Abstract
Peripheral lymphocytes from cancer patients were tested for immune reactivity against cultured target cells derived from carcinomas of colon, rectum, breast, kidney and lung, and a melanoma by microcytotoxicity in plastic plates. Lymphocytes from colon or rectum carcinoma patients were cytotoxic for allogeneic colon or rectum carcinoma cells in 61% of tests, and no difference in reactivity could be detected between pre‐ or post‐operative patients. Breast carcinoma patients' lymphocytes were cytotoxic for breast carcinoma cells in 50% of cases tested. Autochthonous lymphocytes were reactive against melanoma cells, but no lymphocyte cytotoxicity could be demonstrated on cells of a renal carcinoma or a lung carcinoma. None of the lymphocyte preparations tested reacted positively against cells of a tumour different from that of the lymphocyte donor, and none reacted against cells from normal colon. Complement‐dependent cytotoxic humoral antibody was regularly detected against breast carcinomas, but only one sample of colon carcinoma serum, from a post‐operative patient, was reactive against colon carcinoma cells. Sera from melanoma patients likewise were only reactive against melanoma cells in two post‐operative cases.