Autoantibodies to the A/B proteins of the heterogeneous nuclear ribonucleoprotein complex: novel tools for the diagnosis of rheumatic diseases

Int Arch Allergy Immunol. 1996 Dec;111(4):314-9. doi: 10.1159/000237386.


Heterogeneous nuclear ribonucleoprotein (hnRNP) complexes are major constituents of the spliceosome. They are composed of approximately 30 different proteins which can bind to nascent pre-mRNA. Among these, the hnRNP-A/B proteins form a subgroup of highly related proteins: their N-terminal halves consist of two adjacent RNA-binding domains, whereas the C-terminal halves contain almost 50% glycine residues. These proteins represent a group of novel autoantigens which are targeted by autoantibodies from patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and mixed connective tissue disease (MCTD): thus, anti-A2/RA33 autoantibodies target the hnRNP proteins A2, B1, B2 (the 'RA33 complex'), and anti-A1 autoantibodies are directed to the hnRNP proteins A1 and A1b. In SLE, anti-hnRNP-A/B antibodies frequently occur together with antibodies to two other spliceosome-associated antigens, U1 small nuclear RNP (U1-snRNP) and Sm. Epitope-mapping studies have revealed that the major antibody binding sites are located in the RNA-binding regions. Furthermore, there is some indication of disease-specific epitope recognition. Studies in animal models have demonstrated the presence of anti-hnRNP-A/B antibodies in several lupus-prone mouse strains. Thus, autoantibodies to the spliceosomal hnRNP-A/B proteins are a common feature of RA, SLE, and MCTD. However, these diseases differ in their reactivities to other spliceosomal components, such as U1-snRNP and Sm antigens. Therefore, anti-hnRNP-A/B autoantibodies are not only valuable diagnostic markers but may also allow additional insights into the pathogenetic mechanisms of rheumatic autoimmune diseases.

Publication types

  • Review

MeSH terms

  • Animals
  • Autoantibodies*
  • Autoantigens / immunology
  • Biomarkers
  • Heterogeneous Nuclear Ribonucleoprotein A1
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B*
  • Heterogeneous-Nuclear Ribonucleoproteins
  • Humans
  • Mice
  • RNA, Heterogeneous Nuclear / immunology*
  • RNA-Binding Proteins / immunology*
  • Rheumatic Diseases / diagnosis*
  • Rheumatic Diseases / etiology
  • Ribonucleoproteins / immunology*


  • Autoantibodies
  • Autoantigens
  • Biomarkers
  • Heterogeneous Nuclear Ribonucleoprotein A1
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B
  • Heterogeneous-Nuclear Ribonucleoproteins
  • RNA, Heterogeneous Nuclear
  • RNA-Binding Proteins
  • Ribonucleoproteins
  • hnRNP A2