Abstract
Allogeneic hematopoietic stem cell transplantation represents the only curative approach for many hematological malignancies. During the last years the impact of the conditioning regimen has been re-assessed. With the advent of reduced-intensity conditioning the paradigm has changed from cytoreduction executed by high-dose radio-chemotherapy to immunological surveillance of leukemia by donor cells. Distinct subsets of T cells and NK cells contribute to graft-versus-leukemia reactions. So far, cytotoxic T lymphocytes are the mainstay of allogeneic immunotherapy. Here, we summarise the current knowledge of T cell-mediated graft-versus-leukemia reactions and present results from pre-clinical and clinical studies of T cell-based adoptive immunotherapy. We address the issues of feasibility and specificity of adoptive immunotransfer from a clinical point of view and discuss the prerequisites for successful clinical applications. Finally, the prospects for immunological research that have evolved with the increasing use of reduced-intensity conditioning and allogeneic stem cell transplantation are highlighted.