The value of synthetic linear epitope analogues of La/SSB for the detection of autoantibodies to La/SSB; specificity, sensitivity and comparison of methods

In a previous study it was shown that La/SSB contains four linear epitopes, p147–154, p291–302, p301–318 and p349–364. The aim of the present study was to investigate the value of the synthetic epitope analogues of the La/SSB autoantigen for the detection of antibodies to La/SSB, in comparison with...

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Published in:	Clinical and experimental immunology Vol. 112; no. 1; pp. 152 - 158
Main Authors:	YIANNAKI, E. E, TZIOUFAS, A. G, BACHMANN, M, HANTOUMI, J, TSIKARIS, V, SAKARELLOS-DAITSIOTIS, M, SAKARELLOS, C, MOUTSOPOULOS, H. M
Format:	Journal Article
Language:	English
Published:	Oxford BSL Blackwell Science Ltd 01-04-1998 Blackwell Oxford University Press Blackwell Science Inc
Subjects:	Amino Acid Sequence Autoantibodies - analysis Autoantibodies - immunology Autoantigens - chemistry Autoantigens - immunology B cell epitopes Biological and medical sciences diagnostic value Epitopes - chemistry Epitopes - genetics Epitopes - immunology Humans Immunoassay La/SSB Medical sciences Molecular Sequence Data Original Recombinant Proteins - chemistry Recombinant Proteins - immunology Ribonucleoproteins - chemistry Ribonucleoproteins - immunology Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis Sensitivity and Specificity Sjogren's Syndrome - blood Sjogren's Syndrome - immunology Sjögren's syndrome SS-B Antigen systemic lupus erythematosus Human Immunopathology Connective tissue disease Skin disease Antigenic determinant Stomatology Antibody Autoantibody Autoimmune disease Sjögren syndrome Antigen Eye disease Autoantigen Analog Systemic disease Lupus erythematosus Peptide synthesis Diagnosis Disseminated Recombinant protein
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Summary:	In a previous study it was shown that La/SSB contains four linear epitopes, p147–154, p291–302, p301–318 and p349–364. The aim of the present study was to investigate the value of the synthetic epitope analogues of the La/SSB autoantigen for the detection of antibodies to La/SSB, in comparison with recombinant La and fragments of this protein. A total of 122 sera with anti‐La/SSB activity, from patients with primary Sjögren's syndrome (pSS) or systemic lupus erythematosus (SLE), were tested in various peptide‐based assays. In addition, 62 sera from pSS or SLE patients with other autoantibody specificities and 95 sera from healthy individuals were used as controls. The autoantibody specificity was identified by counter immunoelectrophoresis and immunoblot. The peptide‐based ELISA assays presented sensitivities ranging from 78% to 88.8% and specificities from 69% to 94.3%. Dot blot assays exhibited sensitivities ranging from 93.6% to 97%, but remarkably lower specificities from 56% to 88%. The most sensitive and specific peptide 349GSGKGKVQFQGKKTKF364 was synthesized and attached on a tetramer sequential oligopeptide carrier SOC4 and used for immunoassay development. Assays based on the recombinant native La protein, the La‐C terminal (215 aa), and the N‐terminal of La with a mutation at base pair 640 (nine adenines instead of eight) were also developed and compared with the SOC4 peptide‐based assay. Of anti‐La‐positive sera, 88.1% were reactive with both the synthetic peptide SOC4‐(349–364aa) and the recombinant La protein. Eighty‐three percent of sera were reactive with the La N‐terminus and 67.8% of sera were reactive with the La C‐terminus. Using sera that were anti‐Ro‐positive but anti‐La‐negative, 37% were reactive with the recombinant protein, 26% with the La N‐terminus, 33% with the La C‐terminus and only 11% with the synthetic peptide. Our results suggest that the synthetic peptide epitopes exhibit high sensitivity and specificity for the detection of anti‐La/SSB antibodies in ELISA and dot blot techniques. The peptide SOC4‐(349–364aa) has the same sensitivity for the detection of anti‐La/SSB antibodies as the recombinant protein.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0009-9104 1365-2249
DOI:	10.1046/j.1365-2249.1998.00558.x