Killer Immunoglobulin-like Receptors Loci Research Articles

Association of killer cell immunoglobulin-like receptors and their cognate HLA class I ligands with susceptibility to acute myeloid leukemia in Iranian patients

Acute myeloid leukemia (AML) is one of the most prevalent leukemia in adults. Among the various NK receptors, killer immunoglobulin-like receptors (KIRs) carry out indispensable roles in NK cell development and function through engaging with class I human leukocyte antigens (HLA-I) as their ligands. Besides divergent KIR and HLA loci, KIR/HLA-I combinations have a significant effect on NK cell response. In this case–control study, we aimed to verify the association of KIR/HLA-I combinations with susceptibility to AML in the Southwestern Iranian population. KIR and HLA genotyping was performed with PCR-SSP by some novel primers for 181 patients with AML and 181 healthy controls. According to our results, the frequencies of KIR3DS1 (p = 0.0001, OR = 2.32, 95% CI 1.51–3.58), KIR2DS4fl (p = 0.02, OR = 1.53, 95% CI 1.05–2.21), CxT4 genotypes (p = 0.03, OR = 2.0, 95% CI 1.05–3.82), and T4 gene cluster (p = 0.01, OR = 1.99, 95% CI 1.17–3.41) were significantly higher in patients than controls, while C1/C2 genotype (p = 0.00002, OR = 0.39, 95% CI 0.25–0.61), HLA-A Bw4 (p = 0.02, OR = 0.6, 95% CI 0.38–0.94), and HLA-A*11 (p = 0.03, OR = 0.57, 95% CI 0.34–0.95) alleles were more frequent in controls. In addition, inhibitory (i)KIR/HLA-I combinations analysis revealed higher frequencies of KIR2DL1( +)/HLA-C2( +), KIR2DL2/3( +)/HLA-C1( +), KIR3DL1( +)/HLA-A Bw4( +), and KIR3DL2( +)/HLA-A*03/11( +) in the control group (p = 0.002, OR = 0.49, 95% CI 0.3–0.78; p = 0.04, OR = 0.62, 95% CI 0.39–0.99; p = 0.04, OR = 0.63, 95% CI 0.4–0.99; and p = 0.03, OR = 0.62, 95% CI 0.4–0.95, respectively). Overall, the number of iKIR/HLA-I combinations was more in the control group. Moreover, KIR3DS1( +)/HLA-B Bw4Ile80( +) and the sum of HLA-B Bw4/A Bw4 combined with KIR3DS1 as activating KIR/HLA-I combinations were more frequent among patients than controls (p = 0.01, OR = 1.99, 95% CI 1.14–3.49 and p = 0.005, OR = 1.97, 95% CI 1.22–3.19, respectively). In conclusion, our results postulate that inhibitory combinations play a protective role against AML by developing potent NK cells during education. It is noteworthy that KIR/HLA-I combination studies can be applicable in donor selection for allogeneic NK cell therapy in hematological malignancies.

KIR B donors improve the outcome for AML patients given reduced intensity conditioning and unrelated donor transplantation

AbstractNatural killer (NK) cell recognition and killing of target cells are enhanced when inhibitory killer immunoglobulin-like receptors (KIR) are unable to engage their cognate HLA class I ligands. The genes of the KIR locus are organized into either KIR B haplotypes, containing 1 or more activating KIR genes or KIR A haplotypes, which lack those genes. Analysis of unrelated donor (URD) hematopoietic cell transplants (HCT), given to acute myeloid leukemia (AML) patients between 1988 and 2009, showed that KIR B haplotype donors were associated with better outcomes, primarily from relapse protection. Most of these transplants involved marrow grafts, fully myeloablative (MAC) preparative regimens, and significant HLA mismatch. Because the practice of HCT continues to evolve, with increasing use of reduced intensity conditioning (RIC), peripheral blood stem cell grafts, and better HLA match, we evaluated the impact of URD KIR genotype on HCT outcome for AML in the modern era (2010-2016). This analysis combined data from a prospective trial testing URD selection based on KIR genotypes (n = 243) with that from a larger contemporaneous cohort of transplants (n = 2419). We found that KIR B haplotype donors conferred a significantly reduced risk of leukemia relapse and improved disease-free survival after RIC, but not MAC HCT. All genes defining KIR B haplotypes were associated with relapse protection, which was significant only in transplant recipients expressing the C1 epitope of HLA-C. In the context of current HCT practice using RIC, selection of KIR B donors could reduce relapse and improve overall outcome for AML patients receiving an allogeneic HCT.

Variability in Killler Immunglobulin like Receptor Gene Expression As a Periodic Function of Gene Position on Chromosome 19

Killer Immunoglobulin Like Receptors (KIR) are expressed on natural killer (NK) and T cell surface. KIR interactions with KIR-ligands have been implicated in outcomes of hematopoietic stem cell transplantation, placental implantation, autoimmune disease and viral infections. While these KIR interactions are clearly important our understanding of what governs their expression is lacking. The KIR Locus is made up of a highly polymorphic and homologous set of genes located on Chromosome 19q13.4 within the leukocyte receptor complex. Unique to the KIR Gene Cluster, KIR haplotypes not only vary allelically, but they also differ in the number of KIR genes present in different individuals, ranging from 7 to 12 genes. KIR haplotypes have been divided into 2 broad groups; Haplotypes A & B, based on the number of activating and inhibitory KIR genes they possess; where haplotype A contains only one activating allele KIR2DS4 and haplotype B contains various combinations of activating alleles. Expression of KIR on the NK cell surface stochastic, with some KIR found more commonly then others. In this abstract we aim to explore the relationship of KIR gene expression and the organization of the KIR gene locus using available genomic and tissue expression data. KIR gene coordinates on chromosome 19 were collected using the UCSC Genome Browser GRCh38/hg38 gene assembly and the NCBI gene website gene assembly NC_000019.10. Initial KIR gene nucleotide position along chromosome 19 were obtained and converted to angular distance (A.D. in radians) from reference. This was done to account for the double helical nature of DNA molecules, using the following equation A.D. = 2px/10.4; where x is the initial KIR gene nucleotide coordinate. Haplotype A was utilized as an initial test case as gene expression data are available for the genes in this haplotype. GTEX Portal was used to collect mRNA expression for each of the haplotype A genes, KIR-2DL1, -2DL3, -2DL4, -2DP1, -2DS4, -3DL1, -3DL2, -3DL3 & -3DP1, including total (median), splenic and whole blood expression in Reads/Kilobase of transcript/million mapped reads (RPKM). Gene expression was determined via RNA-seq of 53 tissues from 570 donors. KIR haplotype A is located along chromosome 19 between nucleotide position 55,236,713 and 55,370,584 which corresponded with an A.D. of 33,354,476 to 33,435,314 radians. When the KIR gene expression was aligned with the coordinates of the corresponding gene on the KIR locus a distinct periodic pattern of variation in expression levels was observed across the KIR genes comprising Haplotype A (Figure 1). This was true for total KIR expression from across various organs, as well as in blood and splenic tissue. This is borne out by expression data on several Haplotype A KIR genes reported in the literature (Figure 1, yellow curve). These observations suggesting that KIR gene expression may be a periodic function of the gene coordinates on the chromosome are analogous to the periodicity observed in T cell receptor VDJ recombination (Meier et al, BBMT 2019 25(5);868). This observation supports the idea that the spiral structure of the helical DNA molecules coiled around the histone molecules and their arrangement on chromosomes may have a fundamental influence on the expression of different genes, perhaps in conjunction with known epigenetic influence of DNA methylation and histone acetylation. This may also point to a role for the non-coding DNA in regulation of gene expression. We posit that the helical DNA chromosome structure may have a fundamental role in determining gene expression, as exemplified by the KIR and T cell receptor gene loci. This knowledge may allow an improved understanding of variability in global gene expression. Disclosures No relevant conflicts of interest to declare.

KIR2DL3 and the KIR ligand groups HLA-A-Bw4 and HLA-C2 predict the outcome of hepatitis B virus infection.

Killer immunoglobulin-like receptors (KIRs) regulate the activation of natural killer cells through their interaction with human leucocyte antigens (HLA). KIR and HLA loci are highly polymorphic, and certain HLA-KIR combinations have been found to protect against viral infections. In this study, we analysed whether the KIR/HLA repertoire may influence the course of hepatitis B virus (HBV) infection. Fifty-seven subjects with chronic hepatitis B (CHB), 44 subjects with resolved HBV infection and 60 healthy uninfected controls (HC) were genotyped for KIR and their HLA ligands. The frequency of the HLA-A-Bw4 ligand group was higher in CHB (58%) than subjects with resolved infection (23%) (crude OR, 4.67; P<.001) and HC (10%) (crude OR, 12.38; P<.001). Similar results were obtained for the HLA-C2 ligand group, more frequent in CHB (84%), than subjects with resolved infection (70%) (crude OR, 2.24; P<.10) and HC (60%) (crude OR, 3.56; P<.01). Conversely, the frequency of KIR2DL3 was lower in CHB (81%) than in subjects with resolved infection (98%) (crude OR, 0.10; P<.05). These results suggest a detrimental role of HLA-A-Bw4 and HLA-C2 groups, which are associated with the development of CHB, and a protective role of KIR2DL3. A stepwise variable selection procedure, based on multiple logistic regression analysis, identified these three predictive variables as the most relevant, featuring high specificity (90.9%) and positive predictive value (87.5%) for the development of CHB. Our results suggest that a combination of KIR/HLA gene/alleles is able to predict the outcome of HBV infection.

