Epitope mapping with synthetic peptides of 52‐kD SSA/Ro protein reveals heterogeneous antibody profiles in human autoimmune sera

• Published in: Clinical and experimental immunology 1994-03, Vol.95 (3), p.397-407
• Main Authors: RICCHIUTI, V., BRIAND, J. P., MEYER, O., ISENBERG, D. A., PRUIJNJ, G., MULLER, S.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Antibody Specificity; Autoantibodies - blood; Autoantigens - immunology; Autoimmune Diseases - immunology; B cell epitopes; B-Lymphocytes - immunology; Biological and medical sciences; Enzyme-Linked Immunosorbent Assay - methods; Epitopes; Humans; Immunoblotting; Immunoelectrophoresis; Lupus Erythematosus, Systemic - immunology; Medical sciences; Molecular Sequence Data; Peptide Fragments - immunology; Ribonucleoproteins - immunology; RNA, Small Cytoplasmic; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Sjogren's Syndrome - immunology; Sjögren's syndrome; SSA/Ro antigen; synthetic peptides; systemie lupus erythematosus
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.1994.tb07010.x

SUMMARY The reactivity of autoantibodies present in the sera of 489 palicnts with Sjögren's syndrome (SS), systemic lupus crythematosus (SLE) and other autoimmune diseases was investigated by ELISA using recombinani 52‐kD SSA/Ro protein (rRo52) and 39 overlapping synthetic peptides representing the entire sequence of Ro52. We report that IgG antibodies reacting with rRo52 were present in the sera of a large number of patients with SS (67% of patients with primary SS and 46% of patients with SS associated with SLE), whereas they were less frequent (10‐25%) in SLE, rheumatoid arthritis (RA), juvenile chronic arthritis (JCA) and mixed connective tissue disease (MCTD), and absent in scleroderma. Among the 39 peptides tested, live were recognized by sera from 30‐65% of patients with SS, namely peptides representing residues 2 11, 107 122, 107 126, 277 292 and 365 382. Patients with JCA had raised levels of IgG antibodies reacting with peptides 2 11 and 365 382, and 51% of patients with MCTD had raised levels of IgG antibodies reacting with peptide 365 382. None of the five peptides was recognized by more than 20% of sera from patients with SLE and RA. Interestingly, and of importance in the field of diagnostic tests based on peptides, the reactivity of antibodies to the Ro52 synthetic peptides varied greatly according to the origin of sera. Inhibition experiments using either patients' sera or antibodies induced in rabbits against Ro52 peptides showed that the four domains 2‐11. 107 122, 277 292 and 365 382 are accessible on the surface of the Ro52 protein. These regions may thus be involved in the induction of specific antibodies in autoimmune patients.