The development of next-generation sequencing (NGS) technologies for HLA and KIR genotyping is rapidly advancing knowledge of genetic variation of these highly polymorphic loci. NGS genotyping is poised to replace older methods for clinical use, but standard methods for reporting and exchanging these new, high quality genotype data are needed. The Immunogenomic NGS Consortium, a broad collaboration of histocompatibility and immunogenetics clinicians, researchers, instrument manufacturers and software developers, has developed the Minimum Information for Reporting Immunogenomic NGS Genotyping (MIRING) reporting guidelines. MIRING is a checklist that specifies the content of NGS genotyping results as well as a set of messaging guidelines for reporting the results. A MIRING message includes five categories of structured information – message annotation, reference context, full genotype, consensus sequence and novel polymorphism – and references to three categories of accessory information – NGS platform documentation, read processing documentation and primary data. These eight categories of information ensure the long-term portability and broad application of this NGS data for all current histocompatibility and immunogenetics use cases. In addition, MIRING can be extended to allow the reporting of genotype data generated using pre-NGS technologies. Because genotyping results reported using MIRING are easily updated in accordance with reference and nomenclature databases, MIRING represents a bold departure from previous methods of reporting HLA and KIR genotyping results, which have provided static and less-portable data. More information about MIRING can be found online at miring.immunogenomics.org.
NGS; HLA; KIR; MIRING; genotyping; data standards
Mass cytometry was used to investigate the effect of CMV reactivation on lymphocyte reconstitution in hematopoietic cell transplant patients. For eight transplant recipients, four CMV negative and four CMV positive, we studied peripheral blood mononuclear cells (PBMC) obtained six months after unrelated donor hematopoietic cell transplantation (HCT). Forty cell-surface markers, distinguishing all major leukocyte populations in PBMC, were analyzed by mass cytometry. These included 34 NK cell markers. Compared to healthy controls, transplant recipients had higher HLA-C expression on CD56−CD16+ NK cells, B cells, CD33bright myeloid cells and CD4CD8 T cells. The increase in HLA-C expression was greater for CMV-positive HCT recipients than CMV negative recipients. Present in CMV-positive HCT recipients, but not in CMV-negative HCT recipients or controls, is a population of KIR-expressing CD8 T cells not previously described. These CD8 T cells co-express CD56, CD57 and NKG2C. The HCT recipients also have a population of CD57+NKG2A+ NK cells that preferentially express KIR2DL1. An inverse correlation was observed between the frequencies of CD57+NKG2C+ NK cells and CD57+NKG2A+ NK cells. Although CD57+NKG2A+ NK cells are less abundant in CMV-positive recipients, their phenotype is of a more activated cell than the CD57+NKG2A+ NK cells of controls and CMV-negative HCT recipients. These data demonstrate that HCT and CMV reactivation are associated with an increased expression of HLA-C. This could influence NK cell education during lymphocyte reconstitution. The increased inhibitory KIR expression by proliferating CMV-specific CD8 T cells suggests regulatory interactions between HLA-C and KIR might promote GVL effects following transplantation.
Chimpanzees have orthologs of the six, fixed, functional human MHC class I genes. But in addition, the chimpanzee has a seventh functional gene, Patr-AL, which is not polymorphic but contributes substantially to population diversity by its presence on only 50% of MHC haplotypes. The ancestral AL gene emerged long before the separation of human and chimpanzee ancestors and then subsequently and specifically lost function during human evolution, but was maintained in chimpanzees. Patr-AL is an alloantigen that participates in negative and positive selection of the T-cell repertoire. The three-dimensional structure and the peptide-binding repertoire of Patr-AL and HLA-A*02 are surprisingly similar. In contrast, the expression of these two molecules is very different as shown using specific monoclonal and polyclonal antibodies made against Patr-AL. Peripheral blood cells and B cell lines express low levels of Patr-AL at the cell surface. Higher levels are seen for 221-cell transfectants expressing Patr-AL, but in these cells a large majority of Patr-AL molecules are retained in the early compartments of the secretory pathway: mainly the endoplasmic reticulum but also cis-Golgi. Replacing the cytoplasmic tail of Patr-AL with that of HLA-A*02 increased the cell-surface expression of Patr-AL substantially. Four substitutions distinguish the Patr-AL and HLA-A*02 cytoplasmic tails. Systematic mutagenesis showed that each substitution contributes changes in cell-surface expression. The combination of residues present in Patr-AL appears unique, but each individual residue is present in other primate MHC class I molecules, notably MHC-E, the most ancient of the functional human MHC class I molecules.
