1,25-Dihydroxyvitamin D3 receptors in a subset of mitotically active lymphocytes from rat thymus.

Lymphocytes from the rat thymus gland were separated on Percoll gradient in two subsets. The first subset was enriched in large mitotically active cells and the second in small mitotically inert cells. The former cell preparation possessed a 3.3 S macromolecule with high affinity for 1,25-Dihydroxyvitamin D3 (Kd = 3.3 X 10(-10)M) which bound to DNA cellulose and was eluted from this resin with 0.26 M KCl. In contrast, the small-cell-enriched subset of thymic cells was negative for 1,25-Dihydroxyvitamin D3 specific binding. These findings support evidence from studies in human lymphocytes that there exists an association between mitotic activity and 1,25-Dihydroxyvitamin D3 receptor expression in this class of leukocytes.