Lymphocyte Blastogenic Responses to Cultured Allogeneic Tumor Cells in Vitro¹

For development and evaluation of systems through which tumor immunity might be evaluated in man, allogeneic tumor cell-lymphocyte interactions were studied with the one-way mixed culture technique. The critical importance of dose-response studies in the evaluation of this interaction was demonstrated. Maximal blastogenic lymphocyte responses were induced by 5 X 10⁴irradiated tumor cells, and inhibition of blastogenesis was induced by 10⁶tumor cells. The median maximal blastogenic responses produced by the tumor cells was 3, 700 cpm, compared to that produced by phytohemagglutinin (58, 000 cpm), streptolysin O (17, 400 cpm), streptokinase-streptodomase (13, 500 cpm), allogeneic lymphocytes (30, 500 cpm), or allogeneic irradiated lymphoblasts (51, 000 cpm). The inhibition of blastogenesis produced by higher doses of tumor cells was caused by a nondialyzable factor released into the supernatant of cultured, irradiated, or mitomycin-treated cells. This study indicates that inhibitors influence lymphocyte blastogenic responses to tumor cells in vitro and suggests that such factors may influence host response to tumors.