Effect of voxelotor on markers of neutrophil activation, adhesion and aging, and ROS production. (A) Neutrophil markers of activation, adhesion, aging at baseline, and after 3 months of voxelotor treatment. (B) Neutrophil ROS production as measured by Amplex red assay at steady state and when using zymosan, serum-treated zymosan (STZ), phorbol myristate acetate (PMA), N-formylmethionyl leucyl phenylalanine (fMLP), and platelet-activating factor (PAF)–fMLP. Data are presented as medians, with error bars indicating interquartile ranges. NADPH, reduced NAD phosphate.