Transplantation tolerance: from phenomenon to mechanism

The term "transplantation tolerance" is used for a state when a histoincompatible graft, i.e. one from a genetically different donor, survives in a recipient in which it would have been rejected under normal circumstances. Transplantation tolerance was first experimentally induced in 1953 and since that time the mechanisms underlying this phenomenon have been analysed. Originally, attention was paid to passive mechanisms of transplantation tolerance more recently, active mechanisms of tolerance, have been discovered. The recognition of these regulatory mechanisms and the development of ability to manipulate them has already had and will continue to have increasing impact on aimed the immunoregulation in therapeutic transplantation.