Report From the First and Second Spanish Killer Immunoglobulin-Like Receptor Genotyping Workshops: External Quality Control for Natural Killer Alloreactive Donor Selection in Haploidentical Stem Cell Transplantation

An important factor affecting the success in the setting of related haploidentical hematopoietic stem cell transplantation (HSCT) is the graft-versus-leukemia effect mediated by natural killer (NK) cells when the donor displays NK alloreactivity versus the recipient. NK cell function is regulated by killer immunoglobulin-like receptors (KIR) and it has been described that donor KIR genotype influences transplantation outcome. This has led to a requirement of laboratories to have a quality assurance program for validation and control of their KIR genotyping methods. The goal of the 1st and 2nd Spanish KIR Genotyping Workshops was to provide an external proficiency testing program in KIR genotyping for Spanish immunology and transplant laboratories. These workshops were conducted during the years 2014–2016 and consisted of 17 participating laboratories typing a set of 20 samples. The presence/absence of 16 mandatory KIR loci (2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 2DP1, 3DL1, 3DL2, 3DL3, 3DS1, and 3DP1) was evaluated per sample. Methods for KIR genotyping included polymerase chain reaction with the use of sequence-specific primers and sequence-specific oligoprobes. Consensus typing was reached in all samples, and the performance of laboratories in external proficiency testing was satisfactory in all cases. The polymorphism detected in the small sample studied in both workshops is indicative of an ample variety of KIR gene profiles in the Spanish population.

The role of NK cells in HIV-1 protection: autologous, allogeneic or both?

Natural killer (NK) cells specialize in killing virally infected- or tumor cells and are part of the innate immune system. The activational state of NK cells is determined by the balance of incoming activating and inhibitory signals mediated by receptor-ligand binding with the target cell. These receptor-ligand bonds mainly consist of the killer immunoglobulin-like receptors (KIR), which are expressed at the cell surface of NK cells, and their ligands: the highly variable human leukocyte antigen -class I molecules (HLA). Absence of an inhibitory receptor-ligand bond lowers the NK cell activation threshold, whereas an activating receptor-ligand bond stimulates the cell, potentially overcoming this threshold and triggering NK cell activation. NK cells influence the course of infection as well as the acquisition of HIV-1. Several lines of evidence relate the activating NK cell receptor KIR3DS1, in the presence or absence of its putative ligand HLA-Bw4, with slower disease progression as well as resistance to HIV-1 infection. Overall, resistance to HIV-1 infection predominantly correlates with activating KIR/HLA profiles, consisting of e.g. activating KIRs, group B haplotypes, or inhibitory KIRs in absence of their ligands. Such a conclusion is less evident for studies of HIV-1 disease progression, with studies reporting beneficial as well as detrimental effects of activating KIR/HLA genotypes. It is likely that KIR/HLA association studies are complicated by the complexity of the KIR and HLA loci and their mutual interactions, as well as by additional factors like route of HIV exposure, immune activation, presence of co-infections, and the effect of anti-HIV-1 antibodies. One newly discovered NK cell activation pathway associated with resistance to HIV-1 infection involves the presence of an iKIR/HLA mismatch between partners. The absence of such an iKIR/HLA bond renders donor-derived allogeneic HIV-1 infected cells vulnerable to NK cell responses during HIV-1 transmission. Therefore, theoretically, HIV-1 would be eliminated before it has the chance to infect the autologous cells in the recipient. While this “alloreactive” NK cell mechanism is especially relevant to HIV transmission in monogamous couples, it would be interesting to investigate how it could influence resistance to HIV in other settings. The objective of this review is to summarize the knowledge about these autologous and alloreactive NK cell responses with regard to HIV-1 outcome.

Copies of Donor Killer Immunoglobulin-like Receptor Genes and Motifs Titrate Natural Killer (NK) Cells' Functional Response to Epstein - Barr Virus Infections and Influence the Risk of Developing Post-Transplant Lymphoproliferative Disease (PTLD) after Allogeneic Hematopoietic Cell Transplantation

BACKGROUND: Recipientsof allogeneic HCT remain vulnerable to a heightened risk of reactivation of otherwise latent viral infections owing to a compromised immune system early after transplantation. Uncontrolled reactivation of Epstein-Barr virus (EBV) leading to post-transplant lymphoproliferative disorder (PTLD) is one of such major complications after T-cell depleted HCT. Recovering within weeks after transplantation and being first in line of defense against viral infections, 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 Immunoglobulin-like Receptors (KIR). Through these receptors NK cells discriminate healthy cells from 'altered' self-cells by scaling the perturbations in HLA expression after viral transformation of the target cell. Here, we set out to determine whether and how KIR gene and motifs' content of HCT donors and/or recipients influences the development of PTLD after allo-HCT.STUDY DESIGN:Hypothesizing that diverse NK cell receptor repertoires can titrate NK cell functional responses to EBV infections/reactivation and can potentially modify the risk of developing PTLD, we determined the KIR gene repertoires of 356 HLA-matched donor-recipient pairs of first allo-HCT and 50 healthy donors through Next Generation Sequencing of the KIR locus on the Illumina MiSeq platform. Based on the presence/absence and number of copies of individual genes, the KIR genotypes were determined and classified into four common centromeric (cA01, cB01, cB02 and cB03) and two telomeric (tA01 and tB01) motifs along with their variants. PBMNCs from KIR typed healthy volunteers were stimulated with EBV-transformed target cells to enumerate NK cell response to EBV (degranulation and/or IFNγ production) as a function of KIR gene content and motifs' distribution using a multicolor flow cytometry-based assay. Effect of KIR gene profile on development of PTLD was analyzed using binomial competing risks regression statistics. Distribution of NK cell functional response across various KIR characterized groups was analyzed using Mann-Whitney U statistics.RESULTS:Donor telomeric A motifs (tA01, KIR3DL1+ve KIR2DS4+ve; KIR3DS1/2DS1+/-ve), strongly protected against PTLD (p=0.0001, SHR=0.17; Figure 1). An increased protection against PTLD with increasing number of tA01 was noted with at least one copy required for a significant protective effect (Figure 1B). Copy number analysis of tA01 gene contents yielded similar associations. Further, the number of EBV induced functional NK cell subsets were significantly higher in individuals with than without KIR genotypes containing tA01 motifs (Figure 2 A-C) and was found to be increasing with an increasing number of tA01 copies (Figure 2 A'-C'). There was no influence of recipients' KIR repertoire on the risk of developing PTLDCONCLUSIONS:NK cell responsiveness, a function of KIR gene repertoire has a profound effect on the development of PTLD. Appropriately characterized KIR gene profile based identification of HCT recipients at high risk of developing PTLD will enable closer monitoring of EBV DNAemia and facilitate prompt therapy. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Killer-cell immunoglobulin-like receptor genes linkage disequilibrium analysis in population of Vojvodina

