1,25-Dihydroxyvitamin D₃ and the regulation of macrophage function

Vitamin D₃ deficient (D^-) mice show a depressed inflammatory response and both inflammatory peritoneal macrophages and bone marrow polymorphonuclear leukocytes of D^- mice exhibit a decreased spontaneous migration under agarose. The impaired phagocytic response of peritoneal macrophages from D^- mice can be corrected by incubation with 1,25-dihydroxyvitamin D₃ and is not affected by interaction with other vitamin D₃ metabolites. Transfer of mice from the D^- to the D⁺ state results in correction of both the inflammatory and the phagocytic response. Intactness of phagocyte function is thus directly dependent on vitamin D₃ metabolism.