Infection of humans and chimpanzees with Hepatitis C virus (HCV) results in either the resolution of the acute infection or its progression to a persistent infection associated with chronic liver disease. In cohorts of human patients, resolution of HCV infection has been associated with homozygosity for both C1+HLA-C and its cognate inhibitory receptor, KIR2DL3. Compared here are the killer cell immunoglobulin-like receptors (KIR) and major histocompatibility complex (MHC) class I factors of chimpanzees who resolve, or resist, HCV infection with those chimpanzees who progress to chronic infection. Analysis of Pt-KIR gene content diversity associated two of the 12 Pt-KIR with clinical outcome. Activating Pt-KIR3DS2 and inhibitory Pt-KIR2DL9 are strong receptors specific for the C2 epitope. They are encoded by neighboring genes within the Pt-KIR locus that are in strong linkage disequilibrium. HCV-infected chimpanzees with KIR genotypes containing Pt-KIR3DS2 and KIR2DL9 are significantly more likely to progress to chronic infection than infected chimpanzees lacking the genes (p=0.0123 and p=0.0045, respectively), whereas human HLA-B allotypes having the C1 epitope are unusual, such allotypes comprise about one quarter of the chimpanzee Patr-B allotypes. Homozygous C1-+Patr-B are enriched in chimpanzees with chronic HCV infection, and the compound genotype of homozygous C1+Patr-B combined with either Pt-KIR3DS2 or Pt-KIR2DL9 is more strongly associated with disease progression than either factor alone (p=0.0031 and p=0.0013, respectively). Thus, despite similarities suggesting a common basis in disease resistance, there are substantial differences in the KIR and MHC class I correlations observed for HCV-infected humans and chimpanzees, consistent with the divergence of their KIR and MHC class I systems.
MHC; KIR; Hepatitis C virus; Chronic infection; Chimpanzee
The human killer cell immunoglobulin-like receptor (KIR) locus comprises two groups of KIR haplotypes, termed A and B. These are present in all human populations but with different relative frequencies, suggesting they have different functional properties that underlie their balancing selection. We studied the genomic organization and functional properties of the alleles of the inhibitory and activating HLA-C receptors encoded by KIR haplotypes. Because every HLA-C allotype functions as a ligand for KIR, the interactions between KIR and HLA-C dominate the HLA class I mediated regulation of human NK cells. The C2 epitope is recognized by inhibitory KIR2DL1 and activating KIR2DS1, whereas the C1 epitope is recognized by inhibitory KIR2DL2 and KIR2DL3. This study shows that the KIR2DL1 and 2DS1 and KIR2DL2/3 alleles form distinctive phylogenetic clades that associate with specific KIR haplotypes. KIR A haplotypes are characterized by KIR2DL1 alleles that encode strong inhibitory C2 receptors and KIR2DL3 alleles encoding weak inhibitory C1 receptors. In striking contrast, KIR B haplotypes are characterized by KIR2DL1 alleles that encode weak inhibitory C2 receptors and KIR2DL2 alleles encoding strong inhibitory C1 receptors. The wide-ranging properties of KIR allotypes arise from substitutions throughout the KIR molecule. Such substitutions can influence cell-surface expression, as well as the avidity and specificity for HLA-C ligands. Consistent with the crucial role of inhibitory HLA-C receptors in self-recognition, and natural killer cell education and response, most KIR haplotypes have both a functional C1 and C2 receptor, despite the considerable variation that occurs in ligand recognition and surface expression.
Soluble recombinant proteins that comprise the extracellular part of a surface expressed receptor attached to the Fc region of an IgG antibody have facilitated the determination of ligand specificity for an array of immune system receptors. Among such receptors is the family of killer cell immunoglobulin-like receptors (KIR) that recognize HLA class I ligands. These receptors, expressed on natural killer (NK) cells and T cells, play important roles in both immune defense and placental development in early pregnancy. Here we describe a method for the production of two domain KIR-Fc fusion proteins using baculovirus infected insect cells. This method is more scalable than traditional mammalian cell expression systems and produces efficiently folded proteins that carry posttranslational modifications found in native KIR. We also describe a multiplex binding assay using the Luminex platform that determines the avidity and specificity of two domain KIR-Fc for a panel of microbeads, each coated with one of 97 HLA class I allotypes. This assay is simple to perform, and represents a major improvement over the assays used previously, which were limited in the number of KIR and HLA class I combinations that could be assayed at any one time. The results obtained from this assay can be used to predict the response of NK cell and T cells when their KIR recognize HLA class I.
