Killer Ig-like Receptor Genes Research Articles

Polymorphisms of Killer Ig-like Receptors and the Risk of Glioblastoma.

The immune responses of natural killer (NK) cells against cancer cells vary by patient. Killer Ig-like receptors (KIRs), which are some of the major receptors involved in regulating NK cell activity for killing cancer cells, have significant genetic variation. Numerous studies have suggested a potential association between the genetic variation of KIR genes and the risk of development or prognosis of various cancer types. However, an association between genetic variations of KIR genes and glioblastoma (GB) remains uncertain. We sought to evaluate the association of genetic variations of KIRs and their ligand genes with the risk of GB development in Koreans. A case-control study was performed to identify the odds ratios (ORs) of KIR genes and Classes A, B, and, C of the human leukocyte antigen (HLA) for GB. The GB group was comprised of 77 patients with newly diagnosed IDH-wildtype GB at our institution, and the control group consisted of 200 healthy Korean volunteers. There was no significant difference in the frequency of KIR genes and KIR haplotypes between the GB and control groups. Genetic variations of KIR-2DL1, 3DL1, and 3DS1 with their ligand genes (HLA-C2, HLA-Bw4/6, and Bw4, respectively) had effects on the risk of GB in Korean patients. The frequency of KIR-2DL1 with HLA-C2 (OR 2.05, CI 1.19-3.52, p = 0.009), the frequency of KIR-3DL1 without HLA-Bw4 (80I) (OR 8.36, CI 4.06-17.18, p < 0.001), and the frequency of KIR-3DL1 with Bw6 (OR 4.54, CI 2.55-8.09, p < 0.001) in the GB group were higher than in the control group. In addition, the frequency of KIR-2DL1 without HLA-C2 (OR 0.44, CI 0.26-0.75, p = 0.003), the frequency of KIR-3DL1 with HLA-Bw4 (80T) (OR 0.13, CI 0.06-0.27, p < 0.001), the frequency of KIR-3DL1 without Bw6 (OR 0.27, CI 0.15-0.49, p < 0.001), and the frequency of KIR-3DS1 with Bw4 (80I) (OR 0.03, CI 0.00-0.50, p < 0.001) in the GB group were lower than in the control group. This study suggests that genetic variations of KIRs and their ligand genes may affect GB development in the Korean population. Further investigations are needed to demonstrate the different immune responses for GB cells according to genetic variations of KIR genes and their ligand genes.

Ascorbic Acid Promotes KIR Demethylation during Early NK Cell Differentiation.

Variegated expression of killer Ig-like receptors (KIR) in human NK cells is a stochastic process exclusive to subsets of mature NK cells and CD8+ T cells. Allele-specific KIR expression is maintained by DNA methylation within the proximal promoter regions. Because KIR genes are densely methylated in NK cell progenitors, there is an implied stage of human NK cell development in which DNA demethylation takes place to allow for active transcription. When and how this process occurs is unknown. In this study, we show that KIR proximal promoters are densely methylated in less mature CD56bright NK cells and are progressively demethylated in CD56dim NK cells as they mature and acquire KIR. We hypothesized that ten-eleven translocation (TET) enzymes, which oxidize 5mC on DNA could mediate KIR promoter demethylation. The catalytic efficiency of TET enzymes is known to be enhanced by ascorbic acid. We found that the addition of ascorbic acid to ex vivo culture of sorted CD56bright NK cells increased the frequency of KIR expression in a dose-dependent manner and facilitated demethylation of proximal promoters. A marked enrichment of the transcription factor Runx3 as well as TET2 and TET3 was observed within proximal KIR promoters in CD56bright NK cells cultured with ascorbic acid. Additionally, overexpression of TET3 and Runx3 promoted KIR expression in CD56bright NK cells and NK-92 cells. Our results show that KIR promoter demethylation can be induced in CD56bright, and this process is facilitated by ascorbic acid.

Protective and causative killer Ig-like receptor (KIR) and metalloproteinase genetic patterns associated with Herpes simplex virus 1 (HSV-1) encephalitis occurrence

