Human B-lymphocytes Express α2-6-Sialylated 6-Sulfo-N-acetyllactosamine Serving as a Preferred Ligand for CD22/Siglec-2

doi:10.1074/jbc.M702341200

Human B-lymphocytes Express α2-6-Sialylated 6-Sulfo-N-acetyllactosamine Serving as a Preferred Ligand for CD22/Siglec-2^*

^‡Department of Molecular Pathology, Aichi Cancer Center Research Institute, Nagoya 464-8681, the ^§Department of Clinical Pathology, Kyoto University School of Medicine, Kyoto 606-8501, ^¶Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi 332-0012, ^∥Central Research Laboratories, Seikagaku Corporation, Tokyo 207-0021, the ^**Laboratory of Membrane Biochemistry and Biophysics, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, and the ^‡‡Division of Biomolecular Science, Graduate School of Natural Sciences, Nagoya City University, Nagoya 467-8601, Japan

1 To whom correspondence should be addressed: Dept. of Molecular Pathology, Aichi Cancer Center Research Inst., 1-1 Kanokoden, Chikusaku, Nagoya 464-8681, Japan. Tel./Fax: 81-52-764-2973; E-mail: rkannagi{at}aichi-cc.jp.

Abstract

CD22/Siglec-2, an important inhibitory co-receptor on B-lymphocytes, is known to recognize α2-6-sialylated glycan as a specific ligand. Here we propose that the α2-6-sialylated and 6-GlcNAc-sulfated determinant serves as a preferred ligand for CD22 because the binding of a human B-cell line to CD22 was almost completely abrogated after incubating the cells with NaClO₃, an inhibitor of cellular sulfate metabolism, and was also significantly inhibited by a newly generated monoclonal antibody specific to the α2-6-sialylated 6-sulfo-N-acetyllactosamine (LacNAc) determinant (KN343, murine IgM). The α2-6-sialylated 6-sulfo-LacNAc determinant defined by the antibody was significantly expressed on a majority of normal human peripheral B-lymphocytes as well as follicular B-lymphocytes in peripheral lymph nodes. The determinant was also expressed in endothelial cells of high endothelial venules of secondary lymphoid tissues, including lymph nodes, tonsils, and intestine-associated lymphoid tissues, more strongly than on B-lymphocytes, suggesting a role for CD22 in B-cell interaction with blood vessels and trafficking. These results indicate that the α2-6-sialylated 6-sulfo-LacNAc determinant serves as an endogenous ligand for human CD22 and suggest the possibility that 6-GlcNAc sulfation as well as α2-6-sialylation may regulate CD22/Siglec-2 functions in humans.

Footnotes

↵2 The abbreviations used are: LacNAc, N-acetyllactosamine (Galβ1→4GlcNAc); HEC-GlcNAc6ST, high endothelial cell GlcNAc-6-sulfotransferase; ELISA, enzyme-linked immunosorbent assay; HEVs, high endothelial venules.
↵* This work was supported in part by Grant-in-aid 19590298 and Grant-in-aid on Priority Areas 17015051 from the Ministry of Education, Science, Sports, and Culture, Japan; grants-in-aid for the Third Term Comprehensive Ten-year Strategy for Cancer Control from the Ministry of Health and Welfare, Japan; a grant for the Promotion of Fundamental Studies in Health Sciences from the National Institute of Biomedical Innovation; and a grant from the Core Research for Evolutional Science and Technology Program of the Japan Science and Technology Agency. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
- Received March 19, 2007.
- Revision received August 24, 2007.