Impairment of the CD8+T cell response in lungs following infection with human respiratory syncytial virus is specific to the anatomical site rather than the virus, antigen, or route of infection

Background: A subset of the virus-specific CD8+ cytotoxic T lymphocytes (CTL) isolated from the lungs of mice infected with human respiratory syncytial virus (RSV) is impaired in the ability to secrete interferon gamma (IFN gamma), a measure of functionality. It was suggested that the impairment specifically suppressed the host cellular immune response, a finding that could help explain the ability of RSV to re-infect throughout life. Results: To determine whether this effect is dependent on the virus, the route of infection, or the type of infection ( respiratory, disseminated, or localized dermal), we compared the CTL responses in mice following intranasal ( IN) infection with RSV or influenza virus or IN or intradermal ( ID) infection with vaccinia virus expressing an RSV CTL antigen. The impairment was observed in the lungs after IN infection with RSV, influenza or vaccinia virus, and after a localized ID infection with vaccinia virus. In contrast, we observed a much higher percentage of IFN gamma secreting CD8+ lymphocytes in the spleens of infected mice in every case. Conclusion: The decreased functionality of CD8+ CTL is specific to the lungs and is not dependent on the specific virus, viral antigen, or route of infection.