BackgroundThe cerebral innate immune system has a critical role in control processes of viral replication in the brain after primary infactivo and immunologic disregulation and inflammation has been reported as a primary determinant of pathogenesis and prognosis of subsequent HSV-1 related encephalitis (HSE). Interaction linking LTR3-activated DCs is also represented by the killer Ig-like receptor (KIR) + pathways on NK cells. Only a few studies analyzed the role of of MMP-9 activity regulating genetic polymorphism on clinical outcome of viral infections. Susceptibility to symptomatic encephalitis depends on SNC viral invasion and BBB disruption. We hypothesize that certain KIR genes and MMP allele may help to characterize a risk profile of developing an acute encephalitis due to HSV 1. Aim of the studyAnalyze the frequency of KIR genes and the C(−1562)T MMP-9 allels in subjects with HSV-1 encephalitis and to analyze their interaction with regard of the risk of occurrence of a symptomatic encephalitis. Materials and methodsBetween November 2014 and January 2019, all consecutive patients with symptomatic acute encephalitis were recruited from three wards (Internal Medicine, Neurology, and Infectious Diseases) of “P. Giaccone” University Hospital, Palermo. ResultsPatients with acute viral encephalitis in comparison to controls showed a higher frequency AA KIR haplotype, HLA-C2 and of HLA-A-Bw4 alleles. With regard of HLA allele frequency patients with acute viral encephalitis In comparison to controls also showed a higher frequency of HLA-C2 and of HLA-A-Bw4 alleles. With regard of MMP-9 alleles, subjects with acute viral encephalitis were more likely to have the TT genotype. The multiple logistic regression analysis considering variables predictive of the occurrence of acute viral encephalitis showed the detrimental effect of AA KIR, HLAC1, HLA-A-BW4 and HLA-B-BW4T and of TT aplotype of MMP-9 genotype. ConclusionsOur study shows that in immunocompetent adult subjects there is an association between some KIR genes, MMP-9 alleles and HLA-ligand alleles and susceptibility to develop a symptomatic acute viral encephalitis. Definition of the genetic and immunological background of acute viral encephalitis can play a key role to determine personalized medicine.

Killer-cell immunoglobulin-like receptor assessment algorithms in haemopoietic progenitor cell transplantation: current perspectives and future opportunities.

Natural killer cells preferentially target and kill malignant and virally infected cells. Both these properties present compelling clinical utility in the field of haemopoietic progenitor cell transplantation (HPCT), potentially promoting a graft vs leukaemia effect in the absence of graft vs host disease and protecting against cytomegalovirus activation. Killer Ig-like receptors (KIR) play a central role in the cytotoxic action of natural killer cells, providing opportunity for improving transplantation outcomes by prioritising potential donors with optimal characteristics. Numerous algorithms for assessing KIR gene content as part of HPCT donor selection protocols exist, but no single model has been found to be universally applicable in all transplant centres. This review summarises several of the predominant strategies in KIR assessment algorithms, discussing their basic scientific principles, clinical utility and benefits to post-transplant outcomes. Finally, the review will consider how future donor selection protocols could develop towards unifying the concepts of KIR proteomics and genetics for optimising patient care.

Killer Immunoglobulin-Like Receptor Profiles Are not Associated with Risk of Amoxicillin-Clavulanate-Induced Liver Injury in Spanish Patients.

Natural killer cells are an integral part of the immune system and represent a large proportion of the lymphocyte population in the liver. The activity of these cells is regulated by various cell surface receptors, such as killer Ig-like receptors (KIR) that bind to human leukocyte antigen (HLA) class I ligands on the target cell. The composition of KIR receptors has been suggested to influence the development of specific diseases, in particularly autoimmune diseases, cancer and reproductive diseases. The role played in idiosyncratic drug-induced liver injury (DILI) is currently unknown. In this study, we examined KIR gene profiles and HLA class I polymorphisms in amoxicillin-clavulanate (AC) DILI patients in search for potential risk associations. One hundred and two AC DILI patients and 226 controls were genotyped for the presence or absence of 16 KIR loci, including the two pseudogenes 2DP1 and 3DP1. No significant differences were found in the distribution of individual KIRs between patients and controls, which were comparable to previously reported KIR data from ethnically similar cohorts. The 21.6 and 21.2% of the patients and controls, respectively, were homozygous haplotype A carriers, while 78.4 and 78.8%, respectively, contained at least one B haplotype (Bx). The genotypes translated into 27 (AC DILI) and 46 (controls) different gene profiles, with 19 being present in both groups. The most frequent Bx gene profile containing KIRs 2DS2, 2DL2, 2DL3, 2DP1, 2DL1, 3DL1, 2DS4, 3DL2, 3DL3, 2DL4, and 3PD1 was present in 16% of the DILI patients and 14% of the controls. The distribution of HLA class I epitopes did not differ significantly between AC DILI patients and controls. The most frequent receptor-ligand combinations in the DILI patients were 2DL3 + epitope C1 (67%) and 3DL1 + Bw4 motif (67%), while 2DL1 + epitope C2 (69%) and 3DL1 + Bw4 motif (69%) predominated in the controls. This is to our knowledge the first analysis of KIR receptor-HLA ligand associations in DILI, although our findings do not support evidence of these genetic variations playing a major role in AC DILI development.

