Peritoneal cells from congeneic resistant mice infected with BCG displayed differential cytotoxicity toward tumor cells, destroying more allogeneic tumor cells than syngeneic tumor cells. This observation was made regardless of the tumor cells used or the effector cell source. The responsible effector cell remained in a doubly adherent population, was sensitive to carrageenan and silica, insensitive to anti-thymocyte sera, and is probably a macrophage. Activated macrophages were capable of reacting against tumor cells as well as histoincompatible embryonic cells. These observations may indicate that macrophages are capable of discriminating cell surface components linked to the major histocompatibility complex.
This work was supported by National Institutes of Health Research Grant CA-16342 and by a grant from the Ohio Division, American Cancer Society.