Killer Immunoglobulin-like Receptors (KIRs) form a group of regulatory molecules that modulate cytolytic activity of natural killer cells and T cells through interaction with specific human leukocyte antigen (HLA) molecules on target cells. KIRs are encoded by the family of 16 homologous genes that vary substantially between haplotypes and display sequence polymorphism with allelic variation that also contributes to diversity within the complex. The aim of the study is to estimate two locus linkage disequilibrium for 16 KIR loci. In this study, we report the evaluation of KIR gene content, allele, haplotype and genotype frequencies in 175 unrelated healthy individuals from Vojvodina who were KIR typed by polymerase chain reaction-sequence specific primers genotyping assay. The linkage disequilibrium (LD) was studied at the structural level (presence or absence of 16 KIR genes). Our results revealed that linkage disequilibrium is present between telomeric gene pairs KIR2DL1~KIR2DL4, KIR2DP1~KIR2DL4, KIR2DP1~KIR3DL1, KIR2DL1~KIR3DL2, KIR2DP1~KIR3DL2, KIR2DL4~KIR3DL1, KIR2DL4~KIR2DS4, KIR2DL4~KIR3DL2 where (r2=1), but positive association between KIR genes, with higher observed than expected haplotype frequencies were observed for KIR3DS1~KIR2DS1 and KIR2DL5~KIR2DS1 pair of genes (r2=0.646) and (r2=0.371), respectively. Thirty-eight different genotypes were identified, where 12% of the individuals have unique genotype, present in only one person. Our results will help to understand the genetic background of the Vojvodina population, in illustrating the population migration events in the northern part of Serbia, in explaining the extensive genetic admixture amongst the different ethnic groups of the region and also in KIR-related disease studies.

Specific KIR and HLA Genotypes Affect Outcomes Of Single-Agent Anti-CD20 Immunotherapy Of Follicular Lymphoma

