INVOLVEMENT OF REACTIVE OXYGEN INTERMEDIATES IN LECTIN-INDUCED PROTEIN-TYROSINE PHOSPHORYLATION OF SYK IN THP-1 CELLS

Oxidative stress (H2O2) has been shown to be associated with tyrosine phosphorylation and activation of protein-tyrosine kinase Syk. In the present study, we examined the possibility that reactive oxygen interm ediates (ROI) were involved in concanavalin A (Con A)induced tyrosine phosphorylation in THP-1 cells. Rapid tyrosine phosphorylations of Syk , Fc gamma receptor(s) and phospholipase C gamma 2 (PLC gamma 2) were induced by Con A treatment in THP-1 cells. Pretreatment of cells with antioxidants N-acetylcysteine (NAC) and glutathione (GSH) almost compl etely blocked tyrosine phosphorylations of Syk, Fc gamma receptor(s) a nd PLC gamma 2. In addition, THP-1 cells showed significant levels of ROI from the early period of Con A treatment and the levels of ROI wer e inhibited by antioxidant treatment. These data suggest that ROI have an important role in Con A-induced protein-tyrosine kinase(s) signali ng pathways. (C) 1998 Academic Press.