Limited T-cell receptor diversity in liver-infiltrating lymphocytes from patients with primary biliary cirrhosis

Primary biliary cirrhosis is associated with the presence of high-titer anti-mitochondrial autoantibodies as well as T-cell infiltration of the liver, suggesting the involvement of autoimmune mechanisms. We have studied here the sequences of T-cell receptor alpha and beta chains expressed by T-cell clones derived from liver-infiltrating lymphocytes of two patients with primary biliary cirrhosis. Among the eight clones studied from the first patient, four expressed the same member of the V beta 6 subfamily, associated with either V alpha 4 (three clones) or V alpha 21 (one clone) gene segment. Two other clones expressed an identical V beta 12 transcript, and two in-frame alpha chain transcripts, involving V alpha 2 and V alpha 7 gene segments. From the second patient, eight out of the nine clones were found to rearrange V beta 17-J beta 2.1 and V alpha 3 gene segments. The remaining clone expressed distinct T-cell receptor chains, involving V beta 9 and V alpha 11 gene segments. As deduced from the analysis of their junctional regions, the eight T-cell clones expressing V beta 17/V alpha 3 gene segments derived from only three different T cells. Furthermore, conserved amino acid motifs were found to be encoded in both the alpha and the beta-chain junctional regions. Together, these data show a local amplification of unique T lymphocytes in both patients. The use of identical V beta J beta and V alpha gene segments with similar junctional sequences by three different cells, evidenced in one of the two cases, strengthens the view that liver-infiltrating T lymphocytes are selected locally by autoantigens in PBC.