Changes

==Functions==

==Functions==

===Opsonisation===

===Opsonisation===

Once activated the complement system deposits a shell of protein on the bacterial cell surface. C4b, C3b, C5b and C7 molecules contain active binding sites that anchor the complex to the surface and the major protein on the cell surface is iC3b (some of the smaller C3 breakdown products (e.g. C3d) are also present).

Once activated the complement system deposits a shell of protein on the bacterial cell surface. C4b, C3b, C5b and C7 molecules contain active binding sites that anchor the complex to the surface and the major protein on the cell surface is iC3b (also known as C3bi) (some of the smaller C3 breakdown products (e.g. C3d) are also present).

Complement fragments (C2b, C3a, C4a and especially C5a) released after complement activation are chemotactic for phagocytes and iC3b acts as a target for [[Phagocytosis|phagocytosis]]. Phagocytes have receptors that bind avidly with the complement fragments. Complement-mediated opsonisation of microorganisms is several thousand times more efficient that innate receptors.

Complement fragments (C2b, C3a, C4a and especially C5a) released after complement activation are chemotactic for phagocytes and iC3b acts as a target for [[Phagocytosis|phagocytosis]]. Phagocytes have receptors that bind avidly with the complement fragments. Complement-mediated opsonisation of microorganisms is several thousand times more efficient that innate receptors.