Human T-bet Governs Innate and Innate-like Adaptive IFN-γ Immunity against Mycobacteria

Inborn errors of human interferon gamma (IFN-gamma) immunity underlie mycobacterial disease. We report a patient with mycobacterial disease due to inherited deficiency of the transcription factor T-bet. The patient has extremely low counts of circulating Mycobacterium-reactive natural killer (NK), invariant NKT (iNKT), mucosal-associated invariant T (MATT), and V delta 2(+) gamma delta T lymphocytes, and of Mycobacterium-non reactive classic T(H)1 lymphocytes, with the residual populations of these cells also producing abnormally small amounts of IFN-gamma. Other lymphocyte subsets develop normally but produce low levels of IFN-gamma, with the exception of CD8(+) alpha beta T and non-classic CD4(+) cep T(H)1* lymphocytes, which produce IFN-gamma normally in response to mycobacterial antigens. Human T-bet deficiency thus underlies mycobacterial disease by preventing the development of innate (NK) and innate-like adaptive lymphocytes (iNKT, MATT, and V delta 2(+) gamma delta T cells) and IFN-gamma production by them, with mycobacterium-specific, IFN-gamma-producing, purely adaptive CD8(+) alpha beta T and CD4(+) alpha beta T(H)1* cells unable to compensate for this deficit.