[Observation on natural killer cell activity in gastric cancer patients and effect of nonspecific immunopotentiator administration on its postoperative reduction].

Natural killer cell (NK) activity, together with various nonspecific immunologic parameters, was measured preoperatively, and its changes induced by operative stress were examined in gastric cancer patients. Effect of administration of a nonspecific immunopotentiator, OK-432, was evaluated by postoperative changes in NK activity. Peripheral blood NK activity was measured by 51Cr-release assay against K-562 target cells. It was found that NK activity in the gastric cancer patients was significantly lower than that in healthy subjects. The reduction was specially marked in the cases of cancer at stages I and IV. NK activity in the cases with hepatic or peritoneal metastasis was significantly lower than that in the cases without such metastasis. NK activity in the cases of noncurative gastric resection or non-resection was significantly lower than that in the cases of curative gastric resection. NK activity in the cases of stage IV and "por" in histology was significantly lower than that in the cases of stage IV and "tub1" in histology. In the cases at stages I + II, there was a positive correlation between NK activity and IgG FcR(+) T cell ratio. There was a negative correlation between NK activity and alpha 2-globulin ratio and the correlation was especially significant in the cases at stages III + IV. In the cases at stages III + IV, receiving administration of OK-432 only postoperatively, NK activity was significantly reduced or tended to be reduced at 1 through 4 week(s) postoperatively, while such a reduction was not seen in the cases receiving administration of OK-432 pre- and postoperatively. This phenomenon was more marked in the cases showing a serum albumin level lower than 3.5 g/dl or in the cases undergoing operations longer than 4 hours in duration.