1,25-Dihydroxyvitamin D3 receptors in lymphocytes from patients with rheumatoid arthritis

It has been previously found that activation of human lymphocytes in vitro causes the expression of receptors for the hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and that 1,25(OH)2D3 has immunoregulatory properties including the ability to inhibit interleukin-2, to suppress lymphocyte proliferation, and to inhibit antibody production. In the present study we found that 13 of a group of 17 (76%) seropositive patients with rheumatoid arthritis had lymphocytes that possessed 1,25(OH)2D3 receptors (without activation in vitro) compared with only three of 17 (18%) normal individuals. The biochemical characteristics of the 1,25(OH)2D3 receptor, including affinity, sedimentation coefficient, and DNA-binding properties in the rheumatoid arthritis lymphocytes were indistinguishable from those established for this receptor in the classic target tissue of the hormone. This finding raises the possibility that 1,25(OH)2D3, acting through its receptor, might play a previously unsuspected role on lymphocytes of patients with rheumatoid arthritis.