Incidence of antiperinuclear factor in patients with psoriatic arthritis.

Antiperinuclear factor (APF) is considered a disease marker of rheumatoid arthritis (RA) and its diagnostic value is obvious in patients who are seronegative for rheumatoid factor (RF) activity. We have evaluated APF positivites in 76 patients with psoriatic arthritis, 38 uncomplicated psoriatic patients, 119 patients with non-inflammatory rheumatic diseases (NIRD), 36 RF- and 123 RF + RA patients and 204 healthy controls. APFs were investigated with an indirect immunofluorescence (IIF) test using epithelial cells from human buccal mucosa as a substrate 6/76 (7.9%) PA patients were APF+. The incidence was greater than in healthy controls (2/ 204; p<0.01) and similar to the incidences in patients with uncomplicated psoriasis (1/ 38; p=NS) and patients with non-inflammatory rheumatic disease NIRD (5/ 119; p=NS). However, the incidence was much lower than in RF- (191 36; p< 0.001) as well as RF+ (111/ 123; p< 0.001) RA patients. Finally, we emphasise that 3 out of 6 APF positivities shown by PA patients were found in our 3 patients with pustolotic arthroosteitis, a new specific entity in the spectrum of PA.