Hematology - Coursework Example

?Hematology Laboratory Questions Q1. Labelled diagrams and of function of each cell type: - Neutrophil: Neutrophils are granulocytes –white blood cells - produced by the bone marrow. There are about 1.3 x 1011 neutrophils per 80-kg person per day produced by hematopoietic system. Neutrophils contain primary (azurophilic) and secondary granules. Primary granules contain a enzymes and molecules that play a role in killing microbes, including hydrolases, elastase, myeloperoxidase, cationic proteins, defensins, and bactericidal/permeability-increasing protein. Secondary granules contain unique molecules such as lactoferrin, vitamin B12–binding protein, NADPH oxidase (which produces hydrogen peroxide), and chemoattractants receptors. The nucleus of neutrophils normally contains up to four segments, which is why they are also known as polymorphonuclear (PMN) cells. Neutrophils are phagocytes that perform the functions of immune surveillance and in situ elimination of microorganisms and cell debris. They circulate in the blood and also line vascular endothelium. They are the first immune cells to arrive at the site of inflammation through chemotaxis, and rapidly extravasate into the surrounding tissues. In the tissues, they release the degradative enzymes in their secondary granules that kills bacteria but also causes tissue destruction. They carry out phagocytosis to engulf opsonized cell debris and microorganisms that they come in contact with. The vacuole with the phagocytosed organism is fused with the primary granules, causing the oxidative and antimicrobial enzymes to access and kill the ingested microorganism. Neutrophils self-destruct after a life of 1-4 days in tissues. - Lymphocyte There are two main types of lymphocytes: B cells and T cells. They are round cells with a large, round nucleus and scant cytoplasm. Lymphocytes govern the acquired arm of immunity, they are responsible for mounting a specific host immune response targeted against a particular invading organism. B cell precursors are produced in the bone marrow, but they migrate to the peripheral lymphoid organs, where they undergo maturation with antigen exposure to plasma cells. An important function of plasma cells is to produce immunoglobulins (Igs). A major function of immunoglobulins is to act as antibodies. Antibodies help degrade and clear foreign substances by binding to specific microorganisms’ molecules called antigens, a process termed opsonization, and produce specific results including antibody-mediated cellular toxicity and activation of the complement system that destroys foreign cells. There are hundreds of thousands of different B cells in the body at a time, each is capable of producing an immunoglobin specific to a microbe, this arsenal of B cells makes the body capable of mounting an antibody response against nearly every possible virus, bacteria, fungus and protozoa that can be encountered. T cells similarly undergo maturation in peripheral lymphoid organs and the thymus, they produce ‘T cell receptors’ specific to foreign microbes. Activation of T cells requires interaction of the T cell receptor with an antigen-presenting cell; activated T cells are responsible for delayed-type immunity. There are 2 main types of T cells: CD4 cells, called T helper cells, which produce cytokines that activate B cells (by IL-4 and IL-5), macrophages (by IFN-gamma) and other immune cells. CD8 cells, also called T cytotoxic cells, destroy cells with intracellular microorganisms such as M. tuberculosis, virus-infected cells, tumor cells and allografts. - Monocyte Monocytes are circulating agranulocytes with a kidney-shaped nucleus. They have two main functions: phagocytosis of microorganisms, and presentation of antigens to T cells to activate the acquired arm of immunity. They are released from the bone marrow and circulate in blood for about 72 hours before migrating into tissues to transform into macrophages to carry out their functions. They have surface receptors that can recognize bacteria, such as Toll-like receptors and mannose-binding lectin, and become activated. Activated macrophages, apart from carrying out phagocytosis, release a number of prostaglandins that mediate inflammation, and cytokines, including IL-1, responsible for causing fever. They also produce clot-promoting substance. The phagocytosed organism is digested inside the cell by lysosomal enzymes and oxidizing free radicals, after which breakdown particles as antigens are displayed on the cell surface. A specific variant of monocytes, the dendritic cell, has many branches and is highly specialized for the function of presenting antigens to the T cell. Other specialized types of monocytes include Kupffer cells in the liver, and microglia in the central nervous system. - Eosinophil Eosinophils are granulocytes, their name is derived from their intensely eosinophilic (pink) staining on staining for microscopy. They are present in much smaller levels in the blood than neutrophils, monocytes and lymphocytes, they are non-phagocytic cells that contain eosinophilic granules. They are not gamechangers in general bacterial or viral infections, however, they play a special role in the body’s defense against helminthic infections, such as intestinal worms. They are attracted to sites with helminthic burden and allergens through chemoattractants such as eotaxin, and Il-4, 5 and 13. They recognize parasites through specific IgE receptors on their surface, and release their granules’ contents. These include destructive enzymes such as major basic protein, eosinophilic cationic protein, eosinophil peroxidase, and reactive oxygen intermediates. These substances are toxic to helminthes. Eosinophils are also involved in mediating bronchial asthma and allergic reactions, where the allergen is recognized through surface IgE, activating the eosinophil. - Basophil Basophils are also granulocytes found in very small numbers in the blood – they are the rarest type of leukocyte. Their name