- Unrelated volunteer donors who are mismatched for more than one HLA-class I alleles or antigens or for one HLA-class I antigen, but matched by high-resolution typing at HLA-DRB1 and -DQB1, OR who are mismatched for one or more HLA-class II alleles or antigens, but matched by high-resolution typing at HLA-A, -B, and -C