Donor-Recipient Matching for KIR Genotypes Reduces Chronic GVHD and Missing Inhibitory KIR Ligands Protect against Relapse after Myeloablative, HLA Matched Hematopoietic Cell Transplantation

BackgroundAllogeneic hematopoietic cell transplantation (HCT) can be curative for many hematologic diseases. However, complications such as graft-versus-host disease (GVHD) and relapse of primary malignancy remain significant and are the leading causes of morbidity and mortality. Effects of killer Ig-like receptors (KIR)-influenced NK cells on HCT outcomes have been extensively pursued over the last decade. However, the relevance of the reported algorithms on HLA matched myeloablative HCT with rabbit antithymocyte globulin (ATG) is used for GVHD prophylaxis remains elusive. Here we examined the role of KIR and KIR-ligands of donor-recipient pairs in modifying the outcomes of ATG conditioned HLA matched sibling and unrelated donor HCTMethods and FindingsThe study cohort consisted of 281 HLA matched sibling and unrelated donor-recipient pairs of first allogeneic marrow or blood stem cell transplantation allocated into ‘discovery’ (135 pairs) and ‘validation’ (146 pairs) cohorts. High resolution HLA typing was obtained from the medical charts and KIR gene repertoires were obtained by a Luminex® based SSO method. All surviving patients were followed-up for a minimum of two years. KIR and HLA class I distributions of HCT pairs were stratified as per applicable definitions and were tested for their association with cause specific outcomes [acute GVHD grade II-IV (aGVHD), chronic GVHD needing systemic therapy (cGVHD) and relapse] using a multivariate competing risks regression model as well as with survival outcomes [relapse-free survival (RFS), cGVHD & relapse free survival (cGRFS) and overall survival (OS)] by multivariate Cox proportional hazards regression model. A significant association between KIR genotype mismatching (KIR-B/x donor into KIR-AA recipient or vice versa) and cGVHD was found in both discovery (p = 0.001; SHR = 2.78; 95%CI: 1.50–5.17) and validation cohorts (p = 0.005; SHR = 2.61; 95%CI: 1.33–5.11). High incidence of cGVHD associated with KIR genotype mismatching was applicable to both sibling and unrelated donors and was specific to recipients who had one or two C1 bearing HLA-C epitopes (HLA-C1/x, p = 0.001; SHR = 2.40; 95%CI: 1.42–4.06). When compared with KIR genotype mismatched transplants, HLA-C1/x patients receiving grafts from KIR genotype matched donors had a significantly improved cGRFS (p = 0.013; HR = 1.62; 95%CI: 1.11–2.39). Although there was no effect of KIR genotype matching on survival outcomes, a significantly reduced incidence of relapse (p = 0.001; SHR = 0.22; 95%CI: 0.10–0.54) and improved relapse-free survival (p = 0.038; HR = 0.40; 95%CI: 0.17–0.95) was observed with one or more missing ligands for donor inhibitory KIR among the recipients of unrelated donor transplants.ConclusionsThe present study for the first time presents the beneficial effects of KIR genotype matching in reducing cGVHD in myeloablative transplant setting using HLA matched (sibling and unrelated) donors. The findings offer a clinically applicable donor selection strategy that can help control cGVHD without affecting the risk of relapse and/or identify patients at a high risk of developing cGVHD as potential candidates for preemptive therapy. The findings also affirm the beneficial effect of one or more missing inhibitory KIR ligands in the recipient in reducing relapse and improving a relapse free survival in unrelated donor transplants.

Natural Killer (NK) Cells’ Response to Epstein - Barr virus Infections and its Influence on the Risk of Developing Post-transplant Lymphoproliferative Disease (PTLD) after Allogeneic Hematopoietic Cell Transplantation: Effect of Donor Killer Ig-like Receptor Genes and Motifs Copy Numbers

Abstract BACKGROUND Uncontrolled reactivation of Epstein-Barr virus (EBV) leading to post-transplant lymphoproliferative disorder (PTLD) is one of the major complications after T-cell depleted HCT. Recovering within weeks after HCT, natural killer (NK) cells are deemed important in the immunopathogenesis of EBV complications. Their role however remains elusive. NK cell responses are regulated by a series of activating and inhibitory cell surface receptors, central to which are the Killer Ig-like Receptors (KIR). Here we hypothesized and tested whether diverse NK cell receptor repertoires can titrate NK cell functional responses to EBV and can potentially modify the risk of developing PTLD. METHODS KIR genotypes, centromeric and telomeric motifs and their variants were determined for 356 allo-HCT donors through next generation sequencing of KIR locus. PBMNCs from KIR typed healthy volunteers were co-cultured with EBV-transformed cells and degranulation and IFNγ producing NK cells were enumerated using multi-parameter flow cytometry. Effect of donor KIR profile on PTLD was tested using competing risks regression statistics. Segregation of NK cell response to EBV across various KIR repertoires was tested by Mann-Whitney U statistics RESULTS At least one copy of Donor tA01 motifs was required for a strong protection against PTLD (p=0.0001, SHR=0.17). The number of EBV induced NK cells increased with increasing tA01 motifs. There was no influence of recipients’ KIR repertoire on the risk of developing PTLD. CONCLUSIONS KIR-regulated NK cells have a profound effect on the risk of PTLD. KIR gene profile based identification of HCT recipients at high risk of PTLD will enable closer monitoring of EBV DNAemia and facilitate prompt therapy.

