E-selectin receptors on human leukocytes

Selectins on activated vascular endothelium mediate Inflammation by binding to complementary carbohydrates on circulating neutrophils. The human neutrophil receptor for E-selectln has not been established. We report here that sialylated glycosphingolipids with 5 N-acetyllactosamine (LacNAc, Galß1-4Glc-NAcß1-3) repeats and 2 to 3 fucose residues are major functional E-selectin receptors on human neutrophils. Glycolipids were extracted from 10¹⁰ normal peripheral blood human neutrophils. Individual glycollpid species were resolved by chromatography, adsorbed as model membrane monolayers and selectin-mediated cell tethering and rolling under fluid shear was quantified as a function of glycolipid density. E-selectin-expressing cells tethered and rolled on selected glycolipids, whereas P-selectin-expressing cells failed to interact. Quantitatively minor terminally sialylated glycosphingolipids with S to 6 LacNAc repeats and 2 to 3 fucose residues were highly potent E-selectin receptors, constituting more than 60% of the E-selectin-blnding activity In the extract. These glycoliplds are expressed on human blood neutrophils at densities exceeding those required to support E-selectin-mediated tethering and rolling. Blocking glycosphingolipid biosynthesis In cultured human neutrophils diminished E-selectin, but not P-selectin, adhesion. The data support the conclusion that on human neutrophils the glycosphingolipid NeuAcα2-3Gal β1-4GlcNAcβ1-3 [Galβ 1-4(Fucα1-3)Glc-NAcβ1-3]₂[Galβ1-4GlcNAcβ1-3] ₂Galβ1-4GlcβCer (and closely related structures) are functional E-selectin receptors.