title: Calcium-dependent lectin activity with novel distribution on thymocyte subsets.
abstract: In this study we use carbohydrate probes to search for novel cell surface lectins in the immune system. Many carbohydrate binding proteins are members of the C-type lectin superfamily, whose ligand binding is dependent on calcium. To identify potential new members of this superfamily, fluorescein-conjugated carbohydrate polymers were used to probe for calcium-dependent cell surface binding. This approach offers advantages over the use of monoclonal antibody probes since only carbohydrate binding proteins would be identified. We have identified a cell surface lectin, referred to as thy-lec, detected by the probe fucoidan-fuorescein isothiocyanate. This calcium-dependent lectin has a novel distribution on thymocyte subsets. It is present on the surface of immature CD4+8+ and on large, cycling CD4-8- cells and CD8+4- cells, but not on small, mature phenotype CD8+4- or CD4+8- thymocytes. This lectin is not found on mature T cells or other leukocytes in lymph nodes, spleen or bone marrow. It is proposed that this novel cell surface has a function in the maturation of T cells in the thymus.
authors.affiliation: Department of Anatomy, University of California, San Francisco, USA. mallett@molbiol.ox.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Mallett
authors.forename: S D
authors.initials: SD
authors.lastname: Rosen
authors.forename: W
authors.initials: W
authors.lastname: Hyun
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D002241:Carbohydrates / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D000939:Epitopes; D019041:L-Selectin / Q000032:analysis; D037102:Lectins / Q000032:analysis* / Q000378:metabolism; D008024:Ligands; D008565:Membrane Proteins / Q000032:analysis / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D016176:T-Lymphocyte Subsets / Q000737:chemistry* / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D002241:Carbohydrates; D000939:Epitopes; D037102:Lectins; D008024:Ligands; D008565:Membrane Proteins; D019041:L-Selectin; D002118:Calcium