Distribution of Killer Cell Immunoglobulin-Like Receptor Genes in Albanians from Republic of Macedonia

AIM: The aim of this study was to analyze Killer Ig-Like Receptor ( KIR ) gene polymorphisms in Albanians from Republic of Macedonia. MATERIAL NA METHODS: The studied sample consists of 104 healthy unrelated individuals, aged 20-45 years. All individuals are of Albanian nationality, residents of different geographical regions (Skopje, Gostivar, and Tetovo) in Republic of Macedonia. The population genetics analysis package, Arlequin, was used for analysis of the data. RESULTS: All 16 KIR genes known were observed in the Albanian individuals and framework genes (KIR3DL3, KIR 3DP1, KIR 2DL4, and KIR3 DL2) were present in all individuals. The frequencies of other KIR genes were: KIR 2DP1 (0.981) , KIR 2DL1 (1), KIR 2DL2 (0.615), KIR 2DL3 (0.865), KIR 2DL5 (0.414), KIR 3DL1 (0.933), KIR 2DS1 (0.462), KIR 2DS2 (0.606), KIR 2DS3 (0.327), KIR2DS4 (0.875) , KIR 2DS5 (0.298), and KIR 3DS1 (0.442). Tested linkage disequilibrium (LD) among KIR genes demonstrated that KIR genes present a wide range of linkage disequilibrium. CONCLUSION: This is the first study analyzing the polymorphism of KIR genes and genotype frequencies in Albanian individuals in the world. The results can be used for anthropological comparisons.

P108 : KIR-HLA LIGAND GENOTYPIC INTERACTION AND SUSCEPTIBILITY TO INFLAMMATORY BOWEL DISEASE

Aim To elucidate the contribution of the Killer Ig-like Receptors (KIR) and their Human Leukocyte Antigen (HLA) ligands to Crohn’s Disease (CD) and Ulcerative Colitis (UC), the clinical subtypes of inflammatory bowel disease (IBD), an immune-mediated disease of the digestive tract. Methods and Cohorts MALDI-TOF mass spectrometry was used to profile the presence/absence of 16 KIR loci. HLA loci were genotyped using reverse format SSO strip, Luminex rSSO and a Roche 454 NGS system developed in our laboratory for complete HLA class I and II genotyping. Protein sequence data corresponding to HLA allelic typing was used to determine KIR ligands: Bw4/6 and C1/C2 epitope groups were assigned using residues at positions 77–83 in HLA-B and -C. Case-control analysis of 1232 Caucasian IBD patients (461 with UC: 277 medically refractory (MR), 184 non-MR; 771 with CD) and 203 Caucasian controls was performed using the chi-square test to compare the distribution of KIR genes KIR2DL2, KIR2DL3 and KIR3DL1, KIR3DS1 and their respective HLA ligands,C1, C2 and Bw4, across various disease phenotypes, including CD, UC and MR-UC disease. Results The homozygous genotypic combination of KIR2DL3, KIR3DL1 (homozygous KIR A/A haplotype) and Bw6 (absence of Bw4) with both C1 and C2 ligands present was shown to be highly significantly protective against ulcerative colitis (OR = 0.29, p Conclusions These data reveal a central role for a specific combination of KIRs and HLA ligands (i.e., homozygous KIR A haplotype, absence of Bw4 and C1/C2 heterozygosity) in protecting against UC disease and underscore the importance of analyzing genotypes of KIR together with their HLA ligands in disease association studies.

