title: Human peritoneal macrophage cytotoxicity mediated by cytophilic IgG.
abstract: Cells of the human mononuclear phagocyte system have recently been shown to possess cytophilic IgG molecules that promote phagocytosis of staphylococci bearing cell-wall protein A. In the present study, the possible mediation of a cytotoxic response to 51Cr-labeled sheep erythrocytes coated with protein A by cytophilic antibodies on human peritoneal macrophages was evaluated. The target cells were readily lysed by peritoneal macrophages. Cytotoxicity was blocked by pretreatment of macrophages with soluble protein or with anti-Fc F(ab')2 fragments. In contrast, cytotoxicity was not affected by cytochalasin B; this finding suggests that cytolysis is an extracellular event. Perturbation of cytophilic IgG with particle-bound protein A elicited a chemiluminescent response from peritoneal macrophages; however, experiments with scavengers of reactive oxygen species indicated that toxic oxygen radicals may not be required for cytotoxicity. The results indicate that cytophilic antibody-mediated cytotoxicity may contribute to cellular injury as well as host-defense aspects of the inflammatory process.
mesh_terms: D000920:Antibody-Dependent Cell Cytotoxicity; D001202:Ascitic Fluid; D002412:Cations / Q000378:metabolism; D003571:Cytochalasin B / Q000494:pharmacology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D008163:Luminescent Measurements; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010587:Phagocytosis; D013205:Staphylococcal Protein A / Q000276:immunology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002412:Cations; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D003571:Cytochalasin B; D014700:Verapamil; D010100:Oxygen