Evidence for macrophage C3d-receptor active in phagocytosis.

Evidence is presented that guinea pig peritoneal macrophages possess membrane receptors able to recognize the C3b inactivator-cleaved third component of complement. This conclusion is based on the finding that rosette formation and phagocytosis by macrophages of EA-IgM-C1423 were equal regardless of whether EA-IgM-C1423 had been pretreated with C3b inactivator or not.