Table 1.

The importance of allele and antigen mismatches on outcome after HLA-mismatched unrelated donor hematopoietic cell transplantation from marrow and peripheral blood stem cell graft sources.^{6 – 11} Low, intermediate and high risk refer to the relative risks associated with mismatching at the locus of interest.

Locus	Marrow Transplant	PBSC Transplant	Risks Associated with Allele versus Antigen Mismatch
HLA-A	High risk6	Intermediate risk7	BM and PBSC: In general, allele mismatches are as risky as antigen mismatches6,7
HLA-B	Intermediate risk6,7	Intermediate risk6,7	BM: In general, allele mismatches are as risky as antigen mismatches6 PBSC: limited numbers7
HLA-C	Intermediate risk6,7 High risk8	High risk6,7	In general, allele mismatches have lower risks than antigen mismatches6,7,8
HLA- DRB1	High risk6		The limited numbers prevent definitive analysis of allele versus antigen.
HLA- DQB1	Low risk6,7	Low risk6,7	Isolated mismatching at HLA-DQB1 is not associated with higher risks.
HLA- DPB1	High risk9–11	High risk9–11	The allele and antigen definitions are not applicable to HLA-DP typing and nomenclature.2

BM, bone marrow

PBSC, peripheral blood stem cells