Vitamin E Affects Bone Marrow-Derived Dendritic Cells Cytokine Secretion and Ability to Polarize Naïve CD4+ T Cells

Vitamin E, one of the fat soluble vitamins, has been known for its immunomodulative functions. However, little is known about the effect of vitamin E on dendritic cells (DCs), the most potent antigen-presenting cells. To investigate whether the vitamin E could modulate DC function and subsequent immune response, various concentrations of α- and γ-tocopherol (Toc) were added to bone marrow-derived DC (BM-DCs) culture simultaneously with LPS activation. Surface molecules, prostaglandin E2 (PGE2), nitric oxide (NO), IL-12 of the BM-DCs were measured. The results showed that α-Toc had no effect on the expression of these surface molecules but γ-Toc decreased the levels of MHC II, B7.1 and B7.2 molecules. α-Toc increased BM-DC PGE2, and NO production but slightly decreased IL-12p70 production. γ-Toc slightly increased BM-DC PGE2 production but reduced IL-12p70 production. To further investigate whether vitamin E-treated BM-DC would affect T cell function, BM-DCs were preincubated with vitamin E and then cocultured with naïve CD4+ T cells. BM-DCs preincubated with vitamin E induced CD4+ T cell proliferation and IL-2 production. Vitamin E-preincubated BM-DCs did not significantly change IL-4 and IFN-γ secretion of T cells. However, as concentration of α-Toc increased, the ratio of IL-4/ IFN-γ of T cells tended to increase. γ-Toc-treated DC significantly increased the ratio of IL-4/ IFN-γ of T cells. Our results suggested that vitamin E can modulate BM-DC immune function including the influence on BM-DC surface molecules expression, PGE2 and cytokine levels and the ability to induce naïve CD4+ T cell proliferation and Th1/Th2 polarization