Marrow transplants from HLA matched unrelated donors: an NMDP update and the Seattle experience.

It is now possible to access more than one million HLA-A, B typed volunteer individuals willing to donate marrow and a preliminary search through the NMDP registry provides access to more than 200,000 HLA-A, B, DR typed donors. Fifty-four percent of preliminary searches yield at least one potentially HLA-matched donor but the majority of these successful searches involve patients of Caucasian origin. Substantially greater recruitment must occur among different racial and ethnic groups if minority patients are to have a better chance of finding an HLA match. This can be accomplished by recruiting diverse donors within each regional registry or by expanding worldwide the existing international registry network. Molecular typing and matching for alleles in the HLA-D region improve the precision of donor selection and the timeliness of the donor search process. Although the risk of GVHD in unrelated donor transplants remains higher than in HLA-identical sibling transplant is not as good as HLA-identical sibling transplants, newer methods of supportive care and GVHD control are providing and gradual improvement in both the safety of the procedure and long-term relapse-free survival.