Augmented natural killer activity in ovarian cancer patients treated with cimetidine.

The effect of cimetidine on natural killer (NK) activity of peripheral blood lymphocytes (PBL) was studied in 37 post-operative patients with ovarian cancer. There was no significant difference in the NK activities between normal healthy women and patients with no residual tumor after surgery, while those in patients with large residual tumor after surgery were suppressed to less than a half of those in normal healthy women. Cimetidine augmented the NK activities in patients with no residual tumor but not in normal healthy women. Particularly, the NK activities in patients with low baseline NK status before cimetidine treatment was markedly enhanced. Furthermore, the NK boosting by cimetidine was more effective in patients with large residual tumor than in patients with no residual tumor. The NK activity in PBL from such patients was also enhanced by in vitro exposure to cimetidine. These findings suggest that cimetidine may be used as an immunorestorative-therapy for ovarian cancer patients with depressed NK activity.