1,25-Dihydroxyvitamin D₃ inhibits selectively the mitogenic stimulation of mouse medullary thymocytes

Mouse thymocytes were separated into cortical and medullary subpopulations by differential agglutination with peanut agglutinin. A high-affinity receptor for 1,25-dihydroxyvitamin D₃ is present in medullary immunocompetent mouse thymocytes and is absent from cortical immature cells. 1,25-dihydroxyvitamin D₃, at physiological concentrations, inhibits the mitogenic response of the medullary cells to phytohemagglutinin and interleukin-2, but has no effect on the cortical subpopulation. Other less active metabolites of vitamin D had little or no effect on medullary cell stimulation.