抄録
The effects of operation and a streptococcal immunopotentiator, OK-432, were evaluated on natural killer (NK) cell activity in 10 patients with malignant disease. Microassay methods were employed for a 5 hr-51Cr release test using mononuclear cells separated from peripheral blood and 51Cr-labeled K 562 cells as effector cells and target cells respectively with an effector-to-target ratio of 20: 1. The results are as follows: in each of 2 normal healthy donors, NK activity fluctuated from experiment to experiment and the levels of NK activity in one donor were almost always higher than in the other, suggesting that such fluctuation might occur in the process of NK assays. Thus the NK activities in cancer patients were corrected in each assay according to the control activities from the above healthy donors. In the patients with malignant disease, the corrected NK levels after operation were significantly lower in 3 out of 9 patients as compared with preoperative NK levels. When OK-432 was given for 12 consecutive days to each patient, cytotoxic activities of peripheral blood lymphocytes significantly increased in all patients, reached their peak on the 3rd day after administration and declined thereafter in most of the patients. Although the effector cells mediating the enhanced cytotoxic activity against K 562 are not identified yet, the above results suggest that OK-432 enhances NK cell activity in patients with malignant disease.
