Transforming growth factor-beta 1 derived from biliary epithelial cells may attenuate alloantigen-specific immune...

Immune response to liver allografts may be different from that to other organ transplants since immunological manipulation easily attenuates immune-response to liver allografts. Numerous studies on the alloantigen-specific immune response have been carried out, however, the precise mechanisms involved in this attenuation are not clear yet. Here we suggest the attenuation of alloantigen-specific immune response by TGF-beta 1 derived from biliary epithelial cells. The transforming growth factor-beta 1 (TGF-beta 1) expression in rat liver was examined immunohistologically. Rat biliary epithelial cells (BEC) were purified from the perfused liver and added to allogeneic mixed lymphocyte reaction (allo-MLR) to assess their attenuating potential on allo-MLR and alloantigen-specific cytotoxic T lymphocyte (allo-CTL) induction. Immunohistological investigation revealed the expression of TGF-beta 1 in biliary epithelial cells. Both purified biliary epithelial cells and TGF-beta 1 attenuated allo-MLR and allo-CTL induction in a dose-dependent manner, and anti-TGF-beta 1 antibody partially relieved this attenuation. This study reveals that biliary epithelial cells, the major target cells of allo-antigen specific immune response, contain TGF-beta 1 and that they have a capacity to attenuate allo-MLR and allo-CTL induction.