Association of Killer Cell Immunoglobulin-Like Receptor Genes with Pandemic Influenza A (H1N1)pdm09 Infection in Critically Ill Macedonian Patients

Background: Infection by the pandemic influenza A (H1N1)pdm09 virus results in significant pathology disease in many cases in different populations worldwide. The natural killer (NK) cells are among the major effectors important in early innate immune responses to viral infections, interacting with host cells through their activating or inhibiting receptors. Aim: The aim of this study was to analyze Killer Ig-Like Receptor ( KIR ) gene polymorphisms in critically ill Macedonian patients with pandemic influenza A (H1N1)pdm09 infection. Material and Methods: The studied sample consists of 63 critically ill Macedonian patients with pandemic influenza A (H1N1)pdm09 infection. The population genetics analysis package, Arlequin, was used for analysis of the data. Results: We found that all 16 KIR genes were observed in the studied individuals and framework genes ( KIR3DL3, KIR3DP1, KIR2DL4, and KIR3DL2 ) were present in all individuals. The results of tested linkage disequilibrium (LD) among KIR genes demonstrated that KIR genes present a wide range of linkage disequilibrium. Comparison of KIR gene frequencies between critically ill H1N1/09 Macedonian patients and healthy subjects reveals statistically significant difference for frequency of KIR2DL1 (F=1 in the patients group, and 0.94 in the control group, p=0.045). Conclusion: We did not found any significant association of all 16 KIR genes or KIR genotypes with critically ill (H1N1)pdm09 Macedonian patients, except for the KIR2DL1 .

Distribution of killer cell immunoglobulin‐like receptor genes in Roma from Republic of Macedonia

The aim of this study was to analyze Killer Ig-Like Receptor (KIR) gene polymorphisms in Roma people from Republic of Macedonia. The studied sample consists of 103 healthy unrelated individuals, aged 20-45 years. All individuals are of Roma origin, residents of different geographical regions (Gostivar, Skopje, and Kochani). The population genetics analysis package, Arlequin, was used for analysis of the data. We found that all 16 KIR genes were observed in the Roma individuals and framework genes (KIR3DL3, KIR3DP1, KIR- 2DL4, and KIR3DL2) were present in all individuals. The frequencies of other KIR genes were: KIR2DP1 (1), KIR2DL1 (0.961), KIR2DL2 (0.544), KIR2DL3 (0.874), KIR2DL5 (0.311), KIR3DL1 (0.990), KIR- 2DS1 (0.330), KIR2DS2 (0.553), KIR2DS3 (0.359), KIR2DS4 (0.981), KIR2DS5 (0.291), and KIR3DS1 (0.379). The results of tested linkage disequilibrium (LD) among KIR genes demonstrated that KIR genes present a wide range of linkage disequilibrium. The obtained results for KIR genes and genotype frequencies in Macedonian Roma individuals can be used for anthropological comparisons.

KIR genes and KIR ligands affect occurrence of acute GVHD after unrelated, 12/12 HLA matched, hematopoietic stem cell transplantation

Interactions of polymorphic killer Ig-like receptor (KIR) receptors with KIR ligands have been shown to modify the outcome of hematopoietic SCT (HSCT). The association of these genetic factors with different transplantation endpoints, however, varies substantially, depending on clinical and study setup variables. We aimed to assess whether KIR ligands, KIR genes and KIR haplotypes are associated with HSCT outcome of 124 patients with various hematological malignancies, transplanted with 12/12 HLA matched grafts from unrelated donors. For this purpose, patient and donor KIR gene and KIR ligand polymorphisms were determined and correlated with clinical data in simple and multiple models. We found that a missing HLA-C2 ligand for donor inhibitory KIR2DL1 was significantly associated with an increased risk of acute GVHD (aGVHD) (II-IV) (hazard ratio (HR)=2.23, 95% confidence interval (95% CI): 1.21-4.10, P=0.010), as were the AA KIR haplotypes in patients and donors in HLA-C1CX (HR=2.37, 95% CI: 1.16-4.84, P=0.018) and in HLA-Bw4(-) (HR=3.20, 95% CI: 1.35-7.60, P=0.008) patients. On the contrary, transplantation of HLA-C1C2 patients with KIR2DS2 positive grafts were associated with a decreased risk of aGVHD (II-IV) (HR=0.24, 95% CI: 0.07-0.85, P=0.027). Thus, our single center study provides evidence for the modification of aGVHD risk by KIRs and their ligands.

Different KIRs Confer Susceptibility and Protection to Adults with Latent Autoimmune Diabetes in Latvian and Asian Indian Populations

