Impaired cytotoxicity of lymphocytes from patients with cancer

We have investigated the ability of peripheral blood lymphocytes from 57 cancer patients and from 54 normal controls to exert cytotoxic activity in vitro on allogeneic target cells by using a residual tritiated proline assay. Phytohemagglutin was added to the cultures for potentiating the reaction. The cytotoxic potential of lymphocytes from cancer patients was significantly lower than that of healthy controls. Increased survival of target cells was found in numerous reactions with patients' lymphocytes, probably reflecting a "feeder" effect. The source of plasma used for testing, i.e., autologous or pooled normal homologous plasma, did not affect the strength of cytotoxicity reactions displayed by lymphocytes from either normal or cancer patients. A lower reactivity was generally seen in patients with metastatic disease than in patients with no evidence of distant spread.