Synergistic Effect of LPS, IFN- and Iron on Apoptosis of Balb/c Mice Macrophages Following Nitric Oxide Production

Abstract

Objective(s) Previous studies have demonstrated that the nitric oxide (NO) dependent death of murine peritoneal macrophages activated <em>in vitro</em> with IFN-g and LPS is mediated through apoptosis. In the present study, we investigated the synergistic effect of LPS, IFN-g and iron on NO production and apoptosis. Materials and Methods After determination of iron cytotoxicity, the peritoneal macrophages of Balb/c mice were cultured with iron, LPS, and IFN-g separately, or a mixture of these for 18 hr at 37^◦C. Then after 18 hr incubation, the level of NO in supernatant was measured by the Griess method. At the same time, after incubation with ethidium bromide and acridine orange dye, the apoptotic macrophages were detected by fluorescence microscopy. Results NO production was significantly greater than the control group in macrophages exposed to iron,LPS, or IFN-g alone (<em>P</em>=0.02), while no significant difference was detected in apoptosis rate in the presence of LPS (<em>P</em>=0.08). However, the differences were remarkable between NO production and apoptosis rate in the presence of iron, LPS and IFN-g (<em>P</em>≤0.05). Conclusion These findings indicate the immunostimulatory effect of iron on NO production by IFN-g and LPS.