Selection of unrelated bone marrow donors by serology, molecular typing and cellular assays

As compared to hematopoietic stem cell transplantation (HSCT) with HLA genotypically identical donors, phenotypically matched unrelated HSCT is associated with lower survival. Serologically undisclosed HLA disparities account for the increased rate of post-transplant complications. With more than 1300 alleles currently identified, high-resolution molecular typing techniques have to be applied to distinguish the extensive degree of allelic polymorphism of the HLA system. Whereas a HLA-ABDR-serologically identical donor can be identified in the International Registry for >90% of the patients, only half of them can benefit of a highly compatible donor if donor selection is based on allele level matching for HLA-A/B/Cw/DRB1/B3/B5/DQB1 loci. During the last 10 years, we identified only approximately 20% of all known HLA alleles in the searches for our mainly Caucasoid patients. Rare alleles (i.e. alleles that represent