minor histocompatibility antigens

Minor histocompatibility antigens are due to normal proteins that are in themselves polymorphic in a given population.

In a fully H-2 incompatible chimera, T cells of donor origin can respond to minor histocompatibility antigens in association with either donor or host H-2 type.

HLA-identical siblings or HLA-identical unrelated donors often have genetically different proteins (called minor histocompatibility antigens) that can be presented by Major histocompatibility complex (MHC) molecules to the donor's T-cells, which see these antigens as foreign and so mount an immune response.