Natural Killer Cells; MHC; Comparative Immunology/Evolution; Antigens/Peptides/Epitopes
The HLA region of chromosome 6 contains the most polymorphic genes in humans. Spanning ~5Mbp the densely packed region encompasses approximately 175 expressed genes including the highly polymorphic HLA class I and II loci. Most of the other genes and functional elements are also polymorphic, and many of them are directly implicated in immune function or immune-related disease. For these reasons this complex genomic region is subject to intense scrutiny by researchers with the common goal of aiding further understanding and diagnoses of multiple immune-related diseases and syndromes. To aid assay development and characterization of the classical loci, a panel of cell lines partially or fully homozygous for HLA class I and II was assembled over time by the International Histocompatibility Working Group (IHWG). Containing a minimum of 88 unique HLA haplotypes, we show this panel represents a significant proportion of European HLA allelic and haplotype diversity (60–95%). Using a high-density whole genome array that includes 13,331 HLA region SNPs, we analyzed 99 IHWG cells to map the coordinates of the homozygous tracts at a fine scale. The mean homozygous tract length within chromosome 6 from these individuals is 21Mbp. Within HLA the mean haplotype length is 4.3Mbp, and 65% of the cell lines were shown to be homozygous throughout the entire region. In addition, four cell lines are homozygous throughout the complex KIR region of chromosome 19 (~250kbp). The data we describe will provide a valuable resource for characterizing haplotypes, designing and refining imputation algorithms and developing assay controls.
HLA class I; HLA class II; HLA region genes; Homozygous; HLA imputation; KIR
Donor killer immunoglobulin-like receptor (KIR) genotypes associate with relapse protection and survival after allotransplantation for acute myelogenous leukemia. We examined the possibility of a similar effect in a cohort of 614 non-Hodgkin lymphoma (NHL) patients receiving unrelated donor (URD) T-cell replete marrow or peripheral blood grafts. Sixty four percent (n=396) of donor-recipient pairs were 10/10 allele HLA-matched; 26% were 9/10 allele matched. Seventy percent of donors had KIR B/x genotype; the others had KIR A/A genotype. NHL patients receiving 10/10 HLA-matched URD grafts with KIR B/x donors experienced significantly lower relapse at 5 years (26%; CI 21–32% vs. 37%; CI 27–46%, p=0.05) compared with KIR A/A donors, resulting in improved 5 year progression-free survival (PFS) (35%; CI 26–44% vs. 22%; CI 11–35%; p=0.007). In multivariate analysis, use of KIR B/x donors associated with significantly reduced relapse risk (RR 0.63, p=0.02) and improved PFS (RR 0.71, p=0.008). The relapse protection afforded by KIR B/x donors was not observed in HLA-mismatched transplants, and was not specific to any particular KIR-B gene. Selecting 10/10 HLA-matched and KIR B/x donors should benefit patients with NHL receiving URD allogeneic transplantation.
non-Hodgkin lymphoma; KIR; allogeneic transplantation; genotype; NK cells
Cytomegalovirus (CMV) reactivates in >30% of CMV seropositive patients after allogeneic hematopoietic cell transplantation (HCT). Previously, we reported an increase of NK cells expressing NKG2C, CD57 and inhibitory killer-cell immunoglobulin-like receptors (KIRs) in response to CMV reactivation post-HCT. These NK cells persist after the resolution of infection and display ‘adaptive’ or memory properties. Despite these findings, the differential impact of persistent/inactive vs. reactivated CMV on NK vs. T cell maturation following HCT from different graft sources has not been defined. We compared the phenotype of NK and T cells from 292 recipients of allogeneic sibling (n = 118) or umbilical cord blood (UCB; n = 174) grafts based on recipient pre-transplant CMV serostatus and post-HCT CMV reactivation. This cohort was utilized to evaluate CMV-dependent increases in KIR-expressing NK cells exhibiting an ‘adaptive’ phenotype (NKG2C+CD57+). Compared to CMV seronegative recipients, those who reactivated CMV (React+) had the highest adaptive cell frequencies, while intermediate frequencies were observed in CMV seropositive recipients harboring persistent/non-replicating CMV. The same effect was observed in T cells and CD56+ T cells. These adaptive lymphocyte subsets were increased in CMV seropositive recipients of sibling, but not UCB grafts, and correlated with lower rates of CMV reactivation (sibling 33% vs. UCB 51%; p<0.01). These data suggest that persistent/non-replicating recipient CMV induces rapid production of adaptive NK and T cells from mature cells from sibling, but not UCB grafts. These adaptive lymphocytes are associated with protection from CMV reactivation.
