Effects of surgical stress on natural killer activity, proliferative response of spleen cells and cytostatic activity of lung macrophages in rats.

The effects of surgical procedures such as thoracotomy and/or laparotomy on natural killer (NK) activity, proliferative response to phytohemagglutinin (PHA) of spleen cells and cytostatic activity of lung macrophages were investigated in rats. NK activities of rats that had undergone the surgical procedures were significantly depressed on day 1. By day 7, NK activity in the thoracotomy group exceeded that of normal rats, while the activity in the laparotomy group was similar to that in normal rats. However, NK activity in the laparothoracotomy group remained depressed. Spleen cell proliferative response to PHA was also significantly depressed on day 1 in all groups, and in the laparothoracotomy group, a depressed response was still apparent on day 14. The cytostatic activities of lung macrophages were significantly reduced in thoracotomy groups, but the effect was rather slight in the laparotomy group. It is likely that the extensive surgical stress of laparothoracotomy can depress the host's immunological reactivity and furthermore result in an enhancement of tumor growth.