The binding of immobilized IgG2a to Fc gamma 2a receptor activates NF-kappa B via reactive oxygen intermediates and tumor necrosis factor-alpha 1.

The macrophage-like cell line, J774, was found to respond to immobilized mouse monoclonal IgG2a proteins, but not to soluble forms of IgG2a or IgG2b or to immobilized F(ab')2 of IgG2a, by the increase in the nuclear proteins of two different types of NF-kappa B proteins which differed in their electrophoretic mobilities. Fc gamma 2a receptor-mediated activation of NF-kappa B was blocked by the presence of pyrrolidinedithiocarbamate, neutralizing anti-tumor necrosis factor (TNF)-alpha antibodies, various protein kinase inhibitors (H-89, genistein, or heparin) or intracellular calcium chelator (1,2-bis(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra-(acetoxymethyl)-ester, BAPTA/AM) during stimulation. J774 cells were also found to respond to immobilized IgG2a, but not IgG2b, by the increased production of superoxide, H2O2, and TNF-alpha. Fc gamma 2aR-induced production of H2O2 was inhibited by pretreatment of the cells with pyrrolidinedithiocarbamate, H-89, genistein, heparin, or BAPTA/AM, but not with anti-TNF-alpha antibody. Fc gamma 2aR-induced production of TNF-alpha was, on the other hand, not inhibited by pretreatment of the cells with BAPTA/AM. Although J774 cells responded to exogenously added rTNF-alpha, but not to H2O2, by activation of NF-kappa B, the recombinant TNF-alpha-mediated NF-kappa B activation was enhanced by simultaneous presence of H2O2. These results thus suggest that macrophages respond to the stimulation of Fc gamma 2aR by the production of both reactive oxygen intermediates and TNF-alpha and that endogenous TNF-alpha activates NF-kappa B via the pathway involving reactive oxygen intermediates.