Shaping natural killer (NK) cell functions in human immunity and reproduction are diverse killer-cell immunoglobulin-like receptors (KIRs) that recognize polymorphic MHC class I determinants. A survey of placental mammals suggests KIRs serve as variable NK cell receptors only in certain primates and artiodactyls. Divergence of functional and variable KIRs in primates and artiodactyls predates placental reproduction. Among artiodactyls, cattle but not pigs have diverse KIRs. Catarrhine (humans, apes, and Old World monkeys) and platyrrhine (New World monkeys) primates, but not prosimians, have diverse KIRs. Platyrrhine and catarrhine systems of KIR and MHC class I are highly diverged, but within the catarrhines a stepwise co-evolution of MHC class I and KIRs is discerned. In Old World monkeys, diversification focuses on MHC-A and MHC-B and their cognate lineage II KIR. With evolution of C1-bearing MHC-C from MHC-B, as informed by orangutan, the focus changes to MHC-C and its cognate lineage III KIR. Evolution of C2 from C1 and fixation of MHC-C, drove further elaboration of MHC-C-specific KIRs, as exemplified by chimpanzee. In humans, the evolutionary trajectory changes again. Emerging from reorganization of the KIR locus and selective attenuation of KIR avidity for MHC class I are the functionally distinctive KIR A and KIR B haplotypes.
NK cells; KIR; MHC class I; co-evolution
Killer-cell immunoglobulin-like receptors (KIRs) are encoded by one of the most polymorphic families in the human genome. KIRs are expressed on natural killer (NK) cells, which have dual roles: (1) in fighting infection and (2) in reproduction, regulating hemochorial placentation. Uniquely among primates, human KIR genes are arranged into two haplotypic combinations: KIR A and KIR B. It has been proposed that KIR A is specialized to fight infection, whilst KIR B evolved to help ensure successful reproduction. Here we demonstrate that a combination of infectious disease selection and reproductive selection can drive the evolution of KIR B-like haplotypes from a KIR A-like founder haplotype. Continued selection to survive and to reproduce maintains a balance between KIR A and KIR B.
Electronic supplementary material
The online version of this article (doi:10.1007/s00251-016-0935-9) contains supplementary material, which is available to authorized users.
Killer-cell immunoglobulin-like receptors (KIRs); Natural killer cells; Infectious disease; Reproduction; Human evolution
How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.
Natural killer (NK) cells are responsible for recognizing and killing transformed, stressed, and infected cells. They recognize a set of non-antigen-specific features termed “altered self” through combinatorial signals from activating and inhibitory receptors. These natural killer cell receptors (NKR) are also expressed on CD4+ and CD8+ T cells, B cells, and monocytes, though a comprehensive inventory of NKR expression patterns across leukocyte lineages has never been performed. Using mass cytometry, we found that NKR expression patterns distinguish cell lineages in human peripheral blood. In individuals with high levels of CD57, indicative of a mature immune repertoire, NKR are more likely to be expressed on non-NK cells, especially CD8+ T cells. Mature NK and CD8+ T cell populations show increased diversity of NKR surface expression patterns, but with distinct determinants: mature NK cells acquire primarily inhibitory receptors, while CD8+ T cells attain a specific subset of both activating and inhibitory receptors, potentially imbuing them with a distinct functional role. Concurrently, monocytes show decreased expression of the generalized inhibitory receptor LILRB1, consistent with an increased activation threshold. Therefore, NKR expression is coordinately regulated as the immune system matures, resulting in the transfer of “altered self” recognition potential among leukocyte lineages. This likely reduces antigen specificity in the mature human immune system, and implies that vaccines and therapeutics that engage both its innate and adaptive branches may be more effective in the settings of aging and chronic infection.
HLA class I molecules and killer cell immunoglobulin-like receptors (KIR) form a diverse system of ligands and receptors that individualize human immune systems in ways that improve the survival of individuals and populations. Human settlement of Oceania by island-hopping East and Southeast Asian migrants started ~3,500 years ago. Subsequently, New Zealand was reached ~750 years ago by ancestral Māori. To examine how this history impacted KIR and HLA diversity, and their functional interaction, we defined at high resolution the allelic and haplotype diversity of the 13 expressed KIR genes in 49 Māori and 34 Polynesians. Eighty KIR variants, including four ‘new’ alleles, were defined; as were 35 centromeric and 22 telomeric KIR region haplotypes, which combine to give >50 full-length KIR haplotypes. Two new and divergent variant KIR form part of a telomeric KIR haplotype, which appears derived from Papua New Guinea and was probably obtained by the Asian migrants en route to Polynesia. Māori and Polynesian KIR are very similar, but differ significantly from African, European, Japanese and Amerindian KIR. Māori and Polynesians have high KIR haplotype diversity with corresponding allotype diversity being maintained throughout the KIR locus. Within the population each individual has a unique combination of HLA class I and KIR. Characterizing Māori and Polynesians is a paucity of HLA-B allotypes recognized by KIR. Compensating for this deficiency are high frequencies (>50%) of HLA-A allotypes recognized by KIR. These HLA-A allotypes are ones that modern humans likely acquired from archaic humans at a much earlier time.
