Minor Histocompatibility Antigen HA-2 (HA-2)

Minor histocompatibility antigen HA-2 is a peptide antigen derived from a polymorphic protein encoded by the MYO1G gene, which is a novel member of the human class I myosin family. The gene is located on the short arm of chromosome 7 and its expression is restricted to cells of hematopoietic origin. HA-2 plays an important role in immune responses following allogeneic hematopoietic stem cell transplantation (HSCT), particularly in graft-versus-leukemia (GVL) effects. HA-2 acts as a minor histocompatibility antigen: even when donor and recipient are matched for major histocompatibility complex (MHC) genes, differences at minor antigens like HA‑2 can trigger immune responses leading to either beneficial GVL effects or undesirable GVHD, depending on tissue distribution and context. Because its expression is limited to hematopoietic tissues, targeting HA‑2 can promote selective anti-leukemic activity with lower risk of damaging nonhematopoietic tissues—making it an attractive target for post-transplant immunotherapy strategies such as donor lymphocyte infusion (DLI).

Other names

HA2MYO1G peptide

T cell-mediated cytotoxicity