Suppressive activity of neutrophils requires ROS production. (A) Neutrophils were stimulated with the indicated stimuli and production of H₂O₂ was determined by measuring Amplex Red conversion into fluorescent Resorufin (n = 5). (B-D) Purified T cells from control donors (B-C) or CGD patients (D) were cultured with anti-CD3 and anti-CD28 antibodies (red bars) in the presence of neutrophils from control donors (blue bars) or CGD patients (green bars), and/or with indicated stimuli and antioxidants. Cells were harvested after 4 to 6 days and analyzed by flow cytometry for CFSE dilution among CD4⁺ T cells (n = 3 to 5 donors tested in duplicate). Error bars indicate SEM. ****P < .0001; ***P < .001; **P < .01; *P < .05. LBP, lipopolysaccharide binding protein.