title: Sialylation levels of anti-proteinase 3 antibodies are associated with the activity of granulomatosis with polyangiitis (Wegener's).
abstract: OBJECTIVE
  To investigate whether the glycosylation and sialylation levels of anti-proteinase 3 (anti-PR3) antibodies could affect their pathogenicity, and whether these levels could be correlated with the activity of granulomatosis with polyangiitis (Wegener's) (GPA).
  
  
  METHODS
  Forty-two serum samples positive for anti-PR3 antibodies from 42 patients with active or weakly active/inactive GPA were included. Anti-PR3 antibodies were assayed by enzyme-linked immunosorbent assay, and their levels of glycosylation and sialylation were assessed by enzyme-linked lectin assay. The glycosylation and sialylation levels of IgG purified from the serum of healthy donors and patients with active, remitted, or weakly active disease were assessed by permethylation and mass spectrometry analysis of glycans, following neuraminidase digestion. The neutrophil oxidative burst induced by purified IgG was assayed by spectrofluorimetry.
  
  
  RESULTS
  The mean sialylation ratio of anti-PR3 antibodies was significantly lower in patients with active disease than in patients with weakly active or inactive disease, and this was inversely correlated with the Birmingham Vasculitis Activity Score (BVAS) (P < 0.0001). Similar results were obtained using the BVAS/GPA. The area under the receiver operating characteristic curve for the sialylation ratio of anti-PR3 antibodies, as a test to determine the activity of GPA, was 0.82 (P = 0.0006). The characterization of N-glycans showed a decrease in 2,6-linked sialylated N-glycans and an increase in dHex₁ Hex₃ HexNAc₄ (mass/charge 1,836) agalactosylated structures in purified IgG from patients with active disease compared with controls. The anti-PR3 antibody-induced oxidative burst of neutrophils was inversely correlated with the sialylation levels of anti-PR3 IgG.
  
  
  CONCLUSIONS
  The sialylation level of anti-PR3 antibodies contributes to the clinical activity of GPA, by modulating the oxidative burst of neutrophils induced by these autoantibodies.
authors: Université Paris Descartes and Hôpital Cochin, Assistance Publique Hôpitaux de Paris, Paris, France.
authors: Cécile
authors: C
authors: Espy
authors: Willy
authors: W
authors: Morelle
authors: Niloufar
authors: N
authors: Kavian
authors: Philippe
authors: P
authors: Grange
authors: Claire
authors: C
authors: Goulvestre
authors: Vivian
authors: V
authors: Viallon
authors: Christiane
authors: C
authors: Chéreau
authors: Christian
authors: C
authors: Pagnoux
authors: Jean-Claude
authors: JC
authors: Michalski
authors: Loïc
authors: L
authors: Guillevin
authors: Bernard
authors: B
authors: Weill
authors: Frédéric
authors: F
authors: Batteux
authors: Philippe
authors: P
authors: Guilpain
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006031:Glycosylation; D014890:Granulomatosis with Polyangiitis / Q000097:blood / Q000276:immunology*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D053146:Myeloblastin / Q000276:immunology*
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D053146:Myeloblastin