Effect of maleimide derivatives, sulfhydryl reagents, on stimulation of neutrophil superoxide anion generation with concanavalin A

Abstract

Using maleimide derivatives with relatively rare side reactions, their effect on stimulation of O^- ₂ production by guinea-pig neutrophils with Con A was studied. Showdomycin, a very slowly penetrating agent, did not affect O^- ₂ production whereas NEM, a rapidly penetrating agent, markedly inhibited O^- ₂ production without interference with binding of Con A to cells. Particulate fractions from neutrophils stimulated with Con A showed markedly increased NADPH-dependent O^- ₂ production compared with fractions from unstimulated cells. Treatment of neutrophils with NEM before exposure to Con A inhibited the enhancement of NADPH-dependent O^- ₂ production of particulate fractions by Con A. However, particulate fractions from Con A-stimulated and unstimulated cells hardly exhibited reduced NADPH oxidase activity after direct exposure to NEM. Treatment of neutrophils with NEM after activation by Con A had no effect on NADPH-dependent O^- ₂ production of particulate fractions. These results indicate that NEM inhibits the activation process of the O^- ₂-generating enzyme, probably NADPH oxidase with Con A.