OBJECTIVETo investigate the role of different immunoglobulin- like receptor (KIR)haplotypes in haplo- identical hematopoietic stem cell transplantation (HSCT).

METHODKiller cell KIR genotyping was performed on 468 individuals from 156 unrelated families by PCR-SSP. A total of 624 KIR haplotypes from the parents were used for haplotype analysis. Ninety-two patients received haplo-identical HSCT from one of the parents.

RESULTSThe family study showed segregation of one A haplotype and at least 20 unique B haplotypes. The frequency of haplotype A was 72.92% (455/624). The most commonly observed haplotypes in group B were B1, B2, and B3, present at a frequency of 10.26%, 5.77%, and 4.48%, respectively. Compared to KIR gene matched donors (n=17), grafts from KIR gene mismatched donors (n= 14) had a positive effect on survival after haplo- identical HSCT for AML/MDS patients (OS: 88.2%vs 42.9%,P=0.015; RFS: 88.2%vs 35.7%,P=0.007). No effect was observed for ALL/NHL patients (OS: 76.0%vs 75.0%,P=0.727; RFS: 68.0%vs 65.0%,P=0.866). A significantly lower survival rate was observed for transplants from AA (n=52) and AB1/AB2 donors (n=15), compared to other group Bx donors (n=25) (OS: 53.3%vs 96.0%,P=0.017; RFS: 53.3%vs 92.0%,P=0.019). Meanwhile, the risk of relapse was much higher in AA group (n=52) compared to Bx group (n=40) (25.0%vs 5.0%,P=0.009). A higher risk of TRM was observed in AB1/AB2 group (P=0.012). In addition, transplant from donors carried Cen-B was associated with an increased survival compared with Cen-A homozygous donors (OS: 94.7%vs 68.5%,P=0.036; RFS: 89.5%vs 64.4%,P=0.045).

CONCLUSIONOverall, KIR genotyping and haplotype analyses should be useful for selection of the most optimal donors with favorable KIR gene grafts. KIR gene mismatch donors should be preferred for AML/MDS patients. Selecting donors carried Cen- B and avoiding the selection of donors of KIR genotype AA/AB1/AB2 was strongly advisable for haplo-identical HSCT.