KIRs (killer Ig-like receptors) expressed on natural killer (NK) cells are an important component of innate (and adaptive) immunity. They are either activatory or inhibitory, and certain KIRs are known to interact with specific motifs of HLA Class I molecules, which is very crucial in determining whether a cell is targeted to lysis or otherwise. Latent autoimmune diabetes in adults (LADA) is a slowly progressive form of autoimmune diabetes, with an adult onset (>30 years). Because autoantibodies and autoimmunity involved are involved in the etiology of LADA, KIRs might play an important role in conferring susceptibility to or protection against the disease. The purpose of this study was to identify killer immunoglobulin-like receptor (KIR) genes, which are associated with susceptibility to and protection against type 1 diabetes in Latvian and Asian Indian patients with LADA. KIR and HLA-C ligand genotyping was performed using PCR-SSP in LADA patients from Latvia (n= 45) with age- and sex-matched controls (n= 92) and from India (n= 86) with controls (n= 98). Results showed that in Latvian patients with LADA, KIRs 2DL1, 2DS2, and 2DS4 were associated with susceptibility and KIR 2DS5 with protection. In Asian Indian LADA patients, KIRs 2DL5 and 3DL1 were associated with susceptibility and KIRs 2DS1 and 2DS3 with protection. Stratification analyses for KIRs that bind to HLA-C1 and C2 were performed. We concluded that KIRs are important in conferring susceptibility (or protection) to adult patients with LADA in both our study populations. However the KIR genes (and their HLA-C ligands) conferring susceptibility or protection in these two populations differ, showing a role of ethnicity in disease susceptibility.

Differential Impact of Inhibitory and Activating Killer Ig-Like Receptors and HLA Ligand on Outcomes of Transplantation for Myeloid and Lymphoid Malignancies.

Background: NK cell cytotoxicity is modulated by interactions between killer Ig-like receptors (KIR) and their ligands. While previous studies have examined the impact of inhibitory KIR (iKIR) after allogeneic transplantation in patients with myeloid leukemia, the effects in patients with lymphoid malignancies and the impact of activating KIR (aKIR) is poorly studied. The current study examines the differences in outcomes of allogeneic hematopoietic stem cell transplantation (HSCT) between patients with lymphoid and myeloid malignancies with respect to the impact of both aKIR and iKIR.Methods: Thirty four patients with lymphoid malignancies (LM) and 46 patients with myeloid malignancies (MM) transplanted with CD34 selected hematopoietic stem cells from related haploidentical donors following non myeloablative conditioning were studied. KIR genes in the donor and recipient were typed by Luminex-rSSOP. Each patient-donor pair was evaluated fordonor iKIR and lack of corresponding class-I ligand;donor and recipient HLA ligand incompatibility; andpresence or absence of donor and recipient aKIR genes and the effects of these differences on transplant outcomes were studied.Transplant outcomes including overall survival (OS), acute graft versus host disease (aGVHD) and relapse related mortality (RRM) were evaluated by comparison of Kaplan-Meier analysis using log-rank test.Results: LM patients with lymphoma and acute lymphoid leukemia had a median age of 44.1 (range 18–69) yrs and 64.7% had relapsed/refractory disease. Donor-recipient HLA match was 3 or 4 of 6 in 85.1% and 5 to 8 of 10 in 97.1%. MM patients with acute myeloid and chronic myelomonocytic leukemia and myelodysplastic syndrome had a median age of 49.7 (range 21–72) yrs, and 45.7% had relapsed/refractory disease. Donor-recipient HLA match was 3 or 4 of 6 in 84.8% and 5 to 8 of 10 in 80%. In the patients with myeloid malignancies, the OS was significantly higher in patients lacking HLA-C2 ligand to their donor KIR as compared to those expressing HLA C2 ligand (p=0.047). RRM was lower if patients lacked A3/11 ligand against donor KIR (p=0.024). Patients with higher numbers of absent ligands (2 or 3) had significantly lower relapses (p=0.033). However, absent ligand(s) to donor KIR did not influence the incidence of aGvHD. There was no impact of ligand-ligand incompatibility or donor-recipient activating KIR genotype on OS, RRM, or aGVHD. In contrast, in patients with lymphoid malignancies, OS and RRM were similar whether the patients expressed or lacked the ligand to donor KIR genes. Incompatibilities in the ligand-ligand model analyses did not modify OS and RRM. However, OS was better in the presence of activating receptor aKIR 2DS2 (p=0.012) in the donor and the presence of aKIR 2DS1 (p=0.017), 2DS5 (p=0.049) and 3DS1 (p=0.017) in the recipient. In addition, RRM was lower with donor aKIR D-2DS2 (p=0.044).Conclusions: These results suggest that certain missing HLA ligands in patient to donor KIR contribute to graft-versus-leukemia effect without an increase in GVHD in high-risk MM patients undergoing non-myeloablative haploidentical related donor transplants. In contrast, patients with LM undergoing similar transplants are not impacted by missing HLA ligand in patient to donor KIR or ligand to ligand incompatibility. Importantly, presence of certain activating KIR in the patients and/ or donors impact the OS and RRM in LM patients undergoing these transplants.

