Effect of 1,25-dihydroxyvitamin D3 on interferon gamma production in vitro

In recent years, receptors for calcitriol (the active form of vitamin D3) have been identified in monocytes and activated, but not resting, human B and T lymphocytes suggesting that it may be involved in immune regulation. Because lymphokines are central in the regulation and modulation of immune or inflammatory responses and since the calcium translocation is involved in the mitogen-induced activation of lymphocytes, we thought it interesting to study the role of calcitriol on interferon gamma (IFN-gamma) production in vitro. In this study, we report that calcitriol inhibits the IFN-gamma production by staphylococcal enterotoxin A-stimulated peripheral blood mononuclear cells (PBMC) in a dose-dependent fashion. The inhibitory effect was less potent in calcium ionophore A23187-stimulated PBMC and was absent in resting PBMC.