anaphylatoxinmedical dictionary


A substance which stimulates the release of histamine producing an inflammatory reaction as part of an immunological response to a foreign antigen. This can lead to anaphylactic shock.

Anaphylatoxin is fragment of complement from C3a, C4a, C5a, and C5a des-arginine produced in the serum during complement activation. These fragments produce smooth muscle contraction, mast cell histamine release, modify platelet aggregation, and act as mediators of the local inflammatory process.

The order of anaphylatoxin activity from strongest to weakest is C5a, C3a, C4a, and C5a des-arginine.

(22 Feb 2008)