title: Detection and identification of antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing.
abstract: OBJECTIVE
  To provide data on (a) the probability of detecting antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing and (b) the probability of detecting more specific antinuclear reactivities (anti-DNA and anti-extractable nuclear antigens (anti-ENA)) in serum samples with a positive screening test (indirect immunofluorescence on HEp-2 cells).
  
  
  METHODS
  Serum samples from 10 550 consecutive patients sent to the laboratory for ANA detection were analysed. In ANA positive serum samples (23.5% of referred serum samples), ANA were identified by indirect immunofluorescence on Crithidia, by immunodiffusion, and by line immunoassay. Because anti-SSA antibodies were the most frequently identified ANA, sensitively detected by line immunoassay, additional immunoassays were developed to confirm the specificity of the line immunoassay result.
  
  
  RESULTS
  At least one fine reactivity could be identified in 21.1% of ANA positive serum samples: anti-dsDNA in 3.2%; anti-ENA (anti-SSA 10.5%, anti-SSB 6.7%, anti-RNP 2.7%, anti-Sm 1.8%, anti-Scl70 1.2%, anti-Jo-1 0.2%) in 15.8%, rRNP and anti-Cenp-B in respectively 0.5% and 4.0%. Multiple reactivities were found in 7.9%. For anti-ENA antibodies, line immunoassay was more sensitive than immunodiffusion (15.4% v 7.7%; p<0.0001). The sensitive detection of anti-SSA antibodies by line immunoassay was confirmed by additional assays.
  
  
  CONCLUSIONS
  The data from this analysis are useful in estimating the probabilities of detecting specific ANA. Line immunoassay was shown to be a sensitive test for the detection of anti-ENA antibodies.
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Belgium.
authors.forename: I
authors.initials: I
authors.lastname: Peene
authors.forename: L
authors.initials: L
authors.lastname: Meheus
authors.forename: E M
authors.initials: EM
authors.lastname: Veys
authors.forename: F
authors.initials: F
authors.lastname: De Keyser
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood*; D000918:Antibody Specificity; D034961:Antigens, Nuclear; D001324:Autoantigens / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003240:Connective Tissue Diseases / Q000097:blood / Q000175:diagnosis*; D004268:DNA-Binding Proteins / Q000276:immunology; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006801:Humans; D007118:Immunoassay / Q000379:methods; D005779:Immunodiffusion / Q000379:methods; D009687:Nuclear Proteins / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear; D034961:Antigens, Nuclear; D001324:Autoantigens; D015415:Biomarkers; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins