Use of killer cell immunoglobulin-like receptor genes as early markers of hematopoietic chimerism after double-umbilical cord blood transplantation

Abstract

Use of killer cell immunoglobulin-like receptor genes as early markers of hematopoietic chimerism after double-umbilical cord blood transplantationIt has been established that hematopoietic chimerism after double umbilical cord blood transplantation (dUCBT) can predict disease relapse and detect potential engraftment failure.1-3 The use of a precise method to evaluate residual host hematopoiesis is imperative because it has been reported that the risk of relapse is higher in patients with mixed chimerism. 4 Up to now, real-time quantitative polymerase chain reaction (PCR) of single nucleotide polymorphism (SNP) markers remains the best method to accurately assess and quantify chimerism. 5,6 However, this method may be limited by the lack of available in-house SNP discriminant markers between both umbilical cord blood (UCB) units and patients and may not be reliable to assess early chimerism status after dUCBT. In this context, additional approaches are needed. Natural killer (NK) cells are the first population to reconstitute the patient's hematopoietic system following hematopoietic stem cell transplantation, before T lymphocytes, 7 and we previously reported that cord blood NK cells express killer cell immunoglobulin-like receptors (KIR).8 Here, we investigated KIR genes as additional markers for early chimerism assessment after dUCBT. KIR gene content varies between individuals who can exhibit seven to fourteen inhibitory and activating KIR genes, defining multiple KIR genotypes. This broad KIR gene polymorphism should be useful as chimerism markers in the context of dUCBT.In order to determine which UCB unit dominates engraftment, KIR genotyping was performed on 40 patients who underwent dUCBT at Nantes CHU, using a multiplex sequence-specific primer-PCR method 9 on day 90 after dUCBT and was compared to KIR genotyping in patients and in UCB units prior to dUCBT. The presence or absence of each KIR gene among 14 studied in patients, UCB units and recipients led us to determine the identity of cells reconstituting recipient hematopoiesis. As illustrated in Figure 1A, recipient #11 was characterized by the absence of KIR2DL2 and KIR2DS2 genes, which were present in this patient before dUCBT. Interestingly, KIR2DL2 and KIR2DS2 were absent in UCB1, but present in UCB2, highlighting that hematopoietic reconstitution resulted from only one UCB unit (unit 1) in this patient ( Figure 1A). Phenotypic analysis of cord blood KIR + NK cells before dUCBT and recipient KIR + NK cells at day 60 after dUCBT using available anti-KIR monoclonal antibodies 16 allowed discrimination of inhibitory and activating KIR expression between the two UCB units ( Figure 1B) and confirmed KIR genotyping results. In particular, UCB1 NK cells did not express KIR2DS1 and KIR2DL2, unlike NK cells from UCB2. Moreover, KIR3DL1 was only expressed on NK cells from UCB1. We observed that the recipient's KIR + NK cells on day 60 after dUCBT had the same KIR expression profile as NK cells from UCB1, with expression of KIR3DL1 and absence of KIR2DS1 ...

Killer Immunoglobulin-Like Receptor Allele Determination Using Next-Generation Sequencing Technology

“…In the context of HSCT, inclusion of KIR allele typing in addition to HLA typing may provide a better evaluation of HSC donor’s KIR + NK cell repertoire ( 21 , 59 , 60 , 66 , 67 ). An identification of those with the best antileukemic potential will provide a potential tool to determine an early posttransplant hematopoietic chimerism when donor and recipient have identical KIR genotypes ( 68 ) as well as the impact of KIR + NK cell alloreactivity on HSCT outcome ( 69 – 73 ). The functional relevance of typing both KIR and HLA genes at high resolution may help determine their combined effects on outcome of HSCT.…”

Relevance of Polymorphic KIR and HLA Class I Genes in NK-Cell-Based Immunotherapies for Adult Leukemic Patients

“…Recently, a retrospective study performed on a large cohort of AML patients reported that there was no impact of KIR3DL1/2DS1 or a haplotype-motif-based donor selection algorithm on OS and relapse after unrelated HLA matched HSCTs [151]. In line with HSCT protocols, the impact of KIR-L mismatches was investigated in adult patients after dUCBTs [152][153][154][155][156][157][158]. Once again, conflicting data were reported, which were linked either to the competing KIR models used or the heterogeneity of the patients and treatment modalities.…”

New insights on the natural killer cell repertoire from a thorough analysis of cord blood cells

“…When fully HLA-matched related or unrelated donors are unavailable, double umbilical CB transplantation (dUCBT) is an efficient alternative [12,13]. We have recently highlighted the importance of KIR genes in assessing early chimerism status after dUCBT [14]. It has been shown that CB NK cells mature rapidly after UCBT and harbor strong cytotoxic activity against blast cells [15].…”