Hematology Coursework Example | Topics and Well Written Essays - 1750 words

Hematology - Coursework Example 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 func tion 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 m ain 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