ABSTRACT
Rejection of a liver graft, like that of other organs, depends on recognition of foreign major and minor transplantation antigens by the host. There has been considerable progress in understanding the rat major histocompatibility complex in terms of genetic structure and alloantigenicity. The arrangement of the genes coding for class I and II antigens is quite well understood, both from conventional genetics and, from DNA sequencing. The major histocompatibility complex of the laboratory rat, Rattus norvegicus, is called RT1. The RT1A region codes for a polypeptide chain of molecular weight 45,000, which, like all class I molecules, is associated on the cell surface with ß2-microglobulin. Two class II regions are recognized in what used to be called the B region; they are separated in the recombinant r12 bred by Lobel and Cramer. Antibodies against both class I and class II antigens appear in recipient serum after liver grafting or inoculation of liver homogenate.
