Reactive oxygen species activate human peripheral blood dendritic cells

This study investigates the effects of hydrogen peroxide, a potent oxygen f ree radical donor, on the phenotype and function of dendritic cells differe ntiated from peripheral blood precursors. We report that hydrogen peroxide induces an up-regulation of several dendritic cell surface markers involved in interaction with T cells, including MHC Class II molecules (DQ and DR) and the co-stimulatory molecules CD40 and CD86. Moreover we have observed t hat H2O2-treated dendritic cells are more efficient in promoting T cell pro liferation than normal dendritic cells and that this enhancement can be blo cked using the free radical scavenger agent N-acetylcysteine. Oxygen free r adicals are a common by-product of inflammation, and our results suggest th ey may play an important role in activation of sentinel dendritic cells, li nking tissue damage to the initiation of an adaptive immune response. (C) 1 998 Elsevier Science Inc.