Further studies of the binding specificity of the leukocyte adhesion molecule, L-selectin, towards sulphated oligosaccharides—suggestion of a link between the selectin- and the integrin-mediated lymphocyte adhesion systems

Abstract

This communication is concerned with the binding specificity of the leukocyte-adhesion molecule L-selectin (leukocyte homing receptor) towards structurally defined sulphated oligosaccharides of the blood group Le(a) and Le(x) series, and of the glycosaminoglycan series heparin, chondroitin sulphate and keratan sulphate. The recombinant soluble form of the rat L-selectin (L-selectin-IgG Fc chimera) investigated here was shown previously to bind to lipid-linked oligosaccharides 3-O, 4-O and 6-O sulphated at galactose, such as sulphatides and a mixture of 3-sulphated Le(a)/Le(x) type tetrasaccharides isolated from ovarian cystadenoma, as well as to the HNK-1 glycolipid with 3-O sulphated glucuronic acid. In the present study, the L-selectin investigated in both chromatogram binding and plastic microwell binding experiments using neoglycolipids was found to bind to the individual 3-sulphated Le(a) and Le(x) sequences (penta-, tetra- and trisaccharides), and with somewhat lower intensities to their non-fucosylated analogues. Glycosaminoglycan disaccharides of keratan sulphate, heparin and chondroitin sulphate types were also bound by L-selectin in one or both assay systems, leading to the conclusion that clustered glycosaminoglycan oligosaccharides with 6-O sulphation of N-acetylgalactosamine, N-acetylglucosamine or glucosamine, 4-O sulphation of N-acetylgalactosamine, 2-O sulphation of uronic acid, N-sulphation of glucosamine and, to a lesser extent, the non-sulphated uronic acid-containing disaccharides, can support L-selectin adhesion. As inflammatory chemokines (short-range stimulators of lymphocyte migration which trigger integrin activation) are known to bind to endothelial glycosaminoglycans, we propose that the binding of the lymphocyte membrane L-selectin to endothelial glycosaminoglycans may provide a link between the selectin-mediated and integrin-mediated adhesion systems in leukocyte extravasation cascades. The possibility is also raised that lymphocyte L-selectin interactions with glycosaminoglycans may contribute to pathologies of glycosaminoglycan-rich tissues, e.g. cartilage loss in rheumatoid arthritis and inflammatory lesions of the cornea.

L-selectin Interactions with Novel Mono- and Multisulfated Lewisx Sequences in Comparison with the Potent Ligand 3′-Sulfated Lewisa

“…In accord with this finding is an earlier report that L-selectin binding is abolished by modification of the fucose in the 3Ј-sialyl-Le x sequence by removal of oxygen at position 2, 3, or 5 (18). The presence of the fucose is apparently less critical in the 3Ј-sulfo-Le x sequence as it has been observed that the defucosylated 3Ј-sulfo-Le x tri-and tetrasaccharides are bound by L-selectin, albeit less strongly than the 3Ј-fucosyl analogs (4,5).…”

Minimal Sulfated Carbohydrates for Recognition by L-selectin and the MECA-79 Antibody

“…8A). Despite the ability of E-selectin to bind to 3Ј-sulfo-Le X and 3Ј-sulfo-Le a (31,32,55), E-selectin did not bind to 3Ј-sulfolactose or 3Ј,6-disulfolactose and bound only weakly to 3Ј,6Ј-disulfolactose (Fig. 8A).…”

Inhibition of L-selectin-mediated Leukocyte Rolling by Synthetic Glycoprotein Mimics

“…In addition, 3Ј-sulfo Le x inhibits L-selectin-ligand interactions with IC 50 values similar to those of sLe x (34) in static, cell-free binding assays. Moreover, several studies comparing the ability of L-selectin to bind to glycolipid derivatives of 3Ј-sulfo Le x and sLe x indicate that the sulfated derivatives are superior to the corresponding compounds bearing the sialic acid residue (74,75,78), and 3Ј-sulfo Le x -substituted lipids can support L-selectin-mediated rolling (79). Together, these studies suggest that the 3Ј-sulfate substituent can replace the sialic acid residue to afford a mimetic with binding properties similar to sLe x .…”