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Sample records for nonclassical mhc class

  1. A nonclassical MHC class I U lineage locus in zebrafish with a null haplotypic variant

    PubMed Central

    Dirscherl, Hayley; Yoder, Jeffrey A.

    2015-01-01

    Three sequence lineages of MHC class I genes have been described in zebrafish (Danio rerio): U, Z, and L. The U lineage genes encoded on zebrafish chromosome 19 are predicted to provide the classical function of antigen presentation. This MHC class I locus displays significant haplotypic variation and is the only MHC class I locus in zebrafish that shares conserved synteny with the core mammalian MHC. Here we describe two MHC class I U lineage genes, mhc1ula and mhc1uma, that map to chromosome 22. Unlike the U lineage proteins encoded on chromosome 19, Ula and Uma likely play a nonclassical role as they lack conservation of key peptide binding residues, display limited polymorphic variation, and exhibit tissue-specific expression. We also describe a null haplotype at this chromosome 22 locus in which the mhc1ula and mhc1uma genes are absent due to a ∼30 kb deletion with no other MHC class I sequences present. Functional and non-functional transcripts of mhc1ula and mhc1uma were identified; however, mhc1uma transcripts were often not amplified or amplified at low levels from individuals possessing an apparently bona fide gene. These distinct U lineage genes may be restricted to the superorder Ostariophysi as similar sequences only could be identified from the blind cavefish (Astyanyx mexicanus), fathead minnow (Pimephales promelas), goldfish (Carassius auratus), and grass carp (Ctenopharyngodon idellus). PMID:26254596

  2. Molecular characterization of classical and nonclassical MHC class I genes from the golden pheasant (Chrysolophus pictus).

    PubMed

    Zeng, Q-Q; Zhong, G-H; He, K; Sun, D-D; Wan, Q-H

    2016-02-01

    Classical major histocompatibility complex (MHC) class I allelic polymorphism is essential for competent antigen presentation. To improve the genotyping efforts in the golden pheasant, it is necessary to differentiate more accurately between classical and nonclassical class I molecules. In our study, all MHC class I genes were isolated from one golden pheasant based on two overlapping PCR amplifications. In total, six full-length class I nucleotide sequences (A-F) were identified, and four were novel. Two (A and C) belonged to the IA1 gene, two (B and D) were alleles derived from the IA2 gene through transgene amplification, and two (E and F) comprised a third novel locus, IA3 that was excluded from the core region of the golden pheasant MHC-B. IA1 and IA2 exhibited the broad expression profiles characteristic of classical loci, while IA3 showed no expression in multiple tissues and was therefore defined as a nonclassical gene. Phylogenetic analysis indicated that the three IA genes in the golden pheasant share a much closer evolutionary relationship than the corresponding sequences in other galliform species. This observation was consistent with high sequence similarity among them, which likely arises from the homogenizing effect of recombination. Our careful distinction between the classical and nonclassical MHC class I genes in the golden pheasant lays the foundation for developing locus-specific genotyping and establishing a good molecular marker system of classical MHC I loci.

  3. Spatial-Temporal Expression of Non-classical MHC Class I Molecules in the C57 Mouse Brain.

    PubMed

    Liu, Jiane; Shen, Yuqing; Li, Mingli; Lv, Dan; Zhang, Aifeng; Peng, Yaqin; Miao, Fengqin; Zhang, Jianqiong

    2015-07-01

    Recent studies clearly demonstrate major histocompatibility complex (MHC) class I expression in the brain plays an important functional role in neural development and plasticity. A previous study from our laboratory demonstrated the temporal and spatial expression patterns of classical MHC class I molecules in the brain of C57 mice. Studies regarding non-classical MHC class I molecules remain limited. Here we examine the expression of non-classical MHC class I molecules in mouse central nervous system (CNS) during embryonic and postnatal developmental stages using in situ hybridization and immunofluorescence. We find non-classical MHC class I molecules, M3/T22/Q1, are expressed in the cerebral cortex, neuroepithelium of the lateral ventricle, neuroepithelium of aquaeductus and developing cerebellum during embryonic developmental stages. During the postnatal period from P0 to adult, non-classical MHC class I mRNAs are detected in olfactory bulb, hippocampus, cerebellum and some nerve nuclei. Overall, the expression patterns of non-classical MHC class I molecules are similar to those of classical MHC class I molecules in the developing mouse brain. In addition, non-classical MHC class I molecules are present in the H2-K(b) and H2-D(b) double knock-out mice where their expression levels are greatly increased within the same locations as compared to wild type mice. The elucidation and discovery of the expression profile of MHC class I molecules during development is important for supporting an enhanced understanding of their physiological and potential pathological roles within the CNS.

  4. Comparison of the transcriptional regulation of classical and non-classical MHC class II genes.

    PubMed

    Hake, Sandra B; Tobin, Helen M; Steimle, Viktor; Denzin, Lisa K

    2003-09-01

    The class II transactivator (CIITA) regulates expression of the classical and non-classical MHC class II genes, HLA-DR, -DP, -DQ and -DM, but not the B cell-specific HLA-DO (DO). Here we show that only HLA-DR expression is completely dependent on CIITA, since residual expression of HLA-DM, -DP and the beta chain of DQ was observed in CIITA-deficient RJ2.2.5 cells. Although DO shows a unique expression pattern compared to other MHC class II genes, prolonged IFN-gamma treatment of HeLa cells induced DOB expression. Similar to all MHC class II promoters, the DOB promoter contains the highly conserved W, X1, and Y boxes in addition to a putative OCT box. Mutational analysis of the DOB promoter demonstrated that the X1, Y and OCT boxes are necessary for maximum promoter activity.Furthermore, our results demonstrate that CREB-1, RFXANK and Oct-2 occupy the DOB promoter in vivo, However, CIITA and Bob-1 were only minimally recruited. Finally, fusion of Bjab, a DOB-negative B cell line, with.174 B cells that lack the complete MHC class II region (including the DO genes), lead to DO expression. These data indicate that the expression of DO is regulated by an unidentified factor in B cells.

  5. Characterisation of non-classical MHC class I genes in the Tasmanian devil (Sarcophilus harrisii).

    PubMed

    Cheng, Yuanyuan; Belov, Katherine

    2014-12-01

    The Tasmanian devil (Sarcophilus harrisii) is a carnivorous marsupial that is under threat of extinction due to an unusual transmissible disease called Devil Facial Tumour Disease (DFTD). Previous studies on the classical MHC genes have provided important insights into immune responses in this endangered species; however, so far, very little is known about the non-classical MHC genes of this species, which can also play significant roles in the immune system. Here, we report characterisation of five non-classical class I genes in the Tasmanian devil, including Saha-UD, -UK, -UM, -MR1 and -CD1. Saha-UD has been isolated previously and is known to have low genetic polymorphism, though its categorisation as classical or non-classical gene has remained undetermined. In this study, we observed tissue-specific expression of Saha-UD, suggesting that it is more characteristic of a non-classical gene. Restricted tissue expression patterns were also observed for other genes, with an exception of Saha-MR1 being ubiquitously expressed in all examined tissues. Saha-UK, -UM and -MR1 were found to be genetically monomorphic, while four alleles were found at Saha-CD1 with signs of positive selection detected within the α1 domain. Among the four Saha-CD1 alleles, one predominant allele (Saha-CD1*01) showed a high allele frequency of 0.906 in the Tasmanian devil population, resulting in a low heterozygosity (0.188) at this locus. Alternative splicing takes place in Saha-CD1, giving rise to a full-length transcript and a splice variant lacking intact antigen-binding, β2m-binding, transmembrane and cytoplasmic domains.

  6. Characterization of a non-classical MHC class II gene in the vulnerable Chinese egret (Egretta eulophotes).

    PubMed

    Lei, Wei; Fang, Wenzhen; Lin, Qingxian; Zhou, Xiaoping; Chen, Xiaolin

    2015-08-01

    Genes of the major histocompatibility complex (MHC) are valuable makers of adaptive genetic variation in evolutionary ecology research, yet the non-classical MHC genes remain largely unstudied in wild vertebrates. In this study, we have characterized the non-classical MHC class II gene, Egeu-DAB4, in the vulnerable Chinese egret (Ciconiiformes, Ardeidae, Egretta eulophotes). Gene expression analyses showed that Egeu-DAB4 gene had a restricted tissue expression pattern, being expressed in seven examined tissues including the liver, heart, kidney, esophagus, stomach, gallbladder, and intestine, but not in muscle. With respect to polymorphism, only one allele of exon 2 was obtained from Egeu-DAB4 using asymmetric PCR, indicating that Egeu-DAB4 is genetically monomorphic in exon 2. Comparative analyses showed that Egeu-DAB4 had an unusual sequence, with amino acid differences suggesting that its function may differ from those of classical MHC genes. Egeu-DAB4 gene was only found in 30.56-36.56 % of examined Chinese egret individuals. Phylogenetic analysis showed a closer relationship between Egeu-DAB4 and the DAB2 genes in nine other ardeid species. These new findings provide a foundation for further studies to clarify the immunogenetics of non-classical MHC class II gene in the vulnerable Chinese egret and other ciconiiform birds.

  7. Nonclassical MHC class I-dependent invariant T cells are evolutionarily conserved and prominent from early development in amphibians.

    PubMed

    Edholm, Eva-Stina; Albertorio Saez, Liz-Marie; Gill, Ann L; Gill, Steven R; Grayfer, Leon; Haynes, Nikesha; Myers, Jason R; Robert, Jacques

    2013-08-27

    Human and murine MHC nonclassical class Ib-restricted invariant T (iT) cell subsets, such as invariant natural killer T cells (iNKT) and mucosal-associated invariant T cells, have specialized functions early in immune responses, especially in modulating subsequent adaptive immune responses. Here, we characterize a prominent iT population in the amphibian Xenopus laevis and show the requirement of the class Ib molecule, Xenopus nonclassical gene 10, in its differentiation and function. Using Xenopus nonclassical gene 10 tetramers and RNAi loss of function by transgenesis, we identified a large class Ib-dependent CD8(-)/CD4(-) iT subset in unmanipulated frogs and tadpoles. This population is critical for antiviral immunity during early larval stages when classical MHC class Ia function is suboptimal. Furthermore, in young tadpoles with low class Ia expression, deep sequencing revealed additional preponderant invariant T cell receptor (TCR)α rearrangements, implying other iT cell subsets and a predominant selection process mediated by other class Ib molecules. The restriction and requirement of class Ib molecules for development and antiviral immunity of a mammalian iNKT or mucosal-associated invariant T cell counterpart in the amphibian Xenopus show the importance of iT cells in the emergence and evolution of the adaptive immune system.

  8. Characterization of a nonclassical class I MHC gene in a reptile, the Galápagos marine iguana (Amblyrhynchus cristatus).

    PubMed

    Glaberman, Scott; Du Pasquier, Louis; Caccone, Adalgisa

    2008-08-06

    Squamates are a diverse order of vertebrates, representing more than 7,000 species. Yet, descriptions of full-length major histocompatibility complex (MHC) genes in this group are nearly absent from the literature, while the number of MHC studies continues to rise in other vertebrate taxa. The lack of basic information about MHC organization in squamates inhibits investigation into the relationship between MHC polymorphism and disease, and leaves a large taxonomic gap in our understanding of amniote MHC evolution. Here, we use both cDNA and genomic sequence data to characterize a class I MHC gene (Amcr-UA) from the Galápagos marine iguana, a member of the squamate subfamily Iguaninae. Amcr-UA appears to be functional since it is expressed in the blood and contains many of the conserved peptide-binding residues that are found in classical class I genes of other vertebrates. In addition, comparison of Amcr-UA to homologous sequences from other iguanine species shows that the antigen-binding portion of this gene is under purifying selection, rather than balancing selection, and therefore may have a conserved function. A striking feature of Amcr-UA is that both the cDNA and genomic sequences lack the transmembrane and cytoplasmic domains that are necessary to anchor the class I receptor molecule into the cell membrane, suggesting that the product of this gene is secreted and consequently not involved in classical class I antigen-presentation. The truncated and conserved character of Amcr-UA lead us to define it as a nonclassical gene that is related to the few available squamate class I sequences. However, phylogenetic analysis placed Amcr-UA in a basal position relative to other published classical MHC genes from squamates, suggesting that this gene diverged near the beginning of squamate diversification.

  9. Transcription of non-classic major histocompatibility complex (MHC) class I in the bovine placenta throughout gestation and after Brucella abortus infection.

    PubMed

    Dos Santos, Larissa Sarmento; da Silva Mol, Juliana Pinto; de Macedo, Auricélio Alves; Silva, Ana Patrícia Carvalho; Dos Santos Ribeiro, Diego Luiz; Santos, Renato Lima; da Paixão, Tatiane Alves; de Carvalho Neta, Alcina Vieira

    2015-10-15

    Transcription of non-classical major histocompatibility complex class I (MHC-I) was assessed in the bovine placenta throughout gestation. Additionally, the effect of Brucella abortus infection on expression of non-classical MHC-I was also evaluated using a chorioallantoic membrane explant model of infection. The non-classical MHC-I genes MICB and NC3 had higher levels of transcription in the intercotyledonary region when compared to the placentome, which had higher levels of transcription at the second trimester of gestation. NC1 and classical MHC-I had very low levels of transcription throughout gestation. Trophoblastic cells of B. abortus-infected chorioallantoic membrane explants had an increase in transcription of non-classical MHC-I at 4h post infection. Therefore, this study provides an analysis of non-classical MHC-I transcription at different stages of gestation and different placental tissues, and during B. abortus infection. These findings provide additional knowledge on immune regulation in placental tissues, a known immune-privileged site.

  10. Evolution of nonclassical MHC-dependent invariant T cells.

    PubMed

    Edholm, Eva-Stina; Grayfer, Leon; Robert, Jacques

    2014-12-01

    TCR-mediated specific recognition of antigenic peptides in the context of classical MHC molecules is a cornerstone of adaptive immunity of jawed vertebrate. Ancillary to these interactions, the T cell repertoire also includes unconventional T cells that recognize endogenous and/or exogenous antigens in a classical MHC-unrestricted manner. Among these, the mammalian nonclassical MHC class I-restricted invariant T cell (iT) subsets, such as iNKT and MAIT cells, are now believed to be integral to immune response initiation as well as in orchestrating subsequent adaptive immunity. Until recently the evolutionary origins of these cells were unknown. Here we review our current understanding of a nonclassical MHC class I-restricted iT cell population in the amphibian Xenopus laevis. Parallels with the mammalian iNKT and MAIT cells underline the crucial biological roles of these evolutionarily ancient immune subsets.

  11. Evolution of nonclassical MHC-dependent invariant T cells

    PubMed Central

    Edholm, Eva-Stina; Grayfer, Leon; Robert, Jacques

    2014-01-01

    TCR-mediated specific recognition of antigenic peptides in the context of classical MHC molecules is a cornerstone of adaptive immunity of jawed vertebrate. Ancillary to these interactions, the T cell repertoire also includes unconventional T cells that recognize endogenous and/or exogenous antigens in a classical MHC-unrestricted manner. Among these, the mammalian nonclassical MHC class I-restricted invariant T cell (iT) subsets, such as iNKT and MAIT cells, are now believed to be integral to immune response initiation as well as in orchestrating subsequent adaptive immunity. Until recently the evolutionary origins of these cells were unknown. Here we review our current understanding of a nonclassical MHC class I-restricted iT cell population in the amphibian Xenopus laevis. Parallels with the mammalian iNKT and MAIT cells underline the crucial biological roles of these evolutionarily ancient immune subsets. PMID:25117267

  12. Nonclassical antigen-processing pathways are required for MHC class II-restricted direct tumor recognition by NY-ESO-1-specific CD4(+) T cells.

    PubMed

    Matsuzaki, Junko; Tsuji, Takemasa; Luescher, Immanuel; Old, Lloyd J; Shrikant, Protul; Gnjatic, Sacha; Odunsi, Kunle

    2014-04-01

    Tumor antigen-specific CD4(+) T cells that directly recognize cancer cells are important for orchestrating antitumor immune responses at the local tumor sites. However, the mechanisms of direct MHC class II (MHC-II) presentation of intracellular tumor antigen by cancer cells are poorly understood. We found that two functionally distinct subsets of CD4(+) T cells were expanded after HLA-DPB1*04 (DP04)-binding NY-ESO-1157-170 peptide vaccination in patients with ovarian cancer. Although both subsets recognized exogenous NY-ESO-1 protein pulsed on DP04(+) target cells, only one type recognized target cells with intracellular expression of NY-ESO-1. The tumor-recognizing CD4(+) T cells more efficiently recognized the short 8-9-mer peptides than the non-tumor-recognizing CD4(+) T cells. In addition to endosomal/lysosomal proteases that are typically involved in MHC-II antigen presentation, several pathways in the MHC class I presentation pathways, such as the proteasomal degradation and transporter-associated with antigen-processing-mediated peptide transport, were also involved in the presentation of intracellular NY-ESO-1 on MHC-II. The presentation was inhibited significantly by primaquine, a small molecule that inhibits endosomal recycling, consistent with findings that pharmacologic inhibition of new protein synthesis enhances antigen presentation. Together, our data demonstrate that cancer cells selectively present peptides from intracellular tumor antigens on MHC-II by multiple nonclassical antigen-processing pathways. Harnessing the direct tumor-recognizing ability of CD4(+) T cells could be a promising strategy to enhance antitumor immune responses in the immunosuppressive tumor microenvironment.

  13. Analysis of MHC class I genes across horse MHC haplotypes

    PubMed Central

    Tallmadge, Rebecca L.; Campbell, Julie A.; Miller, Donald C.; Antczak, Douglas F.

    2010-01-01

    The genomic sequences of 15 horse Major Histocompatibility Complex (MHC) class I genes and a collection of MHC class I homozygous horses of five different haplotypes were used to investigate the genomic structure and polymorphism of the equine MHC. A combination of conserved and locus-specific primers was used to amplify horse MHC class I genes with classical and non-classical characteristics. Multiple clones from each haplotype identified three to five classical sequences per homozygous animal, and two to three non-classical sequences. Phylogenetic analysis was applied to these sequences and groups were identified which appear to be allelic series, but some sequences were left ungrouped. Sequences determined from MHC class I heterozygous horses and previously described MHC class I sequences were then added, representing a total of ten horse MHC haplotypes. These results were consistent with those obtained from the MHC homozygous horses alone, and 30 classical sequences were assigned to four previously confirmed loci and three new provisional loci. The non-classical genes had few alleles and the classical genes had higher levels of allelic polymorphism. Alleles for two classical loci with the expected pattern of polymorphism were found in the majority of haplotypes tested, but alleles at two other commonly detected loci had more variation outside of the hypervariable region than within. Our data indicate that the equine Major Histocompatibility Complex is characterized by variation in the complement of class I genes expressed in different haplotypes in addition to the expected allelic polymorphism within loci. PMID:20099063

  14. Hsp72 mediates stronger antigen-dependent non-classical MHC class Ib anti-tumor responses than hsc73 in Xenopus laevis.

    PubMed

    Nedelkovska, Hristina; Robert, Jacques

    2013-01-01

    The heat shock proteins (HSPs) gp96 and HSP70 mediate potent antigen-dependent anti-tumor T cell responses in both mammals and Xenopus laevis. We have shown that frogs immunized with total HSP70 generate CD8+ T cell responses against the Xenopus thymic lymphoid tumor 15/0 that expresses several non-classical MHC class Ib (class Ib) genes, but no classical MHC class Ia (class Ia). In the absence of class Ia, we hypothesized that hsp72 can prime class Ib-mediated anti-tumor unconventional CD8+ T cells in an antigen-dependent manner. To test this, we produced Xenopus recombinant HSP70 proteins (both the cognate hsc73 and the inducible hsp72) from stable 15/0 tumor transfectants. We used an in vivo cross-presentation assay to prime animals by adoptive transfer of HSP-pulsed antigen-presenting cells (APCs) and showed that both hsp72-and hsc73-Ag complexes have a similar potential to elicit class Ia-mediated T cell responses against minor histocompatibility (H) Ag skin grafts. In contrast, our in vivo cross-presentation assay revealed that hsp72 was more potent than hsc73 in generating protective immune responses against the class Ia-negative 15/0 tumors in an Ag-dependent and class Ib-mediated manner. These results suggest that hsp72 can stimulate class Ib-mediated immune responses and represents a promising candidate for immunotherapy against malignancies with downregulated class Ia expression.

  15. Characterization and locus-specific typing of MHC class I genes in the red-billed gull (Larus scopulinus) provides evidence for major, minor, and nonclassical loci.

    PubMed

    Cloutier, Alison; Mills, James A; Baker, Allan J

    2011-06-01

    A major challenge facing studies of major histocompatibility complex (MHC) evolution in birds is the difficulty in genotyping alleles at individual loci, and the consequent inability to investigate sequence variation and selection pressures for each gene. In this study, four MHC class I loci were isolated from the red-billed gull (Larus scopulinus), representing both the first characterized MHCI genes within Charadriiformes (shorebirds, gulls, and allies) and the first full-length MHCI sequences described outside Galloanserae (gamebirds + waterfowl). Complete multilocus genotypes were obtained for 470 individuals using a combination of reference-strand conformation analysis and direct sequencing of gene-specific amplification products, and variation of peptide-binding region (PBR) exons was surveyed for all loci. Each gene is transcribed and has conserved sequence features characteristic of antigen-presenting MHCI molecules. However, higher allelic variation, a more even allele frequency distribution, and evidence of positive selection acting on a larger number of PBR residues suggest that only one locus (Lasc-UAA) functions as a major classical MHCI gene. Lasc-UBA, with more limited variation and PBR motifs that encompass a subset of Lasc-UAA diversity, was assigned a putative minor classical function, whereas the divergent and largely invariant binding-groove motifs of Lasc-UCA and -UDA are suggestive of nonclassical loci with specialized ligand-binding roles.

  16. Unusual evolutionary conservation and further species-specific adaptations of a large family of nonclassical MHC class Ib genes across different degrees of genome ploidy in the amphibian subfamily Xenopodinae.

    PubMed

    Edholm, Eva-Stina; Goyos, Ana; Taran, Joseph; De Jesús Andino, Francisco; Ohta, Yuko; Robert, Jacques

    2014-06-01

    Nonclassical MHC class Ib (class Ib) genes are a family of highly diverse and rapidly evolving genes wherein gene numbers, organization, and expression markedly differ even among closely related species rendering class Ib phylogeny difficult to establish. Whereas among mammals there are few unambiguous class Ib gene orthologs, different amphibian species belonging to the anuran subfamily Xenopodinae exhibit an unusually high degree of conservation among multiple class Ib gene lineages. Comparative genomic analysis of class Ib gene loci of two divergent (~65 million years) Xenopodinae subfamily members Xenopus laevis (allotetraploid) and Xenopus tropicalis (diploid) shows that both species possess a large cluster of class Ib genes denoted as Xenopus/Silurana nonclassical (XNC/SNC). Our study reveals two distinct phylogenetic patterns among these genes: some gene lineages display a high degree of flexibility, as demonstrated by species-specific expansion and contractions, whereas other class Ib gene lineages have been maintained as monogenic subfamilies with very few changes in their nucleotide sequence across divergent species. In this second category, we further investigated the XNC/SNC10 gene lineage that in X. laevis is required for the development of a distinct semi-invariant T cell population. We report compelling evidence of the remarkable high degree of conservation of this gene lineage that is present in all 12 species of the Xenopodinae examined, including species with different degrees of ploidy ranging from 2, 4, 8 to 12 N. This suggests that the critical role of XNC10 during early T cell development is conserved in amphibians.

  17. Expression of bovine non-classical major histocompatibility complex class 1 proteins in mouse P815 and human K562 cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Major histocompatibility complex class I (MHC-I) proteins can be expressed as cell surface or secreted proteins. To investigate whether bovine non-classical MHC-I proteins are expressed as cell surface or secreted proteins, and to assess the reactivity pattern of monoclonal antibodies with non-class...

