Effect of SSL5 on adhesion of neutrophils under static conditions. Calcein-labeled neutrophils were incubated with 0.3 to 10 μg/mL SSL5 (•), SSL7 (♦), PSGL-1 mAbs PL1 (▪), PL2 (▴), or KPL1 (▾), or 5 mM EDTA (○) for 10 minutes. Subsequently, the neutrophils were incubated in duplicate wells for 15 minutes in a 96-well microtiterplate to which P-selectin was immobilized. After washing, bound neutrophils were quantified using a microplate reader. Average adherence of untreated cells was 78%. Neutrophil adherence was also examined on the P-selectin surface that was first treated with 30 μg/mL anti–P-selectin mAb WASP12.2 (▵). The data represent relative adhesion of neutrophils compared with untreated cells and are mean values ± SEMs of 3 independent experiments.