INFLUENCE AND FATE OF T-LYMPHOCYTES IN AUTOIMMUNITY

Many T cells with autoaggressive potential are deleted in the thymus b ut some escape to the general circulation. They do not damage organs s uch as the insulin-producing tissue of the pancreas, unless some or al l of the following conditions are met: high affinity of the antigen re ceptor on T cells (TCR) for the target self antigen, priming by enviro nmental antigens which mimic the target antigen, and some inflammatory reaction in the target site. When the liver expresses the antigen, an y circulating T cells specific for this are deleted in the liver. This suggests that the liver may play a role in preventing autoimmune aggr ession by T cells specific for antigens expressed on liver cells. Rece nt experimental models have been set up to test the possibility that a n immunoregulatory T cell may exist and exert some type of preventive influence on the autoaggressive potential of self-reactive T cells. (C ) 1996 Academic Press Limited