The regulation of natural killer cell activity by splenic nonspecific suppressor cells and its modification in cancer patients

Spleen cells (SC), splenic venous blood lymphocytes (SVL) and peripheral blood lymphocytes (PBL) from gastric and esophageal cancer patients were simultaneously tested for natural killer (NK) and nonspecific suppressor (Ts) cell activities. Furthermore, the influence of Ts activity on the augmentation of NK activity by a biological response modifier (BRM) was also investigated. Positive Ts activities were frequently detected in the SC, SVL and PBL of advanced cancer patients. The NK activities of SC and SVL were maintained even in advanced cancer patients, though significantly depressed NK activities were observed in the PBL of advanced cases. Cancer patient SC, SVL and PBL with positive Ts activity showed low NK activities. Moreover, the NK activities of SVL and PBL were low in the patients with positive Ts activity in SC. The NK activity of normal control PBL was strongly augmented by interleukin 2, interferon and OK-432. These BRMs exhibited comparable capacities to augment the NK activities of SC, SVL and PBL with negative Ts activity in cancer patients, however, the effects of these agents seemed to be low in cells with a positive Ts activity. These results suggested that NK activity might be regulated by nonspecific suppressor cells and the presence of suppressor cells might affect the augmentation of NK activity through BRM in circulating blood lymphocytes and also in spleen cells.