Major actions of the complement cascade include:?

Question

a) enhancing vascular permeability and vasodilation, as well as chemotaxis, opsonization and destruction of target cells
b) mast cell degranulation, T cell activation, immunogloubin formation initiation, and enhancement of neovascularization
c) phagocytosis, coagulation, vasodilation and activation of macrophages

Answer 1

I'd choose (a). The ref. below gives the actions and pathways.

Answer 2

antibodies bind to antigen receptors on foreign invader, usually a bacterium. The C1 complex is attracted to the antibody-antigen. C1 is made up of 1 C1q, 2 C1r, and 2 C1s. This complex binds to the antibodies on the antigen. Binding to the antigen induces the C1r and C1s regions to cross proteolisis. This results in calling in another protein C4, the C1 complex cleaves C4 into C4a and C4b. C4a acts as an anaphalatoxin. C4b then covalently bonds to the bacterium via ester or amide linkages. This attracts C2 coenzyme which forms a complex with C4b and C2 is cleaved by activated C1s into C2a and b C2b is yet another anaphalatoxin. C4bC2a complex is also called the C3 convertase. This attracts and binds to C3. The C3 is then cleaved into C3b and C3a, C3a is an anaphalatoxin peptide. The new C4bC2aC3b protease is also called C3C5 convertase. This complex is able to rapidly cleave other C3 proteins which then results in the peppering of the bacterium wall with C3b fragments. This greatly increases the likelyhood of a macrophage noticing it and engulf the bacterium. C3C5convertase is also able to convert C5 into C5a and b. C5a is a very very powerful anaphalatoxin. C5b is the start of the terminal attack complex. C5b forms a complex with C6 and C7. The C7 domain penetrates the membrane and anchors the complex to the membrane, this attracts C8 to the C5bC6C7 complex. C8 penetrates into the cell membrane. The C5bC6C7C8 complex recruits many molecules of C9 which form into a circle, creating a channel through the cell membrane. This disrupts many delicate balances inside the cell and eventually will kill the cell.