Cell mediated immunity to human solid tumors: in vitro detection by lymphocyte blastogenic responses to cell associated and solubilized tumor antigens

Cell mediated immunity to human solid tumors could be demonstrated in vitro by the lymphocyte blastogenesis method. Blastogenic responses to unseparated autochthonous tumor cells were positive in 19 of 29 patients. The intensity of response was dose related, and the maximum response required a tumor cell lymphocyte ratio of l:l. The intensity of response was also correlated inversely with the extent of disease. The effect of serum from cancer patients on such responses in vitro was complex. It could be both inhibitory or facilitory and did not correlate with the extent of the disease. Separation of viable from nonviable tumor cells by specific density solution (Ficoll Hypaque), and their respective treatment with irradiation, mitomycin C, or nothing, showed that viable tumor cells were superior to nonviable cells and irradiation was superior to mitomycin C in inducing lymphocyte blastogenesis. Irradiated viable tumor cells appeared to be the material of choice in the study of lymphocyte blastogenic response to cell associated tumor antigen. Soluble antigen, extracted with 3M KCl induced vigorous blastogenic responses in autologous lymphocytes, but no such stimulation occurred among normal allogeneic lymphocytes. An immunologic difference between cell associated antigens and their soluble form was hypothesized.