  18. Role of MHC class Ib molecule, H2-M3 in host immunity against tuberculosis.

    PubMed

    Mir, Shabir Ahmad; Sharma, Sadhna

    2013-08-20

    The MHC class I family comprises both classical (class Ia) and non-classical (class Ib) members. While the prime function of classical MHC class I molecules (MHC class Ia) is to present peptide antigens to pathogen-specific cytotoxic T cells, non-classical MHC-I (MHC class Ib) antigens perform diverse array of functions in both innate and adaptive immunity. Vaccines against intracellular pathogens such as Mycobacterium tuberculosis need to induce strong cellular immune responses. Recent studies have shown that MHC class I molecules play an important role in the protective immune response to M. tuberculosis infection. Both MHC Ia-restricted and MHC class Ib-restricted M. tuberculosis -reactive CD8(+) T cells have been identified in humans and mice, but their relative contributions to immunity is still uncertain. Unlike MHC class Ia-restricted CD8(+) T cells, MHC class Ib-restricted CD8(+) T cells are constitutively activated in naive animals and respond rapidly to infection challenge, hence filling the temporal gap between innate and adaptive immunity. The present review article summarizes the general host immunity against M. tuberculosis infection highlighting the possible role of MHC class Ib molecule, H2-M3 and their ligands (N-formylated peptides) in protection against tuberculosis.

  19. The role of MHC class Ib-restricted T cells during infection.

    PubMed

    Anderson, Courtney K; Brossay, Laurent

    2016-08-01

    Even though major histocompatibility complex (MHC) class Ia and many Ib molecules have similarities in structure, MHC class Ib molecules tend to have more specialized functions, which include the presentation of non-peptidic antigens to non-classical T cells. Likewise, non-classical T cells also have unique characteristics, including an innate-like phenotype in naïve animals and rapid effector functions. In this review, we discuss the role of MAIT and NKT cells during infection but also the contribution of less studied MHC class Ib-restricted T cells such as Qa-1-, Qa-2-, and M3-restricted T cells. We focus on describing the types of antigens presented to non-classical T cells, their response and cytokine profile following infection, as well as the overall impact of these T cells to the immune system.

  20. Transcriptional profiling of MHC class I genes in rainbow trout infected with infectious hematopoietic necrosis virus

    USGS Publications Warehouse

    Landis, Eric D.; Purcell, Maureen K.; Thorgaard, Gary H.; Wheeler , Paul A.; Hansen, John D.

    2008-01-01

    Major histocompatibility complex (MHC) molecules are important mediators of cell-mediated immunity in vertebrates. MHC class IA molecules are important for host anti-viral immunity as they present intracellular antigens and regulate natural killer cell (NK) activity. MHC class Ib molecules on the other hand are less understood and have demonstrated diverse immune and non-immune functions in mammals. Rainbow trout possess a single classical MHC IA locus (Onmy-UBA) that is believed to function similar to that of mammalian MHC class Ia. Numerous MHC class Ib genes with undetermined functions have also been described in trout. Here we utilize quantitative reverse transcriptase PCR (qRT-PCR) techniques to survey the levels of basal and inducible transcription for selected trout MHC class Ib genes, sIgM and sentinels of IFN induction in response to viral infection. Basal transcription of all the class Ib genes examined in this study was lower than Onmy-UBA in naïve fish. UBA, along with all of the non-classical genes were induced in fish infected with virus but not in control fish. Our results support a non-classical designation for the majority of the class IB genes surveyed in this study based upon expression levels while also indicating that they may play an important role in anti-viral immunity in trout.

  1. Transcriptional profiling of MHC class I genes in rainbow trout infected with infectious hematopoietic necrosis virus

    USGS Publications Warehouse

    Landis, E.D.; Purcell, M.K.; Thorgaard, G.H.; Wheeler, P.A.; Hansen, J.D.

    2008-01-01

    Major histocompatibility complex (MHC) molecules are important mediators of cell-mediated immunity in vertebrates. MHC class IA molecules are important for host anti-viral immunity as they present intracellular antigens and regulate natural killer cell (NK) activity. MHC class Ib molecules on the other hand are less understood and have demonstrated diverse immune and non-immune functions in mammals. Rainbow trout possess a single classical MHC IA locus (Onmy-UBA) that is believed to function similar to that of mammalian MHC class Ia. Numerous MHC class Ib genes with undetermined functions have also been described in trout. Here we utilize quantitative reverse transcriptase PCR (qRT-PCR) techniques to survey the levels of basal and inducible transcription for selected trout MHC class Ib genes, sIgM and sentinels of IFN induction in response to viral infection. Basal transcription of all the class Ib genes examined in this study was lower than Onmy-UBA in nai??ve fish. UBA, along with all of the non-classical genes were induced in fish infected with virus but not in control fish. Our results support a non-classical designation for the majority of the class IB genes surveyed in this study based upon expression levels while also indicating that they may play an important role in anti-viral immunity in trout.

  2. Recent advances in Major Histocompatibility Complex (MHC) class I antigen presentation: Plastic MHC molecules and TAPBPR-mediated quality control

    PubMed Central

    van Hateren, Andy; Bailey, Alistair; Elliott, Tim

    2017-01-01

    We have known since the late 1980s that the function of classical major histocompatibility complex (MHC) class I molecules is to bind peptides and display them at the cell surface to cytotoxic T cells. Recognition by these sentinels of the immune system can lead to the destruction of the presenting cell, thus protecting the host from pathogens and cancer. Classical MHC class I molecules (MHC I hereafter) are co-dominantly expressed, polygenic, and exceptionally polymorphic and have significant sequence diversity. Thus, in most species, there are many different MHC I allotypes expressed, each with different peptide-binding specificity, which can have a dramatic effect on disease outcome. Although MHC allotypes vary in their primary sequence, they share common tertiary and quaternary structures. Here, we review the evidence that, despite this commonality, polymorphic amino acid differences between allotypes alter the ability of MHC I molecules to change shape (that is, their conformational plasticity). We discuss how the peptide loading co-factor tapasin might modify this plasticity to augment peptide loading. Lastly, we consider recent findings concerning the functions of the non-classical MHC I molecule HLA-E as well as the tapasin-related protein TAPBPR (transporter associated with antigen presentation binding protein-related), which has been shown to act as a second quality-control stage in MHC I antigen presentation. PMID:28299193

  3. Nonclassical MHC Ib-restricted CD8+ T Cells Recognize Mycobacterium tuberculosis-Derived Protein Antigens and Contribute to Protection Against Infection.

    PubMed

    Shang, Shaobin; Siddiqui, Sarah; Bian, Yao; Zhao, Jie; Wang, Chyung-Ru

    2016-06-01

    MHC Ib-restricted CD8+ T cells have been implicated in host defense against Mycobacterium tuberculosis (Mtb) infection. However, the relative contribution of various MHC Ib-restricted T cell populations to anti-mycobacterial immunity remains elusive. In this study, we used mice that lack MHC Ia (Kb-/-Db-/-), MHC Ia/H2-M3 (Kb-/-Db-/-M3-/-), or β2m (β2m-/-) to study the role of M3-restricted and other MHC Ib-restricted T cells in immunity against Mtb. Unlike their dominant role in Listeria infection, we found that M3-restricted CD8+ T cells only represented a small proportion of the CD8+ T cells responding to Mtb infection. Non-M3, MHC Ib-restricted CD8+ T cells expanded preferentially in the lungs of Mtb-infected Kb-/-Db-/-M3-/- mice, exhibited polyfunctional capacities and conferred protection against Mtb. These MHC Ib-restricted CD8+ T cells recognized several Mtb-derived protein antigens at a higher frequency than MHC Ia-restricted CD8+ T cells. The presentation of Mtb antigens to MHC Ib-restricted CD8+ T cells was mostly β2m-dependent but TAP-independent. Interestingly, a large proportion of Mtb-specific MHC Ib-restricted CD8+ T cells in Kb-/-Db-/-M3-/- mice were Qa-2-restricted while no considerable numbers of MR1 or CD1-restricted Mtb-specific CD8+ T cells were detected. Our findings indicate that nonclassical CD8+ T cells other than the known M3, CD1, and MR1-restricted CD8+ T cells contribute to host immune responses against Mtb infection. Targeting these MHC Ib-restricted CD8+ T cells would facilitate the design of better Mtb vaccines with broader coverage across MHC haplotypes due to the limited polymorphism of MHC class Ib molecules.

  4. NLRC5: a newly discovered MHC class I transactivator (CITA).

    PubMed

    Meissner, Torsten B; Li, Amy; Kobayashi, Koichi S

    2012-06-01

    Major histocompatibility complex (MHC) class I and class II are crucial for the function of the human adaptive immune system. An NLR protein, CIITA (MHC class II transactivator), is a master regulator of MHC class II gene expression as well as of some of the genes involved in MHC class II antigen presentation. It has recently been discovered that another member of the NLR protein family, NLRC5, transcriptionally activates MHC class I genes, and thus acts as "CITA" (MHC class I transactivator), a counterpart to CIITA. In addition to MHC class I genes, NLRC5 can induce the expression of β2M, TAP1 and LMP2, essential components of MHC class I antigen presentation. These findings indicate that NLRC5 and CIITA are transcriptional regulators that orchestrate the concerted expression of critical components in the MHC class I and MHC class II pathways, respectively.

  5. Subtle Changes in Peptide Conformation Profoundly Affect Recognition of the Non-Classical MHC Class I Molecule HLA-E by the CD94-NKG2 Natural Killer Cell Receptors

    SciTech Connect

    Hoare, Hilary L; Sullivan, Lucy C; Clements, Craig S; Ely, Lauren K; Beddoe, Travis; Henderson, Kate N; Lin, Jie; Reid, Hugh H; Brooks, Andrew G; Rossjohn, Jamie

    2008-03-31

    Human leukocyte antigen (HLA)-E is a non-classical major histocompatibility complex class I molecule that binds peptides derived from the leader sequences of other HLA class I molecules. Natural killer cell recognition of these HLA-E molecules, via the CD94-NKG2 natural killer family, represents a central innate mechanism for monitoring major histocompatibility complex expression levels within a cell. The leader sequence-derived peptides bound to HLA-E exhibit very limited polymorphism, yet subtle differences affect the recognition of HLA-E by the CD94-NKG2 receptors. To better understand the basis for this peptide-specific recognition, we determined the structure of HLA-E in complex with two leader peptides, namely, HLA-Cw*07 (VMAPRALLL), which is poorly recognised by CD94-NKG2 receptors, and HLA-G*01 (VMAPRTLFL), a high-affinity ligand of CD94-NKG2 receptors. A comparison of these structures, both of which were determined to 2.5-Å resolution, revealed that allotypic variations in the bound leader sequences do not result in conformational changes in the HLA-E heavy chain, although subtle changes in the conformation of the peptide within the binding groove of HLA-E were evident. Accordingly, our data indicate that the CD94-NKG2 receptors interact with HLA-E in a manner that maximises the ability of the receptors to discriminate between subtle changes in both the sequence and conformation of peptides bound to HLA-E.

  6. An MHC class Ib-restricted CD8+ T cell response to lymphocytic choriomeningitis virus.

    PubMed

    Chen, Lili; Jay, David C; Fairbanks, Jared D; He, Xiao; Jensen, Peter E

    2011-12-15

    Conventional MHC class Ia-restricted CD8(+) T cells play a dominant role in the host response to virus infections, but recent studies indicate that T cells with specificity for nonclassical MHC class Ib molecules may also participate in host defense. To investigate the potential role of class Ib molecules in anti-viral immune responses, K(b-/-)D(b-/-)CIITA(-/-) mice lacking expression of MHC class Ia and class II molecules were infected with lymphocytic choriomeningitis virus (LCMV). These animals have a large class Ib-selected CD8(+) T cell population and they were observed to mediate partial (but incomplete) virus clearance during acute LCMV infection as compared with K(b-/-)D(b-/-)β(2)-microglobulin(-/-) mice that lack expression of both MHC class Ia and class Ib molecules. Infection was associated with expansion of splenic CD8(+) T cells and induction of granzyme B and IFN-γ effector molecules in CD8(+) T cells. Partial virus clearance was dependent on CD8(+) cells. In vitro T cell restimulation assays demonstrated induction of a population of β(2)-microglobulin-dependent, MHC class Ib-restricted CD8(+) T cells with specificity for viral Ags and yet to be defined nonclassical MHC molecules. MHC class Ib-restricted CD8(+) T cell responses were also observed after infection of K(b-/-)D(b-/-)mice despite the low number of CD8(+) T cells in these animals. Long-term infection studies demonstrated chronic infection and gradual depletion of CD8(+) T cells in K(b-/-)D(b-/-)CIITA(-/-) mice, demonstrating that class Ia molecules are required for viral clearance. These findings demonstrate that class Ib-restricted CD8(+) T cells have the potential to participate in the host immune response to LCMV.

  7. Major Histocompatibility Complex (MHC) Class I and MHC Class II Proteins: Conformational Plasticity in Antigen Presentation

    PubMed Central

    Wieczorek, Marek; Abualrous, Esam T.; Sticht, Jana; Álvaro-Benito, Miguel; Stolzenberg, Sebastian; Noé, Frank; Freund, Christian

    2017-01-01

    Antigen presentation by major histocompatibility complex (MHC) proteins is essential for adaptive immunity. Prior to presentation, peptides need to be generated from proteins that are either produced by the cell’s own translational machinery or that are funneled into the endo-lysosomal vesicular system. The prolonged interaction between a T cell receptor and specific pMHC complexes, after an extensive search process in secondary lymphatic organs, eventually triggers T cells to proliferate and to mount a specific cellular immune response. Once processed, the peptide repertoire presented by MHC proteins largely depends on structural features of the binding groove of each particular MHC allelic variant. Additionally, two peptide editors—tapasin for class I and HLA-DM for class II—contribute to the shaping of the presented peptidome by favoring the binding of high-affinity antigens. Although there is a vast amount of biochemical and structural information, the mechanism of the catalyzed peptide exchange for MHC class I and class II proteins still remains controversial, and it is not well understood why certain MHC allelic variants are more susceptible to peptide editing than others. Recent studies predict a high impact of protein intermediate states on MHC allele-specific peptide presentation, which implies a profound influence of MHC dynamics on the phenomenon of immunodominance and the development of autoimmune diseases. Here, we review the recent literature that describe MHC class I and II dynamics from a theoretical and experimental point of view and we highlight the similarities between MHC class I and class II dynamics despite the distinct functions they fulfill in adaptive immunity. PMID:28367149

  8. Rational design of class I MHC ligands

    NASA Astrophysics Data System (ADS)

    Rognan, D.; Scapozza, L.; Folkers, G.; Daser, Angelika

    1995-04-01

    From the knowledge of the three-dimensional structure of a class I MHC protein, several non natural peptides were designed in order to either optimize the interactions of one secondary anchor amino acid with its HLA binding pocket or to substitute the non interacting part with spacer residues. All peptides were synthesized and tested for binding to the class I MHC protein in an in vitro reconstitution assay. As predicted, the non natural peptides present an enhanced binding to the HLA-B27 molecule with respect to their natural parent peptides. This study constitutes the first step towards the rational design of non peptidic MHC ligands that should be very promising tools for the selective immunotherapy of autoimmune diseases.

  9. Constitutive MHC class I molecules negatively regulate TLR-triggered inflammatory responses via the Fps-SHP-2 pathway.

    PubMed

    Xu, Sheng; Liu, Xingguang; Bao, Yan; Zhu, Xuhui; Han, Chaofeng; Zhang, Peng; Zhang, Xuemin; Li, Weihua; Cao, Xuetao

    2012-04-22

    The molecular mechanisms that fine-tune Toll-like receptor (TLR)-triggered innate inflammatory responses remain to be fully elucidated. Major histocompatibility complex (MHC) molecules can mediate reverse signaling and have nonclassical functions. Here we found that constitutively expressed membrane MHC class I molecules attenuated TLR-triggered innate inflammatory responses via reverse signaling, which protected mice from sepsis. The intracellular domain of MHC class I molecules was phosphorylated by the kinase Src after TLR activation, then the tyrosine kinase Fps was recruited via its Src homology 2 domain to phosphorylated MHC class I molecules. This led to enhanced Fps activity and recruitment of the phosphatase SHP-2, which interfered with TLR signaling mediated by the signaling molecule TRAF6. Thus, constitutive MHC class I molecules engage in crosstalk with TLR signaling via the Fps-SHP-2 pathway and control TLR-triggered innate inflammatory responses.

  10. NLRC5 controls basal MHC class I gene expression in an MHC enhanceosome-dependent manner.

    PubMed

    Neerincx, Andreas; Rodriguez, Galaxia M; Steimle, Viktor; Kufer, Thomas A

    2012-05-15

    Nucleotide-binding domain and leucine-rich repeat (NLR) proteins play important roles in innate immune responses as pattern-recognition receptors. Although most NLR proteins act in cell autonomous immune pathways, some do not function as classical pattern-recognition receptors. One such NLR protein is the MHC class II transactivator, the master regulator of MHC class II gene transcription. In this article, we report that human NLRC5, which we recently showed to be involved in viral-mediated type I IFN responses, shuttles to the nucleus and activates MHC class I gene expression. Knockdown of NLRC5 in different human cell lines and primary dermal fibroblasts leads to reduced MHC class I expression, whereas introduction of NLRC5 into cell types with very low expression of MHC class I augments MHC class I expression to levels comparable to those found in lymphocytes. Expression of NLRC5 positively correlates with MHC class I expression in human tissues. Functionally, we show that both the N-terminal effector domain of NLRC5 and its C-terminal leucine-rich repeat domain are needed for activation of MHC class I expression. Moreover, nuclear shuttling and function depend on a functional Walker A motif. Finally, we identified a promoter sequence in the MHC class I promoter, the X1 box, to be involved in NLRC5-mediated MHC class I gene activation. Taken together, this suggested that NLRC5 acts in a manner similar to class II transactivator to drive MHC expression and revealed NLRC5 as an important regulator of basal MHC class I expression.

  11. Novel classical MHC class I alleles identified in horses by sequencing clones of reverse transcription-PCR products.

    PubMed

    Chung, C; Leib, S R; Fraser, D G; Ellis, S A; McGuire, T C

    2003-12-01

    Improved typing of horse classical MHC class I is required to more accurately define these molecules and to extend the number identified further than current serological assays. Defining classical MHC class I alleleic polymorphism is important in evaluating cytotoxic T lymphocyte (CTL) responses in horses. In this study, horse classical MHC class I genes were analyzed based on reverse transcription (RT)-PCR amplification of sequences encoding the polymorphic peptide binding region and the more conserved alpha 3, transmembrane and cytoplasmic regions followed by cloning and sequencing. Primer sets included a horse classical MHC class I-specific reverse primer and a forward primer conserved in all known horse MHC class I genes. Sequencing at least 25 clones containing MHC class I sequences from each of 13 horses identified 25 novel sequences and three others which had been described. Of these, nine alleles were identified from different horses or different RT-PCR and 19 putative alleles were identified in multiple clones from the same RT-PCR. The primer pairs did not amplify putative non-classical MHC class I genes as only classical MHC class I and related pseudogenes were found in 462 clones. This method also identified classical MHC class I alleles shared between horses by descent, and defined differences in alleles between horses varying in equine leukocyte antigen (ELA)-A haplotype as determined by serology. However, horses sharing ELA-A haplotypes defined by serotyping did not always share cDNA sequences, suggesting subhaplotypic variations within serologically defined ELA-A haplotypes. The 13 horses in this study had two to five classical MHC class I sequences, indicating that multiple loci code for these genes. Sequencing clones from RT-PCR with classical MHC class I-specific primers should be useful for selection of haplotype matched and mismatched horses for CTL studies, and provides sequence information needed to develop easier and more discriminating

  12. MHC and Evolution in Teleosts

    PubMed Central

    Grimholt, Unni

    2016-01-01

    Major histocompatibility complex (MHC) molecules are key players in initiating immune responses towards invading pathogens. Both MHC class I and class II genes are present in teleosts, and, using phylogenetic clustering, sequences from both classes have been classified into various lineages. The polymorphic and classical MHC class I and class II gene sequences belong to the U and A lineages, respectively. The remaining class I and class II lineages contain nonclassical gene sequences that, despite their non-orthologous nature, may still hold functions similar to their mammalian nonclassical counterparts. However, the fact that several of these nonclassical lineages are only present in some teleost species is puzzling and questions their functional importance. The number of genes within each lineage greatly varies between teleost species. At least some gene expansions seem reasonable, such as the huge MHC class I expansion in Atlantic cod that most likely compensates for the lack of MHC class II and CD4. The evolutionary trigger for similar MHC class I expansions in tilapia, for example, which has a functional MHC class II, is not so apparent. Future studies will provide us with a more detailed understanding in particular of nonclassical MHC gene functions. PMID:26797646

  13. MHC class I and MHC class II DRB gene variability in wild and captive Bengal tigers (Panthera tigris tigris).

    PubMed

    Pokorny, Ina; Sharma, Reeta; Goyal, Surendra Prakash; Mishra, Sudanshu; Tiedemann, Ralph

    2010-10-01

    Bengal tigers are highly endangered and knowledge on adaptive genetic variation can be essential for efficient conservation and management. Here we present the first assessment of allelic variation in major histocompatibility complex (MHC) class I and MHC class II DRB genes for wild and captive tigers from India. We amplified, cloned, and sequenced alpha-1 and alpha-2 domain of MHC class I and beta-1 domain of MHC class II DRB genes in 16 tiger specimens of different geographic origin. We detected high variability in peptide-binding sites, presumably resulting from positive selection. Tigers exhibit a low number of MHC DRB alleles, similar to other endangered big cats. Our initial assessment-admittedly with limited geographic coverage and sample size-did not reveal significant differences between captive and wild tigers with regard to MHC variability. In addition, we successfully amplified MHC DRB alleles from scat samples. Our characterization of tiger MHC alleles forms a basis for further in-depth analyses of MHC variability in this illustrative threatened mammal.

  14. Viral immune evasion: Lessons in MHC class I antigen presentation.

    PubMed

    van de Weijer, Michael L; Luteijn, Rutger D; Wiertz, Emmanuel J H J

    2015-03-01

    The MHC class I antigen presentation pathway enables cells infected with intracellular pathogens to signal the presence of the invader to the immune system. Cytotoxic T lymphocytes are able to eliminate the infected cells through recognition of pathogen-derived peptides presented by MHC class I molecules at the cell surface. In the course of evolution, many viruses have acquired inhibitors that target essential stages of the MHC class I antigen presentation pathway. Studies on these immune evasion proteins reveal fascinating strategies used by viruses to elude the immune system. Viral immunoevasins also constitute great research tools that facilitate functional studies on the MHC class I antigen presentation pathway, allowing the investigation of less well understood routes, such as TAP-independent antigen presentation and cross-presentation of exogenous proteins. Viral immunoevasins have also helped to unravel more general cellular processes. For instance, basic principles of ER-associated protein degradation via the ubiquitin-proteasome pathway have been resolved using virus-induced degradation of MHC class I as a model. This review highlights how viral immunoevasins have increased our understanding of MHC class I-restricted antigen presentation.

  15. A Peptide Filtering Relation Quantifies MHC Class I Peptide Optimization

    PubMed Central

    Goldstein, Leonard D.; Howarth, Mark; Cardelli, Luca; Emmott, Stephen; Elliott, Tim; Werner, Joern M.

