INDUCTION OF CELLULAR PROCOAGULANT ACTIVITY BY THE MEMBRANE ATTACK COMPLEX OF COMPLEMENT

ln addition to their well-recognized role in immune defense, there is a growing recognition that the proteins of the complement system impac t directly on vascular homeostatic mechanisms, evoking cellular respon ses that serve to both promote adherence of blood cells to the walls o f blood vessels, and the formation of fibrin through the enzyme mechan isms of the coagulation system. This clot-promoting or 'procoagulant' activity initiated through the complement system entails both receptor -mediated as well as receptor-independent pathways of cell activation. In this review, we will focus specifically upon the rob that is now t hought to be played by the membrane attack complex of the complement s ystem (MAC) in the induction of the procoagulant properties of human p latelets and endothelium.