Minor H antigens: genes and peptides

In this review, we describe the evidence from which the existence of non-MH C histocompatibility (H) antigens was deduced, the clinical setting of bone marrow transplantation in which they are important targets for T-cell resp onses, and the current understanding of their molecular identity. We list t he peptide epitopes of the human and murine minor H antigens now identified at the molecular level, their MHC restriction molecules and the genes enco ding them. Identification of the peptide epitopes allows T-cell responses t o these antigens following transplantation of MHC-matched, minor H-mismatch ed tissues to be enumerated using tetramers and elispot assays. This will f acilitate analysis of correlations with host-versus-graft (HVG), graft-vers us-host (GVH) and graft-versus-leukaemia (GVL) reactions in vivo. The poten tial to use minor H peptides to modulate in vivo responses to minor H antig ens is discussed. Factors controlling immunodominance of T-cell responses t o one or a few of many potential minor H antigens remain to be elucidated b ut are important for making predictions of in vivo HVG, GVH and GVL respons es and tailoring therapy after HLA-matched bone marrow transplantation and donor lymphocyte infusion.