[The complement system].

The complement system represents a multitude of activating factors, associated with the cellular membrane and providing for cell lysis. The system is composed of 21 serum proteins and 8 receptors and may be found in cells of various types. The major function of the system consists in its activation which entails a cascade of events terminated by cell lysis. Two complement system activation mechanisms are generally distinguished, one of which is classical and one is alternative. These two mechanisms converge after the activation of the third component (C3) or as a result of interaction between the terminal components (C5, C6, C7, C8 and C9) of the complement cascade. The complement system is linked with the fibrinolytic, blood coagulating and kinin systems.