Describe two things that the complement factor C3 or its met

Describe two things that the complement factor C3 (or its metabolites) can do.

Solution

Complement C3 is the third and most abundant component of the complement pathway. It plays a central role in complement activation, being involved in both the classical and alternative pathways. C3 or its proteolytic fragments mediate many biological functions such as opsonization and anaphylatoxin activities. C3 is cleaved by the C3 convertases in either pathway (C4b2a, C3iBb, C3bBb) to C3b (176 kDa) comprised of the large C-terminal portion of the -chain and the -chain. C3b interacts with other complement components to initiate the amplification cascade. Studies of C3 function have been facilitated by experimentally induced C3 deficiency in animals by injection of cobra venom factor and more recently with gene ablation technology.

   C3a\'s roles in innate immunity, upon binding C3aR, include increased vasodilation via smooth muscle contraction, increased vascular permeability, and mast cell and basophil degranulation of histamine, induction of respiratory burst and subsequent degradation of pathogens by neutrophils, macrophages, and eosinophils, and regulation of cationic eosinophil protein migration, adhesion, and production

     C3a also plays an important role in adaptive immunity, moderating leukocyte production and proliferation. C3a is able to regulate B cell and monocyte production of IL-6 and TNF-, and human C3a has been shown to dampen the polyclonal immune response through dose-dependent regulation of B cell molecule production