Distribution of IFN-γ responses to bromohydrin pyrophosphate (BrHPP) in patients with tuberculosis, HIV-1–positive patients with tuberculosis, and their household contacts. A, Comparison of IFN-γ responses to BrHPP between HIV-1–positive and HIV-1–negative subjects with and without tuberculosis. Whole blood was diluted and stimulated with BrHPP (50 μmol/L) plus interleukin (IL)–2 (25 U/mL) for 7 days, and IFN-γ was measured by ELISA. The IFN-γ response from each subject was calculated by subtracting the response to IL-2 alone from the response to BrHPP plus IL-2. Box plots represent median IFN-γ responses, with error bars showing the 25th and 75th percentiles and whiskers indicating the 5th and 95th percentiles. B, Histogram of log-transformed IFN-γ response of HIV-1–negative household contacts (n = 85). The IFN-γ response of each subject was calculated by subtracting the response to IL-2 alone from the response to BrHPP plus IL-2. The mean ± SD response was 2.86 ± 0.78. Cutoff values (2.1 and 3.6) were calculated as means ± SD and are indicated at the top of the panel.