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Results for “Receptors, KIR”

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9 recordsLinked to original sources

PubMed2025

Maternal-Foetal HLA-DQB1 Incompatibility Is Associated With Pregnancy-Induced Hypertensive Disorders in a Genetically Isolated Population.

In pregnancy, semi-allogenic foetal trophoblasts express a specific HLA profile mediating maternal leukocyte contact, crucial for placentation. Paradoxically, maternal immunomodulation requires foetal antigen recognition, especially involving certain HLA molecules. Pre-eclampsia, a severe hypertensive complication, has been linked to antigenic similarity. Previously, we showed no selection for HLA (in)compatibility in uncomplicated naturally conceived pregnancies. However, pre-eclamptic pregnancies were associated with increased total maternal-foetal HLA and HLA-C matching. These associations suggest a role for HLA mismatches in immune regulation leading to an uncomplicated pregnancy. To better understand HLA homozygosity in human reproduction, we aimed to determine if there is a preferential selection for HLA compatibility in a genetically isolated population, and its relation to hypertensive complications. A nested case-control study, comprising 125 uncomplicated pregnancies and 50 with hypertensive complications (29 with pregnancy-induced hypertension, 21 with pre-eclampsia) was conducted in a genetically isolated Dutch population (FROH 1.3-3.1). Maternal and foetal HLA-A, -B, -C, -DRB1, -DQA1, -DQB1 and maternal killer-cell immunoglobulin-like receptor (KIR) genotyping were performed. Maternal-foetal HLA (mis)match counts were compared to expected values from randomisation of paternal HLA haplotypes over maternal haplotypes of the foetuses. Mismatched CD4+ T cell epitopes presented by maternal HLA class II were predicted using the PIRCHE-II algorithm. In uncomplicated pregnancies, no difference was found between observed and expected maternal-foetal HLA (mis)matches. However, pregnancies with hypertensive complications showed significantly higher observed HLA-DQB1 mismatches, reflected in PIRCHE-II scores. No significant differences were found in KIR/HLA-C frequencies. Interpretation is limited by the small sample size and the grouping of distinct hypertensive disorders. Nonetheless, maternal-foetal HLA-DQB1 mismatch seems to play a role in the aetiology of hypertensive complications during pregnancy in this population.

Humans↗

PubMed2025

Allele Level Sequencing of Killer Cell Immunoglobulin-Like Receptor Genes Using Oxford Nanopore Long Read Sequencing.

The human Killer cell Immunoglobulin-like Receptor (KIR) genes, found on chromosome 19, encode for cell surface protein receptors that, through interaction with their ligand, modulate the action of Natural Killer (NK) cells and some subsets of T lymphocytes. KIR genes exhibit extensive variation through variable gene content, copy number, and allele polymorphism. The combination of KIR genes and their ligands is implicated in various clinical settings including haematopoietic stem cell and solid organ transplant, and infectious disease progression. KIR gene content has been used in the selection of optimal stem cell donors with haplotype variations in recipient and donor giving differential clinical outcomes. With the introduction of massively parallel clonal next generation sequencing and single molecule long read third generation sequencing, allele level determination of KIR genotypes has become feasible. We describe a method for amplicon-based long read sequencing on the Oxford Nanopore Technologies platform that provides largely unambiguous allele level typing of KIR genes. The method was validated using DNA extracted from 48 10th International Histocompatibility Workshop (IHWS) cell lines with previously published allele level KIR genotypes and 176 Western Australian samples previously tested for the presence or absence of KIR genes. Our long-read sequencing method was able to accurately determine KIR alleles with an overall concordance of 97%-99% with the published data. Importantly, phasing ambiguity caused by the inability to phase heterozygous base positions over long stretches of gene sequence was resolved in several samples. Thus, our long read PCR sequencing strategy can be used to determine KIR genotypes at allele resolution level.

Humans↗

PubMed2026

Graph-KIR: graph-based KIR copy number estimation and allele calling using short-read sequencing data.

MOTIVATION: The Killer-cell Immunoglobulin-like Receptor (KIR) is a highly polymorphic region in the human genome, associated with autoimmune diseases and organ transplantation. The sequences of KIR genes are highly similar among star alleles as well as in between individual genes, with the copy number of each KIR gene typically ranging from 0 to 4. In this study, we introduce Graph-KIR, a tool designed to estimate gene copy numbers and predict full-resolution (7-digit, encompassing both coding and non-coding sequence variations) from a whole genome sequencing (WGS) sample. RESULTS: Graph-KIR is capable of independently typing KIR alleles per sample with no reliance on the distribution of any framework gene in a cohort. In a set of 100 simulated samples, Graph-KIR demonstrated 99.2% accuracy in copy number estimation and high F1-score of allele typing: 91.79% at 7-digit resolution, 97.37% at 5-digit resolution, and 97.11% at 3-digit resolution. Graph-KIR outperforms existing tools such as Geny (96.39% F1-score), PING's WGS version (92.77% F1-score), and T1K (90.44% F1-score) at 5-digit resolution. By analyzing the results on 44 HPRC samples, Graph-KIR achieves better F1-score than Geny and PING at 7-digit resolution. The release of Graph-KIR adds another valuable tool to assist users in accurately estimating copy numbers and calling alleles of KIR genes from WGS samples. AVAILABILITY AND IMPLEMENTATION: The Graph-KIR and paper-related pipeline codes are available at https://github.com/linnil1/KIR_graph.