    2011-01-01

    Major Histocompatibility Complex (MHC) class I molecules enable cytotoxic T lymphocytes to destroy virus-infected or cancerous cells, thereby preventing disease progression. MHC class I molecules provide a snapshot of the contents of a cell by binding to protein fragments arising from intracellular protein turnover and presenting these fragments at the cell surface. Competing fragments (peptides) are selected for cell-surface presentation on the basis of their ability to form a stable complex with MHC class I, by a process known as peptide optimization. A better understanding of the optimization process is important for our understanding of immunodominance, the predominance of some T lymphocyte specificities over others, which can determine the efficacy of an immune response, the danger of immune evasion, and the success of vaccination strategies. In this paper we present a dynamical systems model of peptide optimization by MHC class I. We incorporate the chaperone molecule tapasin, which has been shown to enhance peptide optimization to different extents for different MHC class I alleles. Using a combination of published and novel experimental data to parameterize the model, we arrive at a relation of peptide filtering, which quantifies peptide optimization as a function of peptide supply and peptide unbinding rates. From this relation, we find that tapasin enhances peptide unbinding to improve peptide optimization without significantly delaying the transit of MHC to the cell surface, and differences in peptide optimization across MHC class I alleles can be explained by allele-specific differences in peptide binding. Importantly, our filtering relation may be used to dynamically predict the cell surface abundance of any number of competing peptides by MHC class I alleles, providing a quantitative basis to investigate viral infection or disease at the cellular level. We exemplify this by simulating optimization of the distribution of peptides derived from Human

  16. CITA/NLRC5: A critical transcriptional regulator of MHC class I gene expression.

    PubMed

    Downs, Isaac; Vijayan, Saptha; Sidiq, Tabasum; Kobayashi, Koichi S

    2016-07-08

    Major histocompatibility complex (MHC) class I and class II molecules play essential roles in the development and activation of the human adaptive immune system. An NLR protein, CIITA (MHC class II transactivator) has been recognized as a master regulator of MHC class II gene expression, albeit knowledge about the regulatory mechanism of MHC class I gene expression had been limited. Recently identified MHC class I transactivator (CITA), or NLRC5, also belongs to the NLR protein family and constitutes a critical regulator for the transcriptional activation of MHC class I genes. In addition to MHC class I genes, CITA/NLRC5 induces the expression of β2 -microglobulin, TAP1 and LMP2, essential components of the MHC class I antigen presentation pathway. Therefore, CITA/NLRC5 and CIITA are transcriptional regulators that orchestrate the concerted expression of critical components in the MHC class I and class II pathways, respectively. © 2016 BioFactors, 42(4):349-357, 2016.

  17. Evolution of MHC class I in the order Crocodylia.

    PubMed

    Jaratlerdsiri, Weerachai; Isberg, Sally R; Higgins, Damien P; Ho, Simon Y W; Salomonsen, Jan; Skjodt, Karsten; Miles, Lee G; Gongora, Jaime

    2014-01-01

    The major histocompatibility complex (MHC) is a dynamic genomic region with an essential role in the adaptive immunity of jawed vertebrates. The evolution of the MHC has been dominated by gene duplication and gene loss, commonly known as the birth-and-death process. Evolutionary studies of the MHC have mostly focused on model species. However, the investigation of this region in non-avian reptiles is still in its infancy. To provide insights into the evolutionary mechanisms that have shaped the diversity of this region in the Order Crocodylia, we investigated MHC class I exon 3, intron 3, and exon 4 across 20 species of the families Alligatoridae and Crocodilidae. We generated 124 DNA sequences and identified 31 putative functional variants as well as 14 null variants. Phylogenetic analyses revealed three gene groups, all of which were present in Crocodilidae but only one in Alligatoridae. Within these groups, variants generally appear to cluster at the genus or family level rather than in species-specific groups. In addition, we found variation in gene copy number and some indication of interlocus recombination. These results suggest that MHC class I in Crocodylia underwent independent events of gene duplication, particularly in Crocodilidae. These findings enhance our understanding of MHC class I evolution and provide a preliminary framework for comparative studies of other non-avian reptiles as well as diversity assessment within Crocodylia.

  18. Evolution of innate-like T cells and their selection by MHC class I-like molecules.

    PubMed

    Edholm, Eva-Stina; Banach, Maureen; Robert, Jacques

    2016-08-01

    Until recently, major histocompatibility complex (MHC) class I-like-restricted innate-like αβT (iT) cells expressing an invariant or semi-invariant T cell receptor (TCR) repertoire were thought to be a recent evolutionary acquisition restricted to mammals. However, molecular and functional studies in Xenopus laevis have demonstrated that iT cells, defined as MHC class I-like-restricted innate-like αβT cells with a semi-invariant TCR, are evolutionarily conserved and prominent from early development in amphibians. As these iT cells lack the specificity conferred by conventional αβ TCRs, it is generally considered that they are specialized to recognize conserved antigens equivalent to pathogen-associated molecular patterns. Thus, one advantage offered by the MHC class I-like iT cell-based recognition system is that it can be adapted to a common pathogen and function on the basis of a relatively small number of T cells. Although iT cells have only been functionally described in mammals and amphibians, the identification of non-classical MHC/MHC class I-like genes in other groups of endothermic and ectothermic vertebrates suggests that iT cells have a broader phylogenetic distribution than previously envisioned. In this review, we discuss the possible role of iT cells during the emergence of the jawed vertebrate adaptive immune system.

  19. Ubiquitination by March-I prevents MHC class II recycling and promotes MHC class II turnover in antigen-presenting cells.

    PubMed

    Cho, Kyung-Jin; Walseng, Even; Ishido, Satoshi; Roche, Paul A

    2015-08-18

    MHC class II (MHC-II)-dependent antigen presentation by antigen-presenting cells (APCs) is carefully controlled to achieve specificity of immune responses; the regulated assembly and degradation of antigenic peptide-MHC-II complexes (pMHC-II) is one aspect of such control. In this study, we have examined the role of ubiquitination in regulating pMHC-II biosynthesis, endocytosis, recycling, and turnover in APCs. By using APCs obtained from MHC-II ubiquitination mutant mice, we find that whereas ubiquitination does not affect pMHC-II formation in dendritic cells (DCs), it does promote the subsequent degradation of newly synthesized pMHC-II. Acute activation of DCs or B cells terminates expression of the MHC-II E3 ubiquitin ligase March-I and prevents pMHC-II ubiquitination. Most importantly, this change results in very efficient pMHC-II recycling from the surface of DCs and B cells, thereby preventing targeting of internalized pMHC-II to lysosomes for degradation. Biochemical and functional assays confirmed that pMHC-II turnover is suppressed in MHC-II ubiquitin mutant DCs or by acute activation of wild-type DCs. These studies demonstrate that acute APC activation blocks the ubiquitin-dependent turnover of pMHC-II by promoting efficient pMHC-II recycling and preventing lysosomal targeting of internalized pMHC-II, thereby enhancing pMHC-II stability for efficient antigen presentation to CD4 T cells.

  20. Quantitative analysis of peptide-MHC class II interaction.

    PubMed

    Fleckenstein, B; Jung, G; Wiesmüller, K H

    1999-12-01

    The tremendous progress in the field of basic immunology and immunochemistry made in the last decade has significantly advanced our understanding of antigen processing and presentation by MHC class I and II proteins. In this review different techniques to study peptide interaction with MHC class II molecules are summarized and their impact on the elucidation of quantitative parameters, like affinities or kinetic data, is discussed. A recently introduced method based on synthetic combinatorial peptide libraries allows to quantify the binding contribution of each amino acid residue in a class II ligand and is presented in more detail. As this knowledge is fundamental for current investigations in modern medicine, e.g. for novel immune system based therapy concepts, further aspects like the design of new high affinity MHC class II ligands and the prediction of peptide antigens are discussed.

  1. MHC class I characterization of Indonesian cynomolgus macaques

    PubMed Central

    Pendley, Chad J.; Becker, Ericka A.; Karl, Julie A.; Blasky, Alex J.; Wiseman, Roger W.; Hughes, Austin L.; O’Connor, Shelby L.; O’Connor, David H.

    2008-01-01

    Cynomolgus macaques (Macaca fascicularis) are quickly becoming a useful model for infectious disease and transplantation research. Even though cynomolgus macaques from different geographic regions are used for these studies, there has been limited characterization of full-length Major Histocompatibility Complex (MHC) Class I immunogenetics of distinct geographic populations. Here, we identified 48 MHC class I cDNA nucleotide sequences in eleven Indonesian cynomolgus macaques, including 41 novel Mafa-A and Mafa-B sequences. We found seven MHC class I sequences in Indonesian macaques that were identical to MHC class I sequences identified in Malaysian or Mauritian macaques. Sharing of nucleotide sequences between these geographically distinct populations is also consistent with the hypothesis that Indonesia was a source of the Mauritian macaque population. In addition, we found that the Indonesian cDNA sequence Mafa-B*7601 is identical throughout its peptide binding domain to Mamu-B*03, an allele that has been associated with control of SIV viremia in Indian rhesus macaques. Overall, a better understanding of the MHC class I alleles present in Indonesian cynomolgus macaques improves their value as a model for disease research and it better defines the biogeography of cynomolgus macaques throughout Southeast Asia. PMID:18504574

  2. NLRC5: a key regulator of MHC class I-dependent immune responses.

    PubMed

    Kobayashi, Koichi S; van den Elsen, Peter J

    2012-12-01

    The expression of MHC class I molecules is crucial for the initiation and regulation of adaptive immune responses against pathogens. NOD-, LRR- and CARD-containing 5 (NLRC5) was recently identified as a specific transactivator of MHC class I genes (CITA). NLRC5 and the master regulator for MHC class II genes, class II transactivator (CIITA), interact with similar MHC promoter-bound factors. Here, we provide a broad overview of the molecular mechanisms behind MHC class I transcription and the role of the class I transactivator NLRC5 in MHC class I-dependent immune responses.

  3. Molecular characterization of MHC class II region in guinea fowl.

    PubMed

    Singh, S K; Mathew, J; Gupta, J; Mehra, S; Goyal, G; Sharma, D

    2010-12-01

    1. The MHC class II gene was amplified, cloned and sequenced in guinea fowl. 2. The NumeMHC II sequence of 754 nucleotides included complete exon 1 (91 nt), exon 2 (270 nt), exon 3 (282 nt) and exon 4 (110 nt). 3. The size of β(1) and β(2), domains were 89 and 93 amino acids, respectively in guinea fowl. 4. High amino acid variability (38·2%) was observed within guinea fowl in β(1) domain, while in β(2) domain, amino acid variability (6·3%) was low. 5. Among poultry species, the percent amino acid identity between guinea fowl and chicken, quail, pheasant and duck was 38·8, 42·2, 44·4 and 58·8 in β(1) domain; and 13·8, 17·0, 13·8 and 27·6 in β(2) domain, respectively. 6. Sequence alignment with mammalian and avian MHC showed that many of the conserved features of MHC class II glycoprotein was conserved in guinea fowl. 7. Within-species genetic distances (Poisson correction) based on cumulative amino acid variability in β(1) domain and β(2) domains was 0·141 in guinea fowl. 8. Guinea fowl showed low and similar genetic distances with all the poultry species (0·255-0·268) except duck (0·456). 9. Guinea fowl made separate branch within the major cluster having chicken, quail and pheasant, showing equal distance from these poultry species, whereas duck MHC II clustered separately.

  4. MHC2SKpan: a novel kernel based approach for pan-specific MHC class II peptide binding prediction

    PubMed Central

    2013-01-01

    Background Computational methods for the prediction of Major Histocompatibility Complex (MHC) class II binding peptides play an important role in facilitating the understanding of immune recognition and the process of epitope discovery. To develop an effective computational method, we need to consider two important characteristics of the problem: (1) the length of binding peptides is highly flexible; and (2) MHC molecules are extremely polymorphic and for the vast majority of them there are no sufficient training data. Methods We develop a novel string kernel MHC2SK (MHC-II String Kernel) method to measure the similarities among peptides with variable lengths. By considering the distinct features of MHC-II peptide binding prediction problem, MHC2SK differs significantly from the recently developed kernel based method, GS (Generic String) kernel, in the way of computing similarities. Furthermore, we extend MHC2SK to MHC2SKpan for pan-specific MHC-II peptide binding prediction by leveraging the binding data of various MHC molecules. Results MHC2SK outperformed GS in allele specific prediction using a benchmark dataset, which demonstrates the effectiveness of MHC2SK. Furthermore, we evaluated the performance of MHC2SKpan using various benckmark data sets from several different perspectives: Leave-one-allele-out (LOO), 5-fold cross validation as well as independent data testing. MHC2SKpan has achieved comparable performance with NetMHCIIpan-2.0 and outperformed NetMHCIIpan-1.0, TEPITOPEpan and MultiRTA, being statistically significant. MHC2SKpan can be freely accessed at http://datamining-iip.fudan.edu.cn/service/MHC2SKpan/index.html. PMID:24564280

  5. Assembly of MHC class I molecules within the endoplasmic reticulum.

    PubMed

    Zhang, Yinan; Williams, David B

    2006-01-01

    MHC class I molecules bind cytosolically derived peptides within the endoplasmic reticulum (ER) and present them at the cell surface to cytotoxic T cells. A major focus of our laboratory has been to understand the functions of the diverse proteins involved in the intracellular assembly of MHC class I molecules. These include the molecular chaperones calnexin and calreticulin, which enhance the proper folding and subunit assembly of class I molecules and also retain assembly intermediates within the ER; ERp57, a thiol oxidoreductase that promotes heavy chain disulfide formation and proper assembly of the peptide loading complex; tapasin, which recruits class I molecules to the TAP peptide transporter and enhances the loading of high affinity peptide ligands; and Bap31, which is involved in clustering assembled class I molecules at ER exit sites for export along the secretory pathway. This review describes our contributions to elucidating the functions of these proteins; the combined effort of many dedicated students and postdoctoral fellows.

  6. Defective MHC class II expression in an MHC class II deficiency patient is caused by a novel deletion of a splice donor site in the MHC class II transactivator gene.

    PubMed

    Peijnenburg, A; Van den Berg, R; Van Eggermond, M J; Sanal, O; Vossen, J M; Lennon, A M; Alcaïde-Loridan, C; Van den Elsen, P J

    2000-01-01

    MHC class II deficiency patients are mutated for transcription factors that regulate the expression of major histocompatibility complex (MHC) class II genes. Four complementation groups (A-D) are defined and the gene defective in group A has been shown to encode the MHC class II transactivator (CIITA). Here, we report the molecular characterization of a new MHC class II deficiency patient, ATU. Cell fusion experiments indicated that ATU belongs to complementation group A. Subsequent mutation analysis revealed that the CIITA mRNA lacked 84 nucleotides. This deletion was the result of the absence of a splice donor site in the CIITA gene of ATU. As a result of this novel homozygous genomic deletion, ATU CIITA failed to transactivate MHC class II genes. Furthermore, this truncated CIITA of ATU did not display a dominant negative effect on CIITA-mediated transactivation of various isotypic MHC class II promoters.

  7. MHC class II DR allelic diversity in bighorn sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We hypothesized that decreased diversity and/or unique polymorphisms in MHC class II alleles of bighorn sheep (BHS, Ovis canadensis) are responsible for lower titer of antibodies against Mannheimia haemolytica leukotoxin, in comparison to domestic sheep (DS, Ovis aries). To test this hypothesis, DRA...

  8. Complex MHC class I gene transcription profiles and their functional impact in orangutans

    PubMed Central

    de Groot, Natasja G.; Heijmans, Corrine M.C.; van der Wiel, Marit K.H.; Blokhuis, Jeroen H.; Mulder, Arend; Guethlein, Lisbeth A.; Doxiadis, Gaby G.M.; Claas, Frans H.J.; Parham, Peter; Bontrop, Ronald E.

    2015-01-01

    MHC haplotypes of humans and the African great ape species have one copy of the MHC-A, -B, and -C genes. In contrast, MHC haplotypes of orangutans, the Asian great ape species, exhibit variation in the number of gene copies. An in-depth analysis of the MHC class I gene repertoire in the two orangutan species, Pongo abelii and Pongo pygmaeus, is presented here. This analysis involved Sanger and next-generation sequencing methodologies, revealing diverse and complicated transcription profiles for orangutan MHC-A, -B, and -C. Thirty-five previously unreported MHC class I alleles are described. The data demonstrate that each orangutan MHC haplotype has one copy of the MHC-A gene, and that the MHC-B region has been subject to duplication, giving rise to at least three MHC-B genes. The MHC-B*03 and -B*08 lineages of alleles each account for a separate MHC-B gene. All MHC-B*08 allotypes have the C1-epitope motif recognized by KIR. At least one other MHC-B gene is present, pointing to MHC-B alleles that are not B*03 or B*08. The MHC-C gene is present only on some haplotypes, and each MHC-C allotype has the C1-epitope. The transcription profiles demonstrate that MHC-A alleles are highly transcribed, whereas MHC-C alleles, when present, are transcribed at very low levels. The MHC-B alleles are transcribed to a variable extent and over a wide range. For those orangutan MHC class I allotypes that are detected by human monoclonal anti-HLA class I antibodies, the level of cell-surface expression of proteins correlates with the level of transcription of the allele. PMID:26685209

  9. Neurons Preferentially Respond to Self-MHC Class I Allele Products Regardless of Peptide Presented

    PubMed Central

    Escande-Beillard, Nathalie; Washburn, Lorraine; Zekzer, Dan; Wu, Zhongqi-Phyllis; Eitan, Shoshy; Ivkovic, Sonja; Lu, Yuxin; Dang, Hoa; Middleton, Blake; Bilousova, Tina V.; Yoshimura, Yoshitaka; Evans, Christopher J.; Joyce, Sebastian; Tian, Jide; Kaufman, Daniel L.

    2010-01-01

    Studies of mice lacking MHC class I (MHC I)-associated proteins have demonstrated a role for MHC I in neurodevelopment. A central question arising from these observations is whether neuronal recognition of MHC I has specificity for the MHC I allele product and the peptide presented. Using a well-established embryonic retina explant system, we observed that picomolar levels of a recombinant self-MHC I molecule inhibited neurite outgrowth. We then assessed the neurobiological activity of a panel of recombinant soluble MHC Is, consisting of different MHC I heavy chains with a defined self- or nonself-peptide presented, on cultured embryonic retinas from mice with different MHC I haplotypes. We observed that self-MHC I allele products had greater inhibitory neuroactivity than nonself-MHC I molecules, regardless of the nature of the peptide presented, a pattern akin to MHC I recognition by some innate immune system receptors. However, self-MHC I molecules had no effect on retinas from MHC I-deficient mice. These observations suggest that neuronal recognition of MHC I may be coordinated with the inherited MHC I alleles, as occurs in the innate immune system. Consistent with this notion, we show that MHC I and MHC I receptors are coexpressed by precursor cells at the earliest stages of retina development, which could enable such coordination. PMID:20018625

  10. MHC Class II haplotypes of Colombian Amerindian tribes.

    PubMed

    Yunis, Juan J; Yunis, Edmond J; Yunis, Emilio

    2013-07-01

    We analyzed 1041 individuals belonging to 17 Amerindian tribes of Colombia, Chimila, Bari and Tunebo (Chibcha linguistic family), Embera, Waunana (Choco linguistic family), Puinave and Nukak (Maku-Puinave linguistic families), Cubeo, Guanano, Tucano, Desano and Piratapuyo (Tukano linguistic family), Guahibo and Guayabero (Guayabero Linguistic Family), Curripaco and Piapoco (Arawak linguistic family) and Yucpa (Karib linguistic family). for MHC class II haplotypes (HLA-DRB1, DQA1, DQB1). Approximately 90% of the MHC class II haplotypes found among these tribes are haplotypes frequently encountered in other Amerindian tribes. Nonetheless, striking differences were observed among Chibcha and non-Chibcha speaking tribes. The DRB1*04:04, DRB1*04:11, DRB1*09:01 carrying haplotypes were frequently found among non-Chibcha speaking tribes, while the DRB1*04:07 haplotype showed significant frequencies among Chibcha speaking tribes, and only marginal frequencies among non-Chibcha speaking tribes. Our results suggest that the differences in MHC class II haplotype frequency found among Chibcha and non-Chibcha speaking tribes could be due to genetic differentiation in Mesoamerica of the ancestral Amerindian population into Chibcha and non-Chibcha speaking populations before they entered into South America.

  11. MHC Class II haplotypes of Colombian Amerindian tribes

    PubMed Central

    Yunis, Juan J.; Yunis, Edmond J.; Yunis, Emilio

    2013-01-01

    We analyzed 1041 individuals belonging to 17 Amerindian tribes of Colombia, Chimila, Bari and Tunebo (Chibcha linguistic family), Embera, Waunana (Choco linguistic family), Puinave and Nukak (Maku-Puinave linguistic families), Cubeo, Guanano, Tucano, Desano and Piratapuyo (Tukano linguistic family), Guahibo and Guayabero (Guayabero Linguistic Family), Curripaco and Piapoco (Arawak linguistic family) and Yucpa (Karib linguistic family). for MHC class II haplotypes (HLA-DRB1, DQA1, DQB1). Approximately 90% of the MHC class II haplotypes found among these tribes are haplotypes frequently encountered in other Amerindian tribes. Nonetheless, striking differences were observed among Chibcha and non-Chibcha speaking tribes. The DRB1*04:04, DRB1*04:11, DRB1*09:01 carrying haplotypes were frequently found among non-Chibcha speaking tribes, while the DRB1*04:07 haplotype showed significant frequencies among Chibcha speaking tribes, and only marginal frequencies among non-Chibcha speaking tribes. Our results suggest that the differences in MHC class II haplotype frequency found among Chibcha and non-Chibcha speaking tribes could be due to genetic differentiation in Mesoamerica of the ancestral Amerindian population into Chibcha and non-Chibcha speaking populations before they entered into South America. PMID:23885196

  12. Characterization of MHC class II B polymorphism in bottlenecked New Zealand saddlebacks reveals low levels of genetic diversity.

    PubMed

    Sutton, Jolene T; Robertson, Bruce C; Grueber, Catherine E; Stanton, Jo-Ann L; Jamieson, Ian G

    2013-08-01

    The major histocompatibility complex (MHC) is integral to the vertebrate adaptive immune system. Characterizing diversity at functional MHC genes is invaluable for elucidating patterns of adaptive variation in wild populations, and is particularly interesting in species of conservation concern, which may suffer from reduced genetic diversity and compromised disease resilience. Here, we use next generation sequencing to investigate MHC class II B (MHCIIB) diversity in two sister taxa of New Zealand birds: South Island saddleback (SIS), Philesturnus carunculatus, and North Island saddleback (NIS), Philesturnus rufusater. These two species represent a passerine family outside the more extensively studied Passerida infraorder, and both have experienced historic bottlenecks. We examined exon 2 sequence data from populations that represent the majority of genetic diversity remaining in each species. A high level of locus co-amplification was detected, with from 1 to 4 and 3 to 12 putative alleles per individual for South and North Island birds, respectively. We found strong evidence for historic balancing selection in peptide-binding regions of putative alleles, and we identified a cluster combining non-classical loci and pseudogene sequences from both species, although no sequences were shared between the species. Fewer total alleles and fewer alleles per bird in SIS may be a consequence of their more severe bottleneck history; however, overall nucleotide diversity was similar between the species. Our characterization of MHCIIB diversity in two closely related species of New Zealand saddlebacks provides an important step in understanding the mechanisms shaping MHC diversity in wild, bottlenecked populations.

