Secondary cytotoxic response in vitro against Moloney lymphoma cells antigenically altered by drug treatment in vivo.

Cell-mediated cytotoxic response in vitro to a Moloney strain of murine leukemia virus-induced tumor (LSTRA) altered by 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC) was investigated with the use of mixed-leukocyte tumor cell cultures (MLTC). As assessed by means of a short-term 51Cr-release assay, minimal or no cytolytic activity was generated in primary MLTC. In contrast, high specific cytotoxic response against the altered tumor was obtained in secondary MLTC. Partial cross reactivity was found between the LSTRA and LSTRA/DTIC tumor lines.