Lymphoma immunotherapy with anti-CD20 antibody (rituximab) acts primarily through Antibody Dependent Cellular Cytotoxicity (ADCC), implying a role for NK cells. The activation and inhibition of NK cells are influenced by Killer Immunoglobulin-like Receptors (KIRs) and their HLA ligands. To evaluate the involvement of NK cells in response to immunotherapy, we investigated the role of both KIR and HLA polymorphisms in response to single agent rituximab. We have analyzed the relationship between patient genotype and clinical parameters to determine if there are beneficial KIR/HLA interactions that can lead to improved clinical outcome. Methods204 follicular lymphoma (FL) patients participating in the Eastern Cooperative Oncology Group (ECOG) RESORT trial (E4402) were treated with rituximab. The patients who showed an initial response were randomized into two different rituximab treatment regimens. Approximately 70% of FL patients showed initial response to 4 weekly doses of rituximab, and were randomized between arm A: therapy “as needed” (4 weekly doses, only upon progression) or arm B: scheduled maintenance (1 dose every 13 weeks). Clinical outcomes analyzed included duration of response, time to rituximab failure (TTRF), time to cytotoxic therapy (TCT) and decrease in tumor size. The data presented here represent both treatment arms combined, i.e. arms A+B, for all clinical data parameters mentioned. Genomic DNA samples were used for genotyping patients for the presence of 15 KIR loci using a Real Time PCR-based method as previously published (Alves, Tissue Antigens, 2008). HLA specificities corresponding to KIR ligands (HLA-C1, C2, Bw4 and ABw4) were typed using a combination of PCR-SSP methods (Olerup and Invitrogen). ResultsThose patients homozygous for HLA-C1 (C1C1) showed a trend towards a longer duration of response (p=0.06) as compared to those that were heterozygous (C1C2) or homozygous for HLA-C2 (C2C2). A similar difference was observed where patients that were HLA-C1 positive [C1+ (C1C1 or C1C2)] showed a trend towards longer TTRF (p=0.071), as well as a significantly longer TCT (p=0.003), compared to C2C2 patients. Further analyses revealed that the influence of these HLA C specificities on clinical outcome could be related to the presence or absence of inhibitory and/or activating KIR genes. Specifically, HLA-C1 is a ligand for the inhibitory KIR genes 2DL2 and 2DL3. Among the patients who had the KIR2DL2 inhibitory gene (KIR2DL2+), those that were C1+ showed a prolonged duration of response (p=0.049), TCT [Figure 1A, (p=0.003)] and TTRF (p<0.001)] compared to KIR2DL2+ patients who were C2C2 and thus lacked the C1 cognate ligand. Similarly, KIR2DL3+ patients that were C1+ had a significantly longer TCT (p=0.007) than patients that were C2C2, but significant effects were not observed for these KIR2DL3+/C1+ patients with respect to the three other analyzed clinical parameters. Therefore, further studies are required to confirm that KIR2DL3 has an effect independent of other KIRs. [Display omitted] [Display omitted] HLA-C2 alleles are ligands for an activating KIR gene, KIR2DS1. The observed HLA-C genotype effect on clinical outcome could potentially be conveyed by the interaction of HLA-C2 with KIR2DS1. Among the C2C2 patients, KIR2DS1+ patients had a significantly shorter TTRF than those without KIR2DS1 (p=0.023), as well as a significantly smaller decrease in tumor size (p=0.039), implying that the interaction of the activating KIR receptor (KIR2DS1) with its cognate ligand (HLA-C2) conveys a disadvantage to patient outcome. ConclusionSingle-agent rituximab immunotherapy of FL reveals differences in outcomes based on KIR and HLA polymorphisms. The HLA-C2 homozygous individuals seem to be at a disadvantage. This may relate to 2 significant observations highlighting diverse effects of inhibitory and activating KIR-HLA interactions leading to NK cell “licensing” and “hyporesponsiveness”, respectively. Specifically, the data from this study are consistent with: A) a beneficial effect from inhibitory KIR2DL2 and KIR2DL3 interaction with HLA-C1, and B) a detrimental effect due to the contribution of activating KIR2DS1 interacting with its ligand HLA-C2.BG, AKE and WW are co-first authors. Disclosures:Horning:Genentech: Employment, Equity Ownership. Kahl:Genentech: Consultancy, Research Funding.

Abstract 1332: Functional killer-immunoglobulin-like receptor variation and risk of non-melanoma skin cancer.

Abstract Natural killer (NK) cells of the immune system are the first line of defense against transformed and infected cells. NK cell action is determined through binding of killer immunoglobulin-like receptors (KIR) with specific human leukocyte antigen (HLA) class I ligands on target cells. The KIR gene family is diverse and highly polymorphic, is poorly covered on GWAS platforms, and exhibits significant functional copy number variation. The KIR locus has been primarily studied in the context of HCV, HIV, and transplant outcomes. Here, we have tested the hypothesis that KIR genotypes are associated with Non-Melanoma Skin Cancer (NMSC) etiology. These are among the most prevalent malignancies worldwide with rising incidence. In addition, they are highly antigenic tumors, with a possible viral etiology, making NMSC an ideal model to test KIR as a cancer susceptibility trait. A random subset of a population-based case-control study in New Hampshire was selected for the study: 422 basal cell carcinomas (BCC) (1 BCC=243, 2 BCC=131, ≥3 BCC=48), 132 squamous cell carcinomas (SCC), and 222 controls. KIR genotyping was performed with Lifecodes KIR-SSO typing kit on Luminex using buffy coat derived genomic DNA, capturing KIR loci: 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 2DP1, 2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 3DL1, 3DS1, and 3DL2. Cutaneous HPV status was assessed using serum samples and established Luminex detection assays covering 16 genus beta HPV types. The KIR2DL2/3 locus was associated with a significantly increased risk of BCC (OR=2.65, 95% CI: 1.08-6.48), which was particularly strong for cases with 3 or more tumors (OR=5.77, 95% CI: 1.30-25.66). For SCC, the KIR3DL1 gene was associated with a significantly increased risk of malignancy (OR=3.73, 95% CI: 1.51-9.22). Next we investigated the association of KIR and SCC within HPV strata. The KIR3DL1-SCC association was strongest among those with no evidence of HPV infection (OR=6.81, 95% CI: 1.78-26.12). In contrast, the non-functional KIR2DS4 variant related to an increased risk and the KIR2DL2 gene related to reduced risk of SCC among those with multiple β-HPV infections. Our results implicate a strong role for KIR in the etiology of NMSC. KIR2DL2/3 may be particularly important in the development of multiple BCC, and KIR3DL1 in the pathogenesis of SCC. Finally, we identified a pattern of KIR-SCC associations that supports a potential etiologic role of cutaneous HPV in SCC occurrence. Citation Format: Karin A. Vineretsky, Margaret R. Karagas, Michael Pawlita, Heather H. Nelson. Functional killer-immunoglobulin-like receptor variation and risk of non-melanoma skin cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1332. doi:10.1158/1538-7445.AM2013-1332

KIRs and their HLA ligands in Remitting–Relapsing Multiple Sclerosis

Killer Immunoglobulin-like Receptor (KIR) genes may affect both resistance and susceptibility to autoimmune disorders, but their role in the pathogenesis of Multiple Sclerosis (MS) is still unclear. To evaluate the involvement of KIRs and their HLA ligands in the development of MS we performed genotyping of HLA -A, -B, -Cw, -DRB1 and KIRs loci in 121 RRMS patients and 103 healthy controls (HC). Results evidenced a possible protective role of the activating KIR2DS1 gene (p y = 0.001; OR:0.38), enhanced in the presence of its ligand group HLA-C2 (p y = 0.0001; OR:0.23). Our data suggest that the presence of functional compounds of activating KIR receptors together with their HLA ligands, allowing the immunomodulatory function of NK cells, may have a protective role against the disease.

Report from the killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop: worldwide variation in the KIR loci and further evidence for the co-evolution of KIR and HLA

The killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop (IHIWS) sought to explore worldwide population variation in the KIR loci, and to examine the relationship between KIR genes and their human leukocyte antigen (HLA) ligands. Fifteen laboratories submitted KIR genotype and HLA ligand data in 27 populations from six broad ethnic groups. Data were analyzed for correlations between the frequencies of KIR and their known HLA ligands. In addition, allelic typing was performed for KIR2DL2 and 3DL1 in a subset of populations. Strong and significant correlations were observed between KIR2DL2, 2DL3 genotype frequencies and the frequency of their ligand, HLA-C1. In contrast, only weak associations were seen for 3DL1, 3DS1 and the HLA-Bw4 ligand. Although some aspects of the correlations observed here differ from those reported in other populations, these data provide additional evidence of linked evolutionary histories for some KIR and HLA loci. Investigation of allele-level variation for the B haplotype locus KIR 2DL2 showed that two alleles, *001 and *003, predominate in all populations in this study. Much more allelic variation was observed for the A haplotype locus 3DL1, with several alleles observed at moderate frequencies and extensive variation observed between populations.

Distribution of killer cell immunoglobulinlike receptors in the Macedonian population

The aim of this study was to analyze killer immunoglobulinlike receptor (KIR) gene polymorphism in the Macedonian population. The study sample consists of 214 healthy unrelated individuals, aged 20–35 years. All individuals are of Macedonian origin and nationality, and residents of different geographic regions. The population genetics analysis package, Arlequin, was used for analysis of the data. We found that all 16 KIR genes were observed in the Macedonian population and framework genes KIR3DL3, KIR2DL4, and KIR3DL2 were present in all individuals. A total of 56 different KIR genotypes were found in the Macedonian population, based on the presence of 16 KIR genes. Neighbor-joining phylogenetic tree, constructed on the basis of standard genetic distances of KIR genes, shows that Macedonian population is in the same cluster with England West Midlands Indian Asian, Brazil SouthEast Caucasian, Romania Caucasians, Spain Basque, England West Midlands Caucasian, France Reunion, and Spain Granada populations. The frequency of KIR loci in Macedonian population shares several general features with other Caucasoid populations studied before.

Killer immunoglobulin receptor gene and allele frequencies in Caucasoid, Oriental and Black populations from different continents

Parallel to the growth in interest in the past few years in the killer immunoglobulin-like receptor (KIR) genes has been the elucidation of the presence/absence of these genes and to a very limited extent, the frequency of alleles of these genes in many populations. In the present study, we have chosen seven populations to investigate the presence/absence of the KIR genes and their alleles, i.e. Cuban, Brazilian, Oman, Hong Kong Chinese, Singapore Chinese, South African Xhosa and South African San. The populations were chosen to represent different continents of the world. We show the divergence in the frequencies of these genes, and their alleles, in the different populations. Many new sequence-specific oligonucleotide probe patterns represent new alleles, each occurred in only one of the populations. The KIR gene frequencies of these seven populations were calculated and genetic distances were represented by neighbour-joining dendrograms and correspondence analyses. Also, the presence or absence of 17 KIR loci in the presently studied populations was compared with the presence or absence of the same loci in 56 worldwide populations (available on the website www.allelefrequencies.net). In total, 5134 individuals were analysed and the populations grouped, with some exceptions, according to a geographical gradient.

Global diversity and evidence for coevolution of KIR and HLA

The killer immunoglobulin-like receptor (KIR) gene cluster shows extensive genetic diversity, as do the HLA class I loci, which encode ligands for KIR molecules. We genotyped 1,642 individuals from 30 geographically distinct populations to examine population-level evidence for coevolution of these two functionally related but unlinked gene clusters. We observed strong negative correlations between the presence of activating KIR genes and their corresponding HLA ligand groups across populations, especially KIR3DS1 and its putative HLA-B Bw4-80I ligands (r = -0.66, P = 0.038). In contrast, we observed weak positive relationships between the various inhibitory KIR genes and their ligands. We observed a negative correlation between distance from East Africa and frequency of activating KIR genes and their corresponding ligands, suggesting a balance between selection on HLA and KIR loci. Most KIR-HLA genetic association studies indicate a primary influence of activating KIR-HLA genotypes in disease risk; concomitantly, activating receptor-ligand pairs in this study show the strongest signature of coevolution of these two complex genetic systems as compared with inhibitory receptor-ligand pairs.

