Vitamin D is a seco-steroid involved in calcium and phosphorus metabolism,and bone formation and mineralization, through binding to a specific nuclear receptor,vitamin D receptor（VDR）.Besides its well-established functions on bone health,multiple lines of evidence have indicated the immunomodulatory roles of vitamin D.Vitamin D can affect both innate and adaptive immunity,and prevent autoimmune responses efficiently.Vitamin D regulates the immune responses by suppressing T cell proliferation and modulating macrophage functions.Epidemiological studies have shown that vitamin D deficiency is associated with multiple diseases such as rickets and cancer.Moreover,associations between vitamin D and autoimmune diseases have been confirmed in multiple sclerosis（MS）,rheumatoid arthritis（RA）,etc.The present review mainly summarized the recent findings on the immunomodulatory role of vitamin D in various disorders,with special focus on its role in MS,an autoimmune disease of the nervous system.
