The involvement of Minor histocompatibility antigens (MiHA) in the graft versus tumor is described about three decades ago. Nowadays, there are many evidences that, after HLA-matched allogeneic... Show moreThe involvement of Minor histocompatibility antigens (MiHA) in the graft versus tumor is described about three decades ago. Nowadays, there are many evidences that, after HLA-matched allogeneic hematopoietic stem cell transplantation (HSCT) MiHA specific T cells mediate both graft versus leukemia (GVL) reactivity and graft versus host disease (GVHD), which is a major cause of morbidity and mortality. To identify MiHA we decided to establish a new strategy based on the bone fide eluted ligandome. Then we developed a database dedicated for identification of polymorphic peptides called human short peptide variation database (HSPVdb). To identify potential MiHA among the huge number of polymorphic peptides eluted from HLA-A*0201 or HLA-B*0702 we selected the top 25 MiHA candidates identified in chapter 2. From this set of data we could validate 2 novel potential MiHA being (LB-CLYBL-1Y & LB-TEP1-1S). To find out at which stages the great_est losses occurred, we developed a method to be able to quantitate MiHA on the cell surface. In addition we studied the phenomenon of the unidirectional T cell responses against MiHA. We studied in depth the presentation of non-canonical long peptides in HLA-A*0201 molecules. Show less
T-cell recognition of MiHA plays an important role in the GVT effect of allo-SCT. Selective infusion of T-cells reactive for hematopoiesis-restricted MiHA presented in the context of HLA-class I... Show moreT-cell recognition of MiHA plays an important role in the GVT effect of allo-SCT. Selective infusion of T-cells reactive for hematopoiesis-restricted MiHA presented in the context of HLA-class I molecules may help to separate the beneficial GVT effects from GVHD after allo-SCT. To date, only a few MiHA that form attractive targets for adoptive immunotherapy have been characterized and the number of patients that can be treated with such MiHA-selective cell therapy remains limited. In this thesis we focused on __reverse immunology__ as an attractive strategy to identify clinically relevant MiHA and other T-cell epitopes. In this approach peptide predictions are the starting point and peptide candidates are subsequently screened for their capacity to induce a T-cell response. We investigated the feasibility of computational genome-wide prediction of hematopoietic MiHA and alternatively implemented mass spectrometry based HLA-peptidomics as source for candidate peptides. T-cells that reacted with these antigens were collectively isolated by MHC-tetramer pull down. Subsequently, the composition of MHC-tetramer positive T-cell populations was characterized and tested for reactivity against any of the predicted epitopes that was included in the initial MHC-tetramer panel. We generated an algorithm that could be exploited to selectively target T-cells specific for clinically relevant MiHA. Show less
