Killer Cell Immunoglobulin-like Receptors Repertoire Research Articles

The KIR repertoire of a West African chimpanzee population is characterized by limited gene, allele, and haplotype variation.

The killer cell immunoglobulin-like receptors (KIR) play a pivotal role in modulating the NK cell responses, for instance, through interaction with major histocompatibility complex (MHC) class I molecules. Both gene systems map to different chromosomes but co-evolved during evolution. The human KIR gene family is characterized by abundant allelic polymorphism and copy number variation. In contrast, our knowledge of the KIR repertoire in chimpanzees is limited to 39 reported alleles, with no available population data. Only three genomic KIR region configurations have been mapped, and seventeen additional ones were deduced by genotyping. Previously, we documented that the chimpanzee MHC class I repertoire has been skewed due to an ancient selective sweep. To understand the depth of the sweep, we set out to determine the full-length KIR transcriptome - in our MHC characterized pedigreed West African chimpanzee cohort - using SMRT sequencing (PacBio). In addition, the genomic organization of 14 KIR haplotypes was characterized by applying a Cas9-mediated enrichment approach in concert with long-read sequencing by Oxford Nanopore Technologies. In the cohort, we discovered 35 undescribed and 15 already recorded Patr-KIR alleles, and a novel hybrid KIR gene. Some KIR transcripts are subject to evolutionary conserved alternative splicing events. A detailed insight on the KIR region dynamics (location and order of genes) was obtained, however, only five new KIR region configurations were detected. The population data allowed to investigate the distribution of the MHC-C1 and C2-epitope specificity of the inhibitory lineage III KIR repertoire, and appears to be skewed towards C2. Although the KIR region is known to evolve fast, as observed in other primate species, our overall conclusion is that the genomic architecture and repertoire in West African chimpanzees exhibit only limited to moderate levels of variation. Hence, the ancient selective sweep that affected the chimpanzee MHC class I region may also have impacted the KIR system.

KIR genotype and haplotype repertoire in Kuwaiti healthy donors, hematopoietic cell transplant recipients and healthy family members.

The gene complex located on chromosome 19q13.4 encodes the Killer-cell Immunoglobulin-like Receptors (KIRs), which exhibit remarkable polymorphism in both gene content and sequences. Further, the repertoire of KIR genes varies within and between populations, creating a diverse pool of KIR genotypes. This study was carried out to characterize KIR genotypes and haplotypes among 379 Arab Kuwaiti individuals including 60 subjects from 20 trio families, 49 hematopoietic cell transplantation (HCT) recipients and 270 healthy Kuwaiti volunteer HCT donors. KIR Genotyping was performed by a combination of reverse sequence specific oligonucleotide probes (rSSO) and/or Real Time PCR. The frequencies of KIR genes in 270 healthy Kuwaiti volunteer donors were compared to previously reported frequencies in other populations. In addition, we compared the differences in KIR repertoire of patients and healthy donors to investigate the reproducibility of previously reported significant differences between patients with hematological malignancies and healthy donors. The observed frequencies in our cohort volunteer HCT donors was comparable to those reported in neighboring Arab populations. The activating genes KIR2DS1, KIR2DS5 and KIR3DS1 and the inhibitory gene KIR2DL5 were significantly more frequent in patients compared to healthy donors, however, none of the previously reported differences were reproducible in our Kuwaiti cohort. This report is the first description of KIR gene carrier frequency and haplotype characterization in a fairly large cohort of the Kuwaiti population, which may have implications in KIR based HCT donor selection strategies.

Recurrent Abortion and the Involvement of Killer-Cell Immunoglobulin-like Receptor (KIR) Genes, Activated T Cells, NK Abnormalities, and Cytokine Profiles

Immune tolerance at the feto-maternal interface is crucial for the growth of the semi-allograft fetus in the womb. The outcome of pregnancy is dependent on a fine balance between various immunological forces. For a long time, the potential role of the immune system in pregnancy disorders has remained enigmatic. Current evidence has revealed that natural killer (NK) cells are the predominant immune cell population in the uterine decidua. NK cells cooperate with T-cells to provide an optimal microenvironment for the growth of the developing fetus by producing cytokines, chemokines, and angiogenic factors. These factors support trophoblast migration and angiogenesis which regulates the process of placentation. NK cells differentiate between "self" and "non-self" through their surface receptors known as killer-cell immunoglobulin-like receptors (KIRs). They induce immune tolerance through communication via their KIR and fetal human leucocyte antigens (HLA). KIRs are surface receptors of NKs that comprise both activating and inhibiting receptors. Due to the wide diversity manifested by its genes, the KIR repertoire is different in each individual. Significant evidence has implicated KIRs in recurrent spontaneous abortion (RSA); however, maternal KIR gene diversity in RSA is still unclear. Research has shown that immunological aberrancies including activating KIRs, NK abnormalities, and T cell downregulation are risk factors for RSA. In this review, we discuss relevant data from experimental studies on NK cell abnormalities, KIR, and T-cells in the incidence of recurrent spontaneous abortion.

