mHC/minor histocompatibility complex/mHA/minor histocompatibility antigens

HLA presents the major genetic barrier to stem cell transplantation. However, evidence that other genetic systems are involved includes GVHD and some degree of rejection even when translating with HLA identical siblings. A non HLA system which is thought to contribute to this is the minor histocompatibility antigen (mHA) system.

Minor histocompatibility antigens comprise of peptides derived from proteins in which some degree of polymorphism exists such there may be differences between the patient and donor repertoires. These peptides can be presented to the immune system both HLA class I and II antigen.

The best characterized minor antigens are the Y chromosome derived HY peptide and the autosomal HA1 to HA5 peptides. Minor histocompatibility antigens such as HA1 and HA2 have restricted tissue distribution and are present normally only on hematopoietic cells, making them potential targets for cellular therapy. Minor HLA antigens are restricted by certain HLA types such as HLA-A2 for instance.

References: http://www.histocompatibilityandimmu...lity-antigens/