Anti-Leukemia Activity of Alloreactive NK Cells in Haploidentical HSCT in Pediatric Patients: Re-Defining the Role of Activating and Inhibitory KIR

T-cell depleted hematopoietic stem cell transplantation from haploidentical donors (haplo-HSCT) has been reported to benefit from the graft-versus-leukemia effect mediated by natural killer (NK) cells when donor displays NK alloreactivity versus the recipient. NK alloreactivity is mediated by NK receptors, namely Killer Ig-like receptors (KIR) which are specific for allotypic determinants that are shared by different HLA-class I alleles (referred to as KIR ligands). It is known that KIR2DL1 recognizes HLA-C alleles characterized by Lys at position 80 (C2 group), KIR2DL2/3 recognize HLA-C alleles characterized by Asn at position 80 (C1 group), KIR3DL1 recognizes HLA-B alleles sharing the Bw4 supertypic specificity (Bw4 group) and KIR3DL2 recognizes HLA-A3 and –A11 alleles. KIR2D/3DL are inhibitory receptors that, upon engagement with the cognate ligand, inhibit lysis. Activating KIRs, highly homologous in the extracellular domain to the inhibitory counterparts, are KIR2DS1, KIR2DS2 and KIR3DS1, but only KIR2DS1 has been shown to specifically recognize C2 group of alleles expressed on B-EBV cells. We analyzed 21 children with leukemia receiving haplo-HSCT from a relative after a myeloablative conditioning regimen; in all pairs, the expression of a given KIR ligand (HLA class I allele) of the donor was missing in the patient (i.e. KIR ligand-mismatched haplo-HSCT). T-cell depletion was performed through positive selection of CD34+ cells; no pharmacological immune suppression was employed after HSCT. KIR genotype of all donors was evaluated to detect the presence of the various inhibitory and activating KIR genes. Phenotypic analyses were performed on NK cells derived from the donor and the patient at different time points after HSCT. Thanks to the availability of new mAbs able to discriminate between the inhibitory and the activating forms of a certain KIR, we could identify the alloreactive NK cell subset at the population level. These alloreactive NK cells express the KIR specific for the KIR ligand-mismatch (permissive inhibitory KIR) and the activating KIR (if present), while they do not express all inhibitory KIR specific for the patient HLA alleles and NKG2A. Thus, in most instances, we could precisely identify the size of the alloreactive NK cell subset in the donor and in the reconstituted repertoire of the recipient. Functional assays were performed to assess alloreactivity, using appropriate B-EBV cell lines and, if available, patient's leukemia blasts. In some cases, also NK cell clones were extensively studied, for phenotype and receptor involvement in killing activity. We found that, in most transplanted patients, variable proportions of donor-derived alloreactive NK cells displaying anti-leukemia activity were generated and maintained even at late time-points after transplantation. Donor-derived KIR2DL1+ NK cells isolated from the recipient displayed the expected capability of selectively killing C1/C1 target cells, including patient leukemia blasts. Differently, KIR2DL2/3+ NK cells displayed poor alloreactivity against leukemia cells carrying HLA alleles belonging to the C2 specificity. Unexpectedly, this was due to recognition of C2 by KIR2DL2/3, as revealed by receptor blocking experiments and by binding assays of soluble KIR to HLA-C transfectants. Remarkably, however, C2/C2 leukemia blasts were killed by KIR2DL2/3+ (or by NKG2A+) NK cells that co-expressed KIR2DS1. This could be explained by the ability of KIR2DS1 to directly recognize C2 on leukemia cells. A role for the KIR2DS2 activating receptor in leukemia cell lysis could not be established. Taken together, these findings provide new information on NK alloreactivity in haplo-HSCT that may greatly impact on the selection of the optimal donor.

Complete Characterization of Killer Ig-Like Receptor (KIR) Haplotypes in Mauritian Cynomolgus Macaques: Novel Insights into Nonhuman Primate KIR Gene Content and Organization

Killer Ig-like receptors (KIRs) are implicated in protection from multiple pathogens including HIV, human papillomavirus, and malaria. Nonhuman primates such as rhesus and cynomolgus macaques are important models for the study of human pathogens; however, KIR genetics in nonhuman primates are poorly defined. Understanding KIR allelic diversity and genomic organization are essential prerequisites to evaluate NK cell responses in macaques. In this study, we present a complete characterization of KIRs in Mauritian cynomolgus macaques, a geographically isolated population. In this study we demonstrate that only eight KIR haplotypes are present in the entire population and characterize the gene content of each. Using the simplified genetics of this population, we construct a model for macaque KIR genomic organization, defining four putative KIR3DL loci, one KIR3DH, two KIR2DL, and one KIR1D. We further demonstrate that loci defined in Mauritian cynomolgus macaques can be applied to rhesus macaques. The findings from this study fundamentally advance our understanding of KIR genetics in nonhuman primates and establish a foundation from which to study KIR signaling in disease pathogenesis.

