1,25-Dihydroxyvitamin D3 decreases the interferon-gamma (IFN-gamma) induced HLA-DR expression but not intercellular adhesion molecule 1 (ICAM-1) on human keratinocytes.

In human epidermal keratinocytes (HKC), it is known that interferon gamma (IFN-gamma) induces Major Histocompatibility Complex (MHC) class II antigens and intercellular adhesion molecule 1 (ICAM-1) expression. 1,25 (OH)2D3, the most active metabolite of vitamin D3, has been shown to be produced by keratinocytes (KC). KC possess receptors for 1,25 (OH)2D3 and could be a target of 1,25 (OH)2D3. Although immunological participation of 1,25 (OH)2D3 has been reported, little is known about its effect on MHC class II Ag expression or ICAM-1 expression. In this article, we investigate the effect of 1,25 (OH)2D3 on IFN-gamma induced MHC class II Ag or ICAM-1 expression of HKC and reveal that 1,25 (OH)2D3 decreases the IFN-gamma induced HLA-DR, but not ICAM-1 expression on HKC.