Role of complement in glomerular injury.

Abstract

The alternative and classical pathway of activation enable the complement system to operate in various phases of infection. Both pathways are tightly controlled by membrane-bound and circulating regulatory proteins. The immediate effects of complement activation comprise the direct lysis of target structures, the generation of proinflammatory molecules and the recruitment of circulating leukocytes. In addition, complement is involved in antigen processing and in the regulation of appropriate immune responses. All functions of complement contribute to the development of glomerular injury. The terminal membrane attack complex acts directly on resident glomerular cells, whereas the earlier components are effective via the recruitment of leukocytes. That the early components are critically involved also in the metabolism and clearance of immune complexes is of special relevance to the pathogenesis of certain glomerular diseases. The exact role of complement components produced locally by resident glomerular cells has yet to be determined.