- DONOR: The CB graft(s) must be matched at 4-6 HLA-A, B, DR Beta 1 (DRB1) loci with the recipient and therefore may include 0-2 mismatches at the A or B or DRB1 loci; unit selection will be based on cryopreserved nucleated cell dose and intermediate resolution A, B antigen and DRB1 allele typing for determination of HLA-match; while HLA-C antigen/allele level typing is not considered in the matching criteria, if available, it may be used to optimize unit selection