Anti-perinuclear factor compared with the so called “antikeratin” antibodies and antibodies to human epidermis filaggrin, in the diagnosis of arthritides
- Christian Vincenta,
- Filip de Keyserb,
- Christine Masson-Bessièrea,
- Mireille Sebbaga,
- Eric M Veysb,
- Guy Serrea
- aDepartment of Biology and Pathology of the Cell, INSERM CJF 96–02, IFR 30, Purpan Medical School, University of Toulouse III, Toulouse, France, bDepartment of Rheumatology, Gent Hospital, Gent, Belgium
- Dr C Vincent, Laboratoire de Biologie Cellulaire et Cytologie, Hôpital Purpan, Place du Dr Baylac, 31059 Toulouse cedex, France.
- Accepted 23 September 1998
Abstract
OBJECTIVE Antiperinuclear factor (APF), “antikeratin antibodies” (“AKA”), and antibodies to human epidermis filaggrin (AFA), are highly specific serological markers of rheumatoid arthritis (RA), which recognise epitopes on various isoforms of (pro)filaggrin. It was proposed that these antibodies are globally named antifilaggrin autoantibodies. Here the diagnostic value of the detection of each one is compared and the overlap between the three tests evaluated.
METHODS 492 serum samples were tested, including 279 RA serum samples, taken from patients in France and Belgium. APF and “AKA” titres were estimated by indirect immunofluorescence, and AFA titres by immunoblotting on filaggrin enriched human epidermis extracts.
RESULTS By a convenient choice of the positivity thresholds, the diagnostic sensitivity and specificity of the tests were shown to be similar (0.52 and 0.97, respectively). Although the antibody titres were strongly correlated, the associations APF-AFA or AFA-“AKA” permitted more than 52% or 55% of RA to be diagnosed, with a specificity of 0.99.
CONCLUSION APF, “AKA”, and AFA detection have a similar diagnostic value. However, because the three tests do not totally overlap, associating APF with “AKA” or AFA with “AKA” can improve diagnostic sensitivity. None of the three antigens used bear all the epitopes recognised by anti-filaggrin autoantibodies.
Footnotes
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Funding: this work was supported by grants from the “Association pour la Recherche sur la Polyarthrite”, the “Université Paul Sabatier”, Toulouse (JE-DGRT 1965), the “Institut National de la Santé et de la Recherche Médicale” (CJF 96–02), the “Région Midi-Pyrénées” and the NFWO (grant 3.0028.95).
