Differential enhancement of interferon-gamma-induced MHC class II expression of HEp-2 cells by 1,25-dihydroxyvitamin D3.

Interferon-gamma (IFN-gamma) induces the expression of MHC class II antigens on non-lymphoid cells. In this study we investigated the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the most active metabolite of vitamin D3, on the IFN-gamma-induced expression of MHC class II antigens on HEp-2 cells. We found that 1,25(OH)2D3 enhanced the IFN-gamma-induced expression of HLA-DR on these cells. Differential effects on the MHC class II antigens HLA-DR, -DQ and -DP were also observed.