GMP-140 BINDS TO A GLYCOPROTEIN RECEPTOR ON HUMAN NEUTROPHILS - EVIDENCE FOR A LECTIN-LIKE INTERACTION

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 characterized the interaction of purified GMP-140 with human neutrophils. Unstimulated neutrophils rapidly bound [I-125]GMP-140 at 4-degrees-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 almost-equal-to 1.5 nM. Receptor density and apparent affinity were not altered when neutrophils were stimulated with 4-beta-phorbol 12-myristate 13-acetate. Treatment of neutrophils with proteases abolished specific binding of [I-125]GMP-140. Binding was also diminished when neutrophils were treated with neuraminidase from Vibrio cholerae, which cleaves alpha-2-3-, alpha-2-6-, and alpha-2-8-linked sialic acids, or from Newcastle disease virus, which cleaves only alpha-2-3- and alpha-2-8-linked sialic acids. Binding was not inhibited by an mAb to the abundant myeloid oligosaccharide, Le(x) (CD15), or by the neoglycoproteins Le(x)-BSA and sialyl-Le(x)-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.