Restricted epitope recognition by precipitin‐negative anti‐La/SS‐B‐positive sera

Gordon, Thomas P.; Mavrangelos, Chris; McCluskey, James

doi:10.1002/art.1780350609

Cited by 22 publications

(19 citation statements)

References 13 publications

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“…Sera from precipitin-negative patients show a restricted B cell epitope pattern with sparing of the poorly conserved COOH-terminal epitope (21). If the precipitin-negative patient group represents an early oligoclonal response to La/SS-B, then it might be inferred that antibody reactivity is directed initially to conserved epitopes on the autoantigen, with recruitment of less conserved epitopes as the autoimmune response becomes polyclonal and involves the whole molecule.…”

Section: Discussionmentioning

confidence: 99%

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Identification of a human-specific epitope in a conserved region of the La/SS-B autoantigen.

et al. 1993

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Human anti-La/SS-B autoantibodies are known to react with highly conserved epitopes suggested to be functional or active sites on the La/SS-B polypeptide. This study was designed to determine whether the autoantibodies also react with poorly conserved regions of La/SS-B as predicted by an antigendriven autoimmune response. Binding of human autoantibodies to purified human, mouse, and bovine recombinant fragments representing immunodominant regions of the La/SS-B polypeptide was compared using Western blotting and ELISA. A cross-reactive epitope was located in the highly conserved NH2-terminal region of La/SS-B. Significantly, human-specific epitopes were identified in both the conserved RNA-recognition motif and a poorly conserved COOH-terminal fragment, providing direct evidence for an autoantigen-driven response. The lack of autoantibody cross-reactivity with a conserved domain of mouse and bovine La/ SS-B implies that a small number of residues in human autoepitopes may be critical for autoimmunogenicity. (J. Clin. Invest. 1993Invest. . 92:1104Invest. -1108

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Section: Discussionmentioning

confidence: 99%

“…Binding ofhuman anti La/ SS-B sera (diluted 1:500) to the recombinant human and mouse La/SS-B fusion proteins was determined by ELISA as previously described with coating concentrations chosen to give equivalent OD405nm readings with the rabbit anti-GST serum (8,21 rabbit anti-GST serum (Fig. 2 A).…”

Section: La L2/3mentioning

confidence: 99%

Identification of a human-specific epitope in a conserved region of the La/SS-B autoantigen.

et al. 1993

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“…Binding of titrated human anti-Ro sera to recombinant human and mouse Ro52 protein was determined by ELISA as previously described [16]. The estimation of relative avidity of antibody binding to recombinant human or mouse Ro52 was determined by thiocyanate elution as described [17].…”

Section: Elisa and Antibody Avidity Determinationmentioning

confidence: 99%

Structural differences between the human and mouse 52-kD Ro autoantigens associated with poorly conserved autoantibody activity across species

Keech

Gordon

McCluskey

1996

Clinical and Experimental Immunology

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SUMMARYAnti-nuclear autoantibodies found in human autoimmune diseases frequently cross-react with homologous autoantigens in distant species, supporting the notion that autoantibodies target conserved functional domains. However, the 52-kD Ro(SS-A) protein is an exception, in that human autoantibodies are not known to recognize any equivalent antigen in the cells of rodents and other non-primate species. To understand this lack of cross-reactivity we have isolated cDNAs encoding the mouse 52-kD Ro molecule. The cDNA encoding mouse 52-kD Ro revealed an open reading frame of 470 amino acids, with 70% sequence identity to the human 52-kD Ro antigen. The putative leucine-zipper and zinc-finger motifs present in human Ro52 were conserved in the mouse protein. Recombinant mouse 52-kD Ro protein reacted with human autoantibodies by ELISA and immunoblot, but with approximately 10-fold lower reactivity than recombinant human 52-kD Ro protein under the same conditions. Detection of both human and mouse 52-kD Ro by immunoblot was dependent on antigen concentration which was limiting in the cell equivalents generally used in immunoblot assays. Differential chaotropic disruption of antibody binding suggested a lower avidity of human autoantibody binding to the mouse 52-kD Ro protein compared with the human antigen. Thus the poor reactivity of native mouse 52-kD Ro with human autoantibodies is associated with species divergence diffusely distributed throughout the primary structure of the 52-kD Ro molecule.

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“…Epitope mapping of the La autoantigen in patients with primary SS has revealed three immunodominant regions: LaA [amino acids (aa) ; LaC (aa111-242); and LaL2/3 (aa346-408) [9]. Autoantibodies directed against the conserved winged-helix LaA determinant [10] are of particular significance because: they occur in ∼100% of precipitin-positive sera and appear to arise early in the anti-La response [9,11]; are present at the highest concentration (mg/ml range) of any determinant [12]; bind the analagous LaA apotope on the surface of apoptotic cells where they form immunoglobulin (Ig)G-immune complexes [13,14]; react with a conserved discontinuous epitope [15]; and are present in sera from ∼80% of mothers of children with congenital heart block [14].…”

Section: Introductionmentioning

confidence: 99%

An immunodominant La/SSB autoantibody proteome derives from public clonotypes

Thurgood

Arentz

Lindop

et al. 2013

Clinical and Experimental Immunology

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SummaryThe La/SSB autoantigen is a major target of long-term humoral autoimmunity in primary Sjögren's Syndrome (SS) and systemic lupus erythematosus. A majority of patients with linked anti-Ro60/Ro52/La responses target an NH2-terminal epitope designated LaA that is expressed on Ro/La ribonucleoprotein complexes and the surface membrane of apoptotic cells. In this study, we used high-resolution Orbitrap mass spectrometry to determine the clonality, isotype and V-region sequences of LaA-specific autoantibodies in seven patients with primary SS. Anti-LaA immunoglobulin (Ig)Gs purified from polyclonal sera by epitope-specific affinity chromatography were analysed by combined database and de-novo mass spectrometric sequencing. Autoantibody responses comprised two heavily mutated IgG1 kappa-restricted monoclonal species that were shared (public) across unrelated patients; one clonotype was specified by an IGHV3-30 heavy chain paired with IGKV3-15 light chain and the second by an IGHV3-43/IGKV3-20 pairing. Shared amino acid replacement mutations were also seen within heavy and light chain complementarity-determining regions, consistent with a common breach of B cell tolerance followed by antigendriven clonal selection. The discovery of public clonotypic autoantibodies directed against an immunodominant epitope on La, taken together with recent findings for the linked Ro52 and Ro60 autoantigens, supports a model of systemic autoimmunity in which humoral responses against protein-RNA complexes are mediated by public sets of autoreactive B cell clonotypes.

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Restricted epitope recognition by precipitin‐negative anti‐La/SS‐B‐positive sera

Cited by 22 publications

References 13 publications

Identification of a human-specific epitope in a conserved region of the La/SS-B autoantigen.

Identification of a human-specific epitope in a conserved region of the La/SS-B autoantigen.

Structural differences between the human and mouse 52-kD Ro autoantigens associated with poorly conserved autoantibody activity across species

An immunodominant La/SSB autoantibody proteome derives from public clonotypes

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