IFNG and bacterial infectious disease: This accumulation of IFN-γ-producing CD8 T cells in the thymus is reminiscent of previous reports on signaling mutant strains, including Itk-, Klf2-, Cbp-, and Id3-deficient mice, where CD8 T cells with memory-like phenotype and rapid IFN-γ responsiveness, in the absence of antigen exposure, have been termed “innate-like” and shown to participate in the early response against viral and intracellular bacterial infections [10, 43–46].