Figure 5. Killing of BMJ71 bacteria does not require Nox2 activation.

A. Intracellular killing with inhibited oxidase. Differentiated HL-60 cells were allowed to phagocytose BMJ71 bacteria at 37°C, bacteria/cell ratio 10∶1, in the presence or absence of 10 µM DPI. After a synchronized presentation, the samples were incubated at 37°C as indicated, before killing of extracellular bacteria by PlyC. Intracellular survival of bacteria was determined by diluting HL-60 lysates and counting the number of colonies formed after overnight growth at 37°C. Data shown are expressed as the CFU ability relative to the control value at 1 min. Error bars show SEM, based on a total of five experiments. A significant difference was found between control and DPI-treated cells at the 1 min time point, p<0.05. B. H₂O₂ susceptibility of S. pyogenes. BMJ71 and AP1 bacteria were incubated with 1.5% H₂O₂ at 37°C as indicated. The samples were stained using a bacterial viability kit (Viagram) and analyzed by fluorescence microscopy. As a control, catalase (1,000 U/ml) was added. At least 100 bacteria per condition were analyzed. Error bars show SEM, based on a total of three experiments.