title: BioPlex 2200 multiplexed system: simultaneous detection of anti-dsDNA and anti-chromatin antibodies in patients with systemic lupus erythematosus.
abstract: BACKGROUND
  Antibodies for double-stranded DNA (anti-dsDNA) and chromatin represent specific markers of systemic lupus erythematosus (SLE).
  
  
  OBJECTIVE
  (1) To evaluate the analytical performance of a multiplexed bead assay (BioPlex 2200) for the simultaneous detection of anti-dsDNA and anti-chromatin antibodies, (2) to compare the results for anti-dsDNA with those obtained using Farr assay, and (3) to analyze the clinical relevance of these antibodies when applied to the follow-up of SLE patients with active nephritis.
  
  
  METHODS
  Hundred and five clinically characterized SLE patients and 96 healthy blood donors sera were analyzed by BioPlex 2200.
  
  
  RESULTS
  Prevalence of these antibodies was significantly higher (p < 0.0001) in SLE patients than in controls (68 and 70% for anti-dsDNA and anti-chromatin, vs. 1% for both anti-dsDNA and anti-chromatin, respectively). If you consider a sample positive if either anti-dsDNA and/or anti-chromatin is positive, then the prevalence of these antibodies reached 78% (82/105) in SLE patients. For anti-dsDNA measurements, the kappa coefficient was 0.59 between BioPlex 2200 and Farr assay. Comparison between SLE patients with and without nephritis in a follow-up study showed that patients with active nephritis were associated with an increase of anti-dsDNA and anti-chromatin levels and a reduction of CH50, whereas no variation of antibody levels was observed in SLE patients without nephritis.
  
  
  CONCLUSIONS
  Our results demonstrated a benefit of simultaneously measuring anti-dsDNA and anti-chromatin in SLE patients. The BioPlex 2200 achieved good analytical performances and proved to be a useful method for monitoring and diagnosing SLE.
authors.affiliation: Laboratoire d'Immunologie, Hopital de Conception, Marseille, France. nathalie.bardin@mail.ap-hm.fr
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bardin
authors.forename: Sophie
authors.initials: S
authors.lastname: Desplat-Jego
authors.forename: Laurent
authors.initials: L
authors.lastname: Daniel
authors.forename: Noemie
authors.initials: N
authors.lastname: Jourde Chiche
authors.forename: Marielle
authors.initials: M
authors.lastname: Sanmarco
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000276:immunology; D002460:Cell Line; D002843:Chromatin / Q000276:immunology*; D004247:DNA / Q000276:immunology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D008181:Lupus Nephritis / Q000175:diagnosis / Q000276:immunology; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D015531:Radioimmunoprecipitation Assay; D011933:Reagent Kits, Diagnostic
chemical_list: D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D002843:Chromatin; D011933:Reagent Kits, Diagnostic; D004247:DNA