Respiratory Syncytial Virus Infection of Human Respiratory Epithelial Cells Up-Regulates Class I MHC Expression Through the Induction of IFN-β and IL-1β

CD8⁺ T cells mediate some of the damage to the lung epithelium following respiratory syncytial virus (RSV) infection. Since CD8⁺ T cells recognize antigen-laden class I MHC molecules on the target cells, we examined in this study the expression of class I MHC by RSV-infected respiratory epithelial cells. Respiratory epithelial cell lines and bronchial epithelial cells from normal human tissue responded to RSV infection with an increased expression of class I MHC as determined by flow cytometry and immunoprecipitation of class I MHC from metabolically radiolabeled cells. The increase in class I MHC expression was dependent on infectious, replicating virus. UV-irradiated culture supernatants from RSV-infected A549 cells, when added to fresh A549 cell cultures, induced an increase in class I MHC expression by those cells. The class I MHC increasing activity within supernatants from A549 cells was due, in large part, to IFN-β, and to a lesser extent to IL-1α. The addition of neutralizing Abs to both cytokines completely blocked the increase in class I MHC expression by cells treated with the above-mentioned supernatants. These results demonstrate that RSV infection elicits IFN-β production by respiratory epithelial cells, which in turn leads to an increase in their synthesis of class I MHC, which would facilitate their recognition and lysis by RSV-specific CD8⁺ T cells.