Transplantation immunobiology: thymic T-cell development MHC class 1: structure and function MHC class II: structure and function biological inhibitors of lymphocyte coreceptors for antigen-specific immunosuppression immunosuppression andimmunophilin ligands: cyclosporin A, FK506, and rapamycin leucocyte adhesion, trafficking, and migration cytokine networks mechanisms of T-cell-mediated cytotoxicity in vivo and in vitro natural killer cells. GVHD pathophysiology - target organs: theimmune system: effector and target of Graft-vs.-Host disease cellular pathology of cutaneous Graft-vs-Host disease Graft-vs.-Host disease of the liver intestinal Graft-vs. disease Graft versus leukaemia lung injuries associated with Graftvs.-Hostreactions the effect of GVHD on the haematopoietic system. Network activation and dysregulation: Graft-vs.-Host disease as the Th-1 type process: regulation by donor cells of Th2 cytokine phenotype the role of endotoxin in the pathogenesis of acuteGraft-vs.-Host disease. Clinical GVHD - prevention and treatment: clinical spectrum of Graft-vs.-Host disease the immunobiology of syngeneic/autologous Graft-vs.-Host disease transfusion-associated Graft-vs.-Host disease. Current strategies: role ofhistocompatibility antigens in the development of graft-vs.-Host disease T-cell depletion of GVHD prevention in humans in vivo prevention and treatment of GVHD antagonists of inflammatory cytokines: prophylactic and therapeutic applications the roleof interleukin-10 in transplantation and GVHD. Alternative approaches: positive stem-cell selection for hermatopoietic transplantation adoptive immunotherapy in bone marrow transplantation genetherapy recent advances and future directions.