KIR; NK cells; HLA class I; immune diversity; Māori; Polynesian
Modulating natural killer cell functions in human immunity and reproduction are diverse interactions between the killer cell immunoglobulin-like receptors (KIR) of Natural Killer (NK) cells and HLA class I ligands on the surface of tissue cells. Dominant interactions are between KIR2DL1 and the C2 epitope of HLA-C and between KIR2DL2/3 and the C1 epitope of HLA-C. KhoeSan hunter-gatherers of Southern Africa represent the earliest population divergence known and are the most genetically diverse indigenous people, qualities reflected in their KIR and HLA genes. Of the ten KhoeSan KIR2DL1 alleles, KIR2DL1*022 and KIR2DL1*026 likely originated in the KhoeSan, and later were transmitted at low frequency to the neighboring Zulus through gene flow. These alleles arose by point mutation from other KhoeSan KIR2DL1 alleles that are more widespread globally. Mutation of KIR2DL1*001 gave rise to KIR2DL1*022, causing loss of C2 recognition and gain of C1 recognition. This makes KIR2DL1*022 a more avid and specific C1 receptor than any KIR2DL2/3 allotype. Mutation of KIR2DL1*012 gave rise to KIR2DL1*026, causing premature termination of translation at the end of the transmembrane domain. This makes KIR2DL1*026 a membrane-associated receptor that lacks both a cytoplasmic tail and signaling function. At higher frequencies than their parental allotypes, the combined effect of the KhoeSan-specific KIR2DL1*022 and KIR2DL1*026 is to reduce the frequency of strong inhibitory C2 receptors and increase the frequency of strong inhibitory C1 receptors. Because interaction of KIR2DL1 with C2 is associated with risk of pregnancy disorder, these functional changes are potentially advantageous. Whereas all other KhoeSan KIR2DL1 alleles are present on a wide diversity of centromeric KIR haplotypes, KIR2DL1*026 is present on a single KIR haplotype and KIR2DL1*022 is present on two very similar haplotypes. The high linkage disequilibrium across their haplotypes is consistent with a recent emergence for these KIR2DL1 alleles that have distinctive functions.
The genes that control the response of the human immune system vary enormously between individuals. Understanding the evolution of these genetic differences and how they individualize immune responses is central to understanding how the immune system works in health and disease. In this regard, the KhoeSan of southern Africa are particularly informative because they are genetically diverse, divergent from other modern human populations and have been subject to unique demographic history. In the KhoeSan population, we studied variable genes that control natural killer cell function. We identified two recently evolved, novel gene variants that have unusual function; one completely changed its ligand specificity and the other lost its capacity for signal transduction.
We conducted a nationwide study comparing self-identification to genetic ancestry classifications in a large cohort (n = 1752) from the National Marrow Donor Program. We sought to determine how various measures of self-identification intersect with genetic ancestry, with the aim of improving matching algorithms for unrelated bone marrow transplant. Multiple dimensions of self-identification, including race/ethnicity and geographic ancestry were compared to classifications based on ancestry informative markers (AIMs), and the human leukocyte antigen (HLA) genes, which are required for transplant matching. Nearly 20% of responses were inconsistent between reporting race/ethnicity versus geographic ancestry. Despite strong concordance between AIMs and HLA, no measure of self-identification shows complete correspondence with genetic ancestry. In certain cases geographic ancestry reporting matches genetic ancestry not reflected in race/ethnicity identification, but in other cases geographic ancestries show little correspondence to genetic measures, with important differences by gender. However, when respondents assign ancestry to grandparents, we observe sub-groups of individuals with well- defined genetic ancestries, including important differences in HLA frequencies, with implications for transplant matching. While we advocate for tailored questioning to improve accuracy of ancestry ascertainment, collection of donor grandparents’ information will improve the chances of finding matches for many patients, particularly for mixed-ancestry individuals.
