Immunocytochemical detection of 1,25-dihydroxyvitamin D receptors in normal human tissues

We developed an immunocytochemical technique to visualize the receptors for 1,25-dihydroxyvitamin D [1,25-(OH)2D receptor] in cryostat sections of normal human tissues, using a rat monoclonal antibody (9A7 gamma) to the chick intestinal receptor, which has been found to react with mammalian 1,25-(OH)2D receptors. Localization of the antigen was predominantly nuclear, with little cytoplasmic immunoreactivity. Specific staining was seen in the nuclei of many normal epithelial tissues, including liver, kidney, thyroid, adrenal, gastrointestinal tract, breast, and skin. No nuclear staining was seen when tissue sections were incubated with normal rat immunoglobulin G or when the monoclonal antibody was preincubated with a receptor-enriched chick intestinal cytosol preparation. Our results demonstrate that the receptor for 1,25-(OH)2D is localized in the nucleus and widely distributed in normal human tissues.