Vitamin E has also been shown to regulate the maturation and functions of dendritic cells, which are important for the innate and adaptive immune systems [112]. The immune response mechanisms in which vitamin E is involved are as follows: (i) maintains or improves the cytotoxic activity of NK cells [82] and reduces prostaglandin E2 (PGE2) production by the inhibition of cyclooxygenase-2 (COX-2) activity, mediated through decreasing of nitric oxide production [64, 112, 113]; (ii) the improvement of immune synapse formation in naive T cells, increasing the percentage of memory experienced with the antigen [112]; (iii) the modulation of Th1/Th2 balance. Indeed it improves lymphocyte proliferation and T cell mediated functions, optimizes and improves the Th1 response and suppress Th2 response [95]. The role of this vitamin in the prevention of infections such as influenza has been discussed, but more controlled studies in humans are needed [114].