  13. Automated benchmarking of peptide-MHC class I binding predictions

    PubMed Central

    Trolle, Thomas; Metushi, Imir G.; Greenbaum, Jason A.; Kim, Yohan; Sidney, John; Lund, Ole; Sette, Alessandro; Peters, Bjoern; Nielsen, Morten

    2015-01-01

    Motivation: Numerous in silico methods predicting peptide binding to major histocompatibility complex (MHC) class I molecules have been developed over the last decades. However, the multitude of available prediction tools makes it non-trivial for the end-user to select which tool to use for a given task. To provide a solid basis on which to compare different prediction tools, we here describe a framework for the automated benchmarking of peptide-MHC class I binding prediction tools. The framework runs weekly benchmarks on data that are newly entered into the Immune Epitope Database (IEDB), giving the public access to frequent, up-to-date performance evaluations of all participating tools. To overcome potential selection bias in the data included in the IEDB, a strategy was implemented that suggests a set of peptides for which different prediction methods give divergent predictions as to their binding capability. Upon experimental binding validation, these peptides entered the benchmark study. Results: The benchmark has run for 15 weeks and includes evaluation of 44 datasets covering 17 MHC alleles and more than 4000 peptide-MHC binding measurements. Inspection of the results allows the end-user to make educated selections between participating tools. Of the four participating servers, NetMHCpan performed the best, followed by ANN, SMM and finally ARB. Availability and implementation: Up-to-date performance evaluations of each server can be found online at http://tools.iedb.org/auto_bench/mhci/weekly. All prediction tool developers are invited to participate in the benchmark. Sign-up instructions are available at http://tools.iedb.org/auto_bench/mhci/join. Contact: mniel@cbs.dtu.dk or bpeters@liai.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25717196

  14. TAPBPR and tapasin binding to MHC class I is mutually exclusive

    PubMed Central

    Hermann, Clemens; Strittmatter, Lisa M; Deane, Janet E; Boyle, Louise H

    2013-01-01

    The loading of peptide antigens onto MHC class I molecules is a highly controlled process in which the MHC class I dedicated chaperone tapasin is a key player. We recently identified a tapasin related molecule, TAPBPR, as an additional component in the MHC class I antigen presentation pathway. Here we show that the amino acid residues important for tapasin to interact with MHC class I are highly conserved on TAPBPR. We identify specific residues in the N-terminal and C-terminal domains of TAPBPR involved in associating with MHC class I. Furthermore, we demonstrate that residues on MHC class I crucial for its association with tapasin, such as T134, are also essential for its interaction with TAPBPR. Taken together, the data indicate that TAPBPR and tapasin bind in a similar orientation to the same face of MHC class I. In the absence of tapasin, the association of MHC class I with TAPBPR is increased. However, in the absence of TAPBPR, the interaction between MHC class I and tapasin does not increase. In light of our findings, previous data determining the function of tapasin in the MHC class I antigen processing and presentation pathway must be re-evaluated. PMID:24163410

  15. Balancing selection on MHC class I in wild brown trout Salmo trutta.

    PubMed

    O'Farrell, B; Dennis, C; Benzie, J A; McGinnity, P; Carlsson, J; de Eyto, E; Coughlan, J P; Igoe, F; Meehan, R; Cross, T F

    2012-09-01

    Evidence is reported for balancing selection acting on variation at major histocompatibility complex (MHC) in wild populations of brown trout Salmo trutta. First, variation at an MHC class I (satr-uba)-linked microsatellite locus (mhc1) is retained in small S. trutta populations isolated above waterfalls although variation is lost at neutral microsatellite markers. Second, populations across several catchments are less differentiated at mhc1 than at neutral markers, as predicted by theory. The population structure of these fish was also elucidated.

  16. An MHC class I immune evasion gene of Marek׳s disease virus.

    PubMed

    Hearn, Cari; Preeyanon, Likit; Hunt, Henry D; York, Ian A

    2015-01-15

    Marek׳s disease virus (MDV) is a widespread α-herpesvirus of chickens that causes T cell tumors. Acute, but not latent, MDV infection has previously been shown to lead to downregulation of cell-surface MHC class I (Virology 282:198-205 (2001)), but the gene(s) involved have not been identified. Here we demonstrate that an MDV gene, MDV012, is capable of reducing surface expression of MHC class I on chicken cells. Co-expression of an MHC class I-binding peptide targeted to the endoplasmic reticulum (bypassing the requirement for the TAP peptide transporter) partially rescued MHC class I expression in the presence of MDV012, suggesting that MDV012 is a TAP-blocking MHC class I immune evasion protein. This is the first unique non-mammalian MHC class I immune evasion gene identified, and suggests that α-herpesviruses have conserved this function for at least 100 million years.

  17. MHC class II-assortative mate choice in European badgers (Meles meles).

    PubMed

    Sin, Yung Wa; Annavi, Geetha; Newman, Chris; Buesching, Christina; Burke, Terry; Macdonald, David W; Dugdale, Hannah L

    2015-06-01

    The major histocompatibility complex (MHC) plays a crucial role in the immune system, and in some species, it is a target by which individuals choose mates to optimize the fitness of their offspring, potentially mediated by olfactory cues. Under the genetic compatibility hypothesis, individuals are predicted to choose mates with compatible MHC alleles, to increase the fitness of their offspring. Studies of MHC-based mate choice in wild mammals are under-represented currently, and few investigate more than one class of MHC genes. We investigated mate choice based on the compatibility of MHC class I and II genes in a wild population of European badgers (Meles meles). We also investigated mate choice based on microsatellite-derived pairwise relatedness, to attempt to distinguish MHC-specific effects from genomewide effects. We found MHC-assortative mating, based on MHC class II, but not class I genes. Parent pairs had smaller MHC class II DRB amino acid distances and smaller functional distances than expected from random pairings. When we separated the analyses into within-group and neighbouring-group parent pairs, only neighbouring-group pairs showed MHC-assortative mating, due to similarity at MHC class II loci. Our randomizations showed no evidence of genomewide-based inbreeding, based on 35 microsatellite loci; MHC class II similarity was therefore the apparent target of mate choice. We propose that MHC-assortative mate choice may be a local adaptation to endemic pathogens, and this assortative mate choice may have contributed to the low MHC genetic diversity in this population.

  18. The spatio-temporal expression of MHC class I molecules during human hippocampal formation development.

    PubMed

    Zhang, Aifeng; Yu, Hong; He, Youji; Shen, Yuqing; Pan, Ning; Liu, Jiane; Fu, Bo; Miao, Fengqin; Zhang, Jianqiong

    2013-09-05

    In the immune system, the major histocompatibility complex (MHC) class I molecules mediate both the innate and adaptive immune responses in vertebrates. There has been a dogma that the central nervous system (CNS) is immune privileged and healthy neurons do not express MHC class I molecules. However, recent studies have indicated that the expression and non-immunobiologic roles of MHC class I in mammalian CNS. But data referring to humans are scarce. In this study we report the expression and cellular localization of MHC class I in the human fetal, early postnatal and adult hippocampal formation. The expression of MHC class I was very low in the hippocampus at 20 (gestational weeks) GW and slowly increased at 27-33 GW. The gradually increased expression in the somata of some granular cells in dentate gyrus (DG) was observed at 30-33 GW. Whereas, a rapid increase in MHC class I molecules expression was found in the subiculum and it reached high levels at 31-33 GW and maintained at postnatal 55 days. No expression of MHC class I was found in hippocampal formation in adult. MHC class I heavy chain and β2 microglobulin (β2M) showed similar expression in some cells of the hippocampal formation at 30-33 GW. Moreover, MHC class I molecules were mainly expressed in neurons and most MHC class I-expressing neurons were glutamatergic. The temporal and spatial patterns of MHC class I expression appeared to follow gradients of pyramidal neurons maturation in the subiculum at prenatal stages and suggested that MHC class I molecules are likely to regulate neuron maturation. This article is part of a Special Issue entitled Priority to Publish.

  19. Sibling rivalry: competition between MHC class II family members inhibits immunity.

    PubMed

    Denzin, Lisa K; Cresswell, Peter

    2013-01-01

    Peptide loading of major histocompatibility complex (MHC) class II molecules in the endosomes and lysosomes of antigen-presenting cells is catalyzed by human leukocyte antigen-DM (HLA-DM) and modulated by HLA-DO. In a structural study in this issue, Guce et al. show that HLA-DO is an MHC class II mimic and functions as a competitive and essentially irreversible inhibitor of HLA-DM activity, thereby inhibiting MHC class II antigen presentation.

  20. Co-evolution of MHC class I and variable NK cell receptors in placental mammals.

    PubMed

    Guethlein, Lisbeth A; Norman, Paul J; Hilton, Hugo G; Parham, Peter

    2015-09-01

    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 that KIRs serve as variable NK cell receptors only in certain primates and artiodactyls. Divergence of the 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 KIR 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 KIR, 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.

  1. Co-evolution of MHC class I and variable NK cell receptors in placental mammals

    PubMed Central

    Guethlein, Lisbeth A.; Norman, Paul J.; Hilton, Hugo G.; Parham, Peter

    2015-01-01

    Summary 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. PMID:26284483

  2. Contrasting patterns of selection acting on MHC class I and class II DRB genes in the Alpine marmot (Marmota marmota).

    PubMed

    Kuduk, K; Johanet, A; Allainé, D; Cohas, A; Radwan, J

    2012-08-01

    The major histocompatibility complex (MHC) genes code for proteins that play a critical role in the immune system response. The MHC genes are among the most polymorphic genes in vertebrates, presumably due to balancing selection. The two MHC classes appear to differ in the rate of evolution, but the reasons for this variation are not well understood. Here, we investigate the level of polymorphism and the evolution of sequences that code for the peptide-binding regions of MHC class I and class II DRB genes in the Alpine marmot (Marmota marmota). We found evidence for four expressed MHC class I loci and two expressed MHC class II loci. MHC genes in marmots were characterized by low polymorphism, as one to eight alleles per putative locus were detected in 38 individuals from three French Alps populations. The generally limited degree of polymorphism, which was more pronounced in class I genes, is likely due to bottleneck the populations undergone. Additionally, gene duplication within each class might have compensated for the loss of polymorphism at particular loci. The two gene classes showed different patterns of evolution. The most polymorphic of the putative loci, Mama-DRB1, showed clear evidence of historical positive selection for amino acid replacements. However, no signal of positive selection was evident in the MHC class I genes. These contrasting patterns of sequence evolution may reflect differences in selection pressures acting on class I and class II genes.

  3. Mechanistic understanding and significance of small peptides interaction with MHC class II molecules for therapeutic applications.

    PubMed

    Afridi, Saifullah; Hoessli, Daniel C; Hameed, Muhammad Waqar

    2016-07-01

    Major histocompatibility complex (MHC) class II molecules are expressed by antigen-presenting cells and stimulate CD4(+) T cells, which initiate humoral immune responses. Over the past decade, interest has developed to therapeutically impact the peptides to be exposed to CD4(+) T cells. Structurally diverse small molecules have been discovered that act on the endogenous peptide exchanger HLA-DM by different mechanisms. Exogenously delivered peptides are highly susceptible to proteolytic cleavage in vivo; however, it is only when successfully incorporated into stable MHC II-peptide complexes that these peptides can induce an immune response. Many of the small molecules so far discovered have highlighted the molecular interactions mediating the formation of MHC II-peptide complexes. As potential drugs, these small molecules open new therapeutic approaches to modulate MHC II antigen presentation pathways and influence the quality and specificity of immune responses. This review briefly introduces how CD4(+) T cells recognize antigen when displayed by MHC class II molecules, as well as MHC class II-peptide-loading pathways, structural basis of peptide binding and stabilization of the peptide-MHC complexes. We discuss the concept of MHC-loading enhancers, how they could modulate immune responses and how these molecules have been identified. Finally, we suggest mechanisms whereby MHC-loading enhancers could act upon MHC class II molecules.

  4. Variable NK cell receptors and their MHC class I ligands in immunity, reproduction and human evolution.

    PubMed

    Parham, Peter; Moffett, Ashley

    2013-02-01

    Natural killer (NK) cells have roles in immunity and reproduction that are controlled by variable receptors that recognize MHC class I molecules. The variable NK cell receptors found in humans are specific to simian primates, in which they have progressively co-evolved with MHC class I molecules. The emergence of the MHC-C gene in hominids drove the evolution of a system of NK cell receptors for MHC-C molecules that is most elaborate in chimpanzees. By contrast, the human system of MHC-C receptors seems to have been subject to different selection pressures that have acted in competition on the immunological and reproductive functions of MHC class I molecules. We suggest that this compromise facilitated the development of the bigger brains that enabled archaic and modern humans to migrate out of Africa and populate other continents.

  5. NLRC5/MHC class I transactivator is a target for immune evasion in cancer

    PubMed Central

    Yoshihama, Sayuri; Roszik, Jason; Downs, Isaac; Meissner, Torsten B.; Vijayan, Saptha; Chapuy, Bjoern; Sidiq, Tabasum; Shipp, Margaret A.; Lizee, Gregory A.; Kobayashi, Koichi S.

    2016-01-01

    Cancer cells develop under immune surveillance, thus necessitating immune escape for successful growth. Loss of MHC class I expression provides a key immune evasion strategy in many cancers, although the molecular mechanisms remain elusive. MHC class I transactivator (CITA), known as “NLRC5” [NOD-like receptor (NLR) family, caspase recruitment (CARD) domain containing 5], has recently been identified as a critical transcriptional coactivator of MHC class I gene expression. Here we show that the MHC class I transactivation pathway mediated by CITA/NLRC5 constitutes a target for cancer immune evasion. In all the 21 tumor types we examined, NLRC5 expression was highly correlated with the expression of MHC class I, with cytotoxic T-cell markers, and with genes in the MHC class I antigen-presentation pathway, including LMP2/LMP7, TAP1, and β2-microglobulin. Epigenetic and genetic alterations in cancers, including promoter methylation, copy number loss, and somatic mutations, were most prevalent in NLRC5 among all MHC class I-related genes and were associated with the impaired expression of components of the MHC class I pathway. Strikingly, NLRC5 expression was significantly associated with the activation of CD8+ cytotoxic T cells and patient survival in multiple cancer types. Thus, NLRC5 constitutes a novel prognostic biomarker and potential therapeutic target of cancers. PMID:27162338

  6. NLRC5/MHC class I transactivator is a target for immune evasion in cancer.

    PubMed

    Yoshihama, Sayuri; Roszik, Jason; Downs, Isaac; Meissner, Torsten B; Vijayan, Saptha; Chapuy, Bjoern; Sidiq, Tabasum; Shipp, Margaret A; Lizee, Gregory A; Kobayashi, Koichi S

    2016-05-24

    Cancer cells develop under immune surveillance, thus necessitating immune escape for successful growth. Loss of MHC class I expression provides a key immune evasion strategy in many cancers, although the molecular mechanisms remain elusive. MHC class I transactivator (CITA), known as "NLRC5" [NOD-like receptor (NLR) family, caspase recruitment (CARD) domain containing 5], has recently been identified as a critical transcriptional coactivator of MHC class I gene expression. Here we show that the MHC class I transactivation pathway mediated by CITA/NLRC5 constitutes a target for cancer immune evasion. In all the 21 tumor types we examined, NLRC5 expression was highly correlated with the expression of MHC class I, with cytotoxic T-cell markers, and with genes in the MHC class I antigen-presentation pathway, including LMP2/LMP7, TAP1, and β2-microglobulin. Epigenetic and genetic alterations in cancers, including promoter methylation, copy number loss, and somatic mutations, were most prevalent in NLRC5 among all MHC class I-related genes and were associated with the impaired expression of components of the MHC class I pathway. Strikingly, NLRC5 expression was significantly associated with the activation of CD8(+) cytotoxic T cells and patient survival in multiple cancer types. Thus, NLRC5 constitutes a novel prognostic biomarker and potential therapeutic target of cancers.

  7. Contrasting evolutionary histories of MHC class I and class II loci in grouse--effects of selection and gene conversion.

    PubMed

    Minias, P; Bateson, Z W; Whittingham, L A; Johnson, J A; Oyler-McCance, S; Dunn, P O

    2016-05-01

    Genes of the major histocompatibility complex (MHC) encode receptor molecules that are responsible for recognition of intracellular and extracellular pathogens (class I and class II genes, respectively) in vertebrates. Given the different roles of class I and II MHC genes, one might expect the strength of selection to differ between these two classes. Different selective pressures may also promote different rates of gene conversion at each class. Despite these predictions, surprisingly few studies have looked at differences between class I and II genes in terms of both selection and gene conversion. Here, we investigated the molecular evolution of MHC class I and II genes in five closely related species of prairie grouse (Centrocercus and Tympanuchus) that possess one class I and two class II loci. We found striking differences in the strength of balancing selection acting on MHC class I versus class II genes. More than half of the putative antigen-binding sites (ABS) of class II were under positive or episodic diversifying selection, compared with only 10% at class I. We also found that gene conversion had a stronger role in shaping the evolution of MHC class II than class I. Overall, the combination of strong positive (balancing) selection and frequent gene conversion has maintained higher diversity of MHC class II than class I in prairie grouse. This is one of the first studies clearly demonstrating that macroevolutionary mechanisms can act differently on genes involved in the immune response against intracellular and extracellular pathogens.

  8. Contrasting evolutionary histories of MHC class I and class II loci in grouse—Effects of selection and gene conversion

    USGS Publications Warehouse

    Minias, Piotr; Bateson, Zachary W; Whittingham, Linda A; Johnson, Jeff A.; Oyler-McCance, Sara J.; Dunn, Peter O

    2016-01-01

    Genes of the major histocompatibility complex (MHC) encode receptor molecules that are responsible for recognition of intracellular and extracellular pathogens (class I and class II genes, respectively) in vertebrates. Given the different roles of class I and II MHC genes, one might expect the strength of selection to differ between these two classes. Different selective pressures may also promote different rates of gene conversion at each class. Despite these predictions, surprisingly few studies have looked at differences between class I and II genes in terms of both selection and gene conversion. Here, we investigated the molecular evolution of MHC class I and II genes in five closely related species of prairie grouse (Centrocercus and Tympanuchus) that possess one class I and two class II loci. We found striking differences in the strength of balancing selection acting on MHC class I versus class II genes. More than half of the putative antigen-binding sites (ABS) of class II were under positive or episodic diversifying selection, compared with only 10% at class I. We also found that gene conversion had a stronger role in shaping the evolution of MHC class II than class I. Overall, the combination of strong positive (balancing) selection and frequent gene conversion has maintained higher diversity of MHC class II than class I in prairie grouse. This is one of the first studies clearly demonstrating that macroevolutionary mechanisms can act differently on genes involved in the immune response against intracellular and extracellular pathogens.

  9. Selective export of MHC class I molecules from the ER after their dissociation from TAP.

    PubMed

    Spiliotis, E T; Manley, H; Osorio, M; Zúñiga, M C; Edidin, M

    2000-12-01

    It has been assumed that upon dissociation from TAP, MHC class I molecules exit the ER by nonselective bulk flow. We now show that exit must occur by association with cargo receptors. Inconsistent with exit by bulk flow, loading of MHC class I molecules with high-affinity peptides triggers dissociation from TAP but has no effect on rates of ER-to-Golgi transport. Moreover, peptide-loaded MHC class I molecules accumulate at ER exit sites from which TAP molecules are excluded. Consistent with receptor-mediated exit, ER-to-Golgi transport of MHC class I molecules is independent of their cytoplasmic tails, which themselves lack ER export motifs. In addition, we show that MHC class I molecules associate with the putative cargo receptor BAP31.

  10. A Case of Probable MHC Class II Deficiency with Disseminated BCGitis.

    PubMed

    Alyasin, Soheyla; Abolnezhadian, Farhad; Khoshkhui, Maryam

    2015-09-01

    Major histocompatibility complex (MHC) class II deficiency is a primary immunodeficiency disease characterized by abnormality of MHC class II molecules surface expression on peripheral blood lymphocytes and monocytes. Clinical manifestations include extreme susceptibility to viral, bacterial, and fungal infections but the immunodeficiency is not as severe as SCID (severe combined immunodeficiency), as evidenced by failure to develop disseminated infection after BCG vaccination. Therefore, MHC II deficiency with BCGosis, that is disseminated BCGitis, is not reported commonly. We report an interesting case of BCGosis after vaccination that was diagnosed to have probable MHC II deficiency.

  11. Rheumatoid Rescue of Misfolded Cellular Proteins by MHC Class II Molecules: A New Hypothesis for Autoimmune Diseases.

    PubMed

    Arase, Hisashi

    2016-01-01

    Misfolded proteins localized in the endoplasmic reticulum are degraded promptly and thus are not transported outside cells. However, misfolded proteins in the endoplasmic reticulum are rescued from protein degradation upon association with major histocompatibility complex (MHC) class II molecules and are transported to the cell surface by MHC class II molecules without being processed to peptides. Studies on the misfolded proteins rescued by MHC class II molecules have revealed that misfolded proteins associated with MHC class II molecules are specific targets for autoantibodies produced in autoimmune diseases. Furthermore, a strong correlation has been observed between autoantibody binding to misfolded proteins associated with MHC class II molecules and the autoimmune disease susceptibility conferred by each MHC class II allele. These new insights into MHC class II molecules suggest that misfolded proteins rescued from protein degradation by MHC class II molecules are recognized as "neo-self" antigens by immune system and are involved in autoimmune diseases as autoantibody targets.

  12. Recognition of the Major Histocompatibility Complex (MHC) Class Ib Molecule H2-Q10 by the Natural Killer Cell Receptor Ly49C.

    PubMed

    Sullivan, Lucy C; Berry, Richard; Sosnin, Natasha; Widjaja, Jacqueline M L; Deuss, Felix A; Balaji, Gautham R; LaGruta, Nicole L; Mirams, Michiko; Trapani, Joseph A; Rossjohn, Jamie; Brooks, Andrew G; Andrews, Daniel M

    2016-09-02

    Murine natural killer (NK) cells are regulated by the interaction of Ly49 receptors with major histocompatibility complex class I molecules (MHC-I). Although the ligands for inhibitory Ly49 were considered to be restricted to classical MHC (MHC-Ia), we have shown that the non-classical MHC molecule (MHC-Ib) H2-M3 was a ligand for the inhibitory Ly49A. Here we establish that another MHC-Ib, H2-Q10, is a bona fide ligand for the inhibitory Ly49C receptor. H2-Q10 bound to Ly49C with a marginally lower affinity (∼5 μm) than that observed between Ly49C and MHC-Ia (H-2K(b)/H-2D(d), both ∼1 μm), and this recognition could be prevented by cis interactions with H-2K in situ To understand the molecular details underpinning Ly49·MHC-Ib recognition, we determined the crystal structures of H2-Q10 and Ly49C bound H2-Q10. Unliganded H2-Q10 adopted a classical MHC-I fold and possessed a peptide-binding groove that exhibited features similar to those found in MHC-Ia, explaining the diverse peptide binding repertoire of H2-Q10. Ly49C bound to H2-Q10 underneath the peptide binding platform to a region that encompassed residues from the α1, α2, and α3 domains, as well as the associated β2-microglobulin subunit. This docking mode was conserved with that previously observed for Ly49C·H-2K(b) Indeed, structure-guided mutation of Ly49C indicated that Ly49C·H2-Q10 and Ly49C·H-2K(b) possess similar energetic footprints focused around residues located within the Ly49C β4-stand and L5 loop, which contact the underside of the peptide-binding platform floor. Our data provide a structural basis for Ly49·MHC-Ib recognition and demonstrate that MHC-Ib represent an extended family of ligands for Ly49 molecules.

