In order to analyze the effect of vitamin E on Th1 and Th2 cytokine production, porcine peripheral blood mononuclear cells (PBMC) were isolated from healthy pigs (n=8) and cultured with either 0, 10, 50, or 100muM of vitamin E (alpha-tocopherol). PBMC were stimulated with PHA for either, 24h to determine: (a) the concentration of tocopherol incorporated into the cell membrane, (b) cytokine production and (c) Th1 and Th2 regulators gene expression; or 72h to determine the proliferation of PBMC. Vitamin E was incorporated into the PBMC in a dose dependent manner, giving as a result a high proliferation of cells irrespective of the dose of vitamin E used. Regarding cytokine production, vitamin E consistently decreases the mRNA expression and the percentage of cells producing IL-10. Vitamin E did not influence the production of IFN-gamma but the lowest level of vitamin E (10muM) was sufficient to maximally increase the proportion of cells producing IL-2, to diminish IL-4, and discreetly increase the mRNA expression of TBX21 vs. GATA3. In conclusion, our results revealed that vitamin E is able to suppress IL-10 production and to influence the production of IL-2, IL-4, and maybe TBX21. Vitamin E clearly has immunomodulatory effects, though further work in vivo to determine the physiological nature of these effects is warranted.