Cell-mediated allograft responses in vitro. VI. Studies on macrophage-mediated cytotoxicity.

Normal murine peritoneal macrophages were rendered cytotoxic against 51Cr-labelled allogeneic and syngeneic target cells by incubation with supernatant of selected cell cultures.'Active' culture supernatant was produced both by specifically sensitized cytotoxic T lymphocytes as well as by mitogen-stimulated T cells, but not by mitogen-stimulated B cells. The in vitro induced macrophage-mediated cytotoxicity was found to be non-specific in the sense that 51Cr-labelled target cells of different H-2 haplotype were lysed equally well.