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

The hydroxyl radical (HO ·) scavengers dimethylthiourea (DMTU), tetramethylthiourea (TMTU), dimethylsulfoxide (DMSO) and deferoxamine (DFX), the latter being an iron chelator which prevents HO · formation by blocking the Fenton reaction, were found to inhibit TNF- α production in LPS-stimulated human PBMC but not in PMN. Furthermore, this effect was not LPS-specific, as TNF- α 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 glutathione (GSH), N-acetylcysteine (NAC), ascorbic acid (ASC) and mannitol (MAN) do not have effect on the production of TNF- α either in PBMC or PMN. These results provide evidence that the participation of ROI in the regulation of TNF- α 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.