Rolling velocities of CHO-PSGL-1 transfectants or neutrophils on human L- or P-selectin. (A) CHO cells expressing human, bovine, pig, rat or equine PSGL-1 or (B) neutrophils were perfused under a constant shear stress on recombinant human P-selectin (1.5 dynes/cm2) or L-selectin/μ chimera (1.0 dyne/cm2). Cell velocities were measured at 4–5 min of perfusion. Curves were constructed in (A) using 183–755 or (B) 25–381 independent determinations of cell-rolling velocities and are representative of three experiments. Median rolling velocities, representative of 3 experiments, are indicated.