[The liver--an immunologically privileged organ?].

Some rat strains permanently accept allogenic livers without pharmacological immune suppression. In the same donor/recipient combinations, other organs as heart, kidney or skin are normally rejected. The transplanted liver not only withstands its own rejection, but also induce donor-specific immune tolerance. The mechanisms responsible for this effect may be clonal deletion, activation of suppressor cells or immune suppressive circulating factors as anti-class II-antibodies. An "immune-privilege" of an orthotopically transplanted liver exists also in pigs and, however to a lesser extent, in other large mammalian species including man. Regeneration of liver tissue altered by the transplantation procedure may produce the signals for induction of tolerogenic mechanisms.