The TBAg − Nil IFN-γ levels were significantly higher in the active TB group (4.07 [1.14–8.17] IU/mL) than in the IGRA-positive non-TB (2.19 [0.84–5.84] IU/mL) and IGRA-negative non-TB (0.01 [− 0.01–0.04] IU/mL) groups (P < 0.0001). Here, IFNG is linked to tuberculosis.