Vitamins & Minerals

Vitamin D and Immune System

Abstract

Mosaad YM, Mostafa M, Elwasify M, Youssef HM and Omar NM

Vitamin D interaction with immune system is a well-established although it is a non-classical effect of Vitamin D. Several reports have documented the role of 1,25 hydroxycholecalciferol (OH)2D3 in mediating innate and adaptive immune systems. The 25-hydroxyvitamin D3 (25OHD3) is the main circulating metabolite of Vitamin D and is the most reliable measurement of an individual’s Vitamin D status. It mediates its effect through autocrine or paracrine synthesis of 1, 25(OH)2D3. Therefore, the ability of Vitamin D to influence human immunity is possibly dependent on the vitamin D status of individuals. The vitamin D receptor (VDR) is expressed on various immune cells including B cells, T cells and antigen presenting cells. However, its highest concentration is in immature immune cells of the thymus and mature CD-8 T lymphocytes. These cells can synthesize active Vitamin D metabolite which can act in an autocrine way in a local milieu. As Vitamin D has immune-modulatory effects on both innate and adaptive immune responses, its deficiency or significant insufficiency can be associated with autoimmunity and infection. In autoimmune disease, the immune cells are responsive to ameliorative effects of vitamin D.