title: Endoglycan, a member of the CD34 family of sialomucins, is a ligand for the vascular selectins.
abstract: The interactions of the selectin family of adhesion molecules with their ligands are essential for the initial rolling stage of leukocyte trafficking. Under inflammatory conditions, the vascular selectins, E- and P-selectin, are expressed on activated vessels and interact with carbohydrate-based ligands on the leukocyte surface. While several ligands have been characterized on human T cells, monocytes and neutrophils, there is limited information concerning ligands on B cells. Endoglycan (EG) together with CD34 and podocalyxin comprise the CD34 family of sialomucins. We found that EG, previously implicated as an L-selectin ligand on endothelial cells, was present on human B cells, T cells and peripheral blood monocytes. Upon activation of B cells, EG increased with a concurrent decrease in PSGL-1. Expression of EG on T cells remained constant under the same conditions. We further found that native EG from several sources (a B cell line, a monocyte line and human tonsils) was reactive with HECA-452, a mAb that recognizes sialyl Lewis X and related structures. Moreover, immunopurified EG from these sources was able to bind to P-selectin and where tested E-selectin. This interaction was divalent cation-dependent and required sialylation of EG. Finally, an EG construct supported slow rolling of E- and P-selectin bearing cells in a sialic acid and fucose dependent manner, and the introduction of intact EG into a B cell line facilitated rolling interactions on a P-selectin substratum. These in vitro findings indicate that EG can function as a ligand for the vascular selectins.
authors.affiliation: Department of Anatomy, University of California, San Francisco, CA 94143, USA.
authors.forename: Sheena C
authors.initials: SC
authors.lastname: Kerr
authors.forename: Claudia B
authors.initials: CB
authors.lastname: Fieger
authors.forename: Karen R
authors.initials: KR
authors.lastname: Snapp
authors.forename: Steven D
authors.initials: SD
authors.lastname: Rosen
mesh_terms: D018952:Antigens, CD34 / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D019040:E-Selectin / Q000276:immunology / Q000378:metabolism; D006801:Humans; D019041:L-Selectin / Q000276:immunology / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism*; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D009077:Mucins / Q000276:immunology / Q000378:metabolism*; D019007:P-Selectin / Q000276:immunology / Q000378:metabolism; D014066:Palatine Tonsil / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D019087:Selectins / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D019040:E-Selectin; D008024:Ligands; D008562:Membrane Glycoproteins; D009077:Mucins; D019007:P-Selectin; C084882:P-selectin ligand protein; D019087:Selectins; C406902:endoglycan; D019041:L-Selectin