Self tolerance can not only be established during T cell maturation in
the thymus but also in mature peripheral T cells by several extrathym
ic mechanisms. This has been found by analysing anti-K(b) T cell recep
tor transgenic mice which expressed this transplantation antigen as a
second transgene product in various extrathymic tissues. The described
observations could lead to new strategies to improve immunosuppressio
n in allograft transplantation.