[Immunologic reactions in transplantation].

Transplantation is the therapy of choice for an increasing number of patients. Organ transplantation is used to treat irreversible kidney, heart, lung and liver failure. Stem cell transplantation (previously called bone marrow transplantation) is used to treat leukaemia, bone marrow failure, severe combined immunodeficiencies and various congenital metabolic disorders. After organ transplantation, the recipient's immune system will recognise and reject the transplanted organ. T-lymphocytes transferred along with the stem cells in stem cell transplantation will attack the recipient. This paper describes how immunocompetent cells (T- and B-lymphocytes) recognise and destroy foreign cells. Strategies for the induction of specific immunologic tolerance are briefly explained.