IFNG and tuberculosis: However, we and others detected lower mitogen-induced IFNγ secretion in tuberculosis patients from Ghana than in healthy controls.3,7 Mitogen-induced IFNγ levels were below the detection limit for a subgroup of tuberculosis patients, which led to false-negative or ‘indeterminate’ IGRA results.3 These results suggested generally impaired T-cell cytokine expression as an immunopathognomonic feature in tuberculosis patients.