Minimal sulfated carbohydrates for recognition by L-selectin and the MECA-79 antibody.
Sulfated forms of sialyl-Le(X) containing Gal-6-SO(4) or GlcNAc-6-SO(4) have been implicated as potential recognition determinants on high endothelial venule ligands for L-selectin. The optimal configuration of sulfate esters on the N-acetyllactosamine (Galbeta1-->4GlcNAc) core of sulfosialyl-Le(X), however, remains unsettled. Using a panel of sulfated lactose (Galbeta1-->4Glc) neoglycolipids as substrates in direct binding assays, we found that 6',6-disulfolactose was the preferred structure for L-selectin, although significant binding to 6'- and 6-sulfolactose was observed as well. Binding was EDTA-sensitive and blocked by L-selectin-specific monoclonal antibodies. Surprisingly, 6', 6-disulfolactose was poorly recognized by MECA-79, a carbohydrate- and sulfate-dependent monoclonal antibody that binds competitively to L-selectin ligands. Instead, MECA-79 bound preferentially to 6-sulfolactose. The difference in preferred substrates between L-selectin and MECA-79 may explain the variable activity of MECA-79 as an inhibitor of lymphocyte adhesion to high endothelial venules in lymphoid organs. Our results suggest that both Gal-6-SO(4) and GlcNAc-6-SO(4) may contribute to L-selectin recognition, either as components of sulfosialyl-Le(X) capping groups or in internal structures. By contrast, only GlcNAc-6-SO(4) appears to contribute to MECA-79 binding.
Department of Anatomy, Programs in Immunology and Biomedical Sciences, and the Cardiovascular Research Institute, University of California, San Francisco, California 94143, USA.
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Bruehl
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Bertozzi
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Rosen
D000818:Animals; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000276:immunology*; D001666:Binding Sites, Antibody; D002240:Carbohydrate Sequence; D004492:Edetic Acid; D006017:Glycolipids / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M; D019041:L-Selectin / Q000276:immunology*; D007983:Lewis Blood Group Antigens / Q000276:immunology; D017705:Lignans / Q000138:chemical synthesis / Q000276:immunology; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009077:Mucins / Q000138:chemical synthesis / Q000276:immunology; D009844:Oligosaccharides / Q000276:immunology*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000276:immunology; D000080506:Sialyl Lewis X Antigen; D013431:Sulfates / Q000276:immunology
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D006017:Glycolipids; D007075:Immunoglobulin M; C069886:L-selectin counter-receptors; D007983:Lewis Blood Group Antigens; D017705:Lignans; D008565:Membrane Proteins; D009077:Mucins; D009844:Oligosaccharides; D011993:Recombinant Fusion Proteins; D000080506:Sialyl Lewis X Antigen; D013431:Sulfates; D019041:L-Selectin; C075185:sulfated glycoprotein p50; D004492:Edetic Acid