  13. Regulation of calreticulin–major histocompatibility complex (MHC) class I interactions by ATP

    PubMed Central

    Wijeyesakere, Sanjeeva Joseph; Gagnon, Jessica K.; Arora, Karunesh; Brooks, Charles L.; Raghavan, Malini

    2015-01-01

    The MHC class I peptide loading complex (PLC) facilitates the assembly of MHC class I molecules with peptides, but factors that regulate the stability and dynamics of the assembly complex are largely uncharacterized. Based on initial findings that ATP, in addition to MHC class I-specific peptide, is able to induce MHC class I dissociation from the PLC, we investigated the interaction of ATP with the chaperone calreticulin, an endoplasmic reticulum (ER) luminal, calcium-binding component of the PLC that is known to bind ATP. We combined computational and experimental measurements to identify residues within the globular domain of calreticulin, in proximity to the high-affinity calcium-binding site, that are important for high-affinity ATP binding and for ATPase activity. High-affinity calcium binding by calreticulin is required for optimal nucleotide binding, but both ATP and ADP destabilize enthalpy-driven high-affinity calcium binding to calreticulin. ATP also selectively destabilizes the interaction of calreticulin with cellular substrates, including MHC class I molecules. Calreticulin mutants that affect ATP or high-affinity calcium binding display prolonged associations with monoglucosylated forms of cellular MHC class I, delaying MHC class I dissociation from the PLC and their transit through the secretory pathway. These studies reveal central roles for ATP and calcium binding as regulators of calreticulin–substrate interactions and as key determinants of PLC dynamics. PMID:26420867

  14. Cytosolic aminopeptidases influence MHC class I-mediated antigen presentation in an allele-dependent manner.

    PubMed

    Kim, Eunkyung; Kwak, Heechun; Ahn, Kwangseog

    2009-12-01

    Antigenic peptides presented by MHC class I molecules are generated mainly by the proteasome in the cytosol. Several cytosolic aminopeptidases further trim proteasomal products to form mature epitopes or individual amino acids. However, the distinct function of cytosolic aminopeptidases in MHC class I Ag processing remains to be elucidated. In this study, we show that cytosolic aminopeptidases differentially affect the cell surface expression of MHC class I molecules in an allele-dependent manner in human cells. In HeLa cells, knockdown of puromycin-sensitive aminopeptidase (PSA) by RNA interference inhibited optimal peptide loading of MHC class I molecules, and their cell surface expression was correspondingly reduced. In contrast, depletion of bleomycin hydrolase (BH) enhanced optimal peptide loading and cell surface expression of MHC class I molecules. We did not find evidence on the effect of leucine aminopeptidase knockdown on the MHC class I Ag presentation. Moreover, we demonstrated that PSA and BH influence the peptide loading and surface expression of MHC class I in an allele-specific manner. In the absence of either PSA or BH, the surface expression and peptide-dependent stability of HLA-A68 were reduced, whereas those of HLA-B15 were enhanced. The surface expression and peptide-dependent stability of HLA-A3 were enhanced by BH knockdown, although those of HLA-B8 were increased in PSA-depleted conditions.

  15. Secretory granules of mast cells accumulate mature and immature MHC class II molecules.

    PubMed

    Vincent-Schneider, H; Théry, C; Mazzeo, D; Tenza, D; Raposo, G; Bonnerot, C

    2001-01-01

    Bone marrow-derived mast cells as well as dendritic cells, macrophages and B lymphocytes express major histocompatibility complex (MHC) class II molecules. In mast cells, the majority of MHC class II molecules reside in intracellular cell type-specific compartments, secretory granules. To understand the molecular basis for the localisation of MHC class II molecules in secretory granules, MHC class II molecules were expressed, together with the invariant chain, in the mast cell line, RBL-2H3. Using electron and confocal microscopy, we observed that in RBL-2H3 cells, mature and immature class II molecules accumulate in secretory granules. Two particular features of class II transport accounted for this intracellular localization: first, a large fraction of newly synthesized MHC class II molecules remained associated with invariant chain fragments. This defect, resulting in a slower rate of MHC class II maturation, was ascribed to a low cathepsin S activity. Second, although a small fraction of class II dimers matured (i.e. became free of invariant chain), allowing their association with antigenic peptides, they were retained in secretory granules. As a consequence of this intracellular localization, cell surface expression of class II molecules was strongly increased by cell activation stimuli which induced the release of the contents of secretory granules. Our results suggest that antigen presentation, and thereby antigen specific T cell stimulation, are regulated in mast cells by stimuli which induce mast cell activation.

  16. Neuronal MHC Class I Expression Is Regulated by Activity Driven Calcium Signaling

    PubMed Central

    Peng, Yaqin; Liu, Jiane; Miao, Fengqin; Zhang, Jianqiong

    2015-01-01

    MHC class I (MHC-I) molecules are important components of the immune system. Recently MHC-I have been reported to also play important roles in brain development and synaptic plasticity. In this study, we examine the molecular mechanism(s) underlying activity-dependent MHC-I expression using hippocampal neurons. Here we report that neuronal expression level of MHC-I is dynamically regulated during hippocampal development after birth in vivo. Kainic acid (KA) treatment significantly increases the expression of MHC-I in cultured hippocampal neurons in vitro, suggesting that MHC-I expression is regulated by neuronal activity. In addition, KA stimulation decreased the expression of pre- and post-synaptic proteins. This down-regulation is prevented by addition of an MHC-I antibody to KA treated neurons. Further studies demonstrate that calcium-dependent protein kinase C (PKC) is important in relaying KA simulation activation signals to up-regulated MHC-I expression. This signaling cascade relies on activation of the MAPK pathway, which leads to increased phosphorylation of CREB and NF-κB p65 while also enhancing the expression of IRF-1. Together, these results suggest that expression of MHC-I in hippocampal neurons is driven by Ca2+ regulated activation of the MAPK signaling transduction cascade. PMID:26263390

  17. Evolution of an MHC class Ia gene fragment in four North American Morone species.

    PubMed

    Liu, J-X; Ely, B

    2010-05-01

    A nucleotide sequence analysis of a fragment of a Morone MHC class Ia gene detected high levels of polymorphism in striped bass Morone saxatilis, white perch Morone americana and yellow bass Morone mississippiensis. Extremely low levels of MHC diversity, however, were detected in white bass Morone chrysops, suggesting the possibility of a severe population bottleneck for this species.

  18. Interspecific hybridization increases MHC class II diversity in two sister species of newts.

    PubMed

    Nadachowska-Brzyska, Krystyna; Zieliński, Piotr; Radwan, Jacek; Babik, Wiesław

    2012-02-01

    Our understanding of the evolutionary mechanisms generating variation within the highly polymorphic major histocompatibility complex (MHC) genes remains incomplete. Assessing MHC variation across multiple populations, of recent and ancient divergence, may facilitate understanding of geographical and temporal aspects of variation. Here, we applied 454 sequencing to perform a large-scale, comprehensive analysis of MHC class II in the closely related, hybridizing newts, Lissotriton vulgaris (Lv) and Lissotriton montandoni (Lm). Our study revealed an extensive (299 alleles) geographically structured polymorphism. Populations at the southern margin of the Lv distribution, inhabited by old and distinct lineages (southern Lv), exhibited moderate MHC variation and strong population structure, indicating little gene flow or extensive local adaptation. Lissotriton vulgaris in central Europe and the northern Balkans (northern Lv) and almost all Lm populations had a high MHC variation. A much higher proportion of MHC alleles was shared between Lm and northern Lv than between Lm and southern Lv. Strikingly, the average pairwise F(ST) between northern Lv and Lm was significantly lower than between northern and southern Lv for MHC, but not for microsatellites. Thus, high MHC variation in Lm and northern Lv may result from gene flow between species. We hypothesize that the interspecific exchange of MHC genes may be facilitated by frequency-dependent selection. A marginally significant correlation between the MHC and microsatellite allelic richness indicates that demographic factors may have contributed to the present-day pattern of MHC variation, but unequivocal signatures of adaptive evolution in MHC class II sequences emphasize the role of selection on a longer timescale.

  19. Identification of MHC class II restricted T-cell-mediated reactivity against MHC class I binding Mycobacterium tuberculosis peptides.

    PubMed

    Wang, Mingjun; Tang, Sheila T; Stryhn, Anette; Justesen, Sune; Larsen, Mette V; Dziegiel, Morten H; Lewinsohn, David M; Buus, Søren; Lund, Ole; Claesson, Mogens H

    2011-04-01

    Major histocompatibility complex (MHC) class I restricted cytotoxic T lymphocytes (CTL) are known to play an important role in the control of Mycobacterium tuberculosis infection so identification of CTL epitopes from M. tuberculosis is of importance for the development of effective peptide-based vaccines. In the present work, bioinformatics technology was employed to predict binding motifs of 9mer peptides derived from M. tuberculosis for the 12 HLA-I supertypes. Subsequently, the predicted peptides were synthesized and assayed for binding to HLA-I molecules in a biochemically based system. The antigenicity of a total of 157 peptides with measured affinity for HLA-I molecules of K(D) ≤ 500 nM were evaluated using peripheral blood T cells from strongly purified protein derivative reactive healthy donors. Of the 157 peptides, eight peptides (5%) were found to induce T-cell responses. As judged from blocking with HLA class I and II subtype antibodies in the ELISPOT assay culture, none of the eight antigenic peptides induced HLA class I restricted CD8(+) T-cell responses. Instead all responses were blocked by pan-HLA class II and anti-HLA-DR antibodies. In addition, CD4(+) T-cell depletion before the 10 days of expansion, resulted in total loss of reactivity in the ELISPOT culture for most peptide specificities. FACS analyses with intracellular interferon-γ staining of T cells expanded in the presence of M. tuberculosis peptides confirmed that the responsive cells were indeed CD4(+). In conclusion, T-cell immunity against HLA-I binding 9mer M. tuberculosis-derived peptides might in many cases turn out to be mediated by CD4(+) T cells and restricted by HLA-II molecules. The use of 9mer peptides recognized by both CD8(+) and CD4(+) T cells might be of importance for the development of future M. tuberculosis peptide-based vaccines.

  20. Molecular characterization of MHC class II in the Australian invasive cane toad reveals multiple splice variants.

    PubMed

    Lillie, Mette; Cui, Jian; Shine, Richard; Belov, Katherine

    2016-07-01

    The cane toad has gained notoriety for its invasion across the Australian landscape, with significant impacts on the native Australian fauna. The invasion has accelerated over time, with invading cane toads adapted for highly dispersive traits. This, however, has come at the cost of the immune system, with lower investment in some immune functions. To investigate the cane toad's immunogenetics, we characterized four major histocompatibility complex (MHC) class IIA and three MHC class IIB loci. Preliminary observations suggest very low allelic diversity at all loci. We also observed various splice isoforms. One isoform seen at one class IIA and two class IIB loci was missing exon 2, which is essential to peptide binding and presentation. The other isoform, observed at a class IIA locus, is likely to be a soluble MHC product. These results may suggest a significant role of alternative splicing of MHC loci in the Australian cane toad.

  1. A central role for HSC70 in regulating antigen trafficking and MHC class II presentation.

    PubMed

    Deffit, Sarah N; Blum, Janice S

    2015-12-01

    Cells rely on multiple intracellular trafficking pathways to capture antigens for proteolysis. The resulting peptides bind to MHC class II molecules to promote CD4(+) T cell recognition. Endocytosis enhances the capture of extracellular and cell surface bound antigens for processing and presentation, while autophagy pathways shunt cytoplasmic and nuclear antigens for presentation in the context of MHC class II molecules. Understanding how physiological changes and cellular stress alter antigen trafficking and the repertoire of peptides presented by class II molecules remains challenging, yet important in devising novel approaches to boost immune responses to pathogens and tumors. An abundant, constitutively expressed cytoplasmic chaperone, HSC70 plays a central role in modulating antigen transport within cells to control MHC class II presentation during nutrient stress. HSC70 may serve as a molecular switch to modulate endocytic and autophagy pathways, impacting the source of antigens delivered for MHC class II presentation during cellular stress.

  2. Molecular characterization of major histocompatibility complex class 1 (MHC-I) from squirrel monkeys (Saimiri sciureus).

    PubMed

    Pascalis, Hervé; Heraud, Jean-Michel; Fendel, Rolf; Lavergne, Anne; Kazanji, Mirdad

    2003-12-01

    Little is known about the major histocompatibility complex (MHC) class 1 in squirrel monkeys ( Saimiri sciureus). We cloned, sequenced and characterized two alleles and the cDNA of the coding region of MHC class 1 in these New World monkeys. Phylogenetic analyses showed that these sequences are related to HLA class 1 genes ( HLA-A and HLA-G). The structure and organization of one of the two identified clones was similar to that of a class 1 MHC gene ( HLA-A2). All the exon/intron splice acceptor/donor sites are conserved and their locations correspond to the HLA-A2 gene. The sequences of the newly described cDNAs reveal that they code for the characteristic class 1 MHC proteins, with all the features thought necessary for cell surface expression. Typical sequences for the leader peptide, alpha(1), alpha(2), alpha(3), transmembrane and cytoplasmic domains were found.

  3. MHC evolution in three salmonid species: a comparison between class II alpha and beta genes.

    PubMed

    Gómez, Daniela; Conejeros, Pablo; Marshall, Sergio H; Consuegra, Sofia

    2010-08-01

    The genes of the major histocompatibility complex (MHC) are amongst the most variable in vertebrates and represent some of the best candidates to study processes of adaptive evolution. However, despite the number of studies available, most of the information on the structure and function of these genes come from studies in mammals and birds in which the MHC class I and II genes are tightly linked and class II alpha exhibits low variability in many cases. Teleost fishes are among the most primitive vertebrates with MHC and represent good organisms for the study of MHC evolution because their class I and class II loci are not physically linked, allowing for independent evolution of both classes of genes. We have compared the diversity and molecular mechanisms of evolution of classical MH class II alpha and class II beta loci in farm populations of three salmonid species: Oncorhynchus kisutch, Oncorhynchus mykiss and Salmo salar. We found single classical class II loci and high polymorphism at both class II alpha and beta genes in the three species. Mechanisms of evolution were common for both class II genes, with recombination and point mutation involved in generating diversity and positive selection acting on the peptide-binding residues. These results suggest that the maintenance of variability at the class IIalpha gene could be a mechanism to increase diversity in the MHC class II in salmonids in order to compensate for the expression of one single classical locus and to respond to a wider array of parasites.

  4. Cellular misfolded proteins rescued from degradation by MHC class II molecules are possible targets for autoimmune diseases.

    PubMed

    Arase, Noriko; Arase, Hisashi

    2015-11-01

    The major function of major histocompatibility complex (MHC) class II molecules is the presentation of peptide antigens to helper T cells. However, when misfolded proteins are associated with MHC class II molecules in the endoplasmic reticulum, they are transported to the cell surface by MHC class II molecules without processing to peptides. Of note, misfolded proteins complexed with MHC class II molecules are specifically recognized by autoantibodies produced in patients with autoimmune diseases such as rheumatoid arthritis and antiphospholipid syndrome. Furthermore, autoantibody binding to misfolded proteins complexed with MHC class II molecules is associated with the susceptibility to autoimmune diseases conferred by each MHC class II allele. Therefore, misfolded proteins rescued from degradation by MHC class II molecules may be recognized as 'neo-self' antigens by the immune system and be involved in the pathogenicity of autoimmune diseases.

  5. Protein sorting within the MHC class II antigen-processing pathway.

    PubMed

    Marks, M S

    1998-01-01

    Major histocompatibility complex (MHC) class II molecules are required for the presentation of antigenic peptides that are derived predominantly from internalized proteins. The assembly of MHC class II/peptide complexes occurs within endosomal compartments of antigen-presenting cells (APCs). Therefore, for assembly to occur, MHC class II molecules, foreign proteins, and accessory molecules must be sorted to appropriate intracellular sites. My laboratory is trying to understand how proteins are sorted to various antigen-processing compartments as well as to conventional endosomal organelles. Using chimeric marker proteins and a variety of biochemical and genetic approaches, we are addressing the specificity of protein sorting and the mechanisms by which sorting signals are deciphered. By using a similar chimeric protein approach to target endogenous proteins to distinct compartments, we hope to address the role of processing events in each compartment in the generation of MHC class II ligands.

  6. Improved pan-specific MHC class I peptide-binding predictions using a novel representation of the MHC-binding cleft environment.

    PubMed

    Carrasco Pro, S; Zimic, M; Nielsen, M

    2014-02-01

    Major histocompatibility complex (MHC) molecules play a key role in cell-mediated immune responses presenting bounded peptides for recognition by the immune system cells. Several in silico methods have been developed to predict the binding affinity of a given peptide to a specific MHC molecule. One of the current state-of-the-art methods for MHC class I is NetMHCpan, which has a core ingredient for the representation of the MHC class I molecule using a pseudo-sequence representation of the binding cleft amino acid environment. New and large MHC-peptide-binding data sets are constantly being made available, and also new structures of MHC class I molecules with a bound peptide have been published. In order to test if the NetMHCpan method can be improved by integrating this novel information, we created new pseudo-sequence definitions for the MHC-binding cleft environment from sequence and structural analyses of different MHC data sets including human leukocyte antigen (HLA), non-human primates (chimpanzee, macaque and gorilla) and other animal alleles (cattle, mouse and swine). From these constructs, we showed that by focusing on MHC sequence positions found to be polymorphic across the MHC molecules used to train the method, the NetMHCpan method achieved a significant increase in the predictive performance, in particular, of non-human MHCs. This study hence showed that an improved performance of MHC-binding methods can be achieved not only by the accumulation of more MHC-peptide-binding data but also by a refined definition of the MHC-binding environment including information from non-human species.

  7. Maintenance of MHC Class IIB diversity in a recently established songbird population

    PubMed Central

    Whittaker, Danielle J.; Dapper, Amy L.; Peterson, Mark P.; Atwell, Jonathan W.; Ketterson, Ellen D.

    2012-01-01

    We examined variation at MHC Class IIB genes in a recently established population of dark-eyed juncos (Junco hyemalis) in a coastal urban environment in southern California, USA relative to an ancestral-range population from a nearby species-typical montane environment. The founding population is estimated to have been quite small, but we predicted that variation at the major histocompatibility complex (MHC) among the founders would nevertheless be preserved owing to the high functional significance of MHC. Previous studies of MHC in songbirds have had varying degrees of success in isolating loci, as passerines show extensive MHC gene duplication. In order to compare diversity in the two populations, we employed two published approaches to sequencing MHC Class II exon 2: direct sequencing with exon-based primers, and traditional cloning and sequencing with intron-based primers. Results from both methods show that the colonist population has maintained high levels of variation. Our results also indicate varying numbers of alleles across individuals, corroborating evidence for gene duplication in songbird MHC. While future studies in songbirds may need to take a genomic approach to fully understand the structure of MHC in this lineage, our results show that it is possible to use traditional methods to reveal functional variation across populations. PMID:22685370

  8. Processing and MHC class II presentation of exogenous soluble antigen involving a proteasome-dependent cytosolic pathway in CD40-activated B cells.

    PubMed

    Becker, Hans Jiro; Kondo, Eisei; Shimabukuro-Vornhagen, Alexander; Theurich, Sebastian; von Bergwelt-Baildon, Michael S

    2016-08-01

    Activated B cells have the capacity to present antigen and induce immune responses as potent antigen-presenting cells (APCs). As in other APCs, antigen presentation by B cells involves antigen internalization, antigen processing, and peptide loading onto MHC molecules. However, while the mechanism of antigen processing has been studied extensively in other APCs, this pathway remains elusive in B cells. The aim of this study was to investigate the MHC class II processing pathway in CD40-activated B cells (CD40Bs), as a model for activated, antigen-presenting B cells. Using CMV pp65 as a model antigen, we evaluated processing and presentation of the CD4 + T-cell epitope 509-523 (K509) by human CD40Bs in ELISPOT assays. As expected, stimulation of specific CD4 + T-cell clones was attenuated after pretreatment of CD40Bs with inhibitors of classic class II pathway components. However, proteasome inhibitors such as epoxomicin limited antigen presentation as well. This suggests that the antigen is processed in a non-classical, cytosolic MHC class II pathway. Further experiments with truncated protein variants revealed involvement of the proteasome in processing of the N and C extensions of the epitope. Access to the cytosol was shown to be size dependent. Epoxomicin sensitivity exclusively in CD40B cells, but not in dendritic cells, suggests a novel processing mechanism unique to this APC. Our data suggest that B cells process antigen using a distinct, non-classical class II pathway.

  9. HLA-DM is localized to conventional and unconventional MHC class II-containing endocytic compartments.

    PubMed

    Pierre, P; Denzin, L K; Hammond, C; Drake, J R; Amigorena, S; Cresswell, P; Mellman, I

    1996-03-01

    HLA-DM molecules remove invariant (Ii) chain peptides from newly synthesized MHC class II complexes. Their localization may thus delineate compartments, e.g., MIIC, specialized for loading peptides onto class II molecules. In murine A20 B cells, however, DM is not restricted to specialized endosomal class II-containing vesicles (CIIV). Although DM was found in CIIV, it was also found throughout the endocytic pathway, principally in lysosomes devoid of class II molecules. In human lymphoblasts, HLA-DM was found in structures indistinguishable from late endosomes or lysosomes, although in these cells the lysosomes contained MHC class II molecules. Thus, the distribution of HLA-DM does not necessarily identify specialized class II compartments. Many "MIIC" may represent conventional lysosomes that accumulate MHC class II and HLA-DM in a number of cell types.

  10. Redirecting soluble antigen for MHC class I cross-presentation during phagocytosis.

    PubMed

    Hari, Aswin; Ganguly, Anutosh; Mu, Libing; Davis, Shevaun P; Stenner, Melanie D; Lam, Raymond; Munro, Fay; Namet, Inana; Alghamdi, Enaam; Fürstenhaupt, Tobias; Dong, Wei; Detampel, Pascal; Shen, Lian Jun; Amrein, Matthias W; Yates, Robin M; Shi, Yan

    2015-02-01

    Peptides presented by MHC class I molecules are mostly derived from proteins synthesized by the antigen-presenting cell itself, while peptides presented by MHC class II molecules are predominantly from materials acquired by endocytosis. External antigens can also be presented by MHC class I molecules in a process referred to as cross-presentation. Here, we report that mouse dendritic cell (DC) engagement to a phagocytic target alters endocytic processing and inhibits the proteolytic activities. During phagocytosis, endosome maturation is delayed, shows less progression toward the lysosome, and the endocytosed soluble antigen is targeted for MHC class I cross-presentation. The antigen processing in these arrested endosomes is under the control of NAPDH oxidase associated ROS. We also show that cathepsin S is responsible for the generation of the MHC class I epitope. Taken together, our results suggest that in addition to solid structure uptake, DC phagocytosis simultaneously modifies the kinetics of endosomal trafficking and maturation. As a consequence, external soluble antigens are targeted into the MHC class I cross-presentation pathway.

  11. Redirecting soluble antigen for MHC class I cross-presentation during phagocytosis

    PubMed Central

    Hari, Aswin; Ganguly, Anutosh; Mu, Libing; Davis, Shevaun P.; Stenner, Melanie D.; Lam, Raymond; Munro, Fay; Namet, Inana; Alghamdi, Enaam; Fürstenhaupt, Tobias; Dong, Wei; Detampel, Pascal; Shen, Lian Jun; Amrein, Matthias W.; Yates, Robin M.; Shi, Yan

    2014-01-01

    Peptides presented by MHC class I molecules are derived mostly from proteins synthesized by the antigen-presenting cell itself, while peptides presented by MHC class II molecules are derived predominantly from materials acquired by endocytosis. External antigens can also be presented by MHC class I molecules in a process referred to as cross-presentation. We report that mouse dendritic cell engagement of a phagocytic target alters endocytic processing and inhibits their proteolytic activities. During phagocytosis, endosome maturation is delayed, shows less progression towards the lysosome, and the endocytosed soluble antigen is targeted for MHC class I cross-presentation. The antigen processing in these arrested endosomes is under the control of NAPDH oxidase associated ROS. We also show that cathepsin S is responsible for the generation of the MHC class I epitope. Our results suggest that in addition to solid structure uptake, DC phagocytosis simultaneously modifies the kinetics of endosomal trafficking and maturation. As a consequence, external soluble antigens are targeted into the MHC class I cross-presentation pathway. PMID:25378230

  12. The urgent need to recover MHC class I in cancers for effective immunotherapy.

    PubMed

    Garrido, Federico; Aptsiauri, Natalia; Doorduijn, Elien M; Garcia Lora, Angel M; van Hall, Thorbald

    2016-04-01

    Immune escape strategies aimed to avoid T-cell recognition, including the loss of tumor MHC class I expression, are commonly found in malignant cells. Tumor immune escape has proven to have a negative effect on the clinical outcome of cancer immunotherapy, including treatment with antibodies blocking immune checkpoint molecules. Hence, there is an urgent need to develop novel approaches to overcome tumor immune evasion. MHC class I antigen presentation is often affected in human cancers and the capacity to induce upregulation of MHC class I cell surface expression is a critical step in the induction of tumor rejection. This review focuses on characterization of rejection, escape, and dormant profiles of tumors and its microenvironment with a special emphasis on the tumor MHC class I expression. We also discuss possible approaches to recover MHC class I expression on tumor cells harboring reversible/'soft' or irreversible/'hard' genetic lesions. Such MHC class I recovery approaches might well synergize with complementary forms of immunotherapy.

