Comparison of the effects of 1,25-dihydroxyvitamin D3 on T lymphocyte subpopulations.
Previous studies have demonstrated that 1,25-dihydroxyvitamin D3 (calcitriol) is a potent inhibitor of human T lymphocyte proliferation. It has been reported that only CD4+ cells are sensitive to the anti-proliferative action of calcitriol. To further evaluate this observation, we first performed cell cycle analysis of unfractionated phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMC) in the absence or presence of calcitriol. The CD4/CD8 ratio was similar between control and treated cells for each phase of cycle (G0----G1, S, G2 + M), suggesting that calcitriol did not selectively block proliferation of either T cell subpopulation. Secondly, the growth-inhibitory activity of calcitriol on PBMC selectively depleted of either CD4+ or CD8+ cells was comparable to that observed with unfractionated PBMC. Furthermore, the induction of transferrin receptors was inhibited by calcitriol to a comparable degree in each T cell subset, suggesting that equivalent inhibition of transition into late G1 was observed. Finally, calcitriol inhibited the proliferation of highly purified T cell subsets (greater than 99% pure) to equivalent degrees. These data suggest that T cell subsets defined by either the CD4 or by the CD8 antigen are both sensitive to the growth inhibitory effects of calcitriol.
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002117:Calcitriol / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002469:Cell Separation; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D010835:Phytohemagglutinins; D002117:Calcitriol