title: Antiperinuclear factor in psoriatic arthropathy.
abstract: BACKGROUND
  Antiperinuclear factor (APF) is an autoantibody directed against (pro)-filaggrin molecules.
  
  
  OBJECTIVE
  We evaluated whether APF determination is useful for the diagnosis of psoriatic arthritis (PA).
  
  
  METHODS
  We determined APF titers in sera from patients with PA (n = 76), psoriasis vulgaris (n = 38), noninflammatory rheumatic diseases (NIRDs, n = 119), rheumatoid arthritis (RA, n = 159) both with negative (n = 36) and positive (n = 123) rheumatoid factor (RF) tests, as well as from 204 healthy controls. We used an indirect immunofluorescence test on epithelial cells from human buccal mucosa as a substrate.
  
  
  RESULTS
  In patients with PA, 7.9% of the serum samples were APF-positive. The incidence was greater than in healthy controls (1.0%; P < .01), similar to those with uncomplicated psoriasis (2.6%; P = NS) and NIRDs (4.0%; P = NS), and lower than in RF-negative (52.7%; P < .001) and RF-positive (90.2%; P < .001) patients with RA. Three APF-positive patients with PA had symmetric joint involvement and 3 had pustulotic arthroosteitis.
  
  
  CONCLUSIONS
  The APF test may be useful in differentiating PA from RA, and APF may be specific for two PA subgroups.
authors.affiliation: Department of Dermatology, University of Brescia, Italy.
authors.forename: P G
authors.initials: PG
authors.lastname: Calzavara-Pinton
authors.forename: F
authors.initials: F
authors.lastname: Franceschini
authors.forename: C
authors.initials: C
authors.lastname: Manera
authors.forename: C
authors.initials: C
authors.lastname: Zane
authors.forename: E
authors.initials: E
authors.lastname: Prati
authors.forename: L
authors.initials: L
authors.lastname: Cretti
authors.forename: S
authors.initials: S
authors.lastname: Braga
authors.forename: R
authors.initials: R
authors.lastname: Cattaneo
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood*; D015535:Arthritis, Psoriatic / Q000175:diagnosis / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D005260:Female; D000091344:Filaggrin Proteins; D005455:Fluorescent Antibody Technique; D006801:Humans; D007381:Intermediate Filament Proteins / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012216:Rheumatic Diseases / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear; D015415:Biomarkers; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins