Interferon gamma (IFN-gamma) is a pleiotropic cytokine secreted by T lymphocytes and natural killer (NK) cells and has been noted to be a first line of host defense in the control of viral infections. To examine further the role of this cytokine in the control of viral infections, mice with a targeted mutation in the IFN-gamma gene were infected with influenza virus, and the in vivo antibody and cell-mediated immune response to viral infection were examined. In addition, cell lines and clones were derived from the immunized animals and the in vitro cytokine production and cytotoxic T lymphocyte (CTL) response were analyzed. The absence of IFN-gamma led to increased production of influenza-specific IgG1, IL-4, and IL-5 as compared to wild-type littermate control animals. In contrast, there was no difference noted in the development of an effective CTL response between IFN-gamma-deficient and wild-type animals. In this model of experimental influenza infection, IFN-gamma is not necessary for the development of an effective humoral or cellular immune response to challenge with this respiratory virus.

Graham, M. B., Dalton, D. K., Giltinan, D., Braciale, V. L., Stewart, T. A., & Braciale, T. J. (1993). Response to influenza infection in mice with a targeted disruption in the interferon gamma gene. The Journal of Experimental Medicine, 178(5), 1725–1732.