title: Relationship between ANCA and disease activity in small vessel vasculitis patients with anti-MPO ANCA.
abstract: BACKGROUND
  We analysed the usefulness of antineutrophil cytoplasmic antibodies (ANCA) as a marker of clinical activity in patients with small vessel vasculitis associated with anti-myeloperoxidase (MPO) ANCA.
  
  
  METHODS
  We studied a group of 25 patients, 15 with microscopic polyangitis and 10 with renal limited vasculitis, so-called rapidly progressive glomerulonephritis type III. The clinical and serological follow-up was accomplished quarterly over an average of 2.79 +/- 2.08 years (range 0.25-6 years). ANCA was analysed by indirect immunofluorescence and enzyme-linked immunosorbent assays (ELISAs).
  
  
  RESULTS
  At the time of diagnosis, all patients were ANCA positive (P-ANCA and anti-MPO). Following a standardized treatment, all patients except one achieved complete remission of vasculitis in <3 months. One patient suddenly died during the active phase (1 month of follow-up) and with positive ANCA. Seroconversion from positive to negative occurred in 24/25 patients (96%). Eighteen of these 24 patients (75%) achieved the seroconversion within the first 6 months. During the follow-up, two patients had four major relapses, all of them associated with positive ANCA. ANCA seroconversion from negative to positive was observed in one patient with microscopic polyangitis without clinical relapse of vasculitis.
  
  
  CONCLUSIONS
  ANCA should be used in conjunction with other markers of disease activity in the management of microscopic polyangitis and renal limited vasculitis patients with anti-MPO ANCA.
authors.affiliation: Servei de Nefrologia, Hospital Clínic, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Ara
authors.forename: E
authors.initials: E
authors.lastname: Mirapeix
authors.forename: R
authors.initials: R
authors.lastname: Rodriguez
authors.forename: A
authors.initials: A
authors.lastname: Saurina
authors.forename: A
authors.initials: A
authors.lastname: Darnell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000032:analysis*; D015415:Biomarkers; D002097:C-Reactive Protein / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009195:Peroxidase / Q000276:immunology*; D014657:Vasculitis / Q000276:immunology*
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D002097:C-Reactive Protein; D009195:Peroxidase