<b>Epitope mapping of the Ro/SSA60KD autoantigen reveals disease‐specific antibody‐binding profiles</b>

Abs to Ro/SSA Ags in the sera of patients with systemic lupus erythematosus and Sjögren’s syndrome are influenced by the HLA class II genes. To investigate the role of individual HLA class II genes in immune responses to human Ro60 (hRo60), mice lacking murine class II molecules and carrying either HLA genes DR2(DRB1*1502), DR3(DRB1*0301), DQ6(DQA1*0103/DQB1*0601), or DQ8(DQA1*0301/DQB1*0302), were immunized with rhRo60. The results show that hRo60 induces strong T and B cell responses in DR2, DR3, and DQ8 mice in comparison to weaker responses in DQ6 mice. In all mice, the majority of the dominant T cell epitopes were located in the amino portion (aa 61–185) and the carboxy portion (aa 381–525) of the hRo60 molecules. In contrast, the early dominant B cell epitopes were located in the middle and carboxy portion of the hRo60 molecule (aa 281–315 and 401–538). In DR2, DR3, and DQ8 mice, the B cell epitopes subsequently spread to the amino and carboxy portion of the hRo60 molecule but were limited to the middle and carboxy portion in DQ6 mice. The DR2 and DR3 mice produced the highest titers of immunoprecipitating Abs against hRo60 and native mouse Ro60. In addition, only DR2 mice exclusively produced immunoprecipitating Abs to native mouse Ro52 and Abs to mouse La by slot blot analysis, whereas in other strains of mice Abs to mouse La were cross-reactive with the immunogen. The results of the present study demonstrate the importance of HLA class II in controlling the immune responses to the Ro-ribonucleoprotein.

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“…SLE and SS (32)(33)(34)(35)(36)(37). Our identified dominant B cell epitopes corresponding to aa 281-315 lie within this region.…”

Section: Discussionmentioning

confidence: 81%

“…Previous studies have variably identified B cell epitopes of hRo60 from sera of patients with SLE and SS (32)(33)(34)(35)(36)(37)(38)(39). The discrepancies probably reflect the different populations studied and the types of assays and Ags selected.…”

Section: Discussionmentioning

confidence: 98%

HLA Class II Influences the Immune Response and Antibody Diversification to Ro60/Sjögren’s Syndrome-A: Heightened Antibody Responses and Epitope Spreading in Mice Expressing HLA-DR molecules

Paisansinsup

Deshmukh

Chowdhary

et al. 2002

The Journal of Immunology

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“…The fine B cell epitope mapping of autoantibodies to La/SSB was performed using overlapping synthetic peptides. The length of the peptides used was rather long (20 amino acids), since in previous studies of Ro60kD epitopes it was shown that long peptides exhibited higher specificity [29] compared with overlapping octapeptides [30]. In fact, the mimotope scanning of Ro60kD molecule, using 22 mer overlapping synthetic peptides, revealed two discrete, disease-specific epitopes (one associated with SS and the other with SLE), compared with 14 epitopes defined by the octapeptides.…”

Section: Discussionmentioning

confidence: 99%

Fine specificity of autoantibodies to La/SSB: epitope mapping, and characterization

Tzioufas

Yiannaki

Sakarellos‐Daitsiotis

et al. 1997

Clinical and Experimental Immunology

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SUMMARYThe B cell epitope mapping of La/SSB was performed using 20 mer synthetic peptides overlapping by eight amino acids covering the whole sequence of the protein. IgG, purified from sera of five patients with systemic lupus erythematosus (SLE) and four sera from patients with primary Sjögren's syndrome (pSS) were tested against the overlapping synthetic peptides. Peptides highly reactive with purified IgG were those spanning the regions 145-164, 289-308, 301-320 and 349-368 364 . Predicted features and molecular similarities of the defined epitopes were investigated using protein databases. The La epitope 147 HKAFKGSI 154 presented 83·3% similarity with the 139 HKGFKGVD 146 region of human myelin basic protein (MBP) and 72% similarity with the fragment YKNFKGTI of human DNA topoisomerase II. Peptides corresponding to these sequences cross-reacted with anti-La/SSB antibodies. Sixty-three sera with anti-La/SSB antibodies from patients with pSS or SLE, 35 sera without anti-La/SSB antibodies from patients with SS or SLE and 41 sera from age/sex-matched healthy blood donors were tested against biotinylated synthetic epitope analogues in order to determine their sensitivity and specificity for the detection of anti-La/SSB antibodies. Anti-La/SSB were detected with various frequencies ranging from 20% to epitope 147 HKAFKGSI 154 to 100% to epitope 349 GSGKGKVQGKKTKF 364 . The overall sensitivity and specificity using all assays with the synthetic peptides were found to be 93·6% and 85·6%, respectively. In conclusion, antibodies to La/SSB constitute a heterogeneous population, directed against different linear B cell epitopes of the molecule. The epitope 147 HKAFKGSI 154 presents molecular similarity with fragments of two other autoantigens, i.e. human MBP and DNA topoisomerase II. Finally, synthetic epitope analogues exhibit high sensitivity and specificity for the detection of anti-La/SSB antibodies.

