Donor Killer Cell Immunoglobulin-like Receptor Research Articles

Natural killer cell HLA‐C epitopes and killer cell immunoglobulin‐like receptors both influence outcome of mismatched unrelated donor bone marrow transplants

Matching of donor and recipient for the class I human leukocyte antigen-C (HLA-C)-encoded natural killer (NK) epitopes has been reported to influence stem-cell (SC) graft outcome, but a consistent picture has not yet emerged. We have analyzed transplant outcome in 104 unrelated SC grafts in relation to NK epitope (C1 and C2) matching and donor killer cell immunoglobulin-like receptor (KIR) genotype. NK epitope mismatching in the rejection direction was strongly associated with an increased probability of rejection subsequent to engraftment. The prevalence of grades III-IV acute graft-vs-host disease (GVHD) was significantly higher and occurred significantly earlier when there was NK epitope mismatching in the GVH direction. Higher transplant-related mortality and lower disease-free survival rates were associated with epitope mismatching regardless of the mismatch direction. A greater number of KIR receptors, both activating and inhibitory, in the donor protected against grades III-IV GVHD and improved survival.

Relevance of KIR gene polymorphisms in bone marrow transplantation outcome

Natural Killer (NK) cells may be involved both in allogeneic bone marrow transplantation (BMT) rejection and graft-versus-host disease (GVHD). The physiologic functions of NK cells appear to be regulated by diverse non-inhibitory and inhibitory receptors including the killer cell immunoglobulin-like receptors (KIR). Although human leukocyte antigen (HLA) epitope mismatches are well-known causes of NK alloreactivity, the role of KIR genes in transplantation remains to be further investigated. In this study, we have evaluated whether KIR genotype differences between donors and recipients of HLA identical (related and unrelated) compared with HLA non-identical unrelated BMT, had an impact on transplantation outcome. Our results show that 5 of 15 KIR genes were always identical in donors and recipients and most variations were observed in the number and specificity of noninhibitory KIR genes. Based on the presence or absence of particular KIR genes, 70 different genotypes were obtained from all individuals. According to the donor or recipient KIR genotype, different combination patterns were described. Interestingly, when the recipient KIR genotype was “included” in the donor KIR genotype, 100% (11/11 pairs) of unrelated BMT developed GVHD compared with 60% (18/30) in all other combinations (p = 0.012). In contrast, no GVHD was observed in related BMT when the recipient KIR genotype was “included” in the donor KIR genotype (p = 0.0001). In conclusion, our results reveal a great diversity for KIR genotypes in donors and recipients of BMT and that the risk of GVHD was maximum in unrelated BMT when the recipient KIR genotype was “included” in the donor KIR genotype.