Natural cytotoxic reactivity of peripheral blood lymphocytes from digestive tract cancer patients against a colon cancer cell line and virus-infected HeLa cells.

The natural killer (NK) activity of peripheral blood lymphocytes of gastric cancer patients in all pathological stages from I to IV was less than that of healthy persons or patients with benign diseases. However, there was no significant difference in the antibody-dependent cellular cytotoxicity (ADCC) of cancer patients and healthy individuals, and the correlation between NK and ADCC activities was somewhat lower in cancer patients than in healthy persons. The peripheral blood lymphocytes from digestive tract cancer patients were divided into two fractions on the basis of low affinity erythrocyte (E)-rosette formation. The NK activity of the low affinity E-receptor negative fraction from cancer patients was significantly lower than that of the same fraction from healthy persons. The binding of lymphocytes with target cells is considered to be a first step of natural killing. In cancer patients, there was a decrease in the target-binding capacity of lymphocytes in both fractions. Therefore, the decreased NK activity of cancer patients appeared to be related to a reduced target-binding capacity.