Page 1125 - Veterinary Immunology, 10th Edition

VetBooks.ir Liver Allografts

It was originally reported that a high percentage of liver allografts
between outbred pigs were accepted without immunosuppression.

However, these pigs were not genetically defined, and the degree of
MHC mismatching was unclear. When liver allografts are made
between genetically defined miniature pigs with known MHC
differences, it is found that their rejection rate is similar to that
observed with kidney or skin allografts. Liver graft rejection in dogs

tends to occur fairly slowly. This inhibition of liver allograft
rejection appears to be due to the production of indoleamine 2,3-
dioxygenase (IDO) by hepatocytes. IDO destroys the amino acid

tryptophan (Chapter 20). Since tryptophan is essential for Th1
responses, its absence within the grafted liver is highly
immunosuppressive.

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