Thiourea and dimethylthiourea decrease human neutrophil bactericidal function in vitro

Addition of thiourea (TU) or dimethylthiourea (DMTU) decreased killing of Staphylococcus aureus, 502A, and decreased concentrations of hydrogen peroxide (H2O2), and hydroxyl radical (.OH), but not superoxide anion (O2-.) or lysozyme concentrations, in mixtures containing human neutrophils in vitro. Addition of TU or DMTU also decreased concentrations of H2O2, .OH, or hypochlorous acid (HOCl) in neutrophil-free mixtures exposed to beta-D-glucose and glucose oxidase, gamma irradiation, or HOCl, respectively. Our results suggest that TU or DMTU can decrease neutrophil-mediated killing of bacteria by inhibiting O2 metabolite-dependent bactericidal mechanisms.