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© Dirk Biddle
Neutrophils, also known as polymorphonuclear leucocytes (PMN), represent 50 to 60% of the total circulating leucocytes and constitute the ''first line of defence'' against infectious agents that penetrate the body's physical barriers. Their targets include bacteria, fungi, protozoa, viruses, virally infected cells and tumour cells. Once an inflammatory response is initiated, neutrophils are the first cells to be recruited to the site of infection or injury. Neutrophils are involved in
phagocytosis and are able to leave the blood and migrate through the vessel walls into the surrounding tissue (extravasation).
Although neutrophils are essential to host defence, they have also been implicated in the
pathology of many
chronic inflammatory conditions and
ischemia-reperfusion injury. Cytoplasmic constituents of neutrophils may also be a cause of the formation of anti-neutrophil cytoplasmic antibodies (ANCA), which have been related to the development of systemic vasculitis and
glomerulonephritis.
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Phagocytosis: The engulfing and usually the destruction of particulate matter by phagocytes that serves as an important bodily defense mechanism against infection by microorganisms and against occlusion of mucous surfaces or tissues by foreign particles and tissue debris. (M+)
Pathology: 1: the study of the essential nature of diseases and especially of the structural and functional changes produced by them
2: the anatomic and physiological deviations from the normal that constitute disease or characterize a particular disease
3: a treatise on or compilation of abnormalities (a new pathology of the eye). (M+)
Chronic: 1a: marked by long duration, by frequent recurrence over a long time, and often by slowly progressing seriousness: not acute (chronic indigestion) (her hallucinations became chronic)
b: suffering from a disease or ailment of long duration or frequent recurrence (a chronic arthritic) (chronic sufferers from asthma
2a: having a slow progressive course of indefinite duration -- used especially of degenerative invasive diseases, some infections, psychoses, and inflammations
b: infected with a disease-causing agent (as a virus) and remaining infectious over a long period of time but not necessarily expressing symptoms
Ischemia-Reperfusion Injury: Ischemia is the condition suffered by tissues & organs when deprived of blood flow -- mostly the effects of inadequate nutrient & oxygen. Reperfusion injury refers to the tissue damage inflicted when blood flow is restored after an ischemic period of more than about ten minutes. Ischemia and reperfusion can cause serious brain damage in stroke or cardiac arrest.
ANCA: Antineutrophil cytoplasmic antibodies (ANCAs) are autoantibodies directed against antigens found in cytoplasmic granules of neutrophiles and monocytes.
Antineutrophil cytoplasmic antibodies are closely associated with Wegener granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome and have contributed to new pathogenetic concepts and improved nomenclature of systemic vasculitides (antineutrophil cytoplasmic antibody-associated vasculitides).
Glomerulonephritis: A variety of nephritis characterised by inflammation of the capillary loops in the glomeruli of the kidney. It occurs in acute, subacute and chronic forms and may be secondary to haemolytic streptococcal infection. Evidence also supports possible immune or autoimmune mechanisms. (OMD)