Direct induction of MHC class I, but not class II, expression on endothelial cells by cytomegalovirus infection.

MHC expression on endothelial cells after cytomegalovirus infection was investigated using double antibody radioimmunoassays and immunofluorescence flow cytometry. After CMV infection there was an increase in class I and beta 2 microglobulin expression. This increase corresponds to the percentage of cells that are infected with CMV. There was no evidence that the increased class I expression was due to soluble factors produced by the infected cells. Although CMV only affects approximately 10% of the endothelial cells, class I and beta 2 microglobulin expression on the cell population exceeds that induced by an optimal dose of alpha-interferon. Class II expression is not increased after CMV infection. However, when gamma-interferon was added to the medium after CMV infection a normal increase in class II expression was found, suggesting that CMV infection does not inhibit the gamma-interferon-induced expression of these molecules.