Killer Cell Immunoglobulin-like Receptor Profile in Acute Myeloid Leukemia with Heterogenous Cytogenetic Abnormalities and Its Association with Clinical Outcome

Introduction: Acute myeloid leukemia (AML) is associated with heterogeneous cytogenetic abnormalities which contributes towards biology and prognosis of the disease. Natural killer (NK) cells are the first line of defense against tumor cells. NK cells interact with AML cells via multiple receptors including killer cell immunoglobulin-like receptor (KIR). Evidence of susceptibility of AML cells to NK cells in the context of KIR-ligand mismatch NK immunotherapy has suggested a role of KIR repertoire in the development and clinical outcome of AML. The aim of this study is to determine the KIR profile of AML patients with different cytogenetic abnormalities and to evaluate its association with clinical outcome. Methods: Peripheral blood was collected from patients diagnosed with AML after informed consent in accordance with Declaration of Helsinki and approved from Ethical Review Board of Aga Khan University. Peripheral blood mononuclear cells were isolated and subjected to genomic DNA extraction. KIR genotyping was performed by polymerase chain reaction using sequence-specific primers (Vilches et al, Tissue Antigens 2007). Relationship between KIR loci in AML and healthy individuals was compared using chi-square test. Statistical analysis was performed using SPSS statistics (version 26) and a p value of <0.05 was considered statistically significant. Results: KIR genotyping was performed on 35 cases of AML with mean age of 39 years (range:16-58). Number of male and female patients was 25 and 10 respectively. We found 3 (8.57%) patients with AA KIR haplotype while 33 (91.42%) patients showed Bx haplotype (Figure 1). All the patients with AA haplotype harbored t(15;17) (q22; q21) which has a favorable prognosis while patients with Bx KIR haplotype showed cytogenetic abnormalities with favorable, intermediate, and adverse prognosis. The B-content score of patients with Bx KIR haplotype (n=32) was scored from 1 to 4 based on the total sum of B loci (Cooley et al, Blood 2010). We found that majority of cases had a B-content score of 2 (53.12%) while 7 (21.87%), 6(18.75%) and 2 (6.25%) patients had a score of 1, 3 and 4 respectively. Cytogenetic profile associated with favorable, intermediate, and adverse prognostic risk was found in all groups of patients irrespective of B-content score (Table 1). A standard induction treatment was given to 26 patients with Bx KIR haplotype. Around 67% of patients with B-content score of 1 to 3 showed complete remission (CR) while 100% of patients with B-content score of 4 showed CR after first induction chemotherapy. Estimated KIR gene frequency (gf) in these AML patients was compared with 78 normal individuals recruited from Aga Khan University in Karachi (Norman et al, Gene and Immunity 2002). We found no difference in gf of KIR locus 2DL3 (0.55 vs 0.70), 3DL1 (0.75 vs 0.56), 2DL2 (0.52 vs 0.42), 2DL5 (0.42 vs 0.53), 2DS1 (0.44 vs 0.31), 2DS2 (0.42 vs 0.31),2DS5 (0.28 vs 0.28) and 3DS1 (0.28 vs 0.34) in AML cases vs normal individuals. However, we found significant difference in gene frequency of KIR2DL1 (0.42 vs 0.68) [p=0.002], 2DS4 (0.75 vs 0.47) [p=0.007] and 2DS3 (0.07 vs 0.26) [p=0.002] in AML cases compared to healthy individuals. Conclusion: We found that the majority of patients diagnosed with AML harboring heterogenous cytogenetic abnormalities exhibit a Bx KIR haplotype with B-content score of 2. We did not find any specific cytogenetic abnormality to be associated with a particular B-content score. As we look at our data closely, it seems that it is the cytogenetic abnormality and not the B-content score that dictates the outcome after first induction chemotherapy. We found that patients with AML have decrease in gene frequency of 2DL1 (inhibitory KIR) and 2DS3 (activating KIR) while an increase in gene frequency of 2DS4 (activating KIR) compared to healthy individuals. Further studies are required to determine if variable gene frequency of these 3 KIR loci contributes towards the development of AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Host KIR/HLA-C Genotypes Determine HIV-Mediated Changes of the NK Cell Repertoire and Are Associated With Vpu Sequence Variations Impacting Downmodulation of HLA-C.

NK cells play a pivotal role in viral immunity, utilizing a large array of activating and inhibitory receptors to identify and eliminate virus-infected cells. Killer-cell immunoglobulin-like receptors (KIRs) represent a highly polymorphic receptor family, regulating NK cell activity and determining the ability to recognize target cells. Human leukocyte antigen (HLA) class I molecules serve as the primary ligand for KIRs. Herein, HLA-C stands out as being the dominant ligand for the majority of KIRs. Accumulating evidence indicated that interactions between HLA-C and its inhibitory KIR2DL receptors (KIR2DL1/L2/L3) can drive HIV-1-mediated immune evasion and thus may contribute to the intrinsic control of HIV-1 infection. Of particular interest in this context is the recent observation that HIV-1 is able to adapt to host HLA-C genotypes through Vpu-mediated downmodulation of HLA-C. However, our understanding of the complex interplay between KIR/HLA immunogenetics, NK cell-mediated immune pressure and HIV-1 immune escape is still limited. Therefore, we investigated the impact of specific KIR/HLA-C combinations on the NK cell receptor repertoire and HIV-1 Vpu protein sequence variations of 122 viremic, untreated HIV-1+ individuals. Compared to 60 HIV-1- controls, HIV-1 infection was associated with significant changes within the NK cell receptor repertoire, including reduced percentages of NK cells expressing NKG2A, CD8, and KIR2DS4. In contrast, the NKG2C+ and KIR3DL2+ NK cell sub-populations from HIV-1+ individuals was enlarged compared to HIV-1- controls. Stratification along KIR/HLA-C genotypes revealed a genotype-dependent expansion of KIR2DL1+ NK cells that was ultimately associated with increased binding affinities between KIR2DL1 and HLA-C allotypes. Lastly, our data hinted to a preferential selection of Vpu sequence variants that were associated with HLA-C downmodulation in individuals with high KIR2DL/HLA-C binding affinities. Altogether, our study provides evidence that HIV-1-associated changes in the KIR repertoire of NK cells are to some extent predetermined by host KIR2DL/HLA-C genotypes. Furthermore, analysis of Vpu sequence polymorphisms indicates that differential KIR2DL/HLA-C binding affinities may serve as an additional mechanism how host genetics impact immune evasion by HIV-1.

Donor NK and T Cells in the Periphery of Lung Transplant Recipients Contain High Frequencies of Killer Cell Immunoglobulin-Like Receptor-Positive Subsets

IntroductionFor end-stage lung diseases, double lung transplantation (DLTx) is the ultimate curative treatment option. However, acute and chronic rejection and chronic dysfunction are major limitations in thoracic transplantation medicine. Thus, a better understanding of the contribution of immune responses early after DLTx is urgently needed. Passenger cells, derived from donor lungs and migrating into the recipient periphery, are comprised primarily by NK and T cells. Here, we aimed at characterizing the expression of killer cell immunoglobulin-like receptors (KIR) on donor and recipient NK and T cells in recipient blood after DLTx. Furthermore, we investigated the functional status and capacity of donor vs. recipient NK cells.MethodsPeripheral blood samples of 51 DLTx recipients were analyzed pre Tx and at T0, T24 and 3wk post Tx for the presence of HLA-mismatched donor NK and T cells, their KIR repertoire as well as activation status using flow cytometry.ResultsWithin the first 3 weeks after DLTx, donor NK and T cells were detected in all patients with a peak at T0. An increase of the KIR2DL/S1-positive subset was found within the donor NK cell repertoire. Moreover, donor NK cells showed significantly higher frequencies of KIR2DL/S1-positive cells (p<0.01) 3wk post DLTx compared to recipient NK cells. This effect was also observed in donor KIR+ T cells 3wk after DLTx with higher proportions of KIR2DL/S1 (p<0.05) and KIR3DL/S1 (p<0.01) positive T cells. Higher activation levels of donor NK and T cells (p<0.001) were detected compared to recipient cells via CD25 expression as well as a higher degranulation capacity upon activation by K562 target cells.ConclusionHigher frequencies of donor NK and T cells expressing KIR compared to recipient NK and T cells argue for their origin in the lung as a part of a highly specialized immunocompetent compartment. Despite KIR expression, higher activation levels of donor NK and T cells in the periphery of recipients suggest their pre-activation during the ex situ phase. Taken together, donor NK and T cells are likely to have a regulatory effect in the balance between tolerance and rejection and, hence, graft survival after DLTx.

