Characterization of Autoantibodies against the E1𝜶 Subunit of Branched-Chain 2-Oxoacid Dehydrogenase in Patients with Primary Biliary Cirrhosis

Figure 2

Reactivities of PBC sera against synthesized overlapping peptides of BCOADC-E1𝛼. (a) and (b) Pin ELISA profiles of PBC sera. The reactivities of two high-titer PBC sera (P13 and P18) against the peptides were analyzed by pin ELISA. The location of the major epitope (region 6) is indicated by the blue squares. The two peptides showing the highest OD450 values are also highlighted in blue. (c) Clustering of small epitopes in the major determinant region. In the major determinant region (blue square), which corresponds to the blue squares in (a) and (b), multiple small epitopes are present as shown by the multiple peaks in the ELISA profiles. The reactivities of PBC sera against the peptides are shown (○, P07; ■, P13; •, P18; △, P20). The two octapeptides showing the highest values in (a) and (b) are highlighted in blue. (d) Overlapping epitopes are clustered in the major determinant region. The sequences of the octapeptides that exhibited peaks in (c) are indicated. The two octapeptides with the highest values in (c) are highlighted in blue.