Neutrophils isolated from bone marrows of Ptpn22-/- (ko) and matched wild-type control (wt) mice were used to characterize ROS production following stimulation with PMA (A,B), with fMLF (C,D), or following plating of cells into wells coated with immobilized IC (IgG-BSA) or as a control, BSA (E,F), into fibrinogen coated wells in the presence (stimulated) of absence (control) of TNFα (G, H), or into wells coated with the synthetic integrin ligand poly-Arg-Gly-Asp (polyRGD) or as a control, heat inactivated fetal calf serum (FCS) (I,K). Data shown (means ± range) are representative individual experiments (A,C,E,G,I). Total light emissions (means ± SEM) expressed as percentage of the response obtained with stimulated control neutrophils pooled from a minimum of three separate experiments (B,D,F,H,K).