Shear stress-dependent contribution of PSGL-1 to neutrophil capture by L-selectin. Neutrophils (0.5 × 10⁶/mL) were treated with either MoAb KPL1 (10 μg/mL) or KPL2 ascites (1:500) and perfused over a range of wall shear stresses through a parallel plate flow chamber in which dilutions of human purified L-selectin (1:5; 170 sites/μm²) were adsorbed to the lower wall. Numbers of bound cells were quantitated from 30 fields of view after 1 minute of continuous flow at each shear stress. Mean ± SD of bound cells/mm² in multiple fields from two independent experiments.