FIG. 4.

Production of hydrogen peroxide by alveolar macrophages treated with supernatants from infected neutrophils. Alveolar macrophages (2 × 10⁵/well) were treated with supernatants from neutrophils infected with M. tuberculosis H37Rv (MOI of 5) for 24 h (Sup), and H₂O₂ production was measured by using horseradish peroxide-dependent oxidation of phenol red. Alveolar macrophages treated with supernatants from uninfected neutrophils were used as controls (Un Sup). Some of the alveolar macrophages were treated with anti-recombinant guinea pig TNF-α antibody (1:600 dilution; data not shown). PMA and catalase (Cat) were used by macrophages as a stimulant and an inhibitor of H₂O₂ production, respectively. The other controls used were uninfected, untreated macrophages (Un AM); macrophages infected with M. tuberculosis H37Rv at an MOI of 0.1 (Rv); and alveolar macrophages treated with supernatants from infected neutrophils and also infected with M. tuberculosis at an MOI of 0.1 (Rv + Sup). H₂O₂ concentrations (Conc) were expressed in nanomoles. The levels of production of H₂O₂ by different treatment groups (three animals per group) were compared with that by the untreated control by using ANOVA followed by Duncan's post hoc analysis. *, P < 0.05.