TARGETED DISRUPTION OF THE MURINE GENE CODING FOR THE 3RD COMPLEMENT COMPONENT (C3)

Complement is a system of more than 30 proteins found both in plasma a nd on cell membranes. The complement system has several important func tions in the immune response including initiation of inflammation, neu tralization and elimination of pathogens, regulation of antibody respo nses, clearance of immune complexes and disruption of cell membranes. Under certain conditions complement may, however, act as a mediator of deleterious inflammatory reactions and complement activation has been implicated in the pathogenesis of autoimmune disorders, atheroscleros is, neurodegenerative diseases, bioincompatibility reactions and decom pression sickness. Using gene targeting, we have generated mice defici ent for the third complement component (C3). These mice represent an a nimal model in which complement activation by any pathway is prevented at an early stage. The C3-deficient mice should be valuable for the s tudy of the roles of the complement system in vivo in a variety of phy siological and pathological situations.