CD4+ or CD8+ T cells could control F. tularensis growth in macrophages in vitro in part through the production of IFN-γ [39], and in vivo both subsets produced IFN-γ [38]; interestingly, IFN-γ knockout mice on the C57BL/6 background were previously shown to be more susceptible to UTI than immunocompetent mice [40]. This evidence concerns the gene CD4 and bacterial urinary tract infection.