Effect of anticancer agents on the susceptibility of tumor cells to immune cytolysis.

Effect of anticancer agents on the immune cytolysis of tumor cells was investigated. Cell of ascites hepatoma line of C3H/He strain of mouse, MH134, were treated with anticancer agents and used for target cells in immune cytolysis experiments. In cytotoxicity tests, MH134 cells pretreated with mitomycin C or Adriamycin were lysed by xenogeneic or allogeneic antisera and complement at significantly higher rates than non-treated MH134 cells. To test cytostatic effect of antisera, target MH134 cells were pretreated with much lower concentration of anticancer agents than that in the cytotoxicity tests, the anticancer-agent-treated tumor cells were damaged with complement and the xenogeneic and allogeneic antisera at higher rates than the non-treated tumor cells. Allogeneic spleen cells from DDD mice sensitized with MH134 tumor damaged anticancer-agent-treated MH134 cells at higher rates than non-treated MH134 cells. These results suggested an enhancing effect of anticancer agents on immune cytolysis of tumor cells in hosts who could actively and/or passively immunologically respond against tumor.