Major histocompatibility complex (MHC) class I molecules determine immune responses to viral infections. These polymorphic cell-surface glycoproteins bind peptide antigens, forming ligands for cytotoxic T and natural killer cell receptors. Under pressure from rapidly evolving viruses, hominoid MHC class I molecules also evolve rapidly, becoming diverse and species-specific. Little is known of the impact of infectious disease epidemics on MHC class I variant distributions in human populations, a context in which the chimpanzee is the superior animal model. Population dynamics of the chimpanzees inhabiting Gombe National Park, Tanzania have been studied for over 50 years. This population is infected with SIVcpz, the precursor of human HIV-1. Because HLA-B is the most polymorphic human MHC class I molecule and correlates strongly with HIV-1 progression, we determined sequences for its ortholog, Patr-B, in 125 Gombe chimpanzees. Eleven Patr-B variants were defined, as were their frequencies in Gombe’s three communities, changes in frequency with time, and effect of SIVcpz infection. The growing populations of the northern and central communities, where SIVcpz is less prevalent, have stable distributions comprising a majority of low-frequency Patr-B variants and a few high-frequency variants. Driving the latter to high frequency has been the fecundity of immigrants to the northern community, whereas in the central community, it has been the fecundity of socially dominant individuals. In the declining population of the southern community, where greater SIVcpz prevalence is associated with mortality and emigration, Patr-B variant distributions have been changing. Enriched in this community are Patr-B variants that engage with natural killer cell receptors. Elevated among SIVcpz-infected chimpanzees, the Patr-B*06:03 variant has striking structural and functional similarities to HLA-B*57, the human allotype most strongly associated with delayed HIV-1 progression. Like HLA-B*57, Patr-B*06:03 correlates with reduced viral load, as assessed by detection of SIVcpz RNA in feces.
Wild chimpanzee populations maintain a diversity of major histocompatibility class I variants; one variant, enriched among chimpanzees infected with simian immunodeficiency virus, resembles the human variant that best impedes progression of HIV-1 infection.
Polymorphic major histocompatibility complex (MHC) class I molecules activate immune responses against infection and correlate with susceptibilities to disease. In humans, longitudinal study of how disease epidemics alter MHC frequencies has not been possible. We studied chimpanzees, a species having direct equivalents of all human MHC class I genes. The wild Gombe chimpanzees are naturally infected with simian immunodeficiency virus (SIVcpz) and have been studied long-term. From samples of fecal DNA we sequenced Patr-B—the most polymorphic MHC gene—from 125 chimpanzees and identified eleven Patr-B alleles. Over a 15-year period, two of three social communities flourished, maintaining one or two high-frequency Patr-B alleles and many low-frequency alleles. The high frequencies were caused by the reproductive success of immigrants in one community and socially dominant, fecund individuals in the other. The third community declined, partly because of SIVcpz, experiencing greater change in Patr-B allele frequencies. In SIVcpz-infected chimpanzees, three Patr-B alleles are overrepresented, and one is underrepresented. Allele Patr-B*06:03 resembles HLA-B*57:01—the human MHC molecule that strongly resists HIV by reducing viral load. Patr-B*06:03 correlates with reduced SIVcpz load and likely lessens the impact of SIVcpz infection. HLA-B*57:01 and Patr-B*06:03 are related in structure, function and evolution, forming part of an exceptional trans-species group of hominid MHC-B alleles.
Killer cell immunoglobulin-like receptors (KIR) interact with HLA class I ligands to regulate NK cell development and function. These interactions affect the outcome of unrelated donor (URD) hematopoietic cell transplantation (HCT). We have shown previously that donors with KIR B vs. KIR A haplotypes improve the clinical outcome for patients with acute myelogenous leukemia (AML) by reducing the incidence of leukemic relapse and improving leukemia free survival (LFS). Both centromeric and telomeric KIR B genes contribute to the effect, but the centromeric genes are dominant. They include the genes encoding inhibitory KIR that are specific for the C1 and C2 epitopes of HLA-C. We used an expanded cohort of 1532 T-cell replete transplants to examine the interaction between donor KIR B genes and recipient Class I HLA KIR ligands. The relapse protection associated with donor KIR B is enhanced in recipients who have one or two C1-bearing HLA-C allotypes, compared to C2 homozygous recipients, with no effect based on donor HLA. The protective interaction between donors with ≥2 vs. 0–1 KIR B-motifs and recipient C1 was specific to transplants with class I mismatch at HLA-C (RR of LFS 0.57 [0.40–0.79]; P=0.001) irrespective of the KIR ligand mismatch status of the transplant. The survival advantage and relapse protection in C1/x recipients compared to C2/C2 recipients was similar irrespective of the particular donor KIR B genes. Understanding the interactions between donor KIR and recipient HLA class I can be used to inform donor selection to improve outcome of URD HCT for AML.
