all recipients of allogeneic haemopoietic stem cell transplantation from initiation of conditioning chemoradiotherapy, and during graft-versus-host disease GVHD prophylaxis.
There are others: check the guidelines. Patients at risk of transfusion-associated GVHD should be informed of their need for irradiated blood products and given written information including an alert-card.
Your blood bank has a list of these patients. The prescription and administration of chemotherapy is strictly regulated, requiring specific training and certification. You should not be asked to prescribe or administer without this. If unsure of a drug or its interactions then check! Know the indication for prescribing warfarin, and the target international normalized ratio INR : Venous thromboembolism: first episode, target INR 2.