DIAGNOSTIC-VALUE OF ANTIBODIES TO FILAGGRIN IN RHEUMATOID-ARTHRITIS

Objective. To determine the prevalence of antibodies to filaggrin in a cross sectional sample of patients with rheumatoid arthritis (RA). Me thods. Filaggrin from human skin was either extracted with 0.05% Nonid et P-40 and then partially purified by precipitating in ethanol and re suspending in water (Nonidet preparation) or extracted with 9 M urea a nd then purified by sequential fractionation on a DEAF Sephadex column and on a strong cation exchange column (purified preparation). Antibo dies to filaggrin were detected using immunoblotting techniques with s era diluted 1:50. Antikeratin antibodies (AKA) were detected using ind irect immunofluorescence microscopy on sections of rat esophagus. Resu lts. Antibodies to filaggrin were detected in 5 of 30 sera of patients with RA using filaggrin from the Nonidet preparation and 6 of 49 sera using filaggrin from the purified preparation. AKA were detected in 1 3 of 40 sera. A positive correlation existed between the presence of A KA and the presence of antibodies to filaggrin using the purified prep aration (p=0.017). Conclusion. These data indicate that the reactivity of RA sera with filaggrin is not identical to the presence of AKA and is variable depending upon the preparation of filaggrin used. The dia gnostic value of antibodies to filaggrin remains to be proven.