IFNG and tuberculosis: The popular IGRA, which measures TB-antigen-stimulated IFN-γ levels, was reported to have a poor correlation with the treatment response, showing blunted level changes and fluctuations during the longitudinal monitoring of TB.9,10 This shortcoming is expected because cell-mediated immune reactions may persist throughout the treatment period.19 Furthermore, stimulation with TB antigens further blunts the changes in IFN-γ levels.