title: Abnormal IgA glycosylation in Henoch-Schönlein purpura restricted to patients with clinical nephritis.
abstract: BACKGROUND
  Glomerular deposition of IgA1 is a common feature of Henoch-Schönlein purpura, and is indistinguishable from that seen in IgA nephropathy. Serum IgA1 is abnormally O-glycosylated in IgA nephropathy, and this may contribute to mesangial IgA1 deposition and the development of glomerular injury. This altered O-glycosylation of IgA1 can be detected by its increased binding to the lectin Vicia villosa.
  
  
  METHODS
  To investigate whether IgA1 is abnormally glycosylated in Henoch-Schönlein purpura, the binding of Vicia villosa lectin to serum IgA1 was studied in the following subject groups: IgA nephropathy; adults and children with Henoch-Schönlein purpura and nephritis; children with clinically diagnosed Henoch-Schönlein purpura but no renal involvement; adults and children with non-IgA associated glomerulonephritis; and matched controls.
  
  
  RESULTS
  The abnormality of lectin binding seen in IgA nephropathy was also found in both adults and children with Henoch-Schönlein purpura with nephritis. However, the lectin binding of serum IgA1 from children with Henoch-Schönlein purpura lacking renal involvement did not differ from controls, and similarly, no abnormality of lectin binding was seen in patients with non-IgA associated glomerulonephritis.
  
  
  CONCLUSIONS
  These data indicate that the abnormality of IgA1 O-glycosylation seen in IgA nephropathy is also found in Henoch-Schönlein purpura, but only in those subjects with renal involvement, while IgA1 O-glycosylation is normal in patients with other forms of renal disease. These findings lend strong support to a role for altered IgA1 O-glycosylation in the pathogenesis of IgA-associated glomerular disease.
authors.affiliation: Department of Nephrology, Leicester General Hospital, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Allen
authors.forename: F R
authors.initials: FR
authors.lastname: Willis
authors.forename: T J
authors.initials: TJ
authors.lastname: Beattie
authors.forename: J
authors.initials: J
authors.lastname: Feehally
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D002648:Child; D002675:Child, Preschool; D005260:Female; D005922:Glomerulonephritis, IGA / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D011695:IgA Vasculitis / Q000378:metabolism*; D007070:Immunoglobulin A / Q000378:metabolism*; D037102:Lectins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D037121:Plant Lectins
chemical_list: D007070:Immunoglobulin A; D037102:Lectins; D037121:Plant Lectins; C042242:Vicia lectins