KPL1 inhibits rolling of neutrophils on CHO cells transfected with P-selectin but not E-selectin under defined shear stress. (A) The rolling of neutrophils on CHO cells expressing P-selectin in the presence of W6/32 (isotype control), HDPG2/3 (a blocking anti–P-selectin antibody), KPL1, or a control antibody for KPL1 was performed as described in Materials and Methods. Both KPL1 and HDPG2/3 completely blocked rolling of neutrophils on P-selectin. No effect on rolling was observed when the control antibodies were used. (B) The ability of freshly isolated neutrophils to roll on E-selectin transfected COS cells in the presence of W6/32, HEL3/2 (a blocking anti–E-selectin antibody), KPL1, or control antibody was performed as described in (A). Only the anti–E-selectin antibody inhibited rolling of neutrophils on E-selectin. No inhibition of rolling was observed when neutrophils were pre-incubated with KPL1 or control antibody, or when monolayers were exposed to W6/32. Values are mean ±SD; one of at least three experiments.