Abstract
CD22 is a glycoprotein that associates with the B cell antigen receptor and acts as a negative regulator of receptor signaling; its extracellular domain binds alpha2,6-linked sialoglycoconjugates. Here we show that B cell activation by antigen displayed on the surface of a target cell is depressed if the target co-expresses alpha2,6-sialoglycoconjugates: this inhibition is dependent on CD22. Since sialylation is largely a feature of higher eukaryotes with alpha2,6-sialyltransferase increasing during inflammation, we propose that the CD22 / sialoglycoconjugate interaction allows context-dependent B cell activation, possibly acting as a crude discriminator of self in order to dampen B cell autoreactivity and the initiation of autoimmunity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antigens, CD / metabolism*
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Antigens, Differentiation, B-Lymphocyte / metabolism*
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Autoantigens
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Autoimmunity
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B-Lymphocytes / immunology*
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B-Lymphocytes / metabolism*
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Carbohydrate Conformation
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Cell Adhesion Molecules*
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Cell Line
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Chickens
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Gene Expression
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Glycoconjugates / chemistry
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Glycoconjugates / immunology*
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Glycoconjugates / metabolism*
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H-2 Antigens / metabolism
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Lectins*
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Lymphocyte Activation
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Mice
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Mice, Transgenic
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Muramidase / immunology
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Rats
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Sialic Acid Binding Ig-like Lectin 2
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Sialyltransferases / genetics
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Sialyltransferases / metabolism
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beta-D-Galactoside alpha 2-6-Sialyltransferase
Substances
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Antigens, CD
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Antigens, Differentiation, B-Lymphocyte
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Autoantigens
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Cd22 protein, mouse
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Cell Adhesion Molecules
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Glycoconjugates
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H-2 Antigens
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H-2Kb protein, mouse
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Lectins
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RNA, Messenger
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Sialic Acid Binding Ig-like Lectin 2
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Sialyltransferases
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Muramidase
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beta-D-Galactoside alpha 2-6-Sialyltransferase