Fig. 1.

Role of vitamin D on immune regulation:Vitamin D is converted into 25-hydroxy cholecalciferol in liver and into 1,25 dihydroxy cholecalciferol in kidney and other tissues including dendritic cells (DC). Through paracrine and intracrine action, it regulates dendritic cells and inhibits proliferation of T helper cells (Th1), skewing cytokine production towards T helper 2 (Th2) cells. It has endocrine action on activation of antigen presenting cells like monocytes and on mobility of neutrophils contributing more to its antibacterial activity.