Defects in natural killer cell activity and interferon response in human lung carcinoma and malignant melanoma.

The natural killer (NK) activity of peripheral blood mononuclear cells from 25 patients with squamous cell carcinoma of the lung, malignant melanoma, or epitheloid cancers of the gastrointestinal tract was measured by the lysis of 51Cr-labeled K562 target cells. NK activities of many patients with lung cancer or malignant melanoma were decreased relative to normal controls. This abnormality was significantly correlated with advancing stage of disease and the percentage of monocytes in the cell suspensions. Addition of indomethacin or removal of monocytes did not restore depressed NK function to normal levels. Abnormalities of NK function did not appear to be secondary to the presence of mononuclear suppressor cells. The response to interferon was also impaired in patients with advanced disease. The number of effector:target conjugates was normal even in patients with depressed NK function; however, the number of active lytic effectors was decreased. These results imply that the cells which bind tumor targets are present in patients with advanced cancers, but these cells are either immature or functionally inactive.