Identification of natural killer cell receptor phenotypes associated with leukemia

Natural killer (NK) cells play a key role in defense against tumor cells that have the capacity to downregulate human leukocyte antigen (HLA) class I expression. It has been reported that leukemic cells can have downregulated expression of HLA class I molecules. The polymorphic nature of NK cell receptor (NKR) genes generates diverse repertoires in the human population, which display specificity in the innate immune response. In the present study, 11 KIR and two CD94/NKG2 receptors were genotyped by PCR-SSP in 96 leukemic patients and 148 healthy Caucasians. Here, we report a significant increased frequency of the more inhibitory AB killer cell immunoglobulin-like receptor (KIR) phenotype in leukemic patients compared to the controls (31.1% in healthy controls vs 51.0% in leukemic patients, Pc=0.002), which is related to the high prevalence of the inhibitory KIR2DL2 in this population (Pc=0.007). Moreover, two specific KIR phenotypes AB1 and AB9, including all inhibitory KIRs, were significantly associated with leukemic patients. Our study suggests that an important percentage of leukemic patients express a KIR phenotype in favor of escape from NK cell immunity.