Prevention of transplant rejection can tolerance be achieved with immunosuppressive treatment?

Successful solid organ transplantation is generally attributed to the increasingly precise ability of drugs to control rejection. However, it was recently shown that a few donor haematolymphoid cells can survive for decades in recipients of successful organ allografts, a phenomenon called microchimaerism. The association for decades of haematolymphoid chimaerism with allograft tolerance in experimental transplantation suggests that immunosuppressive drugs merely create a milieu that enables an allograft and its complement of passenger leucocytes to prime the recipient for graft acceptance. Exploitation of this concept requires a fundamental shift in the classical view of passenger leucocytes only as initiators of rejection. Microchimaerism has taught us that solid organ transplantation involves the transfep-öTEwo3öTK}r organ systems to the recipient: the allograft parenchyma an-4oHg-4oonor'-4y&eWtolymphoid system in the form of donor stem cells contajfletwit|4Q(Xj pas-4MTger leucocyte compartment. Each has the potential to integral witty-4-4orrespSnping recipient system and carry out normal physiologi|:a£futy-4ijj£jvwlta5irnmunological self definition. Resistance to initial integralen r-4WMjure £als requires some form of immunosuppression, but mainterçad-4 of donor-4Rjraiine system function will depend on renewable supply of cells, v-4Jrf-4Siyi-4jj-4fvided by engrafted progenitors. Successful clinical application willctepcrrtTon the development of low morbidity methods to enhance engraftment of donor haemopoietic stem cells. Adis international Limited All rights reserved

Allograft and Xenograft Acceptance under FK‐506 and Other Immunosuppressant Treatment

We will focus on two issues, both involving, but not confined to FK-506: first, the meaning of the graft acceptance, which is, after all, the objective of immunosuppression for the transplant surgeon; and second, how to take the next great step of xenotransplantation