- Granulocyte
Granulocytes are a category of
white blood cell s characterised by the presence of granules in theircytoplasm . [eMedicineDictionary|granulocyte] They are also called polymorphonuclear leukocytes (PMN or PML) because of the varying shapes of the nucleus, which is usually lobed into three segments. In common parlance, the term "polymorphonuclear leukocyte" often refers specifically toneutrophil granulocyte s, [eMedicineDictionary|polymorphonuclear+leukocyte] the most abundant of the granulocytes. Granulocytes or PMN are released from the bone marrow by the regulatory complement proteins.Classification
There are three types of granulocytes, distinguished by their appearance under
Wright's stain :
*Neutrophil granulocyte s
*Eosinophil granulocyte s
*Basophil granulocyte sTheir names are derived from their staining characteristics; for example, the most abundant granulocyte is the
neutrophil granulocyte , which has neutrally-stainingcytoplasm ic granules.Other white blood cells which are not granulocytes ("
agranulocyte s") are mainlylymphocyte s andmonocyte s.Toxic materials produced or released
Examples of toxic materials produced or released by
degranulation by granulocytes on the ingestion of microorganism includes:* Low pH vesicles (3.5-4.0)
* Toxicoxygen -derived products (e.g.superoxide ,hydrogen peroxide ,hydroxy radicals, singlet oxygen,hypohalite )
* Toxicnitrogen oxides (nitric oxide )
*Antimicrobial agents (Defensin s andcationic proteins)
*Enzyme s
**Lysozyme : dissolves cell walls of somegram positive bacteria
**Acid hydrolase s: further digest bacteriaPathology
Granulocytopenia is an abnormally low concentration of granulocytes in the blood. This condition reduces the body's resistance to many infections. Closely-related terms include
agranulocytosis (no granulocytes at all) andneutropenia (deficiency ofneutrophil granulocyte s). Transfusion of granulocytes would have been a solution to the problem. However, granulocytes live only ~10 hours in the circulation (for days inspleen or other tissue), which gives a very short-lasting effect. In addition, there are many complications of such procedure.A
granuloma is atumor containing granulocytes, and a "granulomatosis" is anecrotizing granuloma.There is usually a granulocyte
chemotactic defect in individuals who suffer frominsulin dependent diabetes mellitus .
=Additionalee also
*
Blood count
*White blood cell References
External links
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