Distribution of the killer cell immunoglobulin‐like receptors in Mexican Mestizos

Understanding the complex interaction between human leukocyte antigen (HLA) and killer immunoglobulin-like receptor (KIR) requires study of both HLA and KIR diversity in the same population. The presence of KIR genes 2DL1, 2, 3, 4, 5, KIR3DL1, 3DL2, 3DL3, KIR2DS1, 2DS2, 2DS3, 2DS4, 2DS5, KIR3DS1, KIR3DP1, KIR2DP1 was determined in 54 unrelated Mexican Mestizo donors. The PCR sequence-specific oligonucleotide probe One Lambda kit (Luminex) kindly given by J. Lee was used for typing. The software analyses the combination obtained for each of the five exons. Five controls (UCLA DNA exchange) were run as quality control. The gene frequency (GF) was calculated for the 16 KIR loci; the GF of individual genes was 100% for 2DL4, 3DL1, 3DL2, 3DL3, 3DP1. KIR2DL1 (76.43%), KIR2DL2 (37.64%), KIR2DL3 (76.43%), KIR2DL5 (29.29%), KIR3DS1 (23.02%), KIR2DS1 (21.83%), KIR2DS2 (37.64%), KIR2DS3 (50.93%), KIR2DS4 (86.93%), KIR2DS5 (29.29%), KIR2DP1 (86.39%). We observed similar frequencies with Caucasians and Mediterraneans, with exceptions: KIR3DL1 which was present in 100% Mexicans, ranged from 62% to 75% in Caucasians; 2DS3 (50.9%) vs 14-20% 2DS4 (86.39%) vs 65-79% and 2DS5 (29.29%) vs 11-18% in Caucasians. The finding of 23 phenotypes in 54 individuals accounting for both chromosomes, demonstrates the enormous diversity. We found 14 different combinations of stimulatory KIRs in the phenotypes; every subject had at least one stimulatory KIR; in all of them, 2DS4 existed except for one person who may have some new combination: 2DS2 2DS3. Extended family data will offer accurate and precise haplotypes to provide an insight on the significance of ethnic distribution and KIR repertoire.

KIR Ligand Incompatibility in HLA-Identical Sibling Nonmyeloablative Hematopoietic Stem Cell Transplantation for Hematologic Malignancies.

Natural killer (NK) cell alloreactivity based on inhibitory killer immunoglobulin-like receptor (KIR)-ligand incompatibility (i.e., missing KIR ligand) in the graft-vs-host (GVH) direction has been described to favorably influence engraftment, GVHD, and graft-vs-tumor (GVT) effect following haploidentical or matched unrelated HSCT in patients with hematologic malignancies. The degree and effect of KIR-ligand incompatibility has recently been explored following HLA-identical sibling HSCT (Hsu et al., Blood 2005; 105:4878). Based on a murine model, we developed a clinical trial with a goal of deliberately inducing a GVHD-free mixed chimeric platform following nonmyeloablative conditioning (consisting of equine ATG, cyclophosphamide, thymic irradiation, and a brief course of cyclosporine) and HLA-matched sibling HSCT. Donor leukocyte infusions (DLI) were given as early as five weeks post-HSCT to patients without GVHD in an attempt to achieve a conversion to full donor chimerism (FDC) with the goal of fully capturing GVT effect with little or no GVHD. In this study we hypothesized that KIR-ligand incompatibility in the GVH direction and KIR-ligand compatibility in the host-vs-graft (HVG) direction would reduce the rate of graft failure, decrease the incidence of GVHD, and improve overall survival following HLA-matched sibling HSCT. Fourteen transplant recipients (bone marrow, n=9; peripheral blood stem cell, n=5) with refractory hematologic malignancies (NHL, n=7; HD, n=3; MM, n=2; CLL, n=1; AML, n=1) were analyzed. KIR typing was accomplished using PCR amplified DNA from both donor and recipient patient samples. Typing of the amplified DNA was performed using the Lifecodes KIR-SSO typing kits (Tepnel Lifecodes Corporation). By using the SSO (sequence-specific oligonucleotides) technology in conjunction with the Luminex Instrument, KIR loci were identified for each patient and donor sample. KIR-ligand (HLA) incompatibility in the GVH and HVG directions were assessed based on HLA and KIR genotyping (KIR2DL1, KIR2DL2, KIR2DL3 and KIR3DL1) of 14 donors and 12 of the 14 recipients. Six of the 14 patients eventually lost their grafts despite DLI. Seven patients spontaneously achieved FDC and one converted to FDC following DLI. The missing KIR ligand analysis showed 12 patients (86%, n=12/14) with KIR-ligand incompatibility in the GVH direction (1 missing ligand, n=9; 2 missing ligands, n=3) and 10 patients (83%, n=10/12) with KIR-ligand incompatibility in the HVG direction (1 missing ligand, n=9; 2 missing ligands n=1). The presence or the degree of KIR-ligand incompatibility in GVH or HVG direction was not found to be predictive of spontaneous FDC or graft rejection. There was no significant relationship between the number of missing KIR ligands in either direction and the development of acute or chronic GVHD. This study shows a higher rate of KIR-ligand incompatibility in the GVH (86%) and HVG (83%) directions in the setting of HLA-matched sibling HSCT than previously reported. Although the small number of patients does not allow for statistically meaningful conclusions regarding clinical outcome, the observation of a high incidence of KIR-ligand incompatibility in this population justifies the study of larger patient cohorts to determine the influence of NK cell alloreactivity on transplant outcomes.