  13. The multigenic structure of the MHC locus contributes to positive selection efficiency: a role for MHC class II gene-specific restriction.

    PubMed

    Monteiro, Miguel Caetano; Couceiro, Sofia; Penha-Gonçalves, Carlos

    2005-12-01

    The study of T cell positive selection in the thymus has long been focused on the specificity of the MHC-TCR interactions, making use of genetically manipulated mice that display TCR specificities or selecting peptides of limited diversity. However, little is known on the role of the MHC molecules irrespective of the peptide specificity and the implications of MHC multigenic structure in thymic positive selection have not been addressed. Here, we investigated the effect of MHC class II genetic configuration on the positive selection efficiency of naturally generated pre-selection repertoires in the mouse thymus. Analysis of positively selected thymocyte populations in MHC-congenic and -transgenic mice revealed that expression of I-E molecule in the thymic cortex increases positive selection efficiency of CD4 cells by approximately 50%. We show that increments in positive selection attributable to either the I-A and I-E genes are not due to increased MHC class II expression in the thymic cortex and are not affected by the number of MHC alleles. Collectively, our findings imply that MHC class II gene-restricted TCR specificities significantly contribute to positive selection efficiency, introducing the notion that multigenic structure of the MHC locus serves to increase selection of non-overlapping TCR repertoires.

  14. Immunological Functions of the Membrane Proximal Region of MHC Class II Molecules

    PubMed Central

    Harton, Jonathan; Jin, Lei; Hahn, Amy; Drake, Jim

    2016-01-01

    Major histocompatibility complex (MHC) class II molecules present exogenously derived antigen peptides to CD4 T cells, driving activation of naïve T cells and supporting CD4-driven immune functions. However, MHC class II molecules are not inert protein pedestals that simply bind and present peptides. These molecules also serve as multi-functional signaling molecules delivering activation, differentiation, or death signals (or a combination of these) to B cells, macrophages, as well as MHC class II-expressing T cells and tumor cells. Although multiple proteins are known to associate with MHC class II, interaction with STING (stimulator of interferon genes) and CD79 is essential for signaling. In addition, alternative transmembrane domain pairing between class II α and β chains influences association with membrane lipid sub-domains, impacting both signaling and antigen presentation. In contrast to the membrane-distal region of the class II molecule responsible for peptide binding and T-cell receptor engagement, the membrane-proximal region (composed of the connecting peptide, transmembrane domain, and cytoplasmic tail) mediates these “non-traditional” class II functions. Here, we review the literature on the function of the membrane-proximal region of the MHC class II molecule and discuss the impact of this aspect of class II immunobiology on immune regulation and human disease. PMID:27006762

  15. A new self: MHC-class-I-independent natural-killer-cell self-tolerance.

    PubMed

    Kumar, Vinay; McNerney, Megan E

    2005-05-01

    A fundamental tenet of the immune system is the requirement for lymphocytes to respond to transformed or infected cells while remaining tolerant of normal cells. Natural killer (NK) cells discriminate between self and non-self by monitoring the expression of MHC class I molecules. According to the 'missing-self' hypothesis, cells that express self-MHC class I molecules are protected from NK cells, but those that lack this self-marker are eliminated by NK cells. Recent work has revealed that there is another system of NK-cell inhibition, which is independent of MHC class I molecules. Newly discovered NK-cell inhibitory receptors that have non-MHC-molecule ligands broaden the definition of self as seen by NK cells.

  16. Generation of MHC class I diversity in primary tumors and selection of the malignant phenotype.

    PubMed

    Garrido, Federico; Romero, Irene; Aptsiauri, Natalia; Garcia-Lora, Angel M

    2016-01-15

    Intratumor heterogeneity among cancer cells is promoted by reversible or irreversible genetic alterations and by different microenvironmental factors. There is considerable experimental evidence of the presence of a variety of malignant cell clones with a wide diversity of major histocompatibility class I (MHC-I) expression during early stages of tumor development. This variety of MHC-I phenotypes may define the evolution of a particular tumor. Loss of MHC-I molecules frequently results in immune escape of MHC-negative or -deficient tumor cells from the host T cell-mediated immune response. We review here the results obtained by our group and other researchers in animal models and humans, showing how MHC-I intratumor heterogeneity may affect local oncogenicity and metastatic progression. In particular, we summarize the data obtained in an experimental mouse cancer model of a methylcholanthrene-induced fibrosarcoma (GR9), in which isolated clones with different MHC-I expression patterns demonstrated distinct local tumor growth rates and metastatic capacities. The observed "explosion of diversity" of MHC-I phenotypes in primary tumor clones and the molecular mechanism ("hard"/irreversible or "soft"/reversible) responsible for a given MHC-I alteration might determine not only the metastatic capacity of the cells but also their response to immunotherapy. We also illustrate the generation of further MHC heterogeneity during metastatic colonization and discuss different strategies to favor tumor rejection by counteracting MHC-I loss. Finally, we highlight the role of MHC-I genes in tumor dormancy and cell cycle control.

  17. HLA-DO increases bacterial superantigen binding to human MHC molecules by inhibiting dissociation of class II-associated invariant chain peptides.

    PubMed

    Pezeshki, Abdul Mohammad; Azar, Georges A; Mourad, Walid; Routy, Jean-Pierre; Boulassel, Mohamed-Rachid; Denzin, Lisa K; Thibodeau, Jacques

    2013-10-01

    HLA-DO (H2-O in mice) is an intracellular non-classical MHC class II molecule (MHCII). It forms a stable complex with HLA-DM (H2-M in mice) and shapes the MHC class II-associated peptide repertoire. Here, we tested the impact of HLA-DO and H2-O on the binding of superantigens (SAgs), which has been shown previously to be sensitive to the structural nature of the class II-bound peptides. We found that the binding of staphylococcal enterotoxin (SE) A and B, as well as toxic shock syndrome toxin 1 (TSST-1), was similar on the HLA-DO(+) human B cell lines 721.45 and its HLA-DO(-) counterpart. However, overexpressing HLA-DO in MHC class II(+) HeLa cells (HeLa-CIITA-DO) improved binding of SEA and TSST-1. Accordingly, knocking down HLA-DO expression using specific siRNAs decreased SEA and TSST-1 binding. We tested directly the impact of the class II-associated invariant chain peptide (CLIP), which dissociation from MHC class II molecules is inhibited by overexpressed HLA-DO. Loading of synthetic CLIP on HLA-DR(+) cells increased SEA and TSST-1 binding. Accordingly, knocking down HLA-DM had a similar effect. In mice, H2-O deficiency had no impact on SAgs binding to isolated splenocytes. Altogether, our results demonstrate that the sensitivity of SAgs to the MHCII-associated peptide has physiological basis and that the effect of HLA-DO on SEA and TSST-1 is mediated through the inhibition of CLIP release.

  18. No evidence for MHC class I-based disassortative mating in a wild population of great tits.

    PubMed

    Sepil, I; Radersma, R; Santure, A W; De Cauwer, I; Slate, J; Sheldon, B C

    2015-03-01

    Genes of the major histocompatibility complex (MHC) are regarded as a potentially important target of mate choice due to the fitness benefits that may be conferred to the offspring. According to the complementary genes hypothesis, females mate with MHC dissimilar males to enhance the immunocompetence of their offspring or to avoid inbreeding depression. Here, we investigate whether selection favours a preference for maximally dissimilar or optimally dissimilar MHC class I types, based on MHC genotypes, average amino acid distances and the functional properties of the antigen-binding sites (MHC supertypes); and whether MHC type dissimilarity predicts relatedness between mates in a wild great tit population. In particular, we explore the role that MHC class I plays in female mate choice decisions while controlling for relatedness and spatial population structure, and examine the reproductive fitness consequences of MHC compatibility between mates. We find no evidence for the hypotheses that females select mates on the basis of either maximal or optimal MHC class I dissimilarity. A weak correlation between MHC supertype sharing and relatedness suggests that MHC dissimilarity at functional variants may not provide an effective index of relatedness. Moreover, the reproductive success of pairs did not vary with MHC dissimilarity. Our results provide no support for the suggestion that selection favours, or that mate choice realizes, a preference for complimentary MHC types.

  19. MHC class I expression dependent on bacterial infection and parental factors in whitefish embryos (Salmonidae).

    PubMed

    Clark, Emily S; Wilkins, Laetitia G E; Wedekind, Claus

    2013-10-01

    Ecological conditions can influence not only the expression of a phenotype, but also the heritability of a trait. As such, heritable variation for a trait needs to be studied across environments. We have investigated how pathogen challenge affects the expression of MHC genes in embryos of the lake whitefish Coregonus palaea. In order to experimentally separate paternal (i.e. genetic) from maternal and environmental effects, and determine whether and how stress affects the heritable variation for MHC expression, embryos were produced in full-factorial in vitro fertilizations, reared singly, and exposed at 208 degree days (late-eyed stage) to either one of two strains of Pseudomonas fluorescens that differ in their virulence characteristics (one increased mortality, while both delayed hatching time). Gene expression was assessed 48 h postinoculation, and virulence effects of the bacterial infection were monitored until hatching. We found no evidence of MHC class II expression at this stage of development. MHC class I expression was markedly down-regulated in reaction to both pseudomonads. While MHC expression could not be linked to embryo survival, the less the gene was expressed, the earlier the embryos hatched within each treatment group, possibly due to trade-offs between immune function and developmental rate or further factors that affect both hatching timing and MHC expression. We found significant additive genetic variance for MHC class I expression in some treatments. That is, changes in pathogen pressures could induce rapid evolution in MHC class I expression. However, we found no additive genetic variance in reaction norms in our study population.

  20. Evolution of Mhc class II B genes in Darwin's finches and their closest relatives: birth of a new gene.

    PubMed

    Sato, A; Mayer, W E; Tichy, H; Grant, P R; Grant, B R; Klein, J

    2001-12-01

    The 15 extant species of Darwin's finches on the Galápagos and Cocos Islands are the products of an unfinished adaptive radiation from a founder flock of birds related to the South American species Tiaris obscura. Molecular characterization of their major histocompatibility complex ( Mhc) class II B genes has revealed the existence of several related groups of sequences (presumably encoded in distinct loci) from which one (group 5) stands out because of its low divergence over extended time periods. Analysis of group 5 exon 2 and intron 2 sequences has revealed that the encoding locus apparently arose 2-3 million years ago in the Tiaris group of South and Central American Thraupini. The locus shows no evidence of inactivation, but displays a very low degree of polymorphism, both in terms of number of alleles and genetic distances between alleles. Some of the polymorphism, however, appears to be trans-specific. All the observed intergenic differences can be explained by point mutations and most of the exon 2 changes represent non-synonymous substitutions, although the rate of non-synonymous and synonymous substitutions appears to be the same. The origin of the new locus is explained by the birth-and-death model of Mhc evolution with two important extensions. First, the ancestor of the group 5 genes may have arisen without new gene duplication and second, the birth of the new group may have been brought about by a switch from balancing to directional selection. The ancestor of the group 5 genes may have been a classical class II B allele (one of many) which directional selection fixed in the ancestral population and drove into the category of nonclassical genes.

  1. The biogenesis of the MHC class II compartment in human I-cell disease B lymphoblasts

    PubMed Central

    1996-01-01

    The localization and intracellular transport of major histocompatibility complex (MHC) class II molecules nd lysosomal hydrolases were studied in I-Cell Disease (ICD) B lymphoblasts, which possess a mannose 6-phosphate (Man-6-P)-independent targeting pathway for lysosomal enzymes. In the trans-Golgi network (TGN), MHC class II- invariant chain complexes colocalized with the lysosomal hydrolase cathepsin D in buds and vesicles that lacked markers of clathrin-coated vesicle-mediated transport. These vesicles fused with the endocytic pathway leading to the formation of "early" MHC class II-rich compartments (MIICs). Similar structures were observed in the TGN of normal beta lymphoblasts although they were less abundant. Metabolic labeling and subcellular fractionation experiments indicated that newly synthesized cathepsin D and MHC class II-invariant chain complexes enter a non-clathrin-coated vesicular structure after their passage through the TGN and segregation from the secretory pathway. These vesicles were also devoid of the cation-dependent mannose 6-phosphate (Man-6-P) receptor, a marker of early and late endosomes. These findings suggest that in ICD B lymphoblasts the majority of MHC class II molecules are transported directly from the TGN to "early" MIICs and that acid hydrolases cam be incorporated into MIICs simultaneously by a Man-6-P-independant process. PMID:8603911

  2. New Design of MHC Class II Tetramers to Accommodate Fundamental Principles of Antigen Presentation

    PubMed Central

    Landais, Elise; Romagnoli, Pablo A.; Corper, Adam L.; Shires, John; Altman, John D.; Wilson, Ian A.; Garcia, K. Christopher; Teyton, Luc

    2009-01-01

    Direct identification and isolation of antigen-specific T cells became possible with the development of “MHC tetramers”, based on fluorescent avidins displaying biotinylated peptide-MHC (pMHC) complexes. This approach, extensively used for MHC class I–restricted T cells, has met very limited success with MHC class II tetramers (pMHCT-2) for the detection of CD4+ specific T cells. In addition, a very large number of these reagents while capable of specifically activating T cells after being coated on solid support, are still unable to stain. In order to try to understand this puzzle and design usable tetramers, we examined each parameter critical for the production of pMHCT-2 using the I-Ad-OVA system as a model. Through this process the geometry of pMHC display by avidin tetramers was examined, as well as the stability of recombinant MHC molecules. However, we discovered that the most important factor limiting the reactivity of pMHCT-2 was the display of peptides. Indeed, long peptides, as presented by MHC class II molecules, can be bound to I-A/HLA-DQ molecules in more than one register as suggested by structural studies. This mode of anchorless peptide binding allows the selection of a broader repertoire on single peptides and should favor anti-infectious immune responses. Thus, beyond the technical improvements that we propose, the redesign of pMHCT-2 will give us the tools to evaluate the real size of the CD4 repertoire and help us in the production and testing of new vaccines. PMID:19923463

  3. The TRC8 E3 ligase ubiquitinates MHC class I molecules before dislocation from the ER

    PubMed Central

    Stagg, Helen R.; Thomas, Mair; van den Boomen, Dick; Wiertz, Emmanuel J.H.J.; Drabkin, Harry A.; Gemmill, Robert M.

    2009-01-01

    The US2 and US11 gene products of human cytomegalovirus promote viral evasion by hijacking the endoplasmic reticulum (ER)–associated degradation (ERAD) pathway. US2 and US11 initiate dislocation of newly translocated major histocompatibility complex class I (MHC I) from the ER to the cytosol for proteasome-mediated degradation, thereby decreasing cell surface MHC I. Despite being instrumental in elucidating the mammalian ERAD pathway, the responsible E3 ligase or ligases remain unknown. Using a functional small interfering RNA library screen, we now identify TRC8 (translocation in renal carcinoma, chromosome 8 gene), an ER-resident E3 ligase previously implicated as a hereditary kidney cancer gene, as required for US2-mediated MHC I ubiquitination. Depletion of TRC8 prevents MHC I ubiquitination and dislocation by US2 and restores cell surface MHC I. TRC8 forms an integral part of a novel multiprotein ER complex that contains MHC I, US2, and signal peptide peptidase. Our data show that the TRC8 E3 ligase is required for MHC I dislocation from the ER and identify a new complex associated with mammalian ERAD. PMID:19720873

  4. Exogenous cathepsin G upregulates cell surface MHC class I molecules on immune and glioblastoma cells

    PubMed Central

    Giese, Madleen; Turiello, Nadine; Molenda, Nicole; Palesch, David; Meid, Annika; Schroeder, Roman; Basilico, Paola; Benarafa, Charaf; Halatsch, Marc-Eric; Zimecki, Michal; Westhoff, Mike-Andrew; Wirtz, Christian Rainer; Burster, Timo

    2016-01-01

    Major histocompatibility complex (MHC) class I molecules present antigenic peptides to cytotoxic T cells. During an adaptive immune response, MHC molecules are regulated by several mechanisms including lipopolysaccharide (LPS) and interferon gamma (IFN-g). However, it is unclear whether the serine protease cathepsin G (CatG), which is generally secreted by neutrophils at the site of inflammation, might regulate MHC I molecules. We identified CatG, and to a higher extend CatG and lactoferrin (LF), as an exogenous regulator of cell surface MHC I expression of immune cells and glioblastoma stem cells. In addition, levels of MHC I molecules are reduced on dendritic cells from CatG deficient mice compared to their wild type counterparts. Furthermore, cell surface CatG on immune cells, including T cells, B cells, and NK cells triggers MHC I on THP-1 monocytes suggesting a novel mechanism for CatG to facilitate intercellular communication between infiltrating cells and the respective target cell. Subsequently, our findings highlight the pivotal role of CatG as a checkpoint protease which might force target cells to display their intracellular MHC I:antigen repertoire. PMID:27806341

  5. Immunotherapy eradicates metastases with reversible defects in MHC class I expression.

    PubMed

    Garrido, Cristina; Romero, Irene; Berruguilla, Enrique; Cancela, Bárbara; Algarra, Ignacio; Collado, Antonia; García-Lora, Angel; Garrido, Federico

    2011-09-01

    Tumor or metastatic cells lose MHC class I (MHC-I) expression during cancer progression as an escape mechanism from immune surveillance. These defects in MHC-I may be reversible by cytokines or different agents (soft lesions) or irreversible due to structural defects (hard lesions). The nature of these MHC-I alterations might determine the success or failure of immunotherapy treatments. In this study, we have used an MHC-I-positive murine fibrosarcoma tumor clone, GR9-A7, which generates multiple lung and lymph node metastases with reversible MHC-I alterations after treatment with IFN-γ. Four different antitumor treatments were carried out after primary tumor excision to determine their capacity to inhibit spontaneous metastatic colonization of the GR9-A7 tumor clone. We found that 2 different immunotherapy protocols (CpG plus autologous irradiated-GR9-A7 cells and protein-bound polysaccharide K (PSK) and 1 chemoimmunotherapy (docetaxel plus PSK) induced eradication of metastases. In contrast, chemotherapy with docetaxel alone produced only partial reduction in the number of metastases. Flow cytometric analysis of lymphocyte populations showed an immunosuppression in GR9-A7 tumor-bearing host, which could be reverted by immunotherapy treatments. Our results suggest that irreversible or reversible MHC-I alterations in tumor target cells may determine its progression or regression independently of the type of immunotherapy used.

  6. Peptide-independent stabilization of MHC class I molecules breaches cellular quality control.

    PubMed

    Hein, Zeynep; Uchtenhagen, Hannes; Abualrous, Esam Tolba; Saini, Sunil Kumar; Janßen, Linda; Van Hateren, Andy; Wiek, Constanze; Hanenberg, Helmut; Momburg, Frank; Achour, Adnane; Elliott, Tim; Springer, Sebastian; Boulanger, Denise

    2014-07-01

    The intracellular trafficking of major histocompatibility complex class I (MHC-I) proteins is directed by three quality control mechanisms that test for their structural integrity, which is correlated to the binding of high-affinity antigenic peptide ligands. To investigate which molecular features of MHC-I these quality control mechanisms detect, we have followed the hypothesis that suboptimally loaded MHC-I molecules are characterized by their conformational mobility in the F-pocket region of the peptide-binding site. We have created a novel variant of an MHC-I protein, K(b)-Y84C, in which two α-helices in this region are linked by a disulfide bond that mimics the conformational and dynamic effects of bound high-affinity peptide. K(b)-Y84C shows a remarkable increase in the binding affinity to its light chain, beta-2 microglobulin (β2m), and bypasses all three cellular quality control steps. Our data demonstrate (1) that coupling between peptide and β2m binding to the MHC-I heavy chain is mediated by conformational dynamics; (2) that the folded conformation of MHC-I, supported by β2m, plays a decisive role in passing the ER-to-cell-surface transport quality controls; and (3) that β2m association is also tested by the cell surface quality control that leads to MHC-I endocytosis.

  7. Evolution of MHC class I genes in the European badger (Meles meles)

    PubMed Central

    Sin, Yung Wa; Dugdale, Hannah L; Newman, Chris; Macdonald, David W; Burke, Terry

    2012-01-01

    The major histocompatibility complex (MHC) plays a central role in the adaptive immune system and provides a good model with which to understand the evolutionary processes underlying functional genes. Trans-species polymorphism and orthology are both commonly found in MHC genes; however, mammalian MHC class I genes tend to cluster by species. Concerted evolution has the potential to homogenize different loci, whereas birth-and-death evolution can lead to the loss of orthologs; both processes result in monophyletic groups within species. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. We present the first study of MHC class I genes in a species from the superfamily Musteloidea. The European badger (Meles meles) exhibits moderate variation in MHC class I sequences when compared to other carnivores. We identified seven putatively functional sequences and nine pseudogenes from genomic (gDNA) and complementary (cDNA) DNA, signifying at least two functional class I loci. We found evidence for separate evolutionary histories of the α1 and α2/α3 domains. In the α1 domain, several sequences from different species were more closely related to each other than to sequences from the same species, resembling orthology or trans-species polymorphism. Balancing selection and probable recombination maintain genetic diversity in the α1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the α2/α3 domains have most likely undergone concerted evolution, where recombination has homogenized the α2/α3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately. PMID:22957169

  8. Evolution of MHC class I genes in the European badger (Meles meles).

    PubMed

    Sin, Yung Wa; Dugdale, Hannah L; Newman, Chris; Macdonald, David W; Burke, Terry

    2012-07-01

    The major histocompatibility complex (MHC) plays a central role in the adaptive immune system and provides a good model with which to understand the evolutionary processes underlying functional genes. Trans-species polymorphism and orthology are both commonly found in MHC genes; however, mammalian MHC class I genes tend to cluster by species. Concerted evolution has the potential to homogenize different loci, whereas birth-and-death evolution can lead to the loss of orthologs; both processes result in monophyletic groups within species. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. We present the first study of MHC class I genes in a species from the superfamily Musteloidea. The European badger (Meles meles) exhibits moderate variation in MHC class I sequences when compared to other carnivores. We identified seven putatively functional sequences and nine pseudogenes from genomic (gDNA) and complementary (cDNA) DNA, signifying at least two functional class I loci. We found evidence for separate evolutionary histories of the α1 and α2/α3 domains. In the α1 domain, several sequences from different species were more closely related to each other than to sequences from the same species, resembling orthology or trans-species polymorphism. Balancing selection and probable recombination maintain genetic diversity in the α1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the α2/α3 domains have most likely undergone concerted evolution, where recombination has homogenized the α2/α3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately.

