Vitamin E supplementation modulates cytokine production by thymocytes during murine AIDS

Female C57BL/6 mice were infected with LP-BM5 retrovirus, causing murine AIDS, which is functionally similar to human AIDS. Retrovirus infection targeted the thymus, producing altered T cell differentiation via the dysregulation of thymocyte cytokine production. Human AIDS causes vitamin deficiencies, therefore the effects of dietary vitamin E supplementation were determined on the kinetics of cytokine production by concanavalin A-stimulated thymocytes in uninfected normal mice and mice with murine AIDS. Dietary supplementation, with a 15-fold increase in vitamin E (160 IU/l) in the liquid diet (National Research Council), modulated interleukin-2 (IL) production in both uninfected mice and retrovirus-infected mice. Vitamin E significantly reduced the level of IL-4 secretion in the uninfected mice at 4 and 8 weeks, but not at 12 and 16 weeks. It also significantly reduced IL-4 production, elevated by retrovirus infection. Vitamin E significantly reduced IL-6, and interferon-gamma production increased in murine AIDS. The effects of dietary vitamin E on concanavalin A-induced proliferation of thymocytes were consistent with the finding of changes in IL-2 secretion. No effects of dietary vitamin E on thymus weight were observed in uninfected or retrovirus-infected mice, whereas vitamin E significantly increased serum and thymic vitamin E concentration, which had been reduced by retrovirus infection. These data indicate that dietary vitamin E supplementation can modulate cytokine production by thymocytes, affecting T cell differentiation, especially during retrovirus-induced immune dysfunction.