Signaling pathways for Fc gamma receptor-stimulated tumor necrosis factor-alpha secretion and respiratory burst in RAW 264.7 macrophages.

Fc gamma receptor (Fc gammaR) signaling mediates several important macrophage functions including cytokine secretion and respiratory burst. The present study describes the development of a model using the macrophage cell line, RAW 264.7 for studying Fc gammaR-stimulated tumor necrosis factor-alpha (TNF-alpha) secretion and hydrogen peroxide (H2O2) production. In unprimed cells these functions were low but pretreatment with interferon-gamma augmented Fc gammaR-stimulated TNF-alpha secretion and H2O2 production to levels that were about half that caused by lipopolysaccharide (LPS) and zymosan, respectively. Studies on the signaling pathways found that TNF-alpha secretion stimulated by either Fc gammaR or LPS was decreased by inhibitors of PKC, MAPK p42/p44, and MAPK p38. TNF-alpha secretion was also reduced by the combination of PLC and PLD inhibitors but not by the individual inhibitors alone. H2O2 production stimulated by either Fc gammaR or zymosan was blocked by inhibitors of PKC, PLC, PLD, and MAPK p42/44 but not by MAPK p38. Thus, interferon-gamma treated RAW 264.7 cells are a model of inflammatory macrophages and are well suited for further study of these signaling pathways.