Complement receptor type three-dependent degradation of opsonized erythrocytes by mouse macrophages.
The role of the complement receptor type 3 (CR3) on thioglycollate-elicited peritoneal macrophages (TG-PM) in the destruction of opsonized particles was studied. We found that sheep red blood cells (E) that were opsonized with an IgM monoclonal anti-Forssman antibody and complement (E-IgM-C) were lysed by TG-PM, whereas there was little lysis of E pretreated with either the antibody or the complement source alone. Furthermore, this lysis could be inhibited by anti-CR3 monoclonal antibodies that had previously been shown to inhibit binding of E-IgM-C to the CR3. Kinetic studies of phagocytosis and lysis indicated that lysis of E-IgM-C occurs after phagocytosis, suggesting that lysis is an intracellular event. Further findings suggested that intra-cellular lysis was promoted by CR3 bound to the phagocytosed target, because a monoclonal anti-CR3 antibody decreased the rate of phagocytosis of E-IgM-C but not its magnitude, whereas the rate and extent of lysis were strikingly inhibited. Furthermore, TG-PM that had already internalized unopsonized E selectively lysed E-IgM-C that were added later. These data confirm that the interaction of the CR3 with its ligand on E-IgM-C promotes rapid phagocytosis, and further suggest that the CR3 facilitates degradation of the target particle once internalization has occurred.
D000818:Animals; D003165:Complement System Proteins / Q000378:metabolism; D004912:Erythrocytes / Q000276:immunology*; D006461:Hemolysis; D007140:Immunoglobulin Fab Fragments / Q000502:physiology; D007074:Immunoglobulin G / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D007700:Kinetics; D008262:Macrophage Activation; D016177:Macrophage-1 Antigen; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009895:Opsonin Proteins; D011951:Receptors, Complement / Q000502:physiology*; D013864:Thioglycolates
D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016177:Macrophage-1 Antigen; D009895:Opsonin Proteins; D011951:Receptors, Complement; D013864:Thioglycolates; D003165:Complement System Proteins