IFNG and tuberculosis: IGRAs (including T-SPOT.TB and QFT-G) measure IFN-γ in whole blood following incubation with MTB antigen, early secretory antigenic target-6 (ESAT-6), culture filtrate protein-10 (CFP-10), and tuberculosis 7.7 (TB7.7), which are absent in BCG strains and commonly encountered NTM, except M. kansasii, M. gastri, M. marinum, M. szulgai, and M. riyadhense (14).