Systemic Effects of Vitamin D

Traditionally perceived as a seco-steroid hormone involved in the regulation of calcium metabolism, 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] is now known also to be active in tissues not directly contributing to mineral metabolism. New data show that 1α,25(OH)2D3 is produced by and interacts with hematopoietic cells. The hormone promotes myeloid differentiation and modulates the function of activated lymphocytes. Another new target tissue for 1α,25(OH)2D3 is the skin, where 1α,25(OH)2D3 enhances differentiation of epidermal cells. Therapeutic application of 1α,25(OH)2D3 or suitable analogues in differentiation disorders of hematopoietic and skin cells is currently under investigation.