Inhibition of lectin-induced lymphocyte activation by 2-cyclohexene-1-one: Decreased intracellular glutathione inhibits an early event in the activation sequence

The importance of normal intracellular glutathione (GSH) levels in the activation of human peripheral blood lymphocytes (PBL) by mitogenic lectins was explored using 2-cyclohexene-1-one (2-CHX-1), an agent that selectively decreases the levels of intracellular GSH. PBL incubated with mitogenic lectins and graded doses of 2-CHX-1 showed a dose-dependent inhibition of activation assayed by [³H]-thymidine uptake and percentage of blast transformation. 2.5 x 10^-5 M 2-CHX-1, a concentration that decreases GSH levels to <20% of control, caused an 80 to 90% suppression of both [³H]-thymidine uptake and blast transformation; lower concentrations were less effective. Time course studies showed that 2-CHX-1 was maximally effective only if added during the first 4 hr of culture. At the concentrations used, 2-CHX-1 was not cytotoxic to lectin-stimulated or unstimulated PBL and did not interfere with mitogen-lymphocyte interaction. These results suggest that adequate levels of glutathione are necessary for lymphocyte activation and that the glutathione requirement is exerted in the early activation sequence.