An algorithm for permissiveness of HLA-DPB1 mismatches in HSC donor-recipient pairs. Based on the in vitro data from this study, HLA-DPB1 alleles were divided into 3 groups (1-3) according to their predicted immunogenicity (Table 2). The 3 groups of alleles can be present in 6 different combinations in diploid cells. Numbers indicate the group of the first (before the slash) and the second (after the slash) HLA-DPB1 allele of the donor or of the recipient. Classification of HLA-DPB1 mismatches as permissive or nonpermissive in GvH or in HvG direction is indicated for all possible combinations.