Cytotoxic cells induced in tumor-bearing rats by a streptococcus preparation (OK-432).

The characteristics of the cytotoxic cells induced by ip injections of an immunoadjuvant, OK-432 (Picibanil), into ACI/N rats bearing syngeneic bladder cancer, BC47, were examined. The cytostatic activity, but not the cytolytic activity, of peritoneal macrophages was augmented when either normal or cancer-bearing rats were treated with OK-432. In contrast, the plastic nonadherent cells of the peritoneal exudate cells from OK-432-treated cancer bearing rats, but not lymph node cells or spleen cells, killed all ACI/N rat bladder cancers tested as well as ACI/N rat hepatoma cells and Meth-A mouse sarcoma cells. The plastic nonadherent cells from OK-432-treated normal rats also killed hepatoma cells and Meth-A cells, but not bladder cancer cells. The cytolytic cells that were induced in cancer-bearing rats by OK-432 treatment and showed cytolytic activity specific for bladder cancer were found to be sensitive to anti-rat thymocyte serum and complement, nylon-adherent, and Fc receptor-negative. The cells that showed nonselective cytolytic activity were nylon-adherent and insensitive to anti-rat thymocyte serum and complement.