Stem cell transplantation is the first line treatment of many hematological diseases and primary immunodeficiencies. Graft-versus-host disease (GVHD) is still a severe complication after allogeneic transplantation and the main cause of mortality and morbidity. The study of the pathogenesis of GVHD may help to develop ways to prevent the disease, as well as to choose adequate immunosuppressant therapies. This study discusses the main immunological components involved in the pathogenesis of acute and chronic GVHD, with emphasis on the participation of cytokines and their control.302142152Jaksch, M., Mattsson, J., The pathophysiology of acute graft-versus-host disease (2005) Scand J Immunol, 61 (5), pp. 398-409Ferrara, J.L., Yanik, G., Acute graft versus host disease: Pathophysiology, risk factors, and prevention strategies. Clin Adv Hematol Oncol (2005), 3 (5). , 415-9,428Niederwieser, D., Herold, M., Woloszczuk, W., Endogenous IFN-gamma during human bone marrow transplantation. 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