IFNG and tuberculosis: HIV-infected patients with definite TB had a similar IFN-γ response compared to those without HIV-infection when measured using the TSPOT.TB assay [86 (IQR: 31–158) vs. 115 (56–200); p = 0.22], but when measured using QFT-GIT [2.2 (0.4–3.8) vs. 3.7 (0.9–6.1); p = 0.02] or the PPD ELISPOT [62 (20–118) vs. 122 (62–196); p<0.01] the magnitude of response was significantly lower in the HIV-infected group.