Background: Antiperinuclear factor (APF) is an autoantibody directed agains
t (pro)-filaggrin molecules.
Objective: We evaluated whether APF determination is useful for the diagnos
is of psoriatic arthritis (PA),
Methods: We determined APF titers in sera from patients with PA (n = 76), p
soriasis vulgaris (n = 38), noninflammatory rheumatic diseases (NIRDs, n =
119), rheumatoid arthritis (RA, n = 159) both with negative (n = 36) and po
sitive (n = 123) rheumatoid factor (RF) tests, as well as from 204 healthy
controls. We used an indirect immunofluorescence test on epithelial cells f
rom 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 = N
S), 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 symmet
ric joint involvement and had pustulotic arthroosteitis.
Conclusion: The APF test may be useful in differentiating PA from RA, and A
PF may be specific for two PA subgroups.