Macrophage‐mediated cytotoxicity against allogeneic target cells in vitro

A system is described in which monolayers of sensitized peritoneal macrophages destroy allogeneic target cells in vitro . The cytotoxic effect is measured by 51 Cr release from labeled mastocytoma target cells. Different methods were applied to rule out any lymphocyte contamination. Stainings at different stages of the reaction excluded phagocytosis of target cells. At a ratio of 20 macrophages to 1 target cell destruction is complete after 24 h. Macrophages reacted to multiple challenges by repeated lysis of the target cells. Macrophages treated with trypsin lost their cytotoxicity but regained cytotoxic capacity 48 h after treatment. By labeling the sensitized macrophages with 51 Cr it was shown that they keep full viability during the cytotoxic action.