Cell surface proteins reacting with activated complement components

The biologic activities mediated by the products of complement activation include cellular, bacterial, and viral lysis, inflammation, phagocytosis, and immunoregulation. These responses are achieved through the interaction of the activated forms of several of the complement proteins with cell membrane proteins. This report reviews aspects of the structure, ligand specificity, and function of the various complement receptors with particular emphasis on those receptors which bind to the activated fragments of C3. In addition, we briefly summarize the surface proteins on foreign particles that bind C3 and their possible role in the pathogenesis of these organisms.