Allo-HLA reactive T-cells can mediate graft versus host disease (GVHD) after HLA mismatched stem cell transplantation (SCT) and donor lymphocyte infusion (DLI). In addition, these T-cells can... Show moreAllo-HLA reactive T-cells can mediate graft versus host disease (GVHD) after HLA mismatched stem cell transplantation (SCT) and donor lymphocyte infusion (DLI). In addition, these T-cells can mediate graft rejection after HLA mismatched solid organ transplantation and SCT. Both GVHD and graft rejection can have detrimental consequences for patients. It has been demonstrated that in the HLA matched setting GVHD and graft versus tumor response can be separated by selection of T-cells directed against minor histocompatibility antigens exclusively expressed on hematopoietic cells. After HLA mismatched SCT, GVHD is often accompanied by graft versus leukemia response, indicating that allo-HLA reactive T-cells could potentially be useful for beneficial purposes. In this thesis we characterized the composition of an allo-HLA class I directed immune response occurring in vivo during GVHD and investigated which cells were possibly responsible for activating the response. We investigated which T-cells are responsible for allo-HLA reactivity and how these T-cells recognize allo-HLA. Finally we investigated whether allo-HLA reactive T-cells could potentially be used for adoptive T-cell therapy. Show less