Tumor Cytotoxicity In Vitro by Macrophages From Mice Infected With Mycobacterium bovis Strain BCG

Mice were infected intradermally (id) or intraperitoneally (ip) with living BCG. Three days after initiation of ip infection, adherent peritoneal cells (macrophages) were cytotoxic to tumor cells in vitro. Peritoneal cells obtained after initiation of id infection were not cytotoxic. Macrophages from mice infected ip with BCG killed syngeneic, allogeneic, and xenogeneic tumor cell lines. Normal syngeneic, allogeneic, and xenogeneic embryo cells were less susceptible than neoplastic cell lines to macrophage cytotoxicity. Cytotoxicity required close contact between macrophages and target cells and an adequate number of effector cells. Macrophages were cytotoxic to both proliferating and non proliferating target cells.