Figure 1.

Scheme of immunomodulatory effects of active vitamin D on various immune cell lineages (adapted from [6]). Effects of vitamin D on both NK, Mφ, and DCs include inhibition of inflammatory cytokine production and inhibition of DCs differentiation and maturation, which in turn leads to suppression of T cell proliferation and results in a shift from a Th1 to a Th2 phenotype. Vitamin D affects T cell maturation by skewing away from the inflammatory Th17 phenotype and facilitates the induction of Treg cells. In addition, vitamin D reduces B cell activation and proliferation and immunoglobulin synthesis and induces apoptosis of activated B cells. DC: dendritic cell. Mφ: macrophage. NK: natural killer. VDR: vitamin D receptor.