[Suppression of gamma-interferon induced HLA-DR antigen expression on normal and transformed keratinocytes by 1,25 (OH)2 vitamin D3].

Recently, it has been shown that 1,25 (OH)2 Vitamin D3 (VD3) shows growth inhibition and enhances differentiation of keratinocytes in vitro. To elucidate the further effect of VD3 on keratinocytes, we studied the effect of recombinant human gamma interferon (IFN-gamma) and VD3 on the expression of HLA-DR antigen and MHC class I antigen on 3 normal and 6 transformed keratinocytes by means of FACS analysis. IFN-gamma (500 JRU/ml, 72 hr) induced the expression of HLA-DR antigen on 3/3 normal keratinocytes, 3/4 trichilemmoma and 1/2 squamous cell carcinoma cell lines. When these cells were cultured with both IFN-gamma and VD3 at the same time, the expression of HLA-DR antigen was significantly decreased. Sequential treatment of these cells with IFN-gamma and VD3 (each 72 hr), or vice versa, showed significant suppression of HLA-DR antigen expression. The fluorescens intensity of class I antigen was increased after IFN-gamma treatment, however, this effect is inhibited when the cells were treated with combination of IFN-gamma and VD3.