title: Disease spectrum of patients with antineutrophil cytoplasmic autoantibodies of defined specificity: distinct differences between patients with anti-proteinase 3 and anti-myeloperoxidase autoantibodies.
abstract: OBJECTIVE
  To compare the disease spectrum of consecutive patients with antineutrophil cytoplasmic autoantibodies directed against proteinase 3 (anti-PR3) or myeloperoxidase (anti-MPO).
  
  
  METHODS
  Retrospective analysis.
  
  
  METHODS
  Three teaching hospitals in the Netherlands.
  
  
  METHODS
  Clinical features at presentation, histopathological characteristics and outcome.
  
  
  METHODS
  All consecutive patients who tested positive for anti-PR3 (n=46) or anti-MPO (n=46) over an 8-year-period.
  
  
  RESULTS
  At diagnosis, patients with anti-PR3 had a higher vasculitis activity index than patients with anti-MPO (P < 0.001). The mean (SD) number of affected organs in the anti-PR3 group exceeded that of the anti-MPO group (3.9 (1.4) and 2.2 (1.1), respectively; P < 0.01). The combination of renal and respiratory tract involvement was present in as many as 78.3% of patients with anti-PR3 and in only 23.9% of patients with anti-MPO (P < 0.01). Renal-limited disease exclusively occurred in patients with anti-MPO. Granulomas were found in 41.3% of anti-PR3- but in only 4.3% of anti-MPO-positive patients (P < 0.01). All anti-PR3-positive patients had Wegener's granulomatosis or microscopic polyangiitis. By contrast, diagnoses in the anti-MPO group were more diverse: idiopathic necrotizing crescentic glomerulonephritis (26.1%), microscopic polyangiitis (26.1%). Churg-Strauss syndrome (4.3%), Wegener's granulomatosis (2.2%), giant cell arteritis (2.2%), clinically suspected vasculitis (19.6%), as well as miscellaneous nonvasculitic disorders (19.6%). During follow-up, 10 anti-PR3-positive patients had 11 relapses whereas only 3 patients with anti-MPO relapsed (P=0.04).
  
  
  CONCLUSIONS
  A large divergence was seen in the disease spectrum between patients with anti-PR3 and those with anti-MPO. In particular, extra-renal disease manifestations, granuloma formation and relapses were more prominent in anti-PR3- than in anti-MPO-positive patients.
authors.affiliation: Department of Internal Medicine, University Hospital, Groningen, The Netherlands. m.j.s.graler@int.azg.nl
authors.forename: C
authors.initials: C
authors.lastname: Franssen
authors.forename: R
authors.initials: R
authors.lastname: Gans
authors.forename: C
authors.initials: C
authors.lastname: Kallenberg
authors.forename: C
authors.initials: C
authors.lastname: Hageluken
authors.forename: S
authors.initials: S
authors.lastname: Hoorntje
mesh_terms: D000328:Adult; D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D000918:Antibody Specificity; D001324:Autoantigens / Q000276:immunology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053146:Myeloblastin; D009426:Netherlands; D009195:Peroxidase / Q000276:immunology*; D012189:Retrospective Studies; D012697:Serine Endopeptidases / Q000276:immunology*; D014657:Vasculitis / Q000175:diagnosis* / Q000276:immunology*
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D001324:Autoantigens; D009195:Peroxidase; D012697:Serine Endopeptidases; D053146:Myeloblastin