Complement As a Regulator of Interactions Between Immune Complexes and Cell Membranes

Abstract

Soluble immune complexes prepared with limited amounts of complement and injected into mice bind to circulating cells, and are then rapidly released into the plasma. The complex release is complement-dependent. Complexes prepared with excess complement do not bind to the circulating cells or to mouse lymphocytes in vitro; thus the target of the complement activity is the complex, not the cell membrane. Since complement can act to either increase or decrease the affinity of immune complexes for cell membranes, depending upon various factors, we propose that complement serves as a sensitive regulator of interactions between immune complexes and cell membranes.