Regulation of interleukin 2 production, interleukin 2 mRNA expression and intracellular glutathione levels in ex vivo derived T lymphocytes by lactate.

The concentration of L-lactate in the blood plasma of higher vertebrates is about 1 mM but can be as high as 30 mM under certain physiological and pathological conditions or in the vicinity of glycolytically active cells including macrophages. Here we report that high but physiologically relevant concentrations of lactate increase the expression of interleukin 2 (IL 2)-specific mRNA and the production of IL 2 activity in cultures of mitogenically stimulated T cells. Lactate supports IL 2 production most effectively if added 0-8 h after T cell stimulation and only in cultures of CD4+ but not of CD8+ T cells. In contrast to the DNA synthesis activity in these cell cultures, IL 2 production is not augmented but rather inhibited by exogenous glutathione (GSH). Lactate causes a reduction of intracellular GSH levels, and lactate-containing cultures require accordingly higher extracellular cysteine concentrations than control cultures to achieve similar intracellular GSH levels. In view of the strong variations of extracellular lactate concentrations in vivo, our experiments suggest that lactate may be part of a previously unknown mechanism by which the metabolic microenvironment modulates gene expression in T cells.