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Glycosylation of Immunoglobulin A Influences Its Receptor Binding
Author(s) -
Christelle Basset,
Valérie Devauchelle,
Véronique Durand,
C Jamin,
Y.L. Pennec,
Pierre Youinou,
Maryvonne Dueymes
Publication year - 1999
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1046/j.1365-3083.1999.00628.x
Subject(s) - glycosylation , antibody , immunoglobulin g , receptor , chemistry , biochemistry , biology , immunology
Immunoglobulin A (IgA), which is heavily glycosylated, interacts with a variety of receptors, e.g. the asialoglycoprotein receptor (ASGP‐R), which binds terminal galactose residues, and the Fcα receptor (FcαRI). It has thus been proposed that elevated serum levels of IgA in primary Sjögren's syndrome (pSS) are caused by its defective clearance. To test this hypothesis, we developed a method (based on sialyl transferases eluted from a hepatoma cell line) to increase the amount of sialic acid (SA) on IgA, and used a battery of IgA 1 ‐ and IgA 2 ‐specific glycosidases to reduce this amount. Binding of IgA 1 and IgA 2 to ASGP‐R and FcαRI was found to be sugar dependent because oversialylated IgA bound less than native or desialylated IgA. However, individual sugars did not play a direct role in this binding. Given that IgA are oversialylated in pSS, defective clearance of IgA may indeed be ascribed to an excess of SA in IgA 1 and IgA 2 .