Receptors, KIR↗

PubMed2026

Immunogenetic diversity of two South Asian cohorts: From Pakistan and India.

Having critical roles in immune defense and reproduction, killer cell immunoglobulin-like receptors (KIR) and their human leukocyte antigen (HLA) class I ligands are encoded by the most polymorphic regions in the human genome. South Asia comprises over one quarter of the global population and harbors rich genomic diversity. Limiting our understanding of population-specific variation and disease susceptibility, high-resolution immunogenetic studies of South Asian ancestry individuals are lacking. Here, we characterize KIR and HLA class I diversity in two South Asian cohorts: sampling an urban population from Karachi, Pakistan (n = 79), and a Dravidian-speaking Yadav population from southern India (n = 70). Targeted sequencing identified 151 distinct KIR alleles across 13 genes, including 11 previously uncharacterized allotypes. Over 75% of the genotypes were KIR-Bx. We identified 98 HLA class I alleles and extensive haplotypic diversity, with all major KIR binding motifs represented, and a mean of seven potential inhibitory KIR-HLA interactions per individual (6.6 in Karachi, 7.4 in Yadav). Together, these results demonstrate substantial immunogenetic diversity and population-specific KIR and HLA variation within the two studied cohorts. This study expands knowledge of KIR and HLA diversity and offers a framework for further evolutionary and disease-focused in South Asia.

Humans↗

PubMed2025

Genotyping of natural killer cell immunoglobulin-like receptors in human early reproductive losses.

Genotyping of killer cell immunoglobulin-like receptors (KIR) of NK-cells was performed in 634 women with early pregnancy losses (EPL), including 158 women with recurrent implantation failure (RIF) after at least three IVF cycles, and 110 women with at least two intrauterine pregnancy losses characterized by clinically confirmed retention of a non-viable fetus in the uterus without spontaneous miscarriage, defined as recurrent pregnancy loss (RPL). The control group consisted of 431 women with at least two healthy children. In the RIF, a significant shift in the frequency of KIR-genotypes was observed compared with both the control and the RPL groups. A significantly higher frequency of the KIR-AA genotype was observed in the RIF group compared to the control group (χ² = 26.78; p < 0.0001; OR = 2.7) and the RPL group (χ² = 15.83; p < 0.0001; OR = 2.86). Analysis of the frequency of full-length/deletion alleles of KIR2DS4 among AA genotype carriers showed an increased frequency of the 2DS4-del in the RIF compared with the RPL and control groups. A significantly higher frequency of the cenAA was also observed in RIF compared with the control (χ² = 20.10; p < 0.0001) and the RPL(χ² = 12.05; p < 0.005). The significantly increased frequency of the KIR-AA genotype with predominance of deletion KIR2DS4 alleles, along with the elevated frequency of the cenAA in RIF, may indicate insufficient NK-cell activation at the stage of embryo implantation. These findings suggest different etiological mechanisms for RIF and RPL.

Humans↗

PubMed2025

Frequency and Distribution of KIR Genotypes of Donors-Recipient Pairs in the Haploidentical Haematopoietic Stem Cell Transplantation Setting: Collaborative Study by the Spanish Working Group in Histocompatibility and Transplant Immunology (GETHIT) and the Spanish Haematopoietic Transplantation and Cell Therapy Group (GETH-TC).