Under selection pressure from pathogens, variable NK cell receptors that recognize polymorphic MHC class I, evolved convergently in different species of placental mammal. Unexpectedly, the killer cell immunoglobulin-like receptors (KIR) are shared by simian primates, including humans, and cattle but not by other species. Whereas much is known of human KIR genetics and genomics, knowledge of cattle KIR is limited to nine cDNA sequences. To facilitate comparison of the cattle and human KIR gene families, we determined the genomic location, structure and sequence of two cattle KIR haplotypes and defined KIR sequences of aurochs, the extinct wild ancestor of domestic cattle. Larger than its human counterpart, the cattle KIR locus evolved through successive duplications of a block containing ancestral KIR3DL and KIR3DX genes that existed before placental mammals. Comparison of two cattle KIR haplotypes and aurochs KIR show the KIR are polymorphic and the gene organization and content appears conserved. Of 18 genes 8 are functional and 10 were inactivated by point mutation. Selective inactivation of KIR3DL and activating receptor genes, leaves a functional cohort of one inhibitory KIR3DL, one activating KIR3DX and six inhibitory KIR3DX. Functional KIR diversity evolved from KIR3DX in cattle and from KIR3DL in simian primates. Although independently evolved, cattle and human KIR gene families share important function-related key properties, indicating that cattle KIR are NK cell receptors for cattle MHC class I. Combinations of KIR and MHC class I are the major genetic factors associated with human disease and merits investigation in cattle.
The Immuno Polymorphism Database (IPD) was developed to provide a centralized system for the study of polymorphism in genes of the immune system. Through the IPD project we have established a central platform for the curation and publication of locus-specific databases involved either directly or related to the function of the Major Histocompatibility Complex in a number of different species. We have collaborated with specialist groups or nomenclature committees that curate the individual sections before they are submitted to IPD for online publication. IPD consists of five core databases, with the IMGT/HLA Database as the primary database. Through the work of the various nomenclature committees, the HLA Informatics Group and in collaboration with the European Bioinformatics Institute we are able to provide public access to this data through the website http://www.ebi.ac.uk/ipd/. The IPD project continues to develop with new tools being added to address scientific developments, such as Next Generation Sequencing, and to address user feedback and requests. Regular updates to the website ensure that new and confirmatory sequences are dispersed to the immunogenetics community, and the wider research and clinical communities.
Under selection pressure from pathogens, variable NK cell receptors that recognize polymorphic MHC class I evolved convergently in different species of placental mammal. Unexpectedly, diversified killer cell Ig–like receptors (KIRs) are shared by simian primates, including humans, and cattle, but not by other species. Whereas much is known of human KIR genetics and genomics, knowledge of cattle KIR is limited to nine cDNA sequences. To facilitate comparison of the cattle and human KIR gene families, we determined the genomic location, structure, and sequence of two cattle KIR haplotypes and defined KIR sequences of aurochs, the extinct wild ancestor of domestic cattle. Larger than its human counterpart, the cattle KIR locus evolved through successive duplications of a block containing ancestral KIR3DL and KIR3DX genes that existed before placental mammals. Comparison of two cattle KIR haplotypes and aurochs KIR show the KIR are polymorphic and the gene organization and content appear conserved. Of 18 genes, 8 are functional and 10 were inactivated by point mutation. Selective inactivation of KIR3DL and activating receptor genes leaves a functional cohort of one inhibitory KIR3DL, one activating KIR3DX, and six inhibitory KIR3DX. Functional KIR diversity evolved from KIR3DX in cattle and from KIR3DL in simian primates. Although independently evolved, cattle and human KIR gene families share important function-related properties, indicating that cattle KIR are NK cell receptors for cattle MHC class I. Combinations of KIR and MHC class I are the major genetic factors associated with human disease and merit investigation in cattle.
Natural Killer (NK) cells play critical roles in immune defense and reproduction, yet remain the most poorly understood major lymphocyte population. Because their activation is controlled by a variety of combinatorially expressed activating and inhibitory receptors, NK cell diversity and function are closely linked. To provide an unprecedented understanding of NK cell repertoire diversity, we used mass cytometry to simultaneously analyze 35 parameters, including 28 NK cell receptors, on peripheral blood NK cells from five sets of monozygotic twins and twelve unrelated donors of defined HLA and killer cell immunoglobulin-like receptor (KIR) genotype. This analysis revealed a remarkable degree of NK cell diversity, with an estimated 6,000-30,000 phenotypic populations within an individual and >100,000 phenotypes in this population. Genetics largely determined inhibitory receptor expression, whereas activation receptor expression was heavily environmentally influenced. Therefore, NK cells may maintain self-tolerance through strictly regulated expression of inhibitory receptors, while using adaptable expression patterns of activating and costimulatory receptors to respond to pathogens and tumors. These findings further suggest the possibility that discrete NK cell subpopulations could be harnessed for immunotherapeutic strategies in the settings of infection, reproduction, and transplantation.
