Histocompatibility HA1, Minor (HMHA1)

Cytotoxic T lymphocytes directed against minor histocompatibility antigens of the host were demonstrated in blood from recipients of bone marrow from donors who were genotypically HLA identical. Clones of such cytotoxic T cells were isolated from lymphocyte populations in the blood of patients with severe graft-versus-host disease. The HA-1 antigen is present in 69% of normal people who express HLA-A2, whereas the frequencies of the 3 others in this set of HLA-A2-restricted minor histocompatibility antigens are either high (95% for HA-2); or low (16% of HA-4 and 7% for HA-5). The HLA-1-restricted minor histocompatibility antigen HA-3 occurs in 88% of persons positive for HLA-A1. HA-1, -2, -4, and -5 are inherited independently of the HLA genes; each of them is encoded by a single gene, and none has a locus within the HLA region.