[The allogeneic liver transplantation. I. Morphological and functional patterns in pig liver allografts (author's transl)]

Liver allograft rejection in pigs: histology of the graft and role of swine leukocyte antigen-D

The porcine liver is often considered an immunologically privileged organ as liver allografts in unrelated pigs can survive without any form of immunosuppression. When donor and receptor animals were mismatched for swine leukocyte antigen-D (SLA-D) antigens as tested in mixed-lymphocyte culture (MLC), liver allografts were rejected in all but one of the 14 cases studied. In contrast, from the 10 animals receiving a liver from an MLC-matched donor 8 survived without any significant sign of rejection. The diagnosis of rejection was made by histologic examination of serial needle biopsies of the liver. Based on survival time and histological type of cellular infiltrate an early and a late form of rejection could be distinguished. The early form, with a survival time from 6 to 10 days, was characterized by lymphocytic infiltration of the portal tracts and the liver parenchyma. The late form, with a survival time ranging from 15 to 80 days, showed a lymphocytic and plasma cellular infiltration of the portal tracts. These results show that the outcome of liver allotransplantation in pigs is strongly dependent on SLA-D histocompatibility. It is concluded that porcine liver allografts are under immunological control.

Serum total bile acids monitoring after experimental orthotopic liver transplantation

The aim of this study was to evaluate the usefulness of serum total bile acids estimation in monitoring liver allograft recipients. To this end frequent blood samples and simultaneous needle biopsies of the liver were taken after orthotopic liver transplantation in unimmunosuppressed pigs. Serum bile acids were found to rapidly increase during the anhepatic phase of the transplantation procedure and to decrease after implantation of the liver graft. A normal serum bile acids level in the early postoperative phase was indicative of a technically successful transplantation procedure. A total of 28 successful transplantations was performed. Six recipients accepted the allograft without any histological sign of rejection. In 18 pigs the liver was rejected, the survival time of these animals ranged from 6 to 80 days. Four animals showed a transient rejection episode during the first months after transplantation. In nonrejecting animals serum bile acids remained undisturbed during the entire 4-month study period. In all cases of rejection serum bile acids promptly increased to very high levels of 100 to 700 mumol/liter (reference range 1 to 14 mumol/liter). Serum bile acids were found to be superior to standard liver function tests in detecting the process of liver rejection at an earlier stage. These results indicate that serum total bile acid estimation is a simple and useful test to monitor liver allograft recipients.