Individualized genetic makeup that controls natural killer cell function influences the efficacy of isatuximab immunotherapy in patients with multiple myeloma

BackgroundPhase IIb clinical trial with isatuximab (Isa)-lenalidomide (Len)-dexamethasone (Dex) showed an improved progression-free survival (PFS) in patients with relapsed or refractory multiple myeloma (RRMM), but the efficacy varied by patient....

Regulation of KIR3DL3 Expression via Mirna.

Killer-cell immunoglobulin-like receptor (KIR) 3DL3 is a framework gene present in all human KIR haplotypes. Although the structure of KIR3DL3 is suggestive of an inhibitory receptor, the function of KIR3DL3 has not been demonstrated and cognate ligands have not been identified. KIR3DL3 has been shown to be constitutively expressed at a low RNA level in peripheral blood mononuclear cell (PBMC) and decidual natural kill (NK) cells, but cell surface expression of KIR3DL3 cannot be detected. Accordingly, post-transcriptional regulation of KIR3DL3 should exist. Using bioinformatics analysis, we identified three candidate micro ribonucleic acids (miRNAs; miR-26a-5p, -26b-5p and -185-5p) that potentially regulate KIR3DL3 expression. Luciferase reporter assays utilizing constructs with mutated miRNA-binding sites of miR-26a-5p, -26b-5p and -185-5p in the 3’-untranslated region (3’ UTR) of KIR3DL3 resulted in up-regulation of luciferase activity demonstrating a potential mechanism of gene regulation. Furthermore, knockdown of the same endogenous miRNAs using silencing ribonucleic acid (siRNA) led to induced surface expression of KIR3DL3. In conclusion, we provide a novel mechanism of functional regulation of KIR3DL3 via miRNAs. These findings are relevant in understanding the generation of KIR repertoire and NK cell clonality.

Comprehensive Flow-Cytometry-Based Immunophenotyping Analysis for Accurate Diagnosis and Management of Extranodal NK/T Cell Lymphoma, Nasal Type.

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL-N) is an aggressive lymphoma typically diagnosed by examining small biopsy specimens. Flow cytometry is very valuable for the diagnosis and classification of several kinds of hematolymphoid neoplasms but has not been widely used for diagnosing ENKTL-N. We systematically investigated the flow cytometry characteristics of 26 solid tissue biopsy specimens of ENKTL-N at initial diagnosis and compared the results with those from reactive NK-cells in the nasal/nasopharyngeal region and peripheral blood. Our study revealed seven flow cytometry (FCM)-based characteristics for distinguishing between the neoplastic cells and reactive NK-cells, including (1) the proportion of NK-cells among total lymphocytes >10%; (2) forward scatter >105 ; (3) mean fluorescence intensity of CD56 > 5,000; (4) aberrant antigen expression or loss; (5) skewed killer cell immunoglobulin-like receptor repertoire; (6) homogenously positive for CD38; and (7) positive for CD30 or CD336. FCM-based immunophenotyping is a potentially feasible and convenient approach for discriminating cellular lineages, evaluating the activation status of NK-cells, and selecting potential therapy targets of ENKTL-N. Flow cytometry is very valuable for facilitating routine diagnosis, confirming clonality, predicting the cellular lineage, and guiding individual treatment for ENKTL-N. © 2019 International Clinical Cytometry Society.

NK cell development in a human stem cell niche: KIR expression occurs independently of the presence of HLA class I ligands

AbstractThe development of mature natural killer (NK) cells expressing killer cell immunoglobulin-like receptors (KIRs) depends on cell contact–dependent signals from nonhematopoietic cells. So far, detailed studies of this process have been hampered by the lack of an appropriate in vitro model. Here, human bone marrow–derived mesenchymal stem cells (MSCs), generated under good manufacturing practice (GMP) conditions, are established as a supportive niche for in vitro NK cell differentiation. In the presence of MSCs, cord blood and bone marrow–derived hematopoietic stem and progenitor cells (HSPCs) effectively and reproducibly differentiated into mature KIR-expressing NK cells. Notably, the novel in vitro differentiation assay enabled us to analyze the impact of HLA class I ligands on KIR repertoire development. To this end, a panel of MSC lines divergent for expression of the major KIR ligands C1, C2, and Bw4 was used for NK cell differentiation. The resulting NK cell repertoires were independent of the presence of specific KIR ligands on MSCs and were, in fact, invariably dominated by expression of the C1-specific inhibitory KIR2DL3. Similarly, short hairpin RNA–mediated knockdown of HLA class I ligands on MSCs did not delay or change the course of KIR expression. Our data suggest that the initial acquisition of KIRs during NK cell development is biased toward recognition of C1 ligands, irrespective of the presence of self-ligands. Altogether, the MSC/HSPC model constitutes a novel platform to study NK cell development in a human stem cell niche. Moreover, the system constitutes a promising GMP-compliant platform to develop clinical-grade NK cell products from cord blood HSPCs.

