Complement

Complement is part of the innate immune system and underlies one of the main effector mechanisms of antibody-mediated immunity. It has three overarching physiologic activities (Table 1): defending against pyogenic bacterial infection, bridging innate and adaptive immunity, and disposing of immune complexes and the products of inflammatory injury. In this review, each of these activities will be placed in a clinical context.Complement was first identified as a heat-labile principle in serum that “complemented” antibodies in the killing of bacteria. We now know that complement is a system of more than 30 proteins in plasma and on cell surfaces. Complement . . .