[Mechanisms of allogenic recognition in transplantation systems].

Transplantation of organs, tissues or cells triggers in the organism an immune response to foreign (allogenic) proteins of the donor's Major Histocompatibility Complex, eventually resulting in graft rejection. The crucial role in the allogenic immune response belongs to T-lymphocytes. The structure of allogenic targets recognized by alloreactive T-lymphocytes is still open to question. The current state of knowledge concerning allorecognition is reviewed with special reference to the type (direct or indirect) of T-cell recognition of alloantigens and their roles in graft rejection. Special attention is given to the contribution of peptides to allogenic targets formation and the role of tolerance in transplantation systems.