Intracellular free zinc up-regulates IFN-γ and T-bet essential for Th1 differentiation in Con-A stimulated HUT-78 cells

Zinc deficiency impairs cellular immunity. Up-regulation of mRNA levels of IFN-gamma, IL-12R beta 2, and T-bet are essential for Th-1 differentiation. We hypothesized that zinc increases Th-1 differentiation via up-regulation of IFN-gamma and T-bet expression. To test this hypothesis, we used zinc-deficient and zinc-sufficient HUT-78 cells (a Th-0 cell line) under different condition of stimulation in this study. We also used TPEN, a zinc-specific chelator, to decrease the bioavailability of zinc in the cells. We measured intracellular free zinc, cytokines, and the mRNAs of T-bet, IFN-gamma, and IL-12R beta 2. In this study, we show that in zinc-sufficient HUT-78 cells, mRNA levels of IFN-gamma, IL-12R beta 2, and T-bet in PMA/PHA-stimulated cells were increased in comparison to zinc-deficient cells. Although intracellular free zinc was increased slightly in PMA/PHA-stimulated cells, Con-A-stimulated cells in 5 mu M zinc medium showed a greater sustained increase in intracellular free zinc in comparison to cells incubated in 1 mu M zinc. The cells pre-incubated with TPEN showed decreased mRNA levels of IFN-gamma and T-bet mRNAs in comparison to cells without TPEN incubation. We conclude that stimulation of cells by Con-A via TCR, release intracellular free zinc which functions as a signal molecule for generation of IFN-gamma and T-bet, and IL-12R beta 2 mRNAs required for Th-1 cell differentiation. These results suggest that zinc increase Th-1 cell differentiation by up-regulation of IFN-gamma and T-bet, and IL-12R beta 2 mRNAs. (C) 2011 Elsevier Inc. All rights reserved.