Several lymphocyte subsets have been identified as critical producers of IFN-γ and mediators of antimycobacterial immunity: patients with autosomal recessive (AR) SPPL2A or RORγT deficiency, or with autosomal dominant (AD) IRF8 deficiency suffer from MSMD due to a lack of T-helper (TH) 1* cells27,31, whereas AR T-bet deficiency impairs the development and IFN-γ production of NK cells, innate-like adaptive lymphocyte subsets (mucosal-associated invariant T cells [MAIT], Vδ2+ γδ T, and invariant natural killer [iNKT] cells), and TH1 cells34. Here, IRF8 is linked to Mendelian susceptibility to mycobacterial diseases.