Hydroxyl radical scavengers inhibit TNF-alpha production in mononuclear cells but not in polymorphonuclear leukocytes

The hydroxyl radical (HO .)(.) scavengers dimethylthiourea (DMTU), tetramet hylthiourea (TMTU), dimethylsulfoxide (DMSO) and deferoxamine (DFX), the la tter being an iron chelator which prevents HO. formation by blocking the Fe nton reaction, were found to inhibit TNF-alpha production in LPS-stimulated human PBMC but not in PMN. Furthermore, this effect was not LPS-specific, as TNF-alpha production was reduced by HO. radical scavengers to a similar extent upon stimulation of PBMC with immune complexes (IC), concanavalin A (Con A) and phorbol myristate acetate (PMA). Other scavengers such as gluta thione (GSH), N-acetylcysteine (NAC), ascorbic acid (ASC) and mannitol (MAN ) do not have effect on the production of TNF-ol either in PBMC or PMN. The se results provide evidence that the participation of ROI in the regulation of TNF-alpha production differ in different cell types. Particularly, the data presented in this work indicate that HO. radicals have a central role in the production of this inflammatory cytokine by human PBMC. (C) 1998 Int ernational Society for Immunopharmacology. Published by Elsevier Science Lt d.