Tumor necrosis factor as a potent effector molecule for tumor cell killing by activated rat peritoneal macrophages in...

Tumor necrosis factor (TNF) sensitive (BP6-Tu2) and less or insensitive (B77, MC-1) target cell lines were used to examine the role of TNF in lytic phases of activated peritoneal macrophages and/or direct (murine)-TNF alpha cytolytic activity against these targets. Using antibody to murine TNF, it was shown that lysis of BP6-Tu2 cells was TNF-mediated. This macrophage lytic activity was markedly diminished or even abolished by anti-TNF alpha antiserum. Results indicated that TNF alpha is the critical effector of macrophage mediated killing of these targets. The tumoricidal activity and its level was dependent upon the length of cultivation of macrophages, induction period and concentration of activators. The findings not only support the thesis that macrophages possess various means of coping with tumor cells but also suggest that the mechanism becoming operative is determined predominantly by the pathway of macrophages activation and the properties of the tumor-cell type.