Obesity impairs gd T cell homeostasis and antiviral function in humans.

Obese patients are susceptible to increased morbidity and mortality associated with infec-tious diseases such as influenza A virus. γδ T cells and memory αβ T cells play key roles in reducing viral load by rapidly producing IFN-γ and lysing infected cells. In this article we an-alyze the impact of obesity on T lymphocyte antiviral immunity. Obese donors exhibit a re-duction in γδ T cells in the peripheral blood. The severity of obesity negatively correlates with the number of γδ T cells. The remaining γδ T cells have a skewed maturation similar to that observed in aged populations. This skewed γδ T cell population exhibits a blunted anti-viral IFN-γ response. Full γδ T cell function can be restored by potent stimulation with 1-Hy-droxy-2-methyl-buten-4yl 4-diphosphate (HDMAPP), suggesting that γδ T cells retain the ability to produce IFN-γ. Additionally, γδ T cells from obese donors have reduced levels of IL-2Rα. IL-2 is able to restore γδ T cell antiviral cytokine production, which suggests that γδ T cells lack key T cell specific growth factor signals. These studies make the novel finding that the γδ T cell antiviral immune response to influenza is compromised by obesity. This has important implications for the development of therapeutic strategies to improve vaccination and antiviral responses in obese patients.