Figure 3.

Loss of myeloperoxidase (MPO) enhances membrane translocation of αMβ2 integrin and accumulates extracellular H₂O₂ following agonist stimulation. Wild-type (WT) and MPO knockout (KO) neutrophils were stimulated with varying concentrations of formyl-methionyl-leucyl-phenylalanine (fMLP) or PMA. (A–C) Flow cytometric analysis was performed using an anti-αMβ2 antibody (M1/70). (A) Representative histograms. (B,C) Flow cytometric results are shown as a fold increase of the median fluorescence intensity relative to the respective unstimulated control. (D,E) Extracellular H₂O₂ levels were measured in fMLP- or PMA-stimulated WT and MPO KO neutrophils using the Amplex Red assay. The fluorescence signal was converted to the molar amount of H₂O₂ using a standard curve. (F,G) Exogenous H₂O₂ (200 nM) was added prior to stimulation of WT neutrophils with fMLP or PMA. The surface level of αMβ2 integrin was measured by flow cytometry. Data are shown as the mean ± SD (n = 3). *P < 0.05, **P < 0.01, or ***P < 0.001 versus WT after Student’s t-test.