Immunoblotting detection of autoantibodies to human epidermis filaggrin: a new diagnostic test for rheumatoid arthritis.
OBJECTIVE
We previously reported that so-called antikeratin antibodies (AKA) and antiperinuclear factor (APF) recognize epitope(s) present on human epidermal filaggrin. In the present study, we developed a new diagnostic test for rheumatoid arthritis (RA) based on detection of antifilaggrin autoantibodies (AFA) by immunoblotting.


METHODS
We tested 670 serum samples, including 190 RA. AFA titers were estimated by immunoblotting on filaggrin enriched human epidermis extracts, and AKA titers by indirect immunofluorescence (IIF) on rat esophagus epithelium. Diagnostic values of the tests were compared.


RESULTS
Each test resulted in diagnosis of more than 40% of RA samples, with a specificity of 0.99. Although the tests were strongly correlated, their association allowed the diagnosis of more than 60% of RA samples, with the same specificity.


CONCLUSIONS
Immunoblot detection of AFA, a simple and standardizable test, may be an alternative or complement to conventional IIF detection of AKA.
Vincent
C
C
Department of Biology and Pathology of the Cell, INSERM CJF 96-02 Purpan Medical School, University of Toulouse III, France.
Simon
M
M
Sebbag
M
M
Girbal-Neuhauser
E
E
Durieux
J J
JJ
Cantagrel
A
A
Fournié
B
B
Mazières
B
B
Serre
G
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*; D001323:Autoantibodies / Q000032:analysis / Q000097:blood*; D004817:Epidermis / Q000737:chemistry; D004848:Epithelium / Q000737:chemistry; D004947:Esophagus / Q000737:chemistry; D005260:Female; D000091344:Filaggrin Proteins; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D007381:Intermediate Filament Proteins / Q000276:immunology*; D007633:Keratins / Q000276:immunology; D008297:Male; D008875:Middle Aged; D051381:Rats
D001323:Autoantibodies; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D007633:Keratins