GMP-140 binds to a glycoprotein receptor on human neutrophils: Evidence for a lectin-like interaction

Abstract

GMP-140 is a rapidly inducible receptor for neutrophils and monocytes expressed on activated platelets and endothelial cells. It is a member of the selectin family of lectin-like cell surface molecules that mediate leukocyte adhesion. We used a radioligand binding assay to characterize the interaction of purified GMP-140 with human neutrophils. Unstimulated neutrophils rapidly bound [125I]GMP-140 at 4°C, reaching equilibrium in 10-15 min. Binding was Ca2+ dependent, reversible, and saturable at 3-6 nM free GMP-140 with half-maximal binding at ≈1.5 nM. Receptor density and apparent affinity were not altered when neutrophils were stimulated with 4β-phorbol 12-myristate 13-acetate. Treatment of neutrophils with proteases abolished specific binding of [125I]GMP-140. Binding was also diminished when neutrophils were treated with neuraminidase from Vibrio cholerae, which cleaves α2-3-, α2-6-, and α2-8-linked sialic acids, or from Newcastle disease virus, which cleaves only α2-3- and α2-8-linked sialic acids. Binding was not inhibited by an mAb to the abundant myeloid oligosaccharide, Lex(CD15), or by the neoglycoproteins Lex-BSA and sialyl-Lex-BSA. We conclude that neutrophils constitutively express a glycoprotein receptor for GMP-140, which contains sialic acid residues that are essential for function. These findings support the concept that GMP-140 interacts with leukocytes by a lectin-like mechanism.