Enhancement of T cell receptor signaling by a mild oxidative shift in the intracellular thiol pool

Exposure of T cells to the macrophage products hydrogen peroxide (HP) or L- lactate (LAC) was previously shown to enhance IL-2 production and to modula te glutathione (GSH) status, We now found that 50 mu M HP and 30 mM LAC enh anced strongly the transcription from the IL-2 promoter in Jurkat T cells a fter stimulation with anti-CD28 together with or without anti-CD3 but not w ith anti-CD3 Abs alone. Therefore, we used anti-CD3 plus anti-CD28-stimulat ed cells to investigate the effect of the GSH reductase inhibitor 1,3-bis(2 -chloroethyl)-1-nitrosourea (BCNU) on the signal cascade. BCNU enhanced the transcription to a similar extent as HP or LAG. Lowering the intracellular GSH/GSH disulfide ratio by BCNU, HP, or NO resulted in all cases in the fu lminant enhancement of Jun-N-terminal kinase and p38 mitogen-activated prot ein kinase but not extracellular signal-regulated kinase 1/2, Jun-N-termina l kinase and NF-kappa B activation was enhanced through pathways involving Rac, Vav1, PKC Theta, p56(lck), p59(fyn) and I kappa B kinases, In a cell-f ree system, the autophosphorylation of rFyn was stimulated by GSH disulfide but not by HP, These findings suggest that the oxidation of the cellular t hiol pool may play a role as an amplifying mechanism for TCR/CD3 signals in immune responses.