ANALYSIS OF T-CELL RECEPTOR-BETA OF THE T-CELL CLONES REACTIVE TO THEHUMAN PDC-E2-163-176 PEPTIDE IN THE CONTEXT OF HLA-DR53 IN PATIENTS WITH PRIMARY BILIARY-CIRRHOSIS

T-cell-mediated autoimmune mechanisms are considered to be involved in the pathogenesis of primary biliary cirrhosis (PBC). In the previous study, we identified the immunodominant T-cell epitope on the E2 compo nent of pyruvate dehydrogenase complex (PDC-E2) in patients with PBC w ho have HLA-DRB40101. In this report, we revealed that the frequency of the T cells reactive to the human PDC-E2 163-176 peptide is signifi cantly increased in the peripheral blood of patients with PBC as compa red with healthy subjects. We also confirmed that these T cells were a ll restricted with HLA-DRB401 (DR53) by using HLA-DR-transfected L ce lls. These results together with the evidence that the immunodominant B-cell epitope overlaps with the human T-cell epitope of the PDC-E2 an tigen indicate that the T cells reactive to this epitope are closely a ssociated with the pathogenesis of PBC at least in patients who have H LA-DR53. Therefore, we analyzed the T-cell receptor (TCR) V beta seque nce of the five different T-cell clones and the three T-cell clones de rived from three patients with PBC and healthy-subjects, respectively, which are reactive to the human PDC-E2 163-176 peptide in the context of HLA-DR53. The V beta- and the J beta-gene usages were diverse amon g the T-cell clones (V beta 11-J beta 1.4, V beta 8-J beta 1.2, V beta 12-J beta 2.1, V beta 10-J beta 1.5, and V beta 20-J beta 2.1) in pat ients with PBC. By contrast, in the third complementarity determining region (CDR3), G was frequently found and GXG or GXS motif was identif ied in all T-cell clones. Moreover, RGXG motif was found in three clon es generated from two patients. In healthy subjects, the V beta- and t he J beta-gene usages were also diverse, and GXG and RGXG motif were f ound. These results indicate that the T cells may recognize tile ligan d (the human PDC-E2 163-176 peptide/HLA-DR53 complex) using the limite d motif in the CDR3 region and that the design of CDR3-specific immuno therapy would be possible using these motifs.