Decreased phagocytic capacity of rat peritoneal macrophages following photon abdominal irradiation

Photon irradiation of the abdomen may be accompanied by complications due t o a decrease in the immune defense of the recipient. Since peritoneal macro phages are an important component of the immune system, we examined the pha gocytic activity and oxygen superoxide anion generation by peritoneal macro phages from rats 2 and 4 weeks after abdominal irradiation with 6 MV photon s applying a single dose of 2 Gy. Two and 4 weeks after irradiation, perito neal macrophages were harvested and their capacity to engulf latex particle s and to produce oxygen superoxide anions was determined. Non-irradiated ra ts, treated identically otherwise, served as controls. Two weeks after irra diation the phagocytic capacity and oxygen superoxide anion generation decr eased by 61 and 70%, respectively, compared with controls. This tendency pe rsisted after 4 weeks post irradiation, the decrease in both functions bein g 50 and 74%, respectively. It is suggested that the altered function of pe ritoneal macrophages following irradiation may further compromise the immun e defense in patients receiving abdominal radiotherapy. (C) 1999 Elsevier S cience Ireland Ltd. All rights reserved.