The impact of KIR2DS4 alleles and the expression of KIR in the development of acute GVHD after unrelated allogeneic hematopoietic SCT.

The role of killer Ig-like receptors (KIR) in SCT was analyzed. A total of 75 Chinese patients were transplanted with T-depleted hematopoietic stem cells from unrelated donors. Among the 75 donor-recipient pairs, 60 were HLA 10/10 matched and 15 had some mismatches at HLA-C. Transplants from KIR haplotype B/x group donors showed significantly higher overall survival rates compared with those from KIR haplotype A/A donors (relative risk (RR) 3.1 (95% confidence interval (CI) 1.1-8.6), P=0.007). In the haplotype A/A group, a higher risk of acute GVHD (aGVHD) (RR 9.0 (95% CI 1.2-66.9), P=0.01), especially grade III-IV aGVHD (P=0.006), was observed when the donor was homozygous for the full-length expressed KIR2DS4*00101 allele. Real-time PCR showed that a high expression of inhibitory KIR (2DL1 and 3DL1) in the early stages (<90 days) after transplantation correlated with the development of aGVHD (z=2.558, P=0.011). Our findings indicated a significant association of full-length KIR2DS4 or KIR2DL1/3DL1 expression with the occurrence of aGVHD. In aggregate these results suggested that combining KIR and HLA genotyping could help in the selection of transplant donors and improve the outcome of transplantation. Dynamic detection of KIR2DL1/3DL1 expression would be beneficial for prediction of aGVHD after transplantation.