Immunoblotting detection of so-called 'antikeratin antibodies': a new assay for the diagnosis of rheumatoid arthritis

• Published in: Annals of the rheumatic diseases Vol. 53; no. 11; pp. 735 - 742
• Main Authors: Gomès-Daudrix, V, Sebbag, M, Girbal, E, Vincent, C, Simon, M, Rakotoarivony, J, Abbal, M, Fournié, B, Serre, G
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and European League Against Rheumatism 01.11.1994; BMJ; BMJ Publishing Group LTD
• Subjects: Arthritis, Rheumatoid - diagnosis; Arthritis, Rheumatoid - immunology; Autoantibodies - blood; Autoantigens - immunology; Biological and medical sciences; Diseases of the osteoarticular system; Electrophoresis, Polyacrylamide Gel; Epithelium - immunology; Esophagus - immunology; Humans; Immunoblotting - methods; Inflammatory joint diseases; Keratins - immunology; Medical sciences; Rheumatoid Factor - blood; Sensitivity and Specificity; Human; Immunopathology; Antibody; Diseases of the osteoarticular system; Autoantibody; Autoimmune disease; Inflammatory joint disease; Serology; Keratin; Chronic; Sensitivity; Specificity; Immunological investigation; Rheumatoid arthritis; Immunoblotting assay; Serum; Diagnosis; Technique
• ISSN: 0003-4967; 1468-2060
• DOI: 10.1136/ard.53.11.735

OBJECTIVES--To assess the diagnostic value for rheumatoid arthritis (RA), of an immunoblotting assay based on the rat oesophagus epithelium antigens recognised by the so-called 'antikeratin antibodies' ('AKA'), antigens that have been identified as three non-cytokeratin proteins (referred to as A, B and C proteins). METHODS--After polyacrylamide gel electrophoresis in non-denaturing conditions and electrotransfer of an epithelial extract, the immunoreactivities to the A, B and C proteins of a series of serum samples from 88 patients with RA and 100 patients with non-rheumatoid rheumatic diseases, were semiquantitatively evaluated. RESULTS--A total of 81.8% of RA serum samples recognised the three proteins, while 91% of non-RA serum samples only weakly recognised the A and B proteins but not the C protein. Only in the group of RA patients, were the titres of the antibodies to the A, B and C proteins found to be significantly correlated with each other and with the titres of 'AKA' detected by the standard indirect immunofluorescence (IIF) method. For a diagnostic specificity of 99%, the diagnostic sensitivities of the detection of the A and B proteins were 50% and 43.2%, respectively, when those of the detection of 'AKA' by IIF and of IgM-rheumatoid factor by enzyme-linked immunosorbent assay were 42% and 54%, respectively. In contrast, at a same specificity of 99%, the diagnostic sensitivity of the detection of the C protein was significantly higher with a value of 70.5%. CONCLUSION--This immunoblotting assay which is the first immunochemical method proposed for the detection of 'AKA, should be validated on larger series of patients but can already be considered as a very powerful test for the serological diagnosis of RA.