KIR3DS1/HLA-B Bw4-80Ile Genotype Is Correlated with the IFN-α Therapy Response in hepatitis B e antigen-Positive Chronic Hepatitis B.

To date, several on-treatment-level virological and serological indices that may predict the response to interferon alpha (IFN-α) have been reported. However, no effective predictors, such as drug–response genes, that can be detected before administration of anti-hepatitis B virus (HBV) therapy with IFN-α, have been found. In the diverse range of chronic viral infection, genes that affect human immunity play important roles in understanding host and viral co-evolution. Killer-cell immunoglobulin-like receptors (KIRs), which are highly polymorphic at the allele and haplotype levels, participate in the antiviral function of natural killer (NK) cells via fine-tuning inhibition and activation of NK-cell responses that occur when the NK cells interact with human leukocyte antigen (HLA) class I molecules on target cells. For each individual, the pairing of KIR and HLA ligand is genetically determined. To investigate whether a particular KIR and HLA repertoire influences the risk of HBV infection and response to IFN-α treatment for chronic hepatitis B (CHB), we genotyped the KIRs and HLA ligands of 119 hepatitis B e antigen (HBeAg)-positive CHB patients. These patients included 43 patients who achieved sustained response (SR) induced by IFN-α treatment for 48 weeks, 76 patients who achieved no response (NR), and 96 healthy subjects as controls. SR was defined as HBeAg loss with HBV DNA < 2,000 IU/ml and alanine aminotransferase normalization at 24 weeks posttreatment (week 72). In this study, we showed that activating KIR genes were less prevalent in Han Chinese, especially in Han Chinese with CHB, than in Caucasians. Furthermore, the KIR3DS1 gene, in combination with HLA-B Bw4-80Ile, strongly influenced the therapeutic outcomes for CHB patients who were treated with IFN-α. The frequency of the combination of genes encoding KIR3DS1 and HLA-B Bw4-80Ile was higher in patients who had a sustained treatment response than in patients who had NR [35.3 versus 1.3%; odds ratio (OR) = 19.85; P = 0.0008]. Activating KIR3DS1 and HLA-B Bw4-80Ile synergistically predicted SR to IFN-α for HBeAg-positive CHB patients. Genotyping for the KIR3DS1 gene and the HLA-B Bw4-80Ile allele might help physicians choose the optimal candidates for anti-HBV treatment with IFN-α.

Analysis of the Impact of KIR B Haplotype Donors on Outcomes after Haploidentical (HI) and Matched Related (MR) Hematopoietic Stem Cell Transplantation (HSCT)

Introduction:Natural killer (NK) cell alloreactivity has been associated with graft versus leukemia effects in HSCT. These effects are in part mediated through killer cell immunoglobulin-like receptors (KIR) on the surface of NK cells. The absence of inhibition of NK cells via inhibitory KIR in KIR ligand mismatched T-cell depleted HI HSCT, and the use of unrelated donors possessing activating KIR haplotypes (KIR-B) have been associated with improved overall survival (OS) due to relapse protection. Inhibitory KIR ligand mismatch in the setting of T-cell replete HI HSCT has not consistently been shown to be beneficial, and data regarding the impact of using KIR-B donors in T-replete HI and MR HSCT is limited. In this preliminary retrospective review, we compared outcomes between patients with KIR-B donors versus KIR A haplotype (KIR-A) donors after HI and MR HSCT to help inform donor selection.Methods:All patients underwent HSCT on our 2-step approach in which after conditioning, a fixed T cell dose (2 x 108/kg) is administered (step 1), followed 2-3 days later by cyclophosphamide (CY) for bidirectional tolerization. Two days after CY, patients receive a CD 34-selected donor product (step 2). To be included in the analysis, patients had to be alive for at least 1 month post HSCT and be without evidence of graft rejection. Recipients were divided into 2 groups based on whether they were transplanted from a KIR-B (possessing one or more non-framework activating KIR genes) versus a KIR-A donor (genotypically negative for non-framework activating KIR genes). The relationship between the use of a KIR-B donor and the end points of OS, relapse, grades II-IV acute graft versus host disease (GVHD), chronic GVHD and non-relapse mortality (NRM) was examined. Probability of OS was estimated by Kaplan-Meier (KM) method with log-rank analysis and multivariate analyses using Cox proportional hazards. Donor and recipient age and gender, HCT-CI score, Revised Disease Risk Index, presence of any inhibitory KIR ligand mismatch between donor and recipient and CMV reactivation after HSCT were considered as confounding variables. Cumulative incidence functions with competing risk analyses were used to estimate the probabilities of relapse, NRM, acute and chronic GVHD.Results:The study group consisted of 128 consecutive patients with myeloid malignancies (AML=91 MDS=27, CML=1, MPD=9) undergoing HI [n=84] or MR [n=44] HSCT. The median recipient age and follow-up of the study group was 58 (range 19-78) years and 40.6 (range: 1.07-117.27) months respectively. Only 13 (10.2%) patients had grade III or higher acute GVHD and only 7 (5.5%) patients developed severe, chronic GVHD (score of 3) respectively. Seventy-four (58%) and 54 (42%) of recipients had KIR-B versus KIR-A donors respectively. Fifty-five (74.3%) KIR-B donors possessed HLA C1 or C1/2 alleles in the presence of KIR2L2/3/2DS2. On multivariate Cox regression analysis, OS (HR, 0.579; 95% CI, 0.337-0.995; P= 0.048) was significantly higher in patients who received HSCT from KIR-B donors. On competing risk analysis, relapse (HR, 0.756; P=0.403) and NRM (HR, 0.466; P=0.128) were lower in patients who had KIR haplotype B donors though not statistically significant. In contrast, the risk of grades II to IV acute GVHD (with death as a competing event) was higher in patients with KIR-B donors (HR, 1.972; 95% CI, 1.009-3.852; P=0.047). Similarly transplants from KIR-B donors were associated with a higher risk of chronic GVHD (HR, 2.89; P=0.053).Discussion:Our results show that within the context of the 2-step approach, the use of a KIR-B donor is associated with improved OS and an increased risk of acute and chronic GVHD in patients with myeloid neoplasms receiving HI and MR HSCT. While not reaching significance, the results for relapse and NRM suggest that the OS benefit in patients with KIR-B donors was derived from a combination of lower relapse rates and NRM that was not adversely impacted by GVHD which was mostly lower grade in this population. Our findings support the concept of KIR-B donors as more alloreactive than KIR-A donors, specifically those possessing a C1-C1/2/2DL2/3/2DS2 repertoire, the primary type possessed by KIR-B donors in this analysis. The data argues for the continued use of KIR genotyping at our institution and analyses of HSCT outcomes based on donor KIR repertoire and other donor characteristics to optimize donor selection in HI and MR HSCT. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Killer immunoglobulin-like receptor repertoire analysis in a Caucasian Spanish cohort with inflammatory bowel disease.

Immunological molecules are implicated in inflammatory disorders, including inflammatory bowel disease (IBD; Crohn disease [CD] and ulcerative colitis [UC]). Killer cell immunoglobulin-like receptors (KIRs) are also genetically variable proteins involved in immune function. They are expressed by NK cells and certain T lymphocytes, regulate specificity and function by interaction with HLA Class I molecules, may be either inhibitory or activating and are polymorphic both in terms of alleles and haplotype gene content. Genetic associations between activating KIRs and certain autoimmune and inflammatory diseases have been reported; however, a possible association between KIR and IBD remains unclear. The aim of this study was to determine the relationship between KIR repertoire and IBD pathologies in a Spanish cohort. KIR variability was analyzed using PCR-sequence specific oligonucleotide probes (SSOP). Inhibitory KIR2DL5 was found more frequently in UC and IBD patient groups than in healthy controls (P = 0.028 and P = 0.01, respectively), as was activating KIR2DS1 (P = 0.02, Pc > 0.05, UC vs. Controls; P = 0.001, Pc = 0.01, IBD vs Controls; P = 0.01, Pc > 0.05, Controls vs CR), KIR2DS5 (P = 0.0028, Pc = 0.04, Controls vs UC; P = 0.0001, Pc = 0.0017, Controls vs IBD; P = 0.01, Pc > 0.05, Controls vs CD) and KIR3DS1 (P = 0.012, Pc > 0.05, Controls vs IBD). Our data suggest that imbalance between activating and inhibitory KIR may partially explain the different pathogeneses of these IBDs and that there is a hypothetical role for the telomeric B region (which contains both KIR2DS5 and KIR2DS1) in these diseases.

