CD8+ T cells armed with retrovirally transduced IFN-γ

Interferon-gamma (IFN-gamma) is considered a key cytokine involved in the preventive and defensive responses of T cells against infectious pathogens and tumors. Therefore, the transgenic expression of IFN-gamma in specific T cells appears to be an obvious therapeutic possibility. To directly examine whether IFN-gamma production can be increased in T cells, we introduced an IFN-gamma encoding cDNA into IFN-gamma(-/-) and IFN-gamma(+/+) CD8(+) effector Populations by retroviral transduction. Here, we show that CD8 T cells can be equipped with IFN-gamma that increases their capacity to secrete the cytokine. Despite constitutive retroviral IFN-gamma mRNA transcription, translation and secretion of IFN-gamma protein was tightly regulated and only observed in activated T cells. Neither proliferation nor cytolytic activity of CTL was affected by IFN-gamma transduction. Importantly, CD8(+) T cells retrovirally transduced with IFN-gamma exhibit augmented tumor suppressive capacity upon adoptive transfer into IFN-gamma(-/-) mice. Thus, T cells can be readily armed with IFN-gamma without risking immunopathology by dysregulated production of this highly potent proinflammatory cytokine.