Current status of Japan marrow donor program (JMDP) and its roles in international cooperation.

Transplants for patients lacking an HLA identical sibling donor have become possible, and thank to the establishment of large registries of HLA typed volunteers. Japan Marrow Donor Program (JMDP) now stands at about 152,339 volunteer donors, and have provided 4,013 marrows nationally and internationally. Advancements in HLA typing technology and greater precision in donor recipient matching have greatly increased the safety of unrelated donor transplants. In the JMDP retrospective study the strongest risk factor for acute GVHD and mortality was found to be mismatching for the BLA-A locus. Better matching criteria using molecular typing, however, will reduce the likelihood of identification of donors, especially in minorities. The chance of finding a matched unrelated donor is likely to be higher in the registries which share the same ethnic background of a recipient. There are five marrow donor registries have been established in Asia and are actively functioning. The expansion of volunteer donor pool of those registries and their efficient collaboration is very important to increase the probability of finding a match. The identification of permissive antigens may increase flexibility in donor-recipient pair matching may also be achieved through integration of international efforts and the creation of larger HLA data base.