A study of selected hematopoietic stem cell donors provided by an intermediate size registry.

Objective Planning new hematopoietic stem cell (HSC) donor recruitment strategies requires a sound understanding of the factors underlying donor selection, especially considering HLA-matching criteria. Method A total of 182 consecutive workups of Swiss donors performed from 2014 to 2017 were analyzed for HLA match level, locus disparities, number of potentially 10/10 matched donors in the international database, donor ranking on the lists, donor date of registration, age, ABO, CMV, gender matching, patient genotype frequency, and country performing the search. Results Matching status of the selected donors was 10/10 for 38.5%, 10-12/12 for 35.1%, and 8-9/10 for 26.4% donors, without differences in average donor age in the three categories. HLA-A and -C mismatches were most frequent and -DRB1 very rare. 8.2% patients were matched for HLA-DPB1 (12/12). ABO matching was 46.3%, and CMV matching was 59.1%. Based on "HaploStat"-derived genotype frequencies, 50.3% patients belonged to the "good," 38.5% to the "fair," and 11.2% to the "poor" search prognosis categories. 37.9% of transplants were gender-mismatched, and 42.3% of donors were female. Conclusion HLA typing quality (high resolution, all loci typed), great diversity of haplotypes and donor age are main factors impacting the selection of Swiss donors, while gender and ABO matching seem to be of secondary importance.