Effects of oxidants and antioxidants on nuclear factor ϰB activation in three different cell lines: evidence against a universal hypothesis involving oxygen radicals

A model for NFϰB activation involving reactive oxygen intermediates has recently been proposed. We have explored this model in three cell lines, Jurkat T cells, EL4.NOB-1 T cells and KB epidermal cells using hydrogen peroxide and two physiological activators of NFϰB, interleukin-1 (IL1) and tumor necrosis factor (TNF) as stimuli. In agreement with earlier studies hydrogen peroxide activated NFϰB in Jurkat, although only at much higher concentrations (10 mM) than those previously reported. However, hydrogen peroxide failed to activate in the two other cell lines under a range of conditions. Similarly, N-acetylcysteine only proved inhibitory in hydrogen peroxide and TNF treated Jurkat and failed to inhibit IL1 and TNF-activated NFϰB in EL4.NOB-1 and KB cells respectively. N-Acetylcysteine inhibited IL1-induced interleukin-2 in EL4, however, demonstrating that N-acetylcysteine was biologically active. These results suggest that the reactive oxygen model of NFϰB activation may be cell-type restricted. In contrast to the results with N-acetylcysteine, the antioxidant and metal chelator, pyrolidine dithiocarbamate (PDTC) inhibited NFϰB activation, although these effects may be unrelated to any antioxidant properties. PDTC also inhibited IL1-induced interleukin-2. Finally, studies with the pro-oxidant diamide showed that this could not activate NFϰB in any of the cells and in contrast proved inhibitory. The results from this study therefore suggest that the reactive oxygen model of NFϰB activation may be restricted to certain cell types and that the presence of such a system is not required for the activation of NFϰB by ILI and TNF.