DEMONSTRATION OF A HUMAN LYMPHOKINE WHICH RENDERS MACROPHAGES CYTOTOXIC

Abstract

Incubation of human peritoneal macrophages with cell free supernatants of mixed human lymphocyte cultures (MLC) renders them cytotoxic to labeled target tumor cells [human mouth epidermoid carcinoma KB cells and mouse mastocytoma P815 DBA/2 cells]. The factor responsible for this effect is found as early as the second day of MLC. The production of this factor in man does not seem to require previous sensitization. In contrast with observations in mice, in man no clear-cut difference was demonstrated between the macrophage cytotoxicity index observed with supernatants from normal MLC and from MLC between the donor and the recipient of a skin allograft. Human blood monocytes can be rendered cytotoxic by MLC acellular supernatants, but their cytotoxicity is neither as consistent nor as strong as with macrophages. This human factor does not render mouse macrophages cytotoxic.