Effects of platinum antitumor agents on in vitro assays of human antitumor immunity. II. Effects of cis-[Pt(NH3)2Cl2] on spontaneous cell-mediated cytotoxicity

The effects of cis-[Pt(NH3)2Cl2] on the spontaneous cell-mediated cytotoxicity of human lymphoblast cell lines mediated by normal human peripheral blood lymphocytes was investigated. Direct addition of cis-[Pt(NH3)2Cl2], but not its tumor inactive trans isomer, to the in vitro spontaneous cytotoxicity assay resulted in a small but significant enhancement of target cell lysis. Pretreatment of target cell lines with 5 micro M cis-[Pt(NH3)2Cl2] also resulted in a similar increase in target cell susceptibility to lysis.