Description
Activation of the classical or lectin, but not the alternate, complement pathways results in the production of the C4a anaphylatoxin. C4a has been shown to be a weak multi-functional proinflammatory mediator by increasing vascular permeability, and to be spasmogenic.
In blood, plasma or serum, once formed, the nascent C4a anaphylatoxin is rapidly cleaved to the C4a-desArg form by the endogenous serum carboxypeptidase N enzyme. Thus, the quantitation of C4a-desArg in plasma or experimental samples should yield a reliable measurement of the level of classical complement pathway activation that has occurred in the test samples under investigation.
C4a production in vivo may also signal activation of the classical or the lectin complement pathways in several autoimmune diseases including rheumatoid arthritis, lupus erythematosus, and acute glomerulonephritis as well as in early stages of organ transplant rejections