FIGURE 2.

Addition of H₂O₂ to NETs induces MPO-dependent killing. Neutrophils were stimulated with PMA to form NETs then incubated with S. aureus in the presence or absence of (A) varying concentrations of H₂O₂ or (B) 100 μM H₂O₂ (added in 20 μM aliquots every 5 min to facilitate MPO turnover). At the examined concentrations, H₂O₂ in the absence of NETs had no significant effect on S. aureus viability. (A) Bacterial numbers significantly decreased with ≥40 μM H₂O₂ (p< 0.05, t-test on normalized data, n = 3). (B) Bacterial viability decreased with H₂O₂ (p< 0.001), and inhibition of MPO with ABAH and scavenging of HOCl with methionine (Met) prevented killing (p< 0.01; one-way ANOVA with Holm–Sidak pairwise comparison, n = 5). Results are presented as percent of control cells (Con) incubated with NETs alone. Data obtained with permission from Parker et al. (2012a).