1,25-Dihydroxyvitamin D 3 and the Immune System

Abstract

Summary

There is substantial evidence that lymphocytes and monocytes are targets for the actions of the hormonal form of vitamin D, 1,25-(OH)₂D₃ and that 1,25-(OH)₂D₃ acts to modulate the proliferation, differentiation, and immune functions of these cells. The effects of the hormone on lymphocytes are mediated directly as well as indirectly via the accessory monocytes. Depending upon the presence or absence of monocytes and the mode of lymphocyte activation, 1,25-(OH)₂D₃ can either stimulate or suppress lymphocytes. This evidence as well as clinical information and in vivo studies support a role of 1,25-(OH)₂D₃ in immunobiology. The physiologic, pathophysiologic, and pharmacologic implications of the immunomodulating properties of 1,25-(OH)₂D₃ however have not been well established.