Immunological analysis in xenogeneic fetal porcine liver transplantation into a beagle.

Background/aims: While allogeneic organ transplantation has been performed safely, a major barrier in xenogeneic transplantation is how to inhibit hyperacute rejection.
Methodology: We challenged xenogeneic fetal liver transplantation from pig to dog. The graft was investigated by immunohistochemical analysis on recipient's IgG, IgM and C3.
Results: In 1 of 4 cases, the graft escaped hyperacute rejection for about 4 hours after transplantation, however, the recipient died next day due to hemorrhage from the torn capsule of the liver due to the arterial blood pressure of the recipient. Histologically, the parenchyma showed good countenance and no congestion nor hemorrhage was shown in the vessels. On immunohistochemical analysis, canine IgG, IgM and C3 were deposited on the sinusoidal epithelium of the fetal liver more moderately than that of adult control. Fetal porcine liver showed less expression of major histocompatability complex class I antigen than that of the adult one.
Conclusions: We consider that the hyperacute rejection occurred more slowly in xenogeneic fetal liver transplantation than in the adult one due to not only less expression of major histocompatability complex class I, but also lower expression of the epitope recognized by a natural antibody of the recipient.