Regulation of class II MHC molecules on human endothelial cells. Effects of IFN and dexamethasone.

Abstract

Human vascular endothelial cells normally do not express class II MHC molecules in culture. IFN-gamma has been shown to induce expression of class I and class II MHC molecules on endothelial cell cultures from umbilical cord. We could detect these Ag by FACS analysis when endothelial cells were cultured for 3 days in the presence of 200 to 1000 U/ml of rIFN-gamma. Among the class II MHC molecules, HLA-DR and -DP but not -DQ were consistently induced. Addition of rIFN-alpha-D/A to IFN-gamma-treated cells inhibited the expression of class II MHC but not class I MHC molecules. Furthermore, the inhibition was more pronounced when IFN-alpha-D/A was added before or simultaneously as IFN-gamma. Natural IFN-alpha also exhibited similar inhibition and its suppressive effect was abolished in the presence of anti-IFN-alpha antibody. On the contrary, dexamethasone, a known inhibitor of class II MHC molecules on murine macrophages, showed a slight enhancing effect on class II MHC Ag. These results suggest an immunoregulatory role for IFN-alpha on non-lymphoid cells and that controlling elements for expression of class II MHC molecules may be different on various cell types as well as species.