Immune-mediated cholangiohepatitis in neonatally thymectomized mice: the role of T cells and analysis of T-cell receptor Vbeta usage

We have previously reported the induction of immune-mediated cholangiohepatitis following injection of a hybrid recombinant proteins containing the E2 of the pyruvate dehydrogenase (PDC-E2) and the branched-chain keto-acid dehydrogenase (BCOADC-E2) to neonatally thymectomized (Tx) A/J mice. Further, we demonstrated that intrahepatic infiltrating mononuclear cells could transfer pathology to other Tx mice. To further our observations, we examined intrahepatic infiltrating mononuclear cells by flow cytometry and used cell transfer experiments to identify the phenotype involved. Interestingly, following immunization of neonatally Tx A/J mice and immunization with the bihybrid molecule, the number of CD3+infiltrating mononuclear cells were significantly higher (77.8%) compared with the control group. There was a small although not significant increase among intrahepatic infiltrating mononuclear cells and splenic cells of Vbeta 5.1,5.2+, Vbeta7+and Vbeta17+. In addition, Vbeta14+cells accounted for 20.4% of the infiltrating T-cells (P<0.01 vs. the control group). In further experiments, CD3+, CD4+or CD8+cells were isolated and removed from intrahepatic infiltrating mononuclear cells and subpopulations of mononuclear cells transferred to Tx mice. Both CD3+CD4+cells and CD3+CD8+cells are required for development of the lesion, and the damage is mediated by CD3+Vbeta14+cells.