Vitamin D: its role and uses in immunology 1

In recent years there has been an effort to understand possible noncalcemic roles of vitamin D, including its role in the immune system and, in particular, on T cell‐medicated immunity. Vitamin D receptor is found in significant concentrations in the T lymphocyte and macrophage populations. However, its highest concentration is in the immature immune cells of the thymus and the mature CD‐8 T lymphocytes. The significant role of vitamin D compounds as selective immunosuppressants is illustrated by their ability to either prevent or markedly suppress animal models of autoimmune disease. Results show that 1,25‐dihy‐droxyvitamin D 3 can either prevent or markedly suppress experimental autoimmune encephalomyelitis, rheumatoid arthritis, systemic lupus erythematosus, type I diabetes, and inflammatory bowel disease. In almost every case, the action of the vitamin D hormone requires that the animals be maintained on a normal or high calcium diet. Possible mechanisms of suppression of these autoimmune disorders by the vitamin D hormone have been presented. The vitamin D hormone stimulates transforming growth factor TGFβ‐1 and interleukin 4 (IL‐4) production, which in turn may suppress inflammatory T cell activity. In support of this, the vitamin D hormone is unable to suppress a murine model of the human disease multiple sclerosis in IL‐4‐deficient mice. The results suggest an important role for vitamin D in autoimmune disorders and provide a fertile and interesting area of research that may yield important new therapies.—DeLuca, H. F., Cantorna, M. T. Vitamin D: its role and uses in immunology. FASEB J. 15, 2579–2585 (2001)