Vitamin D effects on B cell function in autoimmunity.

Abstract

Vitamin D seems to be implicated in the pathophysiology of autoimmune disorders as a natural immune modulator. Beneficial effects of vitamin D have been associated with different cells of the immune system; however, thus far, Bcells seem to be somewhat neglected. In this paper, we describe the possible direct effects of vitamin D on Bcells, with a focus on antibody production and the more recently identified regulatory B (Breg ) cells. Bcells upregulate the vitamin D receptor (VDR) upon activation. Furthermore, due to regulated expression of the metabolizing enzymes CYP27B1 and CYP24A1, Bcells have the potential to control the local availability of active vitamin D. Bcells, therefore, may participate in vitamin D-mediated immune homeostasis, including plasma cell generation. Whether or not other Bcell subsets, such as Breg cells, are equally responsive to vitamin D remains to be established.