In Vitro Destruction of Tumor Cells by Macrophages from Mice Treated with Corynebacterium Granulosum

Peritoneal macrophages from C3Hf/Bu mice treated with killed Corynebacterium granulosum bacteria were tested for their effect on in vitro growth of syngeneic fibrosarcoma cells, tumorigenic mouse L-P59 cells, human malignant melanoma cells, allogeneic fibroblasts, erythrocytes, and epithelial kidney cells. Only the cell cultures having neoplastic properties were destroyed by stimulated macrophages; the rate of tumor cell destruction was greater as the ratio of effector to target cells was increased. Neither irradiation nor trypsinization of macrophage monolayers altered the cytotoxicity of stimulated macrophages. The results indicated that C. granulosum activated macrophages to destroy tumor cells in an immunologically nonspecific manner but had no cytotoxic effect on normal allogeneic cells.