Diphenyleneiodonium prevents reactive oxygen species generation, tyrosine phosphorylation, and histamine release in RBL-2H3 mast cells

Mast cells play a central role in immediate allergic reactions mediated by immunoglobulin E. It has recently been reported that mast cells generate in tracellular reactive oxygen species (ROS) in response to stimulation with d ivergent physiologically relevant stimulants. However, the physiological ro le of ROS is poorly understood. Here we demonstrate that mast cell model ra t basophilic leukemia (RBL-2H3) cells generate ROS in response to antigen a nd the calcium-ionophore A23187 via activation of diphenylene-iodonuim (DPI )-sensitive enzyme and that blockade of ROS generation by DPI suppresses hi stamine release induced by either stimulant. Increased tyrosine phosphoryla tion of pp125(FAK) and a 77-kDa protein coprecipitating specifically with t he kinase occurred in parallel with the secretion, and blockade of ROS gene ration by DPI also suppressed the tyrosine phosphorylation of both proteins . These findings suggest that ROS generated by a flavoenzyme-dependent mech anism may be involved in histamine release through the pp125(FAK) pathway. (C) 2000 Academic Press.