T-cells secreting IFN-γ following stimulation with either purified protein derivative (PPD) or M. TB-specific antigens (ESAT-6 and CFP-10) have been detected at 10- to 100-fold higher frequency in bronchoalveolar lavage (BAL) fluid compared to peripheral blood specimens in patients with pulmonary TB [5], [6], which may enhance the sensitivity of IGRAs. This evidence concerns the gene IFNG and pulmonary tuberculosis.