The impact of vitamin D on dendritic cell function in patients with systemic lupus erythematosus.

Excessive activity of dendritic cells (DCs) is postulated as a central disease mechanism in Systemic Lupus Erythematosus (SLE). Vitamin D is known to reduce responsiveness of healthy donor DCs to the stimulatory effects of Type I IFN. As vitamin D deficiency is reportedly common in SLE, we hypothesized that vitamin D might play a regulatory role in the IFNalpha amplification loop in SLE. Our goals were to investigate the relationship between vitamin D levels and disease activity in SLE patients and to investigate the effects of vitamin D on DC activation and expression of IFNalpha-regulated genes in vitro.In this study, 25-OH vitamin D (25-D) levels were measured in 198 consecutively recruited SLE patients. Respectively, 29.3% and 11.8% of African American and Hispanic SLE patient had 25-D levels