[Orthotopic liver transplantation in the rat]

In the present study, rat orthotopic liver grafting was performed in order to investigate genetical, immunological and pathological aspects of liver transplantation. In the rat, MHC (RT1) incompatible liver grafts are mostly rejected in an acute fashion like other organs, and Class II antigen-barrier had a stronger effects on the survival of liver grafts than that of class I antigens. But in Some combinations, full RT1 incompatible grafts can survive indefinitely. The mechanisms of long survival of liver grafts are complicated dynamically but regulated systematically. While the hepatocytes are regenerating from the damage by the attack of the host immune reactions, the condition of host immune response is gradually changed from positive to negative. Immunosuppressive humoral factors (anti-Ia antibodies, anti-idiotypic antibodies, class I-like antigens secreted from hepatocytes, etc.) are produced and later suppressor cells are induced. Both of them can suppress the immune reactions (MLR, CTL induction etc.) successfully. These results indicate that liver grafts stand strong having potential regenerating activity and changing the host anti-graft immunity to immunologically unresponsive state.