title: Diagnostic value of antibodies to filaggrin in rheumatoid arthritis.
abstract: OBJECTIVE
  To determine the prevalence of antibodies to filaggrin in a cross sectional sample of patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Filaggrin from human skin was either extracted with 0.05% Nonidet P-40 and then partially purified by precipitating in ethanol and resuspending in water (Nonidet preparation) or extracted with 9 M urea and then purified by sequential fractionation on a DEAE Sephadex column and on a strong cation exchange column (purified preparation). Antibodies to filaggrin were detected using immunoblotting techniques with sera diluted 1:50. Antikeratin antibodies (AKA) were detected using indirect immunofluorescence microscopy on sections of rat esophagus.
  
  
  RESULTS
  Antibodies to filaggrin were detected in 5 of 30 sera of patients with RA using filaggrin from the Nonidet preparation and 6 of 49 sera using filaggrin from the purified preparation. AKA were detected in 13 of 40 sera. A positive correlation existed between the presence of AKA and the presence of antibodies to filaggrin using the purified preparation (p=0.017).
  
  
  CONCLUSIONS
  These data indicate that the reactivity of RA sera with filaggrin is not identical to the presence of AKA and is variable depending upon the preparation of filaggrin used. The diagnostic value of antibodies to filaggrin remains to be proven.
authors.affiliation: Department of Oral Biology, University of Washington School of Medicine, Seattle 98195-6428, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Slack
authors.forename: M
authors.initials: M
authors.lastname: Mannik
authors.forename: B A
authors.initials: BA
authors.lastname: Dale
mesh_terms: D000818:Animals; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D001323:Autoantibodies / Q000032:analysis / Q000097:blood*; D001324:Autoantigens / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D004817:Epidermis / Q000737:chemistry; D000091344:Filaggrin Proteins; D006801:Humans; D015151:Immunoblotting; D007381:Intermediate Filament Proteins / Q000276:immunology* / Q000302:isolation & purification; D007633:Keratins / Q000276:immunology; D051381:Rats
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D007633:Keratins