Anaphylatoxin 1455844 221033068 2008-06-22T19:26:49Z DOI bot 6652755 Citation maintenance. Initiated by [[User:Fconaway|Fconaway]]. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Unreferenced|date=November 2007}} '''Anaphylatoxins''', or '''anaphylotoxins''', are fragments ([[C3 (complement)|C3a]], [[C4a]] and [[C5a]]) that are produced during the pathways of the [[complement system]].<ref name="pmid3542363">{{cite journal | author = Hugli TE | title = Biochemistry and biology of anaphylatoxins | journal = Complement | volume = 3 | issue = 3 | pages = 111–27 | year = 1986 | pmid = 3542363 | doi = | url = | accessdate = }}</ref> ==Functions== Anaphylatoxin is able to trigger [[degranulation]] of (release of substances from) [[mast cells]] or [[basophil]]s, which is an important part of the [[immune system]] in all kinds of [[inflammation]] and especially as part of defense against [[parasite]]s. If the degranulation is too strong, it can cause [[allergic reaction]]s. Anaphylatoxins indirectly mediate: *spasms of [[smooth muscle|smooth muscle cells]], for example [[bronchospasm]]s *increase in the permeability of [[capillary|blood capillaries]] *[[chemotaxis]] &mdash; [[receptor (biochemistry)|receptor]]-mediated movement of [[leukocyte]]s in the direction of the increasing concentration of anaphylatoxins ==Examples== Important anaphylatoxins: * C3a is not as strong as C5a, but stronger than C4a and can trigger degranulation of Mast-cells and serve as a chemotactic targeting molecule for eosinophile granulocytes. * C4a is the least active anaphylatoxin * C5a is the strongest toxin in the row, it is a very strong mediator of inflammation. ** [[co-stimulation]] of C3b at times of phagocytosis (not possible without C5a). ** Chemotactor and activator for granulocytes in general and macrophages ** stimulates respiratory burst in Neutrophils ** increases vascular permeability ** contracts smooth muscle cells ** activates mast cells to release Histamine and TNF-Alpha ==Terminology== Although some drugs ([[morphine]], [[codeine]], synthetic [[ACTH]]) and some [[neurotransmitter]]s ([[norepinephrine]], [[substance P]]) are important mediators of degranulation of mast cells or basophils, they are generally not called anaphylatoxins. This term is reserved only for fragments of the complement. == See also == *[[Allergy]] *[[Anaphylatoxin receptors]] *[[Anaphylaxis]] *[[Complement system]] *[[Inflammation]] *[[Immune system]] *[[Nervous system]] ==References== {{Reflist}} ==External links== * {{MeshName|Anaphylatoxin}} * {{eMedicineDictionary|Anaphylatoxin}} {{Immune system}} [[Category:Complement system]] [[de:Anaphylatoxin]] [[pl:Anafilotoksyny]] [[pt:Anafilatoxina]]