A role for the mevalonate pathway in the induction of subtype cross-reactive immunity to influenza A virus by human gammadelta T lymphocytes.

The major gammadelta T cell subset in the human peripheral blood expresses the Vgamma9delta2 TCR and recognizes non-peptidic prenyl pyrophosphate antigens such as isopentylpyrophosphate (IPP). Upon activation the gammadelta T cells rapidly secrete antiviral cytokines similar to classical memory alphabeta T cells. Here we have investigated the ability of gammadelta T lymphocytes from human PBMC to become activated by influenza A virus infection. Vgamma9Vdelta2 T lymphocytes rapidly upregulate expression of CD25 and CD69 and produce IFN-gamma following influenza infection of PBMC. Moreover, the recognition is cross-reactive between various subtypes of influenza, but not with vaccinia virus. Vgamma9Vdelta2 T cell responses are potently reduced by the HMG-CoA reductase inhibitor mevastatin, which inhibits the mevalonate pathway and IPP synthesis. Our results indicate that influenza virus infection induces the rapid activation and function of Vgamma9Vdelta2 T lymphocytes in the peripheral blood via a mechanism that depends on the mevalonate pathway.