There is limited information regarding the influence of KIR genotype, compared to the HLA system, in haploidentical haematopoietic stem cell transplantation (haplo-HSCT). This study aimed to determine the frequencies of KIR genotypes in Spanish haematologic patients undergoing haplo-HSCT. A study was conducted on 113 oncohaematological patients and their donors, treated across five centres that are members of the Spanish Working Group in Histocompatibility and Transplant Immunology (GETHIT) and the Spanish Haematopoietic Transplantation and Cell Therapy Group (GETH-TC). KIR typing was performed using PCR-rSSO or PCR-SSP. KIR genotypes were identified using the KIR Allele Frequency Net Database. Among donors, the most frequent KIR genotypes were Type 1 (28.3%), Type 2 (12.4%) and Type 4 (10.6%). In patients, Genotypes 1 (23.9%), 4 (23%) and 2 (14.2%) were most prevalent. Donors exhibited AA centromeric (46%) and telomeric (59.3%) types, while patients had a higher AB centromeric frequency (52.2%). Differences were observed in the BB centromeric type (3.5% patients; 16.8% donors, p = 0.002). The AB KIR genotype was the most common (70.8% donors; 75.2% patients). Most were classified as 'neutral' (61.9% donors; 73.5% patients). B-content score1 was the most common (48.7% patients; 33.6% donors). Notably, classification as best was rare (2.7% patients; 16.8% donors, p = 0.002). The study highlights the distribution of KIR genotypes in haplo-HSCT patients and donors, with Genotypes 1, 2 and 4 being the most prevalent. AB KIR genotypes and B-content score 1 were dominant. Moreover, KIR genotypes ID may serve as criteria for future investigation about the immunogenetic predisposition to malignant haematological diseases.

Humans↗

PubMed2026

Identification of elements determining KIR gene demethylation at the CD56-bright stage of NK cell development.

The variegated expression of the KIR family of class I MHC receptors generates specialized natural killer (NK) cells capable of allele-specific HLA recognition. Understanding the mechanism of KIR gene activation will lead to improved methods for the generation of fully functional NK cells. A central RUNX-binding site in the KIR proximal promoter is required for gene activation. RUNX proteins recruit ten-eleven translocation (TET) proteins that generate 5-hydroxymethylcytosine (5hmC) and drive DNA demethylation. Assessment of 5-methylcytosine (5mC) and 5hmC residues at four stages of NK cell development reveals deposition of 5hmC primarily in a CREB site next to the RUNX site at the CD56Bright stage but not the subsequent CD56Dim stage representing fully mature NK cells. KIR promoter demethylation is delayed relative to other lineage-associated genes, indicating a high threshold for KIR gene demethylation in developing NK cells, and a window of opportunity for RUNX/TET-dependent KIR gene activation in CD56Bright NK cells.

6-base sequencing↗

PubMed2005

Comparative genomics of natural killer cell receptor gene clusters.

Many receptors on natural killer (NK) cells recognize major histocompatibility complex class I molecules in order to monitor unhealthy tissues, such as cells infected with viruses, and some tumors. Genes encoding families of NK receptors and related sequences are organized into two main clusters in humans: the natural killer complex on Chromosome 12p13.1, which encodes C-type lectin molecules, and the leukocyte receptor complex on Chromosome 19q13.4, which encodes immunoglobulin superfamily molecules. The composition of these gene clusters differs markedly between closely related species, providing evidence for rapid, lineage-specific expansions or contractions of sets of loci. The choice of NK receptor genes is polarized in the two species most studied, mouse and human. In mouse, the C-type lectin-related Ly49 gene family predominates. Conversely, the single Ly49 sequence is a pseudogene in humans, and the immunoglobulin superfamily KIR gene family is extensive. These different gene sets encode proteins that are comparable in function and genetic diversity, even though they have undergone species-specific expansions. Understanding the biological significance of this curious situation may be aided by studying which NK receptor genes are used in other vertebrates, especially in relation to species-specific differences in genes for major histocompatibility complex class I molecules.

Journal Article↗

PubMed2026

Shared CD4+ T cell receptor specificity groups in Crohn's disease and ulcerative colitis.

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), is marked by chronic intestinal inflammation and dysregulated immunity. Although UC and CD affect different areas of the gastrointestinal tract, both diseases share aberrant CD4+ memory T cell responses, with HLA-DRB1 as a major genetic risk factor. HLA-DRB1 encodes MHC class II molecules that influence the CD4+ T cell receptor (TCR) repertoire, yet how these genotypes shape TCR specificity in IBD remains unclear. Here, we genotyped HLA-DRB1 and profiled 3.13 million TCRβ sequences from circulating memory CD4+ T cells in 33 IBD patients (20 UC, 13 CD) and 14 healthy controls. Using the GLIPH2 algorithm, we distilled 468,441 candidates based on CDR3 amino acid motifs into 440 high-confidence TCR specificity groups significantly enriched among individuals sharing HLA-DRB1 alleles. Notably, 5 specificity groups were IBD-enriched and were shared between UC and CD, suggesting common antigen targets in both diseases. We also observed increased frequencies of clonally expanded cytotoxic GZMB+PRF1+ memory CD4+ T cells and KIR+CD8+ T cells in a subset of risk-allele carriers with IBD. These findings elucidate distinct, HLA-linked TCR specificity groups in IBD and provide mechanistic insights that may advance antigen discovery and personalized medicine.

Humans↗