title: Detection of antibodies to deiminated recombinant rat filaggrin by enzyme-linked immunosorbent assay: a highly effective test for the diagnosis of rheumatoid arthritis.
abstract: OBJECTIVE
  To assay antifilaggrin autoantibodies, we developed an enzyme-linked immunosorbent assay (ELISA) using a "citrullinated" recombinant rat filaggrin. Our objectives were to assess its value for diagnosing rheumatoid arthritis (RA) and to compare the results with those obtained using 4 other reference methods for detection of antifilaggrin autoantibodies, including the commercially available ELISA that uses a modified "citrullinated" synthetic peptide derived from the sequence of human filaggrin (CCP-ELISA).
  
  
  METHODS
  We analyzed 711 sera from patients with well-characterized rheumatic diseases, including 240 patients with RA. Antifilaggrin autoantibodies were detected by an ELISA using a recombinant rat filaggrin deiminated in vitro as immunosorbent (ArFA-ELISA). The results considered were the differences between the optical densities obtained on deiminated and nondeiminated proteins. Antibodies to rat esophagus epithelium were detected by indirect immunofluorescence, while antibodies to human filaggrin were detected by immunoblotting and by a recently described ELISA using a deiminated recombinant human filaggrin. Finally, CCP-ELISA was performed according to the manufacturer's recommendations.
  
  
  RESULTS
  At the titer thresholds allowing diagnostic specificities of 0.95, 0.985, and 0.99 to be reached, the diagnostic sensitivities of the ArFA-ELISA were 0.76, 0.67, and 0.65, respectively. At these 3 thresholds, the sensitivities were significantly higher than those of the 4 other tests. Despite incomplete overlapping of the 5 tests, the high diagnostic performance of the ArFA-ELISA allows us to propose this test to replace all the other methods for antifilaggrin autoantibody detection.
  
  
  CONCLUSIONS
  ArFA-ELISA appears to be the most efficient test among those available for the detection of antifilaggrin autoantibodies, in terms of diagnostic accuracy for RA. Its diagnostic performance in early RA and its prognostic value are currently under evaluation.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (CJF 96-02, IFR30), Purpan School of Medicine, University of Toulouse III, Toulouse, France. cviencent@cict.fr
authors.forename: Christian
authors.initials: C
authors.lastname: Vincent
authors.forename: Leonor
authors.initials: L
authors.lastname: Nogueira
authors.forename: Mireille
authors.initials: M
authors.lastname: Sebbag
authors.forename: Sabine
authors.initials: S
authors.lastname: Chapuy-Regaud
authors.forename: Michel
authors.initials: M
authors.lastname: Arnaud
authors.forename: Odile
authors.initials: O
authors.lastname: Letourneur
authors.forename: Dominique
authors.initials: D
authors.lastname: Rolland
authors.forename: Bernard
authors.initials: B
authors.lastname: Fournié
authors.forename: Alain
authors.initials: A
authors.lastname: Cantagrel
authors.forename: Michel
authors.initials: M
authors.lastname: Jolivet
authors.forename: Guy
authors.initials: G
authors.lastname: Serre
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D004817:Epidermis / Q000276:immunology; D005260:Female; D000091344:Filaggrin Proteins; D006801:Humans; D007381:Intermediate Filament Proteins / Q000097:blood* / Q000276:immunology; D007633:Keratins / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000097:blood / Q000276:immunology; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D011994:Recombinant Proteins; D007633:Keratins