Functional Modifications of Macrophage Activity after Sublethal Whole-Body Irradiation

Abstract

The effect of whole body X-irradiation on macrophage activity was evaluated by in vitro C3b-receptor-mediated ingestion and in vivo C clearance. Peritoneal macrophages from B6D2F1 mice were tested from 20 min to 24 h postirradiation and at doses up to 1000 rad X-irradiation. When compared to peritoneal macrophages from normal unstimulated mice, whole-body irradiation produced an increase in macrophage activity in both C3b-mediated ingestion and C clearance. The enhancement of macrophage activity was optimal at an exposure of 200 rad and waned as the exposure dose increased. Enhanced activity appeared as early as 20 min postirradiation and peaked by 3 h. Although the mechanism for this observation is unknown, lymphocytes from irradiated mice were able to stimulate resident macrophages (from nonirradiated mice) in vitro to ingest C3b-coated erythrocytes.