The association between killer-cell immunoglobulin-like receptor (KIR) and KIR ligand genotypes and the likelihood of BK virus replication after kidney transplantation.

BK virus is a common opportunistic post-transplantation viral infection. Although some risk factors have been studied in this context, the contribution of NK cells has not been assessed in detail. In a group of kidney transplant recipients, we studied the association between (i) the likelihood of BK virus replication during the two-year period after kidney transplantation and (ii) the genotypes of the killer cell immunoglobulin-like receptor (KIR) repertoire and their human leukocyte antigen (HLA) ligands. Other clinical factors (such as defective organ recovery and immunosuppressive treatment) were also assessed. BK virus replication was observed in 43 of the 103 recipients (41%). Patients with BK virus replication in the plasma were more likely to display defective organ recovery in the first seven days post-transplantation. BK virus replication was not associated with Missing KIR ligands. However, BK virus replication was more frequent in patients with responsive NK cells (i.e. when a ligand for activating KIRs was not homozygous in the recipient and present in the donor). Our results suggest that defective organ recovery and the recipient's activating KIR repertoire may be related (depending on HLA ligands present in the couple recipient / donor) to the reactivation of BK virus replication after kidney transplantation.

Editorial: Role of HLA and KIR in Viral Infections.

Editorial: Role of HLA and KIR in Viral Infections.

KIR genotypic diversity in Portuguese and analysis of KIR gene allocation after allogeneic hematopoietic stem cell transplantation.

The diversity of killer-cell immunoglobulin-like receptors (KIR) genes was evaluated in Portuguese and the observed genotypic profiles were found related to the ones reported in European populations. The KIR repertoire after hematopoietic stem cell transplantation is determined by these gene frequencies and the KIR group B motifs are the less common. We estimated donor-KIR/recipient-ligand interactions in transplants with related donors and unrelated donors found in a local registry or from abroad. A large fraction of transplants had all three ligands of inhibitory receptors, and therefore, in theory were not prone to natural killer cell (NK) mediated alloreactivity. Furthermore, the distribution of KIR alloreactive interactions was found independent of the donor-recipient genetic proximity, probably because of different gene segregation and comparable KIR frequencies in the donor pools.

KIR-HLA profiling shows presence of higher frequencies of strong inhibitory KIR-ligands among prognostically poor risk AML patients.

The expression and interaction between killer cell immunoglobulin-like receptors (KIRs) and HLA are known to be associated with pathogenesis of diseases, including hematological malignancies. Presence of B haplotype KIR in donors is associated with a lower relapse risk for acute myeloid leukemia (AML) after hematopoietic stem cell transplants (HSCT). However, the association of KIR and HLA repertoire with disease development and other clinical features is not well studied for AML. In this study, 206 Chinese patients with AML were analyzed for their FAB subtypes, risk groups, and chemo-responsiveness to assess possible association with their KIR and HLA profile. The results revealed that a B-content score of 2 was significantly more prevalent in AML patients when compared to normal controls. Notably, there is also a differential frequency in the distribution of B haplotype KIR across distinct FAB subtypes, where the M3 subtype had significantly lower frequencies of B haplotype KIR compared to the M5 subtype (p < 0.05). In addition, the stronger inhibitory KIR ligands HLA-C2 and HLA-Bw4-80I were present in significantly higher frequencies in the prognostically "poor" risk group compared to those with "favourable" risk (p < 0.01). Taken together, these associations with clinical features of AML suggest a role of the KIR-HLA repertoire in the development and biological behavior of AML.

Polyclonal Expansion of NKG2C(+) NK Cells in TAP-Deficient Patients.

Adaptive natural killer (NK) cell responses to human cytomegalovirus infection are characterized by the expansion of NKG2C+ NK cells expressing self-specific inhibitory killer-cell immunoglobulin-like receptors (KIRs). Here, we set out to study the HLA class I dependency of such NKG2C+ NK cell expansions. We demonstrate the expansion of NKG2C+ NK cells in patients with transporter associated with antigen presentation (TAP) deficiency, who express less than 10% of normal HLA class I levels. In contrast to normal individuals, expanded NKG2C+ NK cell populations in TAP-deficient patients display a polyclonal KIR profile and remain hyporesponsive to HLA class I-negative target cells. Nonetheless, agonistic stimulation of NKG2C on NK cells from TAP-deficient patients yielded significant responses in terms of degranulation and cytokine production. Thus, while interactions with self-HLA class I molecules likely shape the KIR repertoire of expanding NKG2C+ NK cells during adaptive NK cell responses in normal individuals, they are not a prerequisite for NKG2C+ NK cell expansions to occur. The emergence of NKG2C-responsive adaptive NK cells in TAP-deficient patients may contribute to antiviral immunity and potentially explain these patients’ low incidence of severe viral infections.

