Antibody-dependent cell-mediated cytotoxicity in the rat. The role of macrophages

Experiments are described in which the inactivation of macrophage activity by quartz particles is used to investigate the role of macrophages in antibody-dependent cell-mediated cytotoxicity in the rat. The results confirm previous findings which indicated that macrophages play no significant role in assays using cell line cells as targets. On the other hand, previous suggestions that macrophages are active against antibody-coated chick erythrocytes cannot be substantiated. In fact, it is shown that macrophages can play a protective role, and that inhibiting macrophage activity in peritoneal exudates leads to a spectacular increase in antibody-dependent lysis of chick erythrocytes. It is suggested that the confusion surrounding the role of macrophages in this assay has resulted from the failure to recognize that adherence techniques such as carbonyl-iron treatment of cell suspensions can result in substantial depletion of non-phagocytic adherent cells.