Involvement of MHC-Linked Hemopoietic-Histocompatibility Genes in Allogeneic Bone Marrow Transplantation in Mice

Genes controlling resistance of irradiated mice to allogeneic hemopoietic cells were mapped within, or closely linked to the D region of MHC and were designated Hemopoietic-histocompatibility genes (Hha). Hhp genes responsible for resistance to parental hemopoietic cells had also previously been detected on the D-end of MHC. Hh genes are regarded as determinants of cell surface antigens (Hh antigens) phenotypically expressed, in contrast to Histocompatibility antigens (H antigens), only on blood-forming and leukemic cells. The inheritance of Hh genes is not codominant, unlike that of H genes, suggesting that the Hh genes and H genes are independent entities. Hh antigens also seem to exist on rat and dog cells and it is plausible that these antigens also exist in man, and could influence the outcome of clinical bone marrow transplantation.