Glucocorticoid hormones reduce the expression of major histocompatibility class I antigens on human epithelial cells.

Expression of a critical level of major histocompatibility complex (MHC) class I antigens on epithelial cells is a prerequisite for the action of specific cytolytic immune response cells. Glucocorticoid hormones have strong immunosuppressive effects. Therefore, we investigated the influence of the synthetic glucocorticoid dexamethasone on the expression level of MHC class I antigens on human epithelial cell lines. Long-term treatment with dexamethasone leads to reduced MHC class I surface antigen expression and to decreased total membrane-bound MHC class I protein. The steady-state mRNA level is significantly decreased and the transcription rate of MHC class I genes is reduced.