Trojan horse lymphocytes: a vesicular stomatitis virus-specific T-cell clone lyses target cells by carrying virus.

We have isolated a vesicular stomatitis virus (VSV)-specific CD4+ CD8- murine T-cell clone. This clone proliferates only in response to VSV and lyses infected tumor cells bearing class II major histocompatibility antigens in short-term chromium release assays. In addition, the cell has VSV antigens on its surface and is capable of killing uninfected tumor cells without major histocompatibility antigen restriction in a 2-day assay. This latter cytolytic activity is eliminated by anti-VSV antibody, indicating that its lytic activity is provided by the virus. [35S]methionine labeling and immunoprecipitation experiments demonstrated that viral protein translation is initiated after incubation of the clone with a tumor target cell, defining this as the mechanism of its cytolytic activity.