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- Title
Increased N-Linked Glycosylation Leading to Oversialylation of Monomeric Immunoglobulin A[sub 1] from Patients with Sjögren's Syndrome.
- Authors
Basset; Durand; Jamin; Clément; Pennec; Youinou; Dueymes; Roitt
- Abstract
Increased serum immunoglobulin A (IgA) level is a common finding in primary Sjögren's syndrome (pSS). IgA might not be properly eliminated because of an abnormal glycosylation. We reported previously that IgA[sub 1] from patients with pSS was oversialylated. We extend this finding by showing that monomeric IgA[sub 1] contains more sialic acid (SA) in patients than in controls, as determined by enzyme-linked immunosorbent assay (ELISA) and Western blot with Sambucus nigra agglutinin (SNA), a lectin specific for SA. To localize this excess of SA on the N- and/or O-linked oligosaccharides, we analysed them separately, using N- and O-linked oligosaccharide profiling kits based on fluorophore-assisted carbohydrate electophoresis. N-linked, but not O-linked, oligosaccharides of patients' IgA[sub 1] were oversialylated, and this seemed to be linked to an excess of SA on the same number of polysaccharides as normal IgA[sub 1]. To localize the abnormality to the Fab and/or Fc fragments, monomeric IgA[sub 1] was digested with protease, separated and transferred to nitrocellulose, where SA was identified by SNA. Both Fab and Fc fragments appeared to be oversialylated. Oversialylation of N-linked oligosaccharides of IgA[sub 1 ]from patients with pSS might prevent the recognition of IgA by receptors that are responsible for their clearance, resulting in an excess of serum IgA and related immune complexes.
- Subjects
GLYCOSYLATION; IMMUNOGLOBULIN A; SJOGREN'S syndrome; MONOMERS
- Publication
Scandinavian Journal of Immunology, 2000, Vol 51, Issue 3
- ISSN
0300-9475
- Publication type
Article
- DOI
10.1046/j.1365-3083.2000.00685.x