Vitamin D-Binding Protein Directs Monocyte Responses to 25-Hydroxy- and 1,25-Dihydroxyvitamin D

Background: Serum 25-hydroxyvitamin D (25OHD) is a key factor in determining monocyte induction of the antimicrobial protein cathelicidin, which requires intracrine conversion of 25OHD to 1,25-dihydroxyvitamin D [1,25(OH)2D]. Both vitamin D metabolites circulate bound to vitamin D-binding protein (DBP), but the effect of this on induction of monocyte cathelicidin remains unclear