Killer Ig-like receptor (KIR) compatibility plays a role in the prevalence of acute GVHD in unrelated hematopoietic cell transplants for AML

Killer Ig-like receptor (KIR) is a major cluster of the natural killer cell receptors and may play a role in the outcome of hematopoietic cell transplants. A total of 65 AML cases transplanted with T-replete hematopoietic cells from unrelated donors were retrospectively KIR-genotyped by a multiplex PCR method of our own design. The KIR gene frequency and genotype patterns in these 130 samples were consistent with the data in the literature. Based upon overall inhibitory and activating KIR genes in both donors and patients, we developed an algorithm to calculate a compatibility score for each transplant case as plus, zero or minus. Significantly higher incidence (18/20, 90%) of acute (a) GVHD (grade II–IV) was found in the transplant cases with plus scores than that (25/45, 56%) in the cases with zero or minus scores (P<0.01). When the scores are sorted in the opposite way, fewer cases (13/26, 50%) of aGVHD were found in the transplants with minus scores than that (30/39, 77%) in the transplants with zero or plus scores (P<0.05). The difference of aGVHD prevalence between the plus score and minus score groups is highly significant (P<0.01). KIR genotype compatibility calculated by this algorithm may predict aGVHD incidence and be helpful in choosing donors.