Abstract
CD47 modulates a variety of cell functions such as adhesion, spreading, and migration. Using a fusion protein consisting of the extracellular region of Src homology 2 domain bearing protein tyrosine phosphatase substrate-1 (SHPS-1) and the Fc portion of human Ig (SHPS-1-Ig) we investigated the effects of SHPS-1 as a ligand for CD47 on B lymphocytes. Although SHPS-1-Ig binding to human B cell lines was solely mediated via CD47, their binding capacity for soluble and immobilized SHPS-1-Ig varied among cell lines irrespective of the similar expression levels of CD47, suggesting that distinctive affinity/avidity states exist during B cell maturation. Nalm6 cell line and tonsilar B lymphocytes adhered to immobilized SHPS-1-Ig and showed polarization-like morphology. These effects of SHPS-1-Ig were blocked by anti-CD47 mAbs (B6H12 and SE5A5). Wortmannin, a phosphatidylinositol-3 kinase inhibitor, but not pertussis toxin significantly inhibited the polarization induced by the immobilized SHPS-1-Ig. Thus, SHPS-1 acts as an adhesive substrate via CD47 in human B lymphocyte. Immunohistochemical analyses indicated that SHPS-1 is expressed on high endothelial venule as well as macrophages in human tonsils. HUVECs also express SHPS-1 in the absence of any stimuli, and the adhesion of tonsilar B lymphocytes to nonactivated HUVECs was significantly inhibited by SE5A5, indicating that SHPS-1/CD47 interaction is involved in the adhesion. Our findings suggest that SHPS-1/CD47 interaction may contribute to the recruitment of B lymphocytes via endothelial cells under steady state conditions.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Antibodies, Monoclonal / pharmacology
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Antigens, CD / immunology
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Antigens, CD / metabolism*
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Antigens, CD / physiology
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B-Lymphocytes / immunology
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B-Lymphocytes / metabolism
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B-Lymphocytes / physiology*
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CD47 Antigen
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Carrier Proteins / immunology
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Carrier Proteins / metabolism*
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Carrier Proteins / physiology
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Cell Adhesion / genetics
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Cell Adhesion / immunology
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Cell Line / metabolism
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Cell Line / physiology
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Cell Polarity / genetics
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Cell Polarity / immunology
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Cell Size / immunology
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Endothelium, Vascular / cytology*
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Endothelium, Vascular / metabolism
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Endothelium, Vascular / physiology*
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Humans
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Immunoglobulin Fc Fragments / pharmacology
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Immunohistochemistry
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Lymphatic System / metabolism
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Membrane Proteins / genetics
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Membrane Proteins / immunology
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Membrane Proteins / metabolism*
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Membrane Proteins / physiology
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / immunology
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Nerve Tissue Proteins / metabolism*
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Nerve Tissue Proteins / physiology
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Palatine Tonsil / cytology
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Palatine Tonsil / metabolism
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Palatine Tonsil / physiology
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Phosphatidylinositol 3-Kinases / physiology
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Protein Binding / immunology
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Receptor-Like Protein Tyrosine Phosphatases, Class 8
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Recombinant Fusion Proteins / immunology
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Recombinant Fusion Proteins / metabolism
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Recombinant Fusion Proteins / pharmacology
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Signal Transduction / physiology
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Tumor Cells, Cultured / metabolism
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Tumor Cells, Cultured / physiology
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src Homology Domains / genetics
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src Homology Domains / immunology
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src Homology Domains / physiology*
Substances
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Antibodies, Monoclonal
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Antigens, CD
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CD47 Antigen
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CD47 protein, human
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Carrier Proteins
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Immunoglobulin Fc Fragments
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Membrane Proteins
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Nerve Tissue Proteins
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Recombinant Fusion Proteins
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Ptprn protein, rat
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Receptor-Like Protein Tyrosine Phosphatases, Class 8