Inhibitory KIR–HLA receptor–ligand mismatch in autologous haematopoietic stem cell transplantation for solid tumour and lymphoma

Genes that encode killer Ig-like receptors (KIRs) and their HLA class I ligands segregate independently; thus, some individuals may express an inhibitory KIR gene but not its cognate ligand. We hypothesised that these patients with KIR–HLA receptor–ligand mismatch have a low risk of relapse after an autologous haematopoietic stem cell transplantation (HCT). Sixteen consecutive patients with lymphoma or solid tumour were enrolled onto a prospective study. They received high-dose busulphan and melphalan followed by autologous CD133+ HCT. We found that 8 of the 16 patients experienced disease progression after autologous HCT, including 5 of the 6 patients (83%) with no inhibitory KIR–HLA mismatch and 3 of the 6 patients (50%) with 1 mismatched pair; none of the 4 (0%) patients with 2 mismatched pairs experienced disease progression. Survival analyses showed that inhibitory KIR–HLA mismatch was the only significant prognostic factor (P=0.01). The potential applicability of the receptor–ligand mismatch model to autologous HCTs and to patients with lymphoma or solid tumour is clinically significant because of the prevalence of the HCT procedure.

Identification of bidirectional promoters in the human KIR genes

Although the class I MHC receptors expressed by human and mouse natural killer (NK) cells have distinct molecular origins, they are functional analogues that are expressed in a variegated pattern. The murine Ly49 class I receptors contain bidirectional promoters that have been proposed to control the probabilistic expression of these genes. Whether similar elements are present in the human killer Ig-like receptor (KIR) genes is a fundamental question. A detailed analysis of the 2 kb intergenic region separating the KIR2DL4 gene and the adjacent KIR3DL1 gene revealed that additional promoter elements exist in the human KIR genes. Remarkably, the previously characterized KIR3DL1 proximal promoter possesses bidirectional promoter activity that maps to an 88 bp DNA fragment containing CREB, AML, Sp1 and Ets transcription factor binding sites. Individual KIR genes and alleles possess bidirectional promoters with distinct properties. Analysis of KIR(+)and KIR(-) NK cells and NK precursors indicates that reverse transcripts from the bidirectional promoter are found in cells that lack KIR protein expression, but are not present in mature KIR-expressing NK cells, suggesting that reverse transcription from the proximal promoter blocks gene activation in immature NK and precursor cells.

Cutting Edge: Resistance to HIV-1 Infection among African Female Sex Workers Is Associated with Inhibitory KIR in the Absence of Their HLA Ligands

NK cells are regulated in part by killer Ig-like receptors (KIR) that interact with HLA molecules on potential target cells. KIR and HLA loci are highly polymorphic and certain KIR/HLA combinations were found to protect against HIV disease progression. We show in this study that KIR/HLA interactions also influence resistance to HIV transmission. HIV-exposed but seronegative female sex workers in Abidjan, Côte d'Ivoire, frequently possessed inhibitory KIR genes in the absence of their cognate HLA genes: KIR2DL2/KIR2DL3 heterozygosity in the absence of HLA-C1 and KIR3DL1 homozygosity in the absence of HLA-Bw4. HIV-seropositive female sex workers were characterized by corresponding inhibitory KIR/HLA pairings: KIR2DL3 homozygosity together with HLA-C1 and a trend toward KIR3DL1/HLA-Bw4 homozygosity. Absence of ligands for inhibitory KIR could lower the threshold for NK cell activation. In addition, exposed seronegatives more frequently possessed AB KIR genotypes, which contain more activating KIR. The data support an important role for NK cells and KIR/HLA interactions in antiviral immunity.

Predominance of the Group A Killer Ig‐Like Receptor Haplotypes in Korean Patients With T1D

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease in which pancreatic beta cells are selectively destroyed. Although autoimmune diseases are driven by inappropriate adaptive immunity, innate immunity may play a role in the development of T1D. To study the potential involvement of innate immunity in the pathogenesis of autoimmune disease, we investigated associations of the genes for 14 different killer Ig-like receptors (KIRs), the well-characterized receptors in natural killer cells, with Korean T1D patients. Genetic association analyses revealed that some of the KIR genes were associated with T1D. KIR2DL5 and 2DS2 genes were present at significantly low frequency in Korean T1D patients (P < 10(-4)). We did not detect any influence of ligand distribution on KIR association. With the haplotype assignments, 53% of the KIR haplotypes in the control are of type A. Compared with the control (P < 10(-3)) and autoantibody-negative patients (P < 10(-2)), the group A haplotype predominates in Korean patients with T1D. The KIR gene is associated with T1D and distribution differences between T1D and controls were not influenced by the HLA genes (DR-DQ-A-C). T1D, at least in Koreans, is associated with KIR genes, especially in the group A KIR haplotypes. There is a close relationship between innate and adaptive immunity.