Interest in HLA expression was further fostered by the observation that donor-recipient HLA mismatches involving a high-expression variant in the patient are associated with the risks of developing graft-versus-host-disease (GvHD) after Hematopoietic Stem Cell Transplantation (HSCT), both for HLA-C (7) and HLA-DPB1 (8). Here, HLA-DPB1 is linked to graft versus host disease.