RA33

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RA33, also known as heterogeneous nuclear ribonucleoprotein A2/B1, is an autoantigen in human systemic autoimmune diseases.

In 1989, a novel class of autoantibodies was detected in sera of patients with rheumatoid arthritis (RA), which were directed against a protein with an estimated molecular mass of 33 kDa in nuclear extracts from HeLa cells. [1] The antigen was therefore named RA33. Protein sequencing of highly purified RA33 revealed that it was identical to hetergoneous nuclear ribonucleoprotein A2/B1 (hnRPA2B1). [2] Nowadays, the name anti-RA33 defines autoantibodies that are directed against hnRNP A2 and its splice variant hnRNP B1. Anti-RA33 occur in approximately 15-35% of patients with RA, in 20-25% of patients with systemic lupus erythematosus and in 35-40% of patients with mixed connective tissue disease, being rare or absent in other forms of arthritis. [3] Anti-RA33 antibodies can be easily detected by immunoblotting employing crude nuclear extracts or the recombinant antigen. ELISA can also be employed which has been found to be less sensitive than immunoblotting.

The pathogenic role of anti-RA33 antibodies is not fully understood. Anti-RA33 antibodies and T cells directed against RA33 might contribute to autoimmunity and inflammation by immune complex formation or by virtue of secretion of cytokines that may initiate and drive the pathogenic process. [4] Of note, anti-RA33 are detectable already in the earliest disease stage of RA or even years before the onset of actual clinical disease. However, anti-RA33 antibodies are not associated with significant bone erosions or disease activity. In the absence of rheumatoid factor and anti-citrullinated protein antibody they are associated with a milder disease in RA.

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<span class="mw-page-title-main">Antinuclear antibody</span> Autoantibody that binds to contents of the cell nucleus

Antinuclear antibodies are autoantibodies that bind to contents of the cell nucleus. In normal individuals, the immune system produces antibodies to foreign proteins (antigens) but not to human proteins (autoantigens). In some cases, antibodies to human antigens are produced; these are known as autoantibodies.

<span class="mw-page-title-main">Anti-neutrophil cytoplasmic antibody</span> Group of autoantibodies

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An autoantibody is an antibody produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases are associated with such antibodies.

<span class="mw-page-title-main">Citrullination</span> Biological process

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Gideon Dreyfuss is an American biochemist, the Isaac Norris Professor of Biochemistry and Biophysics at the University of Pennsylvania School of Medicine, and an investigator of the Howard Hughes Medical Institute. He was elected to the National Academy of Sciences in 2012.

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snRNP70 Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">HNRNPL</span> Protein-coding gene in the species Homo sapiens

Heterogeneous nuclear ribonucleoprotein L is a protein that in humans is encoded by the HNRNPL gene.

<span class="mw-page-title-main">TROVE2</span> Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">RALY</span> Protein-coding gene in the species Homo sapiens

RNA-binding protein Raly is a protein that in humans is encoded by the RALY gene.

<span class="mw-page-title-main">Anti–citrullinated protein antibody</span> Autoantibodies

Anti-citrullinated protein antibodies (ACPAs) are autoantibodies that are directed against peptides and proteins that are citrullinated. They are present in the majority of patients with rheumatoid arthritis. Clinically, cyclic citrullinated peptides (CCP) are frequently used to detect these antibodies in patient serum or plasma.

<span class="mw-page-title-main">Anti-dsDNA antibodies</span> Group of anti-nuclear antibodies

Anti-double stranded DNA (Anti-dsDNA) antibodies are a group of anti-nuclear antibodies (ANA) the target antigen of which is double stranded DNA. Blood tests such as enzyme-linked immunosorbent assay (ELISA) and immunofluorescence are routinely performed to detect anti-dsDNA antibodies in diagnostic laboratories. They are highly diagnostic of systemic lupus erythematosus (SLE) and are implicated in the pathogenesis of lupus nephritis.

Anti-nRNP is a type of antibody.

Detection of autoantibodies against mutated citrullinated vimentin is part of rheumatoid arthritis (RA) diagnostics, especially in sera negative for rheumatoid factor. Anti-MCV antibodies are a member of the ACPA family, a group of the so-called antibodies to citrullinated protein/peptide antigens.

Rheumatoid lung disease is a disease of the lung associated with RA, rheumatoid arthritis. Rheumatoid lung disease is characterized by pleural effusion, pulmonary fibrosis, lung nodules and pulmonary hypertension. Common symptoms associated with the disease include shortness of breath, cough, chest pain and fever. It is estimated that about one quarter of people with rheumatoid arthritis develop this disease, which are more likely to develop among elderly men with a history of smoking.

<span class="mw-page-title-main">Anti-SSA/Ro autoantibodies</span> Type of anti-nuclear autoantibodies

Anti-SSA autoantibodies are a type of anti-nuclear autoantibodies that are associated with many autoimmune diseases, such as systemic lupus erythematosus (SLE), SS/SLE overlap syndrome, subacute cutaneous lupus erythematosus (SCLE), neonatal lupus and primary biliary cirrhosis. They are often present in Sjögren's syndrome (SS). Additionally, Anti-Ro/SSA can be found in other autoimmune diseases such as systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), rheumatoid arthritis (RA), and mixed connective tissue disease (MCTD), and are also associated with heart arrhythmia.

References

  1. Hassfeld et al.: Demonstration of a new antinuclear antibody (anti-RA33) that is highly specific for rheumatoid arthritis. Arthritis & Rheumatism 1989; 32:1515-20.
  2. Steiner et al.: Purification and partial sequencing of the nuclear autoantigen RA33 shows that it is indistinguishable from the A2 protein of the heterogeneous nuclear ribonucleoprotein complex. Journal of Clinical Investigation 1992; 90:1061-66
  3. Steiner et al.: Autoantibodies to the A/B proteins of the heterogeneous nuclear ribonucleoprotein complex: Novel tools for the diagnosis of rheumatic diseases. International Archives of Allergology and Immunology 1996;111:314-19.
  4. Fritsch et al.: Characterization of autoreactive T cells to the autoantigens RA33 (hnRNP A2) and filaggrin in patients with rheumatoid arthritis. Journal of Immunology 2002 169:1068-76