Heterogeneous nuclear ribonucleoprotein A2/B1 identified as an autoantigen in autoimmune hepatitis by proteome analysis.

Our aim was to characterize antinuclear antibody (ANA) targets in type 1 autoimmune hepatitis (AIH1) using a proteomic tool. ANA-positive sera from 29 patients with AIH1 and 14 negative controls were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The principal antigens identified were a 30 kDa triplet band which was recognized by 79% of patient sera and 14% of control sera, and a 36 kDa antigen which was recognized by 52% and 14% of sera, respectively. The latter antigen was studied in more detail using two-dimensional electrophoresis (2-DE) and mass spectrometry (MS). Its identification corresponded to heterogeneous nuclear ribonucleoprotein A2/B1. This paper presents the first description of this protein as an antigen in AIH1.