KPL1 inhibits rolling of all CD4⁺ T cells on CHO cells transfected with P-selectin but not E-selectin under defined shear stress. Freshly isolated CD4 T cells were assayed for their ability to roll on CHO cells transfected with either P- or E-selectin. (A) Rolling was assessed as described in Materials and Methods after exposure to either W6/32 (isotype control antibody), HDPG2/3 (a blocking anti–P-selectin antibody), KPL1, or a control antibody. Rolling of freshly isolated CD4 T cells was completely inhibited by pre-incubation of CD4 cells with KPL1 or monolayers with HDPG2/3. (B) Rolling of CD4 T cells on CHO cells transfected with E-selectin after exposure to either W6/32, HEL3/2 (a blocking anti–E-selectin antibody), KPL1, or a control antibody for KPL1 was performed as described for (A). Rolling of CD4 T cells was completely inhibited by preincubation of the E-selectin expressing monolayer with HEL3/2, whereas incubation of CD4 cells with either KPL1 or control antibodies had no effect. Values are mean ±SD; one of at least three experiments.