CONTRIBUTION OF CR3 TO NITRIC-OXIDE PRODUCTION FROM MACROPHAGES STIMULATED WITH HIGH-DOSE OF LPS

The contribution of the complement receptor type 3 (CR3) to nitric oxi de (NO) production from macrophages stimulated by LPS was investigated . When thioglycollate-elicited mouse peritoneal macrophages were stimu lated with a high dose of LPS (10 mu g/ml) in both the presence and ab sence of fetal calf serum, a source of LPS binding protein (LBP) neces sary for the binding of LPS to CD14, NO production was observed. These findings suggest that CD14-dependent and CD14-independent signaling p athways for NO production are present in macrophages, Because binding and phagocytosis of bacteria by macrophages through the CR3 has been p reviously reported, we investigated whether the CR3 acts in CD14-indep endent signaling pathway for NO production, By flow cytometric analysi s, the binding of FITC-labeled anti-CR3 monoclonal antibody (anti-CR3 mAb) to macrophages was inhibited by LPS, Anti-CR3 mAb induced iNOS pr otein and produced NO in a dose dependent manner, Further, NO producti on induced by anti-CR3 mAb was also inhibited by zymocel, beta-glucan with a high affinity to CR3. These results suggest that the CR3 molecu le acts in a CD14-independent signaling pathway, and contributes to NO production by macrophages stimulated with high doses of LPS. (C) 1998 Academic Press.