The level of IFN-γ in the TB antigen tube of QFT-GIT is not related to the severity of TB, but is related to infection activity, and the level of IFN-γ stimulated by TB antigen is as follows: patients with residual TB lesions  <  patients with low TB activity  <  patients with high TB activity; mitogen-induced IFN-γ secretion was negatively correlated with lung pathological morphology and the area of affected lung tissue26,27. This evidence concerns the gene IFNG and infection.