Treatments for the activating macrophages that reduces surgical stress and postoperative mortalities from bacterial infections and tumor metastases.

Background: Some of the mortalities caused by infectious diseases and/or distant metastases following surgery are thought to be due to immunological suppression. For this reason, techniques that reduce immunological suppression following surgery may reduce mortalities and/or incidences of micrometastases in distant organs.

Materials And Methods: Mice were anesthetized and their peritoneal cavities were opened for 30 min. Immunological suppression was estimated by the presence of tumor necrosis factor-a (TNF) after injection with OK-432 (dead bacterial bodies). The mice were administered with either Staphylococcus aureus or cancer cells of Meth A fibrosarcoma. Survival times and lung metastastic foci were then observed at 3 weeks. Results were compared for mice with or without treatment by OK432 or TNF prior to surgery.

Results: While significant suppression of TNF production was observed after laparotomy, administration of a macrophage-activating agent (TNF or OK-432) 3 h prior to laparotomy prevented immune suppression after the laparotomy. Laparotomy increased mortalities from bacterial infections and promoted the number of lung metastases. By contrast, administration of TNF or OK-432 3 h prior to the laparotomy decreased mortalities and metastases after the laparotomy.

Conclusion: These results suggest that appropriate activation of macrophages prior to surgery is a method to reduce some of the detrimental effects caused by surgical operations.