IFNG and tuberculosis: After stimulated by ESAT-6 or CFP-10 peptides, the frequencies of total IFN-γ-secreting T cells detected by FluoroSpot assay strongly and significantly correlated with those of T-SPOT.TB (r = 0.910 for ESAT-6, P < 0.001, r = 0.845 for CFP-10, P < 0.001) (Fig. 3).