title: Anticytoplasmic autoantibodies: their immunodiagnostic value in Wegener granulomatosis.
abstract: OBJECTIVE
  To determine disease specificity and sensitivity of anticytoplasmic autoantibodies (ACPA) for Wegener granulomatosis, as well as their value as a marker of disease activity.
  
  
  METHODS
  Blind analysis of serum samples, retrospective analysis of clinical data on patients, and prospective follow-up of a subgroup of patients with Wegener granulomatosis.
  
  
  METHODS
  The study included 277 patients with Wegener granulomatosis (222 with biopsy-proven disease) and 1657 control patients.
  
  
  METHODS
  University hospital and academic medical center. LABORATORY INVESTIGATIONS: Analysis of 2653 serum samples from 1934 patients for ACPA. Antibody detection was by indirect immunofluorescence and a new type of enzyme-linked immunoadsorbent assay (ELISA). Prospective follow-up was on 172 patients with Wegener granulomatosis.
  
  
  RESULTS
  Specificity of ACPA for Wegener granulomatosis measured by indirect immunofluorescence was 99% (CI, 98.9% to 99.7%) and 98% (CI, 97.4% to 99.2%) by ELISA. Sensitivity of ACPA depended on disease activity and extent: It was 67% (CI, 38% to 89%) by immunofluorescence and 60% (CI, 32% to 84%) by ELISA for patients with active locoregional symptomatology (n = 15); and 32% (CI, 14% to 54%) by immunofluorescence and 40% (CI, 21% to 61%) by ELISA for patients in full remission after initial locoregional symptoms (n = 25). The sensitivity was 96% (CI, 89% to 99%) by immunofluorescence and 93% (CI, 86% to 98%) by ELISA for patients with active generalized disease (n = 92). Serial testing was done; every patient with active generalized disease eventually had at least one positive serum sample. Sensitivity decreased to 41% (CI, 22% to 62%) by both immunofluorescence and ELISA for patients in full remission after active generalized disease (n = 27). Levels of ACPA expressed both as immunofluorescence titers and ELISA values (U/mL) correlated well with disease activity.
  
  
  CONCLUSIONS
  Testing for ACPA in serum of patients with Wegener granulomatosis is valuable for differential diagnosis; furthermore, APCA can be used as a marker to follow disease activity. A new type of ELISA yielded the same results as indirect immunofluorescence for the specificity, sensitivity, and correlation with disease activity of ACPA.
authors.affiliation: Klinikum der Christian-Albrechts-Universität, Kiel, Federal Republic of Germany.
authors.forename: B
authors.initials: B
authors.lastname: Nölle
authors.forename: U
authors.initials: U
authors.lastname: Specks
authors.forename: J
authors.initials: J
authors.lastname: Lüdemann
authors.forename: M S
authors.initials: MS
authors.lastname: Rohrbach
authors.forename: R A
authors.initials: RA
authors.lastname: DeRemee
authors.forename: W L
authors.initials: WL
authors.lastname: Gross
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000032:analysis*; D015415:Biomarkers / Q000097:blood; D003593:Cytoplasm / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D005500:Follow-Up Studies; D014890:Granulomatosis with Polyangiitis / Q000175:diagnosis / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D009504:Neutrophils / Q000276:immunology; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D015415:Biomarkers