Next-generation sequencing technology a new tool for killer cell immunoglobulin-like receptor allele typing in hematopoietic stem cell transplantation.

Killer cell Immunoglobulin-like Receptor (KIR) genes are a family of genes located together within the leukocyte receptor cluster on human chromosome 19q13.4. To date, 17 KIR genes have been identified including nine inhibitory genes (2DL1/L2/L3/L4/L5A/L5B, 3DL1/L2/L3), six activating genes (2DS1/S2/S3/S4/S5, 3DS1) and two pseudogenes (2DP1, 3DP1) classified into group A (KIR A) and group B (KIR B) haplotypes. The number and the nature of KIR genes vary between the individuals. In addition, these KIR genes are known to be polymorphic at allelic level (907 alleles described in July 2017). KIR genes encode for receptors which are predominantly expressed by Natural Killer (NK) cells. KIR receptors recognize HLA class I molecules and are able to kill residual recipient leukemia cells, and thus reduce the likelihood of relapse. KIR alleles of Hematopoietic Stem Cell (HSC) donor would require to be known (Alicata et al. Eur J Immunol 2016) because the KIR allele polymorphism may affect both the KIR+ NK cell phenotype and function (Gagne et al. Eur J Immunol 2013; Bari R, et al. Sci Rep 2016) as well as HSCT outcome (Boudreau et al. JCO 2017). The introduction of the Next Generation Sequencing (NGS) has overcome current conventional DNA sequencing method limitations, known to be time consuming. Recently, a novel NGS KIR allele typing approach of all KIR genes was developed by our team in Nantes from 30 reference DNAs (Maniangou et al. Front in Immunol 2017). This NGS KIR allele typing approach is simple, fast, reliable, specific and showed a concordance rate of 95% for centromeric and telomeric KIR genes in comparison with high-resolution KIR typing obtained to those published data using exome capture (Norman PJ et al. Am J Hum Genet 2016). This NGS KIR allele typing approach may also be used in reproduction and to better study KIR+ NK cell implication in the control of viral infections.