is derived from their intensely blue staining granules seen on Wright staining for microscopy. They play a role in allergic reactions, they are found concentrated in tissues where foreign proteins are present, and they mediate inflammation by releasing cytokines including IL-4 and IL-13. Mast cells are immune cells derived from the same progenitor cells in the bone marrow as basophils, they appear morphologically similar to basophils and reside in connective tissue. Both mast cells and basophils release histamine, peroxidases and hydrolases stored in their granules upon activation by allergenic proteins that bind to their surface IgE receptors, to produce edema, inflammation and tissue destruction in hypersensitivity reactions. In large amounts of degranulation, the inflammation due to histamine can be severe life-threatening, as occurs in anaphylactic shock. Q2. Answer the following (write approx 200 words each): a) Describe how to make a good blood film - state what you would expect a good blood film to look like. To make a blood film, we require clear glass slides, measuring 75 ? 25 mm, and 1 mm thick. We place a drop of blood, about 4 mm in diameter, on one end of the glass. Then the drop is spread along this slide; to do this, another slide’s edge (the spreader) is placed at an angle of 45° and applied to the slide surface to push the drop towards the slide edge, and then dragged in the opposite direction to pull and spread the drop along the length of the slide by capillary action. The smear is then air-dried and dipped in methanol to fix the cells, after which a drop of stain such as Wright’s stain is applied for 10-20 seconds. The slide is then rinsed with distilled water and left to dry. When a good blood film is seen under the microscope, the central area should show a monolayer of cells barely touching or separated from each other. No clumps of cells should be seen in this area. The part of the film at the start of the drag should be too thick with too many cells, and the slide at the end of the drag should be too thin, with too few cells seen far apart. b) Describe the principles of Romanowski staining- give 2 examples of stain types A Romanowsky stain is any stain combination that includes eosin (Y or B) and methylene blue, or any of its oxidation products. Romanowsky staining is based on the principle of one cationic dye and one anionic dye. results in purple coloration of leukocyte nuclei and neutrophilic granules, and bright pink coloration of eosinophilic granules. Red blood cells appear reddish pink, cytoplasm of leukocytes is varying shades of light blue. Examples of Romanowsky staining include Wright’s stain and Giemsa stain. c) Discuss the full blood count and blood film results you would expect in a case of glandular fever and what further tests could be carried out to confirm the diagnosis. Glandular fever, also known as infectious mononucleosis, is a systemic viral infection caused by Epstein-Barr virus. The full blood count in glandular fever typically shows leukocytosis, which is specifically lymphocytosis. An increase in the white blood cell count is seen, which consists predominantly of lymphocytes. On blood film, atypical lymphocytes are seen, which are abnormal-looking lymphocytes with different cells of different morphologies. Other tests that can be done are: -The Monospot test, also known as the heterophile antibody test. It is a latex agglutination assay that detects non-EBV antibodies that are produced in the body during EBV infection, which cause agglutination of animal red blood cells. -EBV –specific antibodies IgM and IgG to VCA (viral capsid antigen). d) What does the term neutropenia mean and what could be the cause of this? A decrease in the number of blood neutrophils is called neutropenia. Specifically, neutropenia is defined by a blood absolute neutrophil count that is less than two standard deviations below the normal population mean. Severe neutropenia usually refers to counts less than 500 neutrophils/microliter. Neutropenia can occur as "selective" neutropenia, where neutrophils are the only type of white blood cells with reduced counts. This can occur, for example,with drug-induced neutropenia. In other conditions, several types of white blood cells are affected but the reduction in neutrophil is more prominent. The latter is called pancytopenia Neutropenia can be inherited or acquired. It usually results from decreased production of neutrophils in the bone marrow, in conditions such as anemia, chemotherapy treatment, leukemias, lymphomas, or with thrombocytopenia. It can also occur when neutrophils shift from the circulation into the marginated cell pools and tissues. Neutropenia can also manifest due to increased destruction of neutrophils. Neutropenia may also occur in some systemic diseases such as vitamin B12 deficiency. Neutropenia increases the patient’s susceptibility to bacterial or fungal infections and impairs the resolution of these infections. e) what does the term neutrophilia mean and what could be the cause? An increase in the number of blood neutrophils is called neutrophilia. It is an increase in the absolute neutrophil count to a concentration greater than two standard deviations above the normal population mean value. Neutrophilia usually occurs with inflammatory conditions and infectious diseases. Bacterial infections usually produce neutrophilia, while viral infections raise the neutrophil count by only a small percentage or not at all. Cancer can sometimes induce a significant neutropenia. Blood cancers that produce neutrophilic precursor cells, such as variants of chronic myeloid leukemia and chronic neutrophilic leukemia, can give neutrophilia. When the neutrophil count is very high, it may be referred to as a leukemoid reaction. Demargination of neutrophils from the vascular endothelium, which occurs with corticosteroid use, and a rapid release of neutrophils from a large bone marrow pool, can also cause a passing increase the absolute neutrophil count. Read More