KPL1 inhibits the binding of HL60 cells, neutrophils, and PBMCs to P-selectin but not E-selectin expressing COS cells in a low shear adhesion assay. (A) Adhesion of HL60 cells (▪), neutrophils (▧), and PBMC (□) to COS cells transiently transfected with P-selectin was performed as described in Materials and Methods. All three cell types adhered well to P-selectin. KPL1 almost completely blocked these interactions, whereas a control antibody had no effect on adhesion. (B) HL60 cells (▪), neutrophils (▧) and PBMC (□) bound well to E-selectin, but neither KPL1 nor a control antibody inhibited adhesion to E-selectin expressing COS cells. Values are mean ±SD; one of at least five experiments.