The Killer Immunoglobulin-Like Receptor Gene Cluster: Tuning the Genome for Defense

Killer immunoglobulin-like receptors (KIRs) are molecules expressed on the surface of natural killer (NK) cells, which play an important role in innate immunity. KIR recognition of major histocompatability complex (MHC) class I allotypes represents one component of the complex interactions between NK cells and their targets in determining NK cell reactivity. KIRs are encoded by a gene cluster at human chromosome 19q13.4. Despite their high degree of sequence identity, KIR genes encode proteins that have diverse recognition patterns (specific HLA class I allotypes) and confer opposing signals (activating or inhibitory) to the NK cell. The KIR gene cluster is highly polymorphic, with individual genes exhibiting allelic variability and individual haplotypes differing in gene content. The polymorphism of the KIR locus parallels that of the MHC, facilitating the adaptation of the immune system to a dynamic, challenging environment. This variation is associated with a growing number of human diseases, which is likely to extend to levels observed for the HLA loci. Here we review current progress in understanding KIR biology and genetics.

Hierarchy of resistance to cervical neoplasia mediated by combinations of killer immunoglobulin-like receptor and human leukocyte antigen loci

Killer immunoglobulin-like receptor (KIR) recognition of specific human histocompatibility leukocyte antigen (HLA) class I allotypes contributes to the array of receptor–ligand interactions that determine natural killer (NK) cell response to its target. Contrasting genetic effects of KIR/HLA combinations have been observed in infectious and autoimmune diseases, where genotypes associated with NK cell activation seem to be protective or to confer susceptibility, respectively. We show here that combinations of KIR and HLA loci also affect the risk of developing cervical neoplasia. Specific inhibitory KIR/HLA ligand pairs decrease the risk of developing neoplasia, whereas the presence of the activating receptor KIR3DS1 results in increased risk of disease, particularly when the protective inhibitory combinations are missing. These data suggest a continuum of resistance conferred by NK cell inhibition to susceptibility involving NK cell activation in the development of cervical neoplasia and underscore the pervasive influence of KIR/HLA genetic variation in human disease pathogenesis.

Killer Immunoglobulin-Like Receptors (KIRs) Genotypes in a Belgian Population.

KIRs (Killer cell Immunoglobulin-like Receptors) are expressed on NK (Natural Killer) cells and a subpopulation of T lymphocytes namely memory CD8+ T cells. The distribution of KIR genes varies among individuals and populations. These genes are encoded on chromosome 19 (19q13.4). Till now 17 KIR genes and pseudogenes have been identified. KIRs recognise groups of HLA class I alleles. NK activity is partially controlled through the interaction between KIRs and their HLA ligands. Several studies report that KIRs may affect the outcome of Hematopoietic Stem-Cell Transplantations.We performed KIR typing of 17 genes and pseudogenes in 100 healthy Belgian unrelated individuals in “West-Vlaanderen” from Caucasoid origin using a PCR-SSP method. Three genes (KIR3DL3, 2DL4 and 3DL2), named frame-work genes, and the pseudogene 3DP1 were found in all individuals. KIR2DL1 and 2DP1 genes were present in a frequency of 99%. In addition, KIR3DL1 and 2DS4 genes represented a frequency of 97. The KIR2DL3 was found in 90% and the frequencies of other genes varied between 56% and 24%. The individual KIR gene content ranged from 8 to 17 genes. A total of 19 KIR locus profiles was observed. The most common KIR locus profile (32%) consisted of a combination of genes characterising A haplotypes (KIR2DL1 and 2DL3) without the presence of genes characteristic of B haplotypes (KIR2DL2 and 2DS2). The second most common KIR locus profile, accounting for 20% contained a combination of genes characteristics for both A and B haplotypes. The allele KIR2DS4*003 was found in 89% and KIR2DS4*00101/00102/002 only in 41%. KIR3DP1*00301/00302 was present in all individuals and KIR3DP1*001/002 only in 35%.Our results show that frequencies of most KIR loci in our Belgian population were comparable to literature data of other Caucasian populations. Only KIR2DS1 was lower (27% vs 47.7% with a p-value of 0.0002).In the future, KIR typing of donor and patient before a Hematopoietic Stem-cell Transplantation may be necessary, due to the diversity in KIR genotypes.