P053 : DISTRIBUTION OF KIR HLA LIGANDS IN TRANSPLANT PATIENTS AND THEIR CORD BLOOD UNIT (CBU) DONORS

Aim Killer cell immunoglobulin-like receptor (KIR) genes are receptors expressed on the surface of natural killer cells. KIR genes recognize polymorphic epitopes of HLA class I-A, B & C, called KIR HLA ligands (HLA-L). After binding specific ligands the KIR may transmit inhibitory or activating signals. NKC sense & kill target cells missing MHC class I molecules. Studies showed that hematopoietic stem cells (HSC) transplant patients may benefit from NK alloreactivity of the donor or HLA-C alleles (C1/x) of the recipients. Previously we reported the diversification of KIR HLA-L in CBU from MD Anderson Cord Bank. The goal of this study was to further explore the frequency (Freq) of HLA-L in selected CBU from the bank and their transplant recipients aimed at providing information for finding the best donor and improving graft outcome. Methods 640 CBU selected from MD Anderson Cord Bank and 589 recipients were included. HLA typing of class I & II loci were obtained using PCR/probe based methods & sequence-based typing as needed. Freq of Bw4, C1, and C2 group of HLA-C alleles were examined. Results KIR3DL1 recognizes allotypes with HLA-Bw4 motif; KIR2DL1 recognizes HLA-C epitope with lysine at codon 80 (group 2-C2); while KIR2DL2 and KIR2DL3 recognize C alleles with asparagine at residue 80 (group 1-C1). Among the 640 CBU and 589 recipients, 70.0% and 72.0%, respectively, carry Bw4 bearing phenotypes. HLA-C1 bearing phenotypes (C1/x) were found to be predominated in both CBU (85.2%) and their transplant recipients(81.5%). Missing HLA-C1 was lower (C2/C2, 18.5%) than missing C2 (C1/C1, 33.1%) in recipients (Table 1). Conclusion Here we show that CBU can be classified based on their KIR repertoire (licensed versus unlicensed) and the presence of KIR-ligand mismatch with the recipient. Analysis of graft outcome in these HSC transplant recipients is underway. The ultimate goal of our study is to develop algorithms based on the KIR profile of CB units to select the units with maximum antileukemic activity to improve the outcome of CBU transplant.

Activating KIRs in Chronic Lymphoproliferative Disorder of NK Cells: Protection from Viruses and Disease Induction?

Human natural killer (NK) cells are functionally regulated by killer cell immunoglobulin-like receptors (KIRs) and their interactions with HLA class I molecules. As KIR expression in a given NK cell is stochastically established, KIR repertoire perturbations reflect a dominance of discrete NK-cell subsets as the consequence of adaptation of the NK-cell compartment to exogenous agents, more often represented by virus infection. Although inhibitory interactions between KIR and their cognate HLA class I ligands abrogate effector responses of NK cells, they are also required for the functional education of NK cell. The biology and molecular specificities of the activating KIRs are less well defined, and most interactions with presumed HLA class I ligands are weak. Interestingly, epidemiologic studies link activating KIR genes to resistance against numerous virus infections. Chronic lymphoproliferative disorder of NK cells (CLPD-NK) is an indolent NK cell disease characterized by a persistent increase of circulating NK cells (usually exceeding 500 NK cells/mm3). The mechanism through which NK cells are induced to proliferate during CLPD-NK pathogenesis is still a matter of debate. Accumulating data suggest that exogenous agents, in particular viruses, might play a role. The etiology of CLPD-NK, however, is largely unknown. This is likely due to the fact that not a single, specific agent is responsible for the NK cells proliferation, which perhaps represents the expression of an abnormal processing of different foreign antigens, sharing a chronic inflammatory background. Interestingly, proliferating NK cells are typically characterized by expression of a restricted pattern of KIR, which have been demonstrated to be mostly represented by the activating form. This finding indicates that these receptors may be directly involved in the priming of NK cells proliferation.