RA-33 (Heterogeneous Nuclear Ribonucleoprotein Complex) Autoantibodies

Abstract

This chapter includes methods of purification and detection of heterogeneous nuclear ribonucleoprotein (hnRNP) complex autoantibodies. These autoantibodies were initially detected from patients with rheumatoid arthritis (RA); the antigen was given the name “RA33.” Autoantibodies to the A/B proteins of the hnRNP complex are newly described serologic markers that are of high value for the diagnosis of RA, especially as they occur independently of rheumatoid factor. These antibodies can also be detected in sera from patients with other connective tissue diseases particularly systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD), but there they frequently occur together with antibodies to small nuclear ribonucleoproteins (snRNP)-associated antigens. There is a strong functional and structural relationship between snRNPs and hnRNPs during the process of messenger RNA maturation that takes place at the spliceosome. The antibodies to hnRNP-associated components of the spliceosome are found in sera of RA patients demonstrate that this disease is immunologically closely linked to SLE and MCTD than previously assumed.