title: Effect of antioxidants on primary alloantigen-induced T cell activation and proliferation.
abstract: Because oxygen-centered free radicals are involved in cell-mediated immune responses, we examined the possibility that these reactive species could also have a role in the lymphoproliferative response to alloantigens in the mixed lymphocyte culture (MLC). Three classes of agents that prevent the formation, or damaging effects, of oxygen radicals were tested: the non-permeant electron acceptor ferricyanide; the iron chelators desferrioxamine, desferrithiocin, octanohydroxamic acid, and pyridoxal isonicotinoyl hydrazone, which are thought to be capable of preventing the iron-catalyzed reduction of H2O2 to more reactive species; and the lipid-soluble free radical scavenger butylated hydroxyanisole. These compounds inhibited the proliferation of all potential responder cells in the MLC in a dose-dependent manner. Inhibition was observed only if these agents were present early (less than 40 hr) in the MLC; if added later, their effects were significantly reduced. In contrast, the interleukin 2 (IL 2)-dependent proliferation of CTLL-2 cells or Con A blasts was not affected by these compounds at concentrations that inhibited proliferation in MLC by greater than 90%. Interleukin 1 (IL 1) production by peritoneal exudate cells and IL 2 and IL 1 levels in MLC were not affected by any of the agents tested. By flow microfluorometry, the expression of IL 2 receptors on stimulated T cells was found to be inhibited in the presence of these drugs. Taken together, the data point to an important role for free radical-mediated processes during the early stages of T lymphocyte activation, before IL 2 receptor expression.
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D007376:Interleukin-2 / Q000032:analysis; D007519:Isoantigens / Q000276:immunology*; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects*; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*
chemical_list: D000975:Antioxidants; D007376:Interleukin-2; D007519:Isoantigens