Allotypes of the natural killer (NK) cell receptor KIR3DL1 vary in both NK cell expression patterns and inhibitory capacity upon binding to their ligands, HLA-B Bw4 molecules, present on target cells. Using a sample size of over 1,500 human immunodeficiency virus (HIV)+ individuals, we show that various distinct allelic combinations of the KIR3DL1 and HLA-B loci significantly and strongly influence both AIDS progression and plasma HIV RNA abundance in a consistent manner. These genetic data correlate very well with previously defined functional differences that distinguish KIR3DL1 allotypes. The various epistatic effects observed here for common, distinct KIR3DL1 and HLA-B Bw4 combinations are unprecedented with regard to any pair of genetic loci in human disease, and indicate that NK cells may have a critical role in the natural history of HIV infection.
Targeted capture of genomic regions reduces sequencing cost while generating
higher coverage by allowing biomedical researchers to focus on specific loci
of interest, such as exons. Targeted capture also has the potential to
facilitate the generation of genomic data from DNA collected via saliva or
buccal cells. DNA samples derived from these cell types tend to have a lower
human DNA yield, may be degraded from age and/or have contamination from
bacteria or other ambient oral microbiota. However, thousands of samples
have been previously collected from these cell types, and saliva collection
has the advantage that it is a non-invasive and appropriate for a wide
variety of research.
We demonstrate successful enrichment and sequencing of 15 South African
KhoeSan exomes and 2 full genomes with samples initially derived from
saliva. The expanded exome dataset enables us to characterize genetic
diversity free from ascertainment bias for multiple KhoeSan populations,
including new exome data from six HGDP Namibian San, revealing substantial
population structure across the Kalahari Desert region. Additionally, we
discover and independently verify thirty-one previously unknown KIR
alleles using methods we developed to accurately map and call the highly
polymorphic HLA and KIR loci from exome capture data.
Finally, we show that exome capture of saliva-derived DNA yields sufficient
non-human sequences to characterize oral microbial communities, including
detection of bacteria linked to oral disease (e.g. Prevotella
melaninogenica). For comparison, two samples were sequenced using
standard full genome library preparation without exome capture and we found
no systematic bias of metagenomic information between exome-captured and
DNA from human saliva samples, collected and extracted using standard
procedures, can be used to successfully sequence high quality human exomes,
and metagenomic data can be derived from non-human reads. We find that
individuals from the Kalahari carry a higher oral pathogenic microbial load
than samples surveyed in the Human Microbiome Project. Additionally, rare
variants present in the exomes suggest strong population structure across
different KhoeSan populations.
Exomes; KhoeSan; Genetic diversity; Metagenomics; Microbiome
Monoclonal antibodies with specificity for HLA class I determinants of HLA were originally characterized using serological assays in which the targets were cells expressing 3-6 HLA class I variants. Because of this complexity, the specificities of the antibodies were defined indirectly by correlation. Here we use a direct binding assay, in which the targets are synthetic beads coated with one of 111 HLA class I variants, representing the full range of HLA-A, -B and -C variation. We studied one monoclonal antibody with monomorphic specificity (W6/32) and four with polymorphic specificity (MA2.1, PA2.1, BB7.2 and BB7.1) and compared the results with those obtained previously. W6/32 reacted with all HLA class I variants. MA2.1 exhibits high specificity for HLA-A*02, -B*57 and -B*58, but also exhibited cross-reactivity with HLA-A*11 and -B*15:16. At low concentration (1μg/ml) PA2.1 and BB7.2 were both specific for HLA-A*02 and -A*69, and at high concentration (50μg/ml) exhibited significant cross-reactions with HLA-A*68, -A*23, and -A*24. BB7.1 exhibits specificity for HLA-B*07 and -B*42, as previously described, but reacts equally well with HLA-B*81, a rare allotype defined some 16 years after the description of BB7.1. The results obtained with cell-based and bead-based assays are consistent and, in combination with amino acid sequence comparison, increase understanding of the polymorphic epitopes recognized by the MA2.1, PA2.1, BB7.2 and BB7.1 antibodies. Comparison of two overlapping but distinctive bead sets from two sources gave similar results, but the overall levels of binding were significantly different. Several weaker reactions were observed with only one of the bead sets.
HLA class I; monoclonal antibodies; epitope; polymorphism