Human neutrophils roll on immobilized L-selectin under flow conditions. Human neutrophils (1 × 10⁶/mL) were infused 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. (A) Displacement as a function of time for neutrophils rolling on L-selectin under a continuous wall shear stress (1 dyne/cm²). Tracings represent positions of five independent cells measured at 0.03-second intervals. Bold solid line (arrow) represents the tracking of a noninteracting neutrophil traveling at critical velocity near the wall of the flow chamber. (B) Neutrophil attachment to purified L-selectin under continuous flow conditions is shear stress-dependent. Adhesion to L-selectin was specific based on inhibition of neutrophil attachment after inclusion of EDTA (5 mmol/L) in the perfusion media and treatment of the adsorbed L-selectin substrate with L-selectin MoAb, DREG56 (10 μg/mL). Metabolic inhibition with 0.06% azide and 50 mmol/L 2-deoxy-D-glucose for 30 minutes at room temperature or incubation of neutrophils with CD18 MoAb, TS1/18 (10 μg/mL), did not block attachment to L-selectin. Treatment of neutrophils with PSGL-1 MoAbs PL1 (Fab fragments) (10 μg/mL) or KPL1 (10 μg/mL), but not KPL2 ascites (1:500), partially inhibited attachment to L-selectin. Mean ± SEM of bound cells/mm² in multiple fields from two to four independent experiments.