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“…Indeed, some studies have suggested that the separate analysis of the two Ro antibodies may be important in the differentiation of SLE from SS, as anti-Ro60 would be prevalent in patients with SLE and anti-Ro52 would be prevalent in patients with SS (3,29,32). Other studies, however, were less positive on this point, having found overlapping features between antibody specificity and the kind of disease (1).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, in view of reports that autoantibodies to the 52-kDa component are more frequently found in the sera of SS patients, whereas autoantibodies to the 60-kDa component are more often observed in SLE patients (3,29,32), and that this different behavior may be helpful in the differential diagnosis of these autoimmune disorders, we also evaluated the prevalence and distribution of the two anti-Ro antibodies in patients with an established diagnosis of SS or SLE.…”

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confidence: 99%

New Coupled-Particle Light-Scattering Assay for Detection of Ro/SSA (52 and 60 Kilodaltons) and La/SSB Autoantibodies in Connective Tissue Diseases

Bizzaro

Bonelli²,

Tonutti

et al. 2001

Clin Diagn Lab Immunol

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The diagnostic and analytical performance of the coupled-particle light-scattering assay in detecting antiRo/SSA autoantibodies (the 60-kDa [Ro60] and the 52-kDa [Ro52] antibodies) and anti-La/SSB autoantibodies was evaluated. The antigens were obtained by recombinant DNA procedures to include the most immunogenic epitopes for each protein by using a prokaryotic expression system. Serum samples from 151 patients with connective tissue diseases and 52 control subjects (including patients with viral infections, patients with Lyme disease, and healthy subjects) were studied. Sensitivities for detection of anti-Ro/SSA and anti-La/SSB were 88.2 and 95.2%, respectively; specificities were 97.6 and 98.1%, respectively. The intra-assay coefficient of variation (CV) ranged from 4.3 to 10.9% for anti-Ro/SSA and from 2.8 to 12.5% for anti-La/SSB; interassay CVs ranged from 6.5 to 13.2% and from 8.2 to 14.5%, respectively. Among the anti-Ro/SSA-positive samples, Ro60 was recognized by 66% of the test sera and Ro52 was recognized by 95% of the test sera. Thirty-four percent of the Ro/SSA-positive sera were reactive only with the Ro52 antigen, indicating that anti-Ro52 is the most common antibody specificity recognized by anti-Ro/SSA autoantibodies. No differences were found between the prevalences of anti-Ro60 and anti-Ro52 in relation to systemic lupus erythematosus or Sjögren's syndrome. The results of the present study indicate that this new immunoassay is an efficient diagnostic tool for the detection of anti-Ro/SSA and anti-La/SSB antibodies in patients with autoimmune disorders.

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Epitope mapping of the Ro/SSA60KD autoantigen reveals disease‐specific antibody‐binding profiles

Cited by 42 publications

References 31 publications

HLA Class II Influences the Immune Response and Antibody Diversification to Ro60/Sjögren’s Syndrome-A: Heightened Antibody Responses and Epitope Spreading in Mice Expressing HLA-DR molecules

HLA Class II Influences the Immune Response and Antibody Diversification to Ro60/Sjögren’s Syndrome-A: Heightened Antibody Responses and Epitope Spreading in Mice Expressing HLA-DR molecules

Fine specificity of autoantibodies to La/SSB: epitope mapping, and characterization

New Coupled-Particle Light-Scattering Assay for Detection of Ro/SSA (52 and 60 Kilodaltons) and La/SSB Autoantibodies in Connective Tissue Diseases

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