Antiperinuclear factor in psoriatic arthropathy.
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.
Calzavara-Pinton
P G
PG
Department of Dermatology, University of Brescia, Italy.
Franceschini
F
F
Manera
C
C
Zane
C
C
Prati
E
E
Cretti
L
L
Braga
S
S
Cattaneo
R
R
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
D000974:Antibodies, Antinuclear; D015415:Biomarkers; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins