PMN binding to P-selectin is inhibited by sulfatide.

The endothelial adhesion protein P-selectin binds to a ligand present on the surface of leukocytes. We have characterized the binding interaction between P-selectin and polymorphonuclear leukocytes (PMNs) in an in vitro assay. These studies have utilized a soluble chimeric protein termed receptor globulin (Rg), which consists of the lectin-EGF-CR-CR extracellular domains of P-selectin fused to a human immunoglobulin G Fc domain. The PMNs bound to immobilized Rg in a saturable and concentration-dependent manner. The binding was specific for the Rg, as preincubation of the cells with soluble Rg inhibited binding to immobilized Rg, and binding was dependent on the presence of free divalent cations. The PMNs expressed a ligand for both P-selectin and E-selectin but not for L-selectin. Previously it was shown that sulfatide is a ligand for P-selectin binding in transformed cells. We have demonstrated that the presence of sulfatide in the P-selectin-PMN adhesion assay inhibits binding in a dose-dependent manner.