Transplantation tolerance: mechanisms and strategies?

The goal of transplantation is to induce tolerance to the transplanted tissue. We believe that this will only be possible by exploring strategies normally used to endure and maintain self-tolerance. Tolerance can be defined as a state where the immune system does not respond to a specific antigen. This is in sharp contrast with immunosuppression, which decreases the immune response to a myriad of antigens and requires continued medication. T cells play an essential role in the immune response to alloantigens, because animals devoid of T cells do not reject transplanted organs. In this article we will focus on the mechanism of T cell tolerance and how the immune system may be manipulated to achieve tolerance to alloantigens.