Calcitriol stimulates prolactin expression in non-activated human peripheral blood mononuclear cells: Breaking paradigms

► Calcitriol stimulated PRL in resting lymphocytes by a VDR-mediated mechanism. ► CYP24A1 induction by calcitriol is stronger in resting vs. activated lymphocytes. ► Factors restraining VDR-transcriptional process are induced upon activation. ► Lymphocyte activation reduced CYP24A1 while induced CYP27B1 and VDR gene expression. ► Calcitriol actions in resting lymphocytes are probably mediated by a VDR variant.