Upregulation of interleukin-1β production by 1,25-dihydroxyvitamin D(3) in activated human macrophages.

1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) plays important roles in the immune system. In contrast to its well known function in the adaptive immune system, much less is known about the immunoregulatory effects of 1,25(OH)(2)D(3) in the innate immune system, especially on activated human macrophages. Here we found that 1,25(OH)(2)D(3) strongly stimulated the production of interleukin-1β (IL-1β) in PMA-differentiated U937 cells and human monocyte-derived macrophages treated with lipopolysaccharide (LPS) or PMA.