Pristane-induced arthritis (PIA) in rats is considered an excellent model for rheumatoid arthritis (RA) since it fulfils the criteria for RA including a chronic relapsing disease course and is not dependent on immunization with exogenous antigen. Although the adjuvant pristane is not immunogenic, the disease is MHC associated and dependent on the activation of (autoreactive) T cells. However, so far it has not been possible to link the immune response to joint antigens or other endogenous components. HnRNP A2, the RA33 autoantigen (A2/RA33), is a multi-functional RNA binding protein involved in splicing and other aspects of post-transcriptional regulation of gene expression. Autoantibodies as well as autoreactive T cells against A2/RA33 have been found in patients with RA but the pathogenetic role of these autoimmune responses is unresolved . It was therefore the aim of this study to elucidate a potential involvement of A2/RA33 in PIA.