  9. Analysis of cDNA coding MHC class II beta chain of the chimpanzee (Pan troglodytes).

    PubMed

    Hatta, Yuki; Kanai, Tomoko; Matsumoto, Yoshitsugu; Kyuwa, Shigeru; Hayasaka, Ikuo; Yoshikawa, Yasuhiro

    2002-04-01

    The chimpanzee (Pan troglodytes, Patr) is the closest zoological living relative of humans and shares approximately 98.6% genetic homology to human beings. Although major histocompatibility complex (MHC) plays a critical role in T cell-mediated immune responses in vertebrates, the information on Patr MHC remains at a relatively poor level. Therefore, we attempted to isolate Patr MHC class II genes and determine their nucleotide sequences. The cDNAs encoding Patr MHC class II DP, DQ and DR beta chains were isolated from the cDNA library of a chimpanzee B lymphocyte cell line Bch261. As a result of screening, the clone 6-3-1 as a representative of Patr DP clone, clone 30-1 as a Patr DQ clone, and clones 4-7-1 and 55-1 having different sequences as Patr DR clones were detected. The clone 6-3-1 consisted of 1,062 nucleotides including an open reading frame (ORF) of 777 bp. In the same way, clone 30-1 consisted of 1,172 nucleotides including ORF of 786 bp, clones 4-7-1 and 55-1 consisted of 1,163 nucleotides including ORF of 801 bp. Except for five nucleotide changes, clones 4-7-1 and 55-1 were the same sequence. By comparison with the nucleotide sequences already reported on chimpanzee MHC class II beta 1 genes, clones 6-3-1, 30-1, 4-7-1 and 55-1 were classified as PatrDPB1*16, PatrDQB1*0302, PatrDRB1*0201 and PatrDRB1*0204, respectively. This is the first report to describe complete cDNA sequences of Patr DP and DQ molecules. The nucleotide sequence data of Patr MHC class II genes obtained in this study will be useful for the genotyping of Patr MHC class II genes in individual chimpanzees.

  10. Loss of antigen-presenting molecules (MHC class I and TAP-1) in lung cancer.

    PubMed Central

    Korkolopoulou, P.; Kaklamanis, L.; Pezzella, F.; Harris, A. L.; Gatter, K. C.

    1996-01-01

    Presentation of endogenous antigenic peptides to cytotoxic T lymphocytes is mediated by the major histocompatibility complex (MHC) class I molecules. For the stable assembly of MHC class I complex it is necessary that the antigenic peptide is transported by the MHC-encoded transporters TAP-1 and TAP-2 into a pre-Golgi region. T-cell-mediated host-vs-tumour response might therefore depend on the presence of these molecules on tumour cells. The presence of MHC class I antigens and TAP-1 was studied in a series of 93 resection specimens of non-small-cell lung carcinomas (NSCLCs) by immunohistochemical methods using antibodies against the assembled class I molecule, beta 2-microglobulin (beta 2-m), heavy-chain A locus, A2 allele and TAP-1 protein. Eighty-six patients were included in the survival analysis. Total loss of class I molecule was observed in 38% of the cases and was usually accompanied by loss of beta 2-m and of heavy chain A locus. Selective loss of A locus was seen in 8.3% and of A2 allele in 27% of the cases. TAP-1 loss was always combined with beta 2-m and/or heavy chain A locus loss. No correlation was found between the expressional status of any of the above molecules, including the selective A2 allelic loss and histological type, degree of differentiation, tumoral stage, nodal stage and survival. Our findings suggest that loss of antigen-presenting molecules (including both MHC class I alleles and TAP-1) is a frequent event in lung cancer. However, the immunophenotypic profile of MHC class I and TAP-1 seems to be unrelated in vivo to the phenotype, growth or survival of NSCLC. Images Figure 1 PMID:8546899

  11. Evolution of MHC class I loci in marsupials: characterization of sequences from koala (Phascolarctos cinereus)

    PubMed

    Houlden, B A; Greville, W D; Sherwin, W B

    1996-10-01

    We demonstrate that koala (Phascolarctos cinereus) MHC class I constitutes a variable multigene family. A total of nine partial exon 2 and 3 major histocompatibility complex (MHC) class I sequences are presented, including six sequences from at least three loci from one koala. Variation was detected by examination of sequences from a number of individuals and family groups. The koala is the second marsupial species characterized to date, and comparisons reveal approximately 80% similarity with sequences from the red necked wallaby (Macropus rufogriseus). The latter sequences represent at least two, and probably three, different loci. Phylogenetic analysis demonstrates that all koala sequences are more related to one another than they are to any of the wallaby loci. This indicates that the koala sequences are probably not orthologous to the wallaby genes, and thus represent a new class I gene family. In addition, marsupial gene families cluster away from human gene families, supporting a different origin of MHC genes for marsupials and eutherians.

  12. The nucleotide sequence of the sheep MHC class II DNA gene

    SciTech Connect

    Wright, H.; Redmond, J.; Ballingall, K.T.; Wright, F.

    1995-01-11

    The human MHC class II DNA gene was identified and sequenced by Trowsdale and Kelly. When a molecular map of the HLA-D region became available, it was shown that the HLA-DNA gene was unusual in not having a B gene partner situated within a few kilobases (kb), the nearest B gene being HLA-DPB1. The nearest unpaired B gene is HLA-DOB which is approximately 160 kb telomeric of HLA-DNA. More recently, the mouse MHC class II genes H-20A and H-20B were shown to be equivalent to the HLA-DNA and HLA-DOB genes. Moreover, the mouse genes expressed an MHC class II protein whose tissue distribution was restricted to B cells and epithelial cell of the thymic medulla. No corresponding HLA-DN protein has been reported. 21 refs., 3 figs.

  13. Targeting the MHC Class II antigen presentation pathway in cancer immunotherapy.

    PubMed

    Thibodeau, Jacques; Bourgeois-Daigneault, Marie-Claude; Lapointe, Réjean

    2012-09-01

    The success of immunotherapy relies on the participation of all arms of the immune system and the role of CD4+ T lymphocytes in preventing tumor growth is now well established. Understanding how tumors evade immune responses holds the key to the development of cancer immunotherapies. In this review, we discuss how MHC Class II expression varies in cancer cells and how this influences antitumor immune responses. We also discuss the means that are currently available for harnessing the MHC Class II antigen presentation pathway for the development of efficient vaccines to activate the immune system against cancer.

  14. The β2-microglobulin-free heterodimerization of rhesus monkey MHC class I A with its normally spliced variant reduces the ubiquitin-dependent degradation of MHC class I A.

    PubMed

    Dai, Zheng-Xi; Zhang, Gao-Hong; Zhang, Xi-He; Xia, Hou-Jun; Li, Shao-You; Zheng, Yong-Tang

    2012-03-01

    The MHC class I (MHC I) molecules play a pivotal role in the regulation of immune responses by presenting antigenic peptides to CTLs and by regulating cytolytic activities of NK cells. In this article, we show that MHC I A in rhesus macaques can be alternatively spliced, generating a novel MHC I A isoform (termed "MHC I A-sv1") devoid of α(3) domain. Despite the absence of β2-microglobulin (β2m), the MHC I A-sv1 proteins reached the cell surface of K562-transfected cells as endoglycosidase H-sensitive glycoproteins that could form disulfide-bonded homodimers. Cycloheximide-based protein chase experiments showed that the MHC I A-sv1 proteins were more stable than the full-length MHC I A in transiently or stably transfected cell lines. Of particular interest, our studies demonstrated that MHC I A-sv1 could form β2m-free heterodimers with its full-length protein in mammalian cells. The formation of heterodimers was accompanied by a reduction in full-length MHC I A ubiquitination and consequent stabilization of the protein. Taken together, these results demonstrated that MHC I A-sv1 and MHC I A can form a novel heterodimeric complex as a result of the displacement of β2m and illustrated the relevance of regulated MHC I A protein degradation in the β2m-free heterodimerization-dependent control, which may have some implications for the MHC I A splice variant in the fine tuning of classical MHC I A/TCR and MHC I A/killer cell Ig-like receptor interactions.

  15. A new polymorphic and multicopy MHC gene family related to nonmammalian class I

    SciTech Connect

    Leelayuwat, C.; Degli-Esposti, M.A.; Abraham, L.J.; Townend, D.C.; Dawkins, R.L. ||

    1994-12-31

    The authors have used genomic analysis to characterize a region of the central major histocompatibility complex (MHC) spanning {approximately} 300 kilobases (kb) between TNF and HLA-B. This region has been suggested to carry genetic factors relevant to the development of autoimmune diseases such as myasthenia gravis (MG) and insulin dependent diabetes mellitus (IDDM). Genomic sequence was analyzed for coding potential, using two neural network programs, GRAIL and GeneParser. A genomic probe, JAB, containing putative coding sequences (PERB11) located 60 kb centromeric of HLA-B, was used for northern analysis of human tissues. Multiple transcripts were detected. Southern analysis of genomic DNA and overlapping YAC clones, covering the region from BAT1 to HLA-F, indicated that there are at least five copies of PERB11, four of which are located within this region of the MHC. The partial cDNA sequence of PERB11 was obtained from poly-A RNA derived from skeletal muscle. The putative amino acid sequence of PERB11 shares {approximately} 30% identity to MHC class I molecules from various species, including reptiles, chickens, and frogs, as well as to other MHC class I-like molecules, such as the IgG FcR of the mouse and rat and the human Zn-{alpha}2-glycoprotein. From direct comparison of amino acid sequences, it is concluded that PERB11 is a distinct molecule more closely related to nonmammalian than known mammalian MHC class I molecules. Genomic sequence analysis of PERB11 from five MHC ancestral haplotypes (AH) indicated that the gene is polymorphic at both DNA and protein level. The results suggest that the authors have identified a novel polymorphic gene family with multiple copies within the MHC. 48 refs., 10 figs., 2 tabs.

  16. Isolation and characterization of three class II MHC genomic clones from the chicken.

    PubMed

    Xu, Y X; Pitcovski, J; Peterson, L; Auffray, C; Bourlet, Y; Gerndt, B M; Nordskog, A W; Lamont, S J; Warner, C M

    1989-03-15

    A genomic library was constructed from sperm DNA from an individual of the inbred chicken line G-B2, MHC haplotype B6. The library was screened with a chicken class II probe (beta 2 exon specific) and three MHC class II beta chain genomic clones were isolated. The restriction maps of the three clones showed that each of the three clones was unique. The position of the beta chain sequence was located in each of the three genomic clones by Southern blot hybridization. Subclones containing the beta chain gene were produced from each of the genomic clones and the orientation of the leader peptide, beta 1, beta 2, transmembrane, and cytoplasmic exons was determined by Southern blot hybridization and nucleotide sequencing. The complete nucleotide sequence of two of the three subclones was determined. Comparison of the nucleotide and predicted amino acid sequences of the two subclones with other class II beta chain sequences showed that the B6 chicken beta chain genes are evolutionarily related to the class II beta chain genes from chickens of other MHC haplotypes, and to class II beta chain genes from other species. Analysis of Southern blots of B6 chicken DNA, as well as the isolation of the three beta chain genes, suggests that chickens of the B6 haplotype possess at least three MHC class II beta chain genes.

  17. Allospecific rejection of MHC class I-deficient bone marrow by CD8 T cells

    PubMed Central

    Haspot, Fabienne; Li, Hao Wei; Lucas, Carrie L.; Fehr, Thomas; Beyaz, Semir; Sykes, Megan

    2014-01-01

    Avoidance of long-term immunosuppression is a desired goal in organ transplantation. Mixed chimerism offers a promising approach to tolerance induction, and we have aimed to develop low-toxicity, non-immunodepleting approaches to achieve this outcome. In a mouse model achieving fully MHC-mismatched allogeneic bone marrow engraftment with minimal conditioning (3 Gy total body irradiation followed by anti-CD154 and T cell-depleted allogeneic bone marrow cells), CD4 T cells in the recipient are required to promote tolerance of pre-existing alloreactive recipient CD8 T cells and thereby permit chimerism induction. We now demonstrate that mice devoid of CD4 T cells and NK cells reject MHC class-I deficient and class I/class II-deficient marrow in a CD8 T cell-dependent manner. This rejection is specific for donor alloantigens, since recipient hematopoiesis is not affected by donor marrow rejection and MHC class-I deficient bone marrow that is syngeneic to the recipient is not rejected. Recipient CD8 T cells are activated and develop cytotoxicity against MHC class I-deficient donor cells in association with rejection. These data implicate a novel CD8 T cell-dependent bone marrow rejection pathway, wherein recipient CD8 T cells indirectly activated by donor alloantigens promote direct killing, in a TCR-independent manner, of class I-deficient donor cells. PMID:24304495

  18. MHC class II β genes in the endangered Hainan Eld's deer (Cervus eldi hainanus).

    PubMed

    Liu, Hong-Yi; Xue, Fei; Wan, Qiu-Hong; Ge, Yun-Fa

    2013-01-01

    Contrary to neutral markers, the major histocompatibility complex (MHC) can reflect the fitness and adaptive potential of a given species due to its association with the immune system. For this reason, the use of MHC in endangered wildlife management has increased greatly in recent years. Here, we isolated complementary DNA (cDNA) and genomic DNA (gDNA) sequences to characterize the MHC class II β genes in Hainan Eld's deer (Cervus eldi hainanus), a highly endangered cervid, which recovered from a severe population bottleneck consisting of 26 animals. Analysis of 7 individuals revealed the presence of 3 DRB and 3 DQB putatively functional gDNA sequences. The Ceel-DRB and DQB sequences displayed high variability in exon 2, and most nonsynonymous substitutions were detected in this region. Phylogenetic analysis indicated that trans-species evolution of MHC class II β might occur in the Cervinae subfamily. Comparison of the number of sequences between gDNA and cDNA revealed that all sequences isolated from the genome were detectable in the cDNA libraries derived from different tissues (including the liver, kidney, and spleen), suggesting none of these sequences were derived from silent genes or pseudogenes. Characterization of the MHC class II β genes may lay the foundation for future studies on genetic structure, mate choice, and viability analysis in Hainan Eld's deer.

  19. Characterization, polymorphism, and evolution of MHC class II B genes in birds of prey.

    PubMed

    Alcaide, Miguel; Edwards, Scott V; Negro, Juan J

    2007-11-01

    During the last decade, the major histocompatibility complex (MHC) has received much attention in the fields of evolutionary and conservation biology because of its potential implications in many biological processes. New insights into the gene structure and evolution of MHC genes can be gained through study of additional lineages of birds not yet investigated at the genomic level. In this study, we characterized MHC class II B genes in five families of birds of prey (Accipitridae, Pandionidae, Strigidae, Tytonidae, and Falconidae). Using PCR approaches, we isolated genomic MHC sequences up to 1300 bp spanning exons 1 to 3 in 26 representatives of each raptor lineage, finding no stop codons or frameshift mutations in any coding region. A survey of diversity across the entirety of exon 2 in the lesser kestrel Falco naumanni reported 26 alleles in 21 individuals. Bayesian analysis revealed 21 positively selected amino acid sites, which suggests that the MHC genes described here are functional and probably expressed. Finally, through interlocus comparisons and phylogenetic analysis, we also discuss genetic evidence for concerted and transspecies evolution in the raptor MHC.

  20. Single-Molecule Motions of MHC Class II Rely on Bound Peptides

    PubMed Central

    Kozono, Haruo; Matsushita, Yufuku; Ogawa, Naoki; Kozono, Yuko; Miyabe, Toshihiro; Sekiguchi, Hiroshi; Ichiyanagi, Kouhei; Okimoto, Noriaki; Taiji, Makoto; Kanagawa, Osami; Sasaki, Yuji C.

    2015-01-01

    The major histocompatibility complex (MHC) class II protein can bind peptides of different lengths in the region outside the peptide-binding groove. Peptide-flanking residues (PFRs) contribute to the binding affinity of the peptide for MHC and change the immunogenicity of the peptide/MHC complex with regard to T cell receptor (TCR). The mechanisms underlying these phenomena are currently unknown. The molecular flexibility of the peptide/MHC complex may be an important determinant of the structures recognized by certain T cells. We used single-molecule x-ray analysis (diffracted x-ray tracking (DXT)) and fluorescence anisotropy to investigate these mechanisms. DXT enabled us to monitor the real-time Brownian motion of the peptide/MHC complex and revealed that peptides without PFRs undergo larger rotational motions than peptides with PFRs. Fluorescence anisotropy further revealed that peptides without PFRs exhibit slightly larger motions on the nanosecond timescale. These results demonstrate that peptides without PFRs undergo dynamic motions in the groove of MHC and consequently are able to assume diverse structures that can be recognized by T cells. PMID:25606683

  1. MHC class I antigen presentation and implications for developing a new generation of therapeutic vaccines.

    PubMed

    Comber, Joseph D; Philip, Ramila

    2014-05-01

    Major histocompatibility complex class I (MHC-I) presented peptide epitopes provide a 'window' into the changes occurring in a cell. Conventionally, these peptides are generated by proteolysis of endogenously synthesized proteins in the cytosol, loaded onto MHC-I molecules, and presented on the cell surface for surveillance by CD8(+) T cells. MHC-I restricted processing and presentation alerts the immune system to any infectious or tumorigenic processes unfolding intracellularly and provides potential targets for a cytotoxic T cell response. Therefore, therapeutic vaccines based on MHC-I presented peptide epitopes could, theoretically, induce CD8(+) T cell responses that have tangible clinical impacts on tumor eradication and patient survival. Three major methods have been used to identify MHC-I restricted epitopes for inclusion in peptide-based vaccines for cancer: genetic, motif prediction and, more recently, immunoproteomic analysis. Although the first two methods are capable of identifying T cell stimulatory epitopes, these have significant disadvantages and may not accurately represent epitopes presented by a tumor cell. In contrast, immunoproteomic methods can overcome these disadvantages and identify naturally processed and presented tumor associated epitopes that induce more clinically relevant tumor specific cytotoxic T cell responses. In this review, we discuss the importance of using the naturally presented MHC-I peptide repertoire in formulating peptide vaccines, the recent application of peptide-based vaccines in a variety of cancers, and highlight the pros and cons of the current state of peptide vaccines.

  2. Influenza Virus Targets Class I MHC-Educated NK Cells for Immunoevasion.

    PubMed

    Mahmoud, Ahmad Bakur; Tu, Megan M; Wight, Andrew; Zein, Haggag S; Rahim, Mir Munir A; Lee, Seung-Hwan; Sekhon, Harman S; Brown, Earl G; Makrigiannis, Andrew P

    2016-02-01

    The immune response to influenza virus infection comprises both innate and adaptive defenses. NK cells play an early role in the destruction of tumors and virally-infected cells. NK cells express a variety of inhibitory receptors, including those of the Ly49 family, which are functional homologs of human killer-cell immunoglobulin-like receptors (KIR). Like human KIR, Ly49 receptors inhibit NK cell-mediated lysis by binding to major histocompatibility complex class I (MHC-I) molecules that are expressed on normal cells. During NK cell maturation, the interaction of NK cell inhibitory Ly49 receptors with their MHC-I ligands results in two types of NK cells: licensed ("functional"), or unlicensed ("hypofunctional"). Despite being completely dysfunctional with regard to rejecting MHC-I-deficient cells, unlicensed NK cells represent up to half of the mature NK cell pool in rodents and humans, suggesting an alternative role for these cells in host defense. Here, we demonstrate that after influenza infection, MHC-I expression on lung epithelial cells is upregulated, and mice bearing unlicensed NK cells (Ly49-deficient NKCKD and MHC-I-deficient B2m-/- mice) survive the infection better than WT mice. Importantly, transgenic expression of an inhibitory self-MHC-I-specific Ly49 receptor in NKCKD mice restores WT influenza susceptibility, confirming a direct role for Ly49. Conversely, F(ab')2-mediated blockade of self-MHC-I-specific Ly49 inhibitory receptors protects WT mice from influenza virus infection. Mechanistically, perforin-deficient NKCKD mice succumb to influenza infection rapidly, indicating that direct cytotoxicity is necessary for unlicensed NK cell-mediated protection. Our findings demonstrate that Ly49:MHC-I interactions play a critical role in influenza virus pathogenesis. We suggest a similar role may be conserved in human KIR, and their blockade may be protective in humans.

  3. Development of MHC class I and II B primers in common carp and its molecular characterization.

    PubMed

    Jia, Zhiying; Chi, Xifeng; Li, Chitao; Shi, Lianyu

    2010-08-01

    The major histocompatibility complex (MHC) has an important role in immune response and is known as the most polymorphic locus in vertebrates. We developed three pairs of polymerase chain reaction primers of the alpha-2 domain (exon 3) of MHC class I and the beta-2 (exon 3) and beta-3 domains (exon 4) of MHC class II B gene in the German mirror common carp (Cyprinus carpio L.). We analyzed the three loci in a population of 65 individuals that had suffered the serious disease of gill rot. Five to six variable nucleotide sites and two to six variable amino acid sites (71.43%) were detected in the exon sequence of the sampled populations, indicating that many of them corresponded to amino acids involved in antigen recognition. Deviation from Hardy-Weinberg equilibrium and linkage disequilibrium were differentially found in some loci, which will be important for further study of disease resistance/susceptibility and population evolution.

  4. Extensive sharing of MHC class II alleles between rhesus and cynomolgus macaques.

    PubMed

    Doxiadis, Gaby G M; Rouweler, Annemiek J M; de Groot, Natasja G; Louwerse, Annet; Otting, Nel; Verschoor, Ernst J; Bontrop, Ronald E

    2006-05-01

    In contrast to rhesus monkeys, substantial knowledge on cynomolgus monkey major histocompatibility complex (MHC) class II haplotypes is lacking. Therefore, 17 animals, including one pedigreed family, were thoroughly characterized for polymorphic Mhc class II region genes as well as their mitochondrial DNA (mtDNA) sequences. Different cynomolgus macaque populations appear to exhibit unique mtDNA profiles reflecting their geographic origin. Within the present panel, 10 Mafa-DPB1, 14 Mafa-DQA1, 12 Mafa-DQB1, and 35 Mafa-DRB exon 2 sequences were identified. All of these alleles cluster into lineages that were previously described for rhesus macaques. Moreover, about half of the Mafa-DPB1, Mafa-DQA1, and Mafa-DQB1 alleles and one third of the Mafa-DRB exon 2 sequences are identical to rhesus macaque orthologues. Such a high level of Mhc class II allele sharing has not been reported for primate species. Pedigree analysis allowed the characterization of nine distinct Mafa class II haplotypes, and seven additional ones could be deduced. Two of these haplotypes harbor a duplication of the Mafa-DQB1 locus. Despite extensive allele sharing, rhesus and cynomolgus monkeys do not appear to possess identical Mhc class II haplotypes, thus illustrating that new haplotypes were generated after speciation by recombination-like processes.

  5. Spectrum of MHC Class II Variability in Darwin’s Finches and Their Close Relatives

    PubMed Central

    Sato, Akie; Tichy, Herbert; Grant, Peter R.; Grant, B. Rosemary; Sato, Tetsuji; O’hUigin, Colm

    2011-01-01

    The study describes >400 major histocompatibility complex (MHC) class II B exon 2 and 114 intron 2 sequences of 36 passerine bird species, 13 of which belong to the group of Darwin’s finches (DFs) and the remaining 23 to close or more distant relatives of DFs in Central and South America. The data set is analyzed by a combination of judiciously selected statistical methods. The analysis reveals that reliable information concerning MHC organization, including the assignment of sequences to loci, and evolution, as well as the process of species divergence, can be obtained in the absence of genomic sequence data, if the analysis is taken several steps beyond the standard phylogenetic tree construction approach. The main findings of the present study are these: The MHC class II B region of the passerine birds is as elaborate in its organization, divergence, and genetic diversity as the MHC of the eutherian mammals, specifically the primates. Hence, the reported simplicity of the fowl MHC is an oddity. With the help of appropriate markers, the divergence of the MHC genes can be traced deep in the phylogeny of the bird taxa. Transspecies polymorphism is rampant at many of the bird MHC loci. In this respect, the DFs behave as if they were a single, genetically undifferentiated population. There is thus far no indication of alleles that could be considered species, genus, or even DF group specific. The implication of these findings is that DFs are in the midst of adaptive radiations, in which morphological differentiation into species is running ahead of genetic differentiation in genetic systems such as the MHC or the mitochondrial DNA. The radiations are so young that there has not been enough time to sort out polymorphisms at most of the loci among the morphologically differentiating species. These findings parallel those on Lake Victoria haplochromine fishes. Several of the DF MHC allelic lineages can be traced back to the MHC genes of the species Tiaris obscura

  6. An MHC Class I Immune Evasion Gene of Marek's Disease Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marek’s Disease Virus (MDV) is a widespread pathogen of chickens that causes T cell tumors. Acute, but not latent, MDV infection has previously been shown to lead to MHC class I down-regulation (Virology 282:198–205 (2001)), but the gene(s)involved have not been identified. Here we demonstrate tha...

  7. AN MHC class I immune evasion gene of Marek's disease virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marek's disease virus (MDV) is a widespread a-herpesvirus of chickens that causes T cell tumors. Acute, but not latent, MDV infection has previously been shown to lead to downregulation of cell-surface MHC class I (Virology 282:198–205 (2001)), but the gene(s) involved have not been identified. Here...

  8. Characterization and expression of MHC class II alpha and II beta genes in mangrove red snapper (Lutjanus argentimaculatus).

    PubMed

    Wang, Tianyan; Tan, Shangjin; Cai, Zhonghua

    2015-12-01

    The major histocompatibility complex (MHC) class II plays a key role in adaptive immunity by presenting foreign peptides to CD4(+) T cells and by triggering the adaptive immune response. While the structure and function of MHC class II have been well characterized in mammalian, limited research has been done on fishes. In this study, we characterized the gene structure and expression of MHC class II α (Lunar-DAA) and II β (Lunar-DAB) of mangrove red snapper (Lutjanus argentimaculatus). Both genes shared, respectively, a high similarity and typical features with other vertebrate MHC class II α and II β. The phylogenetic analysis of the deduced peptides revealed that both Lunar-DAA and Lunar-DAB were located in the teleost subclass. Western blotting analyses indicated that both MHC class II α and II β were expressed ubiquitously in immune-related cells, tissues and organs, and that MHC class II α and II β chains existed mainly as heterodimers. While it was highly expressed in gills, thymus, head kidney (HK), spleen, head kidney macrophage and spleen leucocytes, MHC class II β chain was expressed with a low abundance in skin, intestine, stomach and heart. The highest expression of MHC class II β in thymus confirmed the conclusion that thymus is one of the primary lymphoid organs in fishes. The detection of MHC class II αβ dimers in HK macrophages and spleen leucocytes indicated that HK macrophages and spleen leucocytes play a critical role in the adaptive immunity in fishes. All these results provide valuable information for understanding the structure of MHC class II α and II β and their function in immune responses.

  9. Horse cDNA clones encoding two MHC class I genes

    SciTech Connect

    Barbis, D.P.; Maher, J.K.; Stanek, J.; Klaunberg, B.A.; Antczak, D.F.

    1994-12-31

    Two full-length clones encoding MHC class I genes were isolated by screening a horse cDNA library, using a probe encoding in human HLA-A2.2Y allele. The library was made in the pcDNA1 vector (Invitrogen, San Diego, CA), using mRNA from peripheral blood lymphocytes obtained from a Thoroughbred stallion (No. 0834) homozygous for a common horse MHC haplotype (ELA-A2, -B2, -D2; Antczak et al. 1984; Donaldson et al. 1988). The clones were sequenced, using SP6 and T7 universal primers and horse-specific oligonucleotides designed to extend previously determined sequences.

  10. Characterisation of class II B MHC genes from a ratite bird, the little spotted kiwi (Apteryx owenii).

    PubMed

    Miller, Hilary C; Bowker-Wright, Gemma; Kharkrang, Marie; Ramstad, Kristina

    2011-04-01

    Major histocompatibility complex (MHC) genes are important for vertebrate immune response and typically display high levels of diversity due to balancing selection from exposure to diverse pathogens. An understanding of the structure of the MHC region and diversity among functional MHC genes is critical to understanding the evolution of the MHC and species resilience to disease exposure. In this study, we characterise the structure and diversity of class II MHC genes in little spotted kiwi Apteryx owenii, a ratite bird representing the basal avian lineage (paleognaths). Results indicate that little spotted kiwi have a more complex MHC structure than that of other non-passerine birds, with at least five class II MHC genes, three of which are expressed and likely to be functional. Levels of MHC variation among little spotted kiwi are extremely low, with 13 birds assayed having nearly identical MHC genotypes (only two genotypes containing four alleles, three of which are fixed). These results suggest that recent genetic drift due to a species-wide bottleneck of at most seven birds has overwhelmed past selection for high MHC diversity in little spotted kiwi, potentially leaving the species highly susceptible to disease.

  11. Influence of kinship and MHC class II genotype on visual traits in zebrafish larvae (Danio rerio).

    PubMed

    Hinz, Cornelia; Gebhardt, Katharina; Hartmann, Alexander K; Sigman, Lauren; Gerlach, Gabriele

    2012-01-01

    Kin recognition can drive kin selection and the evolution of social behaviour. In zebrafish (Danio rerio, Hamilton 1822), kin recognition is based on olfactory and visual imprinting processes. If larvae are exposed to visual and chemical cues of kin at day 5 and 6 post fertilization they will recognize kin throughout life, while exposure to non-kin fails to trigger any recognition. Chemical imprinting signals are transcribed by polymorphic genes of the major histocompatibility complex (MHC) code; however, the underlying mechanism for visual imprinting remains unclear. Here we provide evidence for the existence of family-specific differences in morphometry and pigmentation pattern of six day old zebrafish larvae. While rump, tail and body pigmentation were dependent on relatedness, iris pigmentation and morphometry were also influenced by MHC class II genotype. Our study revealed that the MHC not only influences the chemical signature of individuals, but also their visual appearance.

  12. Expressed MHC class II genes in sea otters (Enhydra lutris) from geographically disparate populations

    USGS Publications Warehouse

    Bowen, L.; Aldridge, B.M.; Miles, A.K.; Stott, J.L.

    2006-01-01

    The major histocompatibility complex (MHC) is central to maintaining the immunologic vigor of individuals and populations. Classical MHC class II genes were targeted for partial sequencing in sea otters (Enhydra lutris) from populations in California, Washington, and Alaska. Sequences derived from sea otter peripheral blood leukocyte mRNAs were similar to those classified as DQA, DQB, DRA, and DRB in other species. Comparisons of the derived amino acid compositions supported the classification of these as functional molecules from at least one DQA, DQB, and DRA locus and at least two DRB loci. While limited in scope, phylogenetic analysis of the DRB peptide-binding region suggested the possible existence of distinct clades demarcated by geographic region. These preliminary findings support the need for additional MHC gene sequencing and expansion to a comprehensive study targeting additional otters. ?? 2006 Blackwell Munksgaard.

  13. Expressed MHC class II genes in sea otters (Enhydra lutris) from geographically disparate populations.

    PubMed

    Bowen, L; Aldridge, B M; Miles, A K; Stott, J L

    2006-05-01

    The major histocompatibility complex (MHC) is central to maintaining the immunologic vigor of individuals and populations. Classical MHC class II genes were targeted for partial sequencing in sea otters (Enhydra lutris) from populations in California, Washington, and Alaska. Sequences derived from sea otter peripheral blood leukocyte mRNAs were similar to those classified as DQA, DQB, DRA, and DRB in other species. Comparisons of the derived amino acid compositions supported the classification of these as functional molecules from at least one DQA, DQB, and DRA locus and at least two DRB loci. While limited in scope, phylogenetic analysis of the DRB peptide-binding region suggested the possible existence of distinct clades demarcated by geographic region. These preliminary findings support the need for additional MHC gene sequencing and expansion to a comprehensive study targeting additional otters.

  14. Overexpression of MHC Class I Heavy Chain Protein in Young Skeletal Muscle Leads to Severe Myositis

    PubMed Central

    Li, Charles Kwok-chong; Knopp, Paul; Moncrieffe, Halima; Singh, Bhanu; Shah, Sonia; Nagaraju, Kanneboyina; Varsani, Hemlata; Gao, Bin; Wedderburn, Lucy R.

    2009-01-01

    Folding and transport of proteins, such as major histocompatibility complex (MHC) class I, through the endoplasmic reticulum (ER) is tightly regulated in all cells, including muscle tissue, where the specialized ER sarcoplasmic reticulum is also critical to muscle fiber function. Overexpression of MHC class I protein is a common feature of many muscle pathologies including idiopathic myositis and can induce ER stress. However, there has been no comparison of the consequences of MHC overexpression in muscle at different ages. We have adapted a transgenic model of myositis induced by overexpression of MHC class I protein in skeletal muscle to investigate the effects of this protein overload on young muscle fibers, as compared with adult tissue. We find a markedly more severe disease phenotype in young mice, with rapid onset of muscle weakness and pathology. Gene expression profiling to compare the two models indicates rapid onset of ER stress in young muscle tissue but also that gene expression of key muscle structural proteins is affected more rapidly in young mice than adults after this insult. This novel model has important implications for our understanding of muscle pathology in dermatomyositis of both adults and children. PMID:19700752

  15. Species-specific evolution of class I MHC genes in iguanas (order: Squamata; subfamily: Iguaninae).

    PubMed

    Glaberman, Scott; Caccone, Adalgisa

    2008-07-01

    Over the last few decades, the major histocompatibility complex (MHC) has emerged as a model for understanding the influence of natural selection on genetic diversity in populations as well as for investigating the genetic basis of host resistance to pathogens. However, many vertebrate taxa remain underrepresented in the field of MHC research, preventing its application to studies of disease, evolution, and conservation genetics in these groups. This is particularly true for squamates, which are by far the most diversified order of non-avian reptiles but have not been the subject of any recent MHC studies. In this paper, we present MHC class I complementary DNA data from three squamate species in the subfamily Iguaninae (iguanas): the Galápagos marine iguana (Amblyrhynchus cristatus), the Galápagos land iguana (Conolophus subcristatus), and the green iguana (Iguana iguana). All sequences obtained are related to the few published class I genes from other squamates. There is evidence for multiple loci in each species, and the conserved alpha-3 domain appears to be evolving in a species-specific manner. Conversely, there is some indication of shared polymorphism between species in the peptide-binding alpha-1 and alpha-2 domains, suggesting that these two regions have different phylogenetic histories. The great similarity between alpha-3 sequences in marine iguanas in particular suggests that concerted evolution is acting to homogenize class I loci within species. However, while less likely, the data are also compatible with a birth and death model of evolution.

  16. Identification, inheritance, and linkage of B-G-like and MHC class I genes in cranes

    USGS Publications Warehouse

    Jarvi, S.I.; Goto, R.M.; Gee, G.F.; Briles, W.E.; Miller, M.M.

    1999-01-01

    We identified B-G-like genes in the whooping and Florida sandhill cranes and linked them to the major histocompatibility complex (MHC). We evaluated the inheritance of B-G-like genes in families of whooping and Florida sandhill cranes using restriction fragment patterns (RFPs). Two B-G-like genes, designated wcbgl and wcbg2, were located within 8 kb of one another. The fully sequenced wcbg2 gene encodes a B-G IgV-like domain, an additional Ig-like domain, a transmembrane domain, and a single heptad domain typical of '-helical coiled coils. Patterns of restriction fragments in DNA from the whooping crane and from a number of other species indicate that the B-G-like gene families of cranes are large with diverse sequences. Segregation of RFPs in families of Florida sandhill cranes provide evidence for genetic polymorphism in the B-G-like genes. The restriction fragments generally segregated in concert with MHC haplotypes assigned by serological typing and by single stranded conformational polymorphism (SSCP) assays based in the second exon of the crane MHC class I genes. This study supports the concept of a long-term association of polymorphic B-G-like genes with the MHC. It also establishes SSCP as a means for evaluating MHC genetic variability in cranes.

  17. Susceptibility of amphibians to chytridiomycosis is associated with MHC class II conformation

    PubMed Central

    Bataille, Arnaud; Cashins, Scott D.; Grogan, Laura; Skerratt, Lee F.; Hunter, David; McFadden, Michael; Scheele, Benjamin; Brannelly, Laura A.; Macris, Amy; Harlow, Peter S.; Bell, Sara; Berger, Lee; Waldman, Bruce

    2015-01-01

    The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) can cause precipitous population declines in its amphibian hosts. Responses of individuals to infection vary greatly with the capacity of their immune system to respond to the pathogen. We used a combination of comparative and experimental approaches to identify major histocompatibility complex class II (MHC-II) alleles encoding molecules that foster the survival of Bd-infected amphibians. We found that Bd-resistant amphibians across four continents share common amino acids in three binding pockets of the MHC-II antigen-binding groove. Moreover, strong signals of selection acting on these specific sites were evident among all species co-existing with the pathogen. In the laboratory, we experimentally inoculated Australian tree frogs with Bd to test how each binding pocket conformation influences disease resistance. Only the conformation of MHC-II pocket 9 of surviving subjects matched those of Bd-resistant species. This MHC-II conformation thus may determine amphibian resistance to Bd, although other MHC-II binding pockets also may contribute to resistance. Rescuing amphibian biodiversity will depend on our understanding of amphibian immune defence mechanisms against Bd. The identification of adaptive genetic markers for Bd resistance represents an important step forward towards that goal. PMID:25808889

  18. Susceptibility of amphibians to chytridiomycosis is associated with MHC class II conformation.

    PubMed

    Bataille, Arnaud; Cashins, Scott D; Grogan, Laura; Skerratt, Lee F; Hunter, David; McFadden, Michael; Scheele, Benjamin; Brannelly, Laura A; Macris, Amy; Harlow, Peter S; Bell, Sara; Berger, Lee; Waldman, Bruce

    2015-04-22

    The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) can cause precipitous population declines in its amphibian hosts. Responses of individuals to infection vary greatly with the capacity of their immune system to respond to the pathogen. We used a combination of comparative and experimental approaches to identify major histocompatibility complex class II (MHC-II) alleles encoding molecules that foster the survival of Bd-infected amphibians. We found that Bd-resistant amphibians across four continents share common amino acids in three binding pockets of the MHC-II antigen-binding groove. Moreover, strong signals of selection acting on these specific sites were evident among all species co-existing with the pathogen. In the laboratory, we experimentally inoculated Australian tree frogs with Bd to test how each binding pocket conformation influences disease resistance. Only the conformation of MHC-II pocket 9 of surviving subjects matched those of Bd-resistant species. This MHC-II conformation thus may determine amphibian resistance to Bd, although other MHC-II binding pockets also may contribute to resistance. Rescuing amphibian biodiversity will depend on our understanding of amphibian immune defence mechanisms against Bd. The identification of adaptive genetic markers for Bd resistance represents an important step forward towards that goal.

  19. Identification, inheritance, and linkage of B-G-like and MHC class I genes in cranes.

    PubMed

    Jarvi, S I; Goto, R M; Gee, G F; Briles, W E; Miller, M M

    1999-01-01

    We identified B-G-like genes in the whooping and Florida sandhill cranes and linked them to the major histocompatibility complex (MHC). We evaluated the inheritance of B-G-like genes in families of whooping and Florida sandhill cranes using restriction fragment patterns (RFPs). Two B-G-like genes, designated wcbg1 and wcbg2, were located within 8 kb of one another. The fully sequenced wcbg2 gene encodes a B-G IgV-like domain, an additional Ig-like domain, a transmembrane domain, and a single heptad domain typical of alpha-helical coiled coils. Patterns of restriction fragments in DNA from the whooping crane and from a number of other species indicate that the B-G-like gene families of cranes are large with diverse sequences. Segregation of RFPs in families of Florida sandhill cranes provide evidence for genetic polymorphism in the B-G-like genes. The restriction fragments generally segregated in concert with MHC haplotypes assigned by serological typing and by single stranded conformational polymorphism (SSCP) assays based in the second exon of the crane MHC class I genes. This study supports the concept of a long-term association of polymorphic B-G-like genes with the MHC. It also establishes SSCP as a means for evaluating MHC genetic variability in cranes.

  20. Large-scale MHC class II genotyping of a wild lemur population by next generation sequencing.

    PubMed

    Huchard, Elise; Albrecht, Christina; Schliehe-Diecks, Susanne; Baniel, Alice; Roos, Christian; Kappeler, Peter M; Peter, Peter M Kappeler; Brameier, Markus

    2012-12-01

    The critical role of major histocompatibility complex (MHC) genes in disease resistance, along with their putative function in sexual selection, reproduction and chemical ecology, make them an important genetic system in evolutionary ecology. Studying selective pressures acting on MHC genes in the wild nevertheless requires population-wide genotyping, which has long been challenging because of their extensive polymorphism. Here, we report on large-scale genotyping of the MHC class II loci of the grey mouse lemur (Microcebus murinus) from a wild population in western Madagascar. The second exons from MHC-DRB and -DQB of 772 and 672 individuals were sequenced, respectively, using a 454 sequencing platform, generating more than 800,000 reads. Sequence analysis, through a stepwise variant validation procedure, allowed reliable typing of more than 600 individuals. The quality of our genotyping was evaluated through three independent methods, namely genotyping the same individuals by both cloning and 454 sequencing, running duplicates, and comparing parent-offspring dyads; each displaying very high accuracy. A total of 61 (including 20 new) and 60 (including 53 new) alleles were detected at DRB and DQB genes, respectively. Both loci were non-duplicated, in tight linkage disequilibrium and in Hardy-Weinberg equilibrium, despite the fact that sequence analysis revealed clear evidence of historical selection. Our results highlight the potential of 454 sequencing technology in attempts to investigate patterns of selection shaping MHC variation in contemporary populations. The power of this approach will nevertheless be conditional upon strict quality control of the genotyping data.

  1. Human cytomegalovirus US3 modulates destruction of MHC class I molecules.

    PubMed

    Noriega, Vanessa M; Hesse, Julia; Gardner, Thomas J; Besold, Katrin; Plachter, Bodo; Tortorella, Domenico

    2012-06-01

    Human cytomegalovirus (HCMV), a member of the Herpesviridae family, is proficient at establishing lifelong persistence within the host in part due to immune modulating genes that limit immune recognition. HCMV encodes at least five glycoproteins within its unique short (US) genomic region that interfere with MHC class I antigen presentation, thus hindering viral clearance by cytotoxic T lymphocytes (CTL). Specifically, US3 retains class I within the endoplasmic reticulum (ER), while US2 and US11 induce class I heavy chain destruction. A cooperative effect on class I down-regulation during stable expression of HCMV US2 and US3 has been established. To address the impact of US3 on US11-mediated MHC class I down-regulation, the fate of class I molecules was examined in US3/US11-expressing cells and virus infection studies. Co-expression of US3 and US11 resulted in a decrease of surface expression of class I molecules. However, the class I molecules in US3/US11 cells were mostly retained in the ER with an attenuated rate of proteasome destruction. Analysis of class I levels from virus-infected cells using HCMV variants either expressing US3 or US11 revealed efficient surface class I down-regulation upon expression of both viral proteins. Cells infected with both US3 and US11 expressing viruses demonstrate enhanced retention of MHC class I complexes within the ER. Collectively, the data suggests a paradigm where HCMV-induced surface class I down-regulation occurs by diverse mechanisms dependent on the expression of specific US genes. These results validate the commitment of HCMV to limiting the surface expression of class I levels during infection.

  2. Independent evolution of functional MHC class II DRB genes in New World bat species.

    PubMed

    Schad, Julia; Voigt, Christian C; Greiner, Sabine; Dechmann, Dina K N; Sommer, Simone

    2012-07-01

    Genes of the major histocompatibility complex (MHC) play a pivotal role in the vertebrate immune system and are attractive markers for functional, fitness-related, genetic variation. Although bats (Chiroptera) represent the second largest mammalian order and are prone to various emerging infectious diseases, little is known about MHC evolution in bats. In the present study, we examined expressed MHC class II DRB sequences (exons 1 to 4) of New World bat species, Saccopteryx bilineata, Carollia perspicillata, Noctilio albiventris and Noctilio leporinus (only exon 2). We found a wide range of copy number variation of DRB loci with one locus detected in the genus Noctilio and up to ten functional loci observed in S. bilineata. Sequence variation between alleles of the same taxa was high with evidence for positive selection. We found statistical support for recombination or gene conversion events among sequences within the same but not between bat species. Phylogenetic relationships among DRB alleles provided strong evidence for independent evolution of the functional MHC class II DRB genes in the three investigated species, either by recent gene duplication, or homogenization of duplicated loci by frequent gene conversion events. Phylogenetic analysis of all available chiropteran DRB exon 2 sequences confirmed their monophyletic origin within families, but revealed a possible trans-species mode of evolution pattern in congeneric bat species, e.g. within the genera Noctilio and Myotis. This is the first study investigating phylogenetic relationships of MHC genes within bats and therefore contributes to a better understanding of MHC evolution in one of the most dominant mammalian order.

  3. MHC class I of saltwater crocodiles (Crocodylus porosus): polymorphism and balancing selection.

    PubMed

    Jaratlerdsiri, Weerachai; Isberg, Sally R; Higgins, Damien P; Gongora, Jaime

    2012-11-01

    Saltwater crocodiles are in high demand for the production of luxury fashion items. However, their susceptibility to disease incurs substantial losses and it is hoped to be able to genetically select these animals for disease resistance. So far, this has only been enabled by phenotypic selection. Investigating the major histocompatibility complex (MHC) could provide insight into the ability of an individual to respond to pathogens acting as a selective pressure on the host. Here, we assessed genetic diversity and a role of selection in shaping the diversity of MHC class I exon 3 among 42 saltwater crocodiles from nine river basins in the Northern Territory, Australia. We generated 640 sequences using cloning and sequencing methods and identified 43 MHC variants among them. Phylogenetic analyses clustered these variants into two major clades, which may suggest two gene lineages. We found the number of variants within an individual varying between one and seven, indicating that there are at least four gene loci in this species. Selection detection analyses revealed an elevated ratio of nonsynonymous to synonymous substitutions (mean = 1.152 per codon), suggesting balancing selection. Population differentiation analyses revealed that the MHC did not show structuring among the river basins, and there were some shared variants among them. This may be a result of possible gene flow and/or similar selection pressures among populations. These findings provide background knowledge to identify potential MHC markers, which could be used for selecting genetically variable individuals for future disease associations. All MHC class I exon 3 sequences reported in this paper were submitted to the GenBank database with following accession numbers: HQ008785-HQ008789, HQ008791-HQ008798, HQ008808-HQ008815, HQ008824, HQ008826-HQ008830, HQ008835, HQ008839, HQ008842-HQ008850, and JX023536-JX023540.

  4. Restricting nonclassical MHC genes coevolve with TRAV genes used by innate-like T cells in mammals

    PubMed Central

    Boudinot, Pierre; Mondot, Stanislas; Jouneau, Luc; Teyton, Luc; Lefranc, Marie-Paule; Lantz, Olivier

    2016-01-01

    Whereas major histocompatibility class-1 (MH1) proteins present peptides to T cells displaying a large T-cell receptor (TR) repertoire, MH1Like proteins, such as CD1D and MR1, present glycolipids and microbial riboflavin precursor derivatives, respectively, to T cells expressing invariant TR-α (iTRA) chains. The groove of such MH1Like, as well as iTRA chains used by mucosal-associated invariant T (MAIT) and natural killer T (NKT) cells, respectively, may result from a coevolution under particular selection pressures. Herein, we investigated the evolutionary patterns of the iTRA of MAIT and NKT cells and restricting MH1Like proteins: MR1 appeared 170 Mya and is highly conserved across mammals, evolving more slowly than other MH1Like. It has been pseudogenized or independently lost three times in carnivores, the armadillo, and lagomorphs. The corresponding TRAV1 gene also evolved slowly and harbors highly conserved complementarity determining regions 1 and 2. TRAV1 is absent exclusively from species in which MR1 is lacking, suggesting that its loss released the purifying selection on MR1. In the rabbit, which has very few NKT and no MAIT cells, a previously unrecognized iTRA was identified by sequencing leukocyte RNA. This iTRA uses TRAV41, which is highly conserved across several groups of mammals. A rabbit MH1Like gene was found that appeared with mammals and is highly conserved. It was independently lost in a few groups in which MR1 is present, like primates and Muridae, illustrating compensatory emergences of new MH1Like/Invariant T-cell combinations during evolution. Deciphering their role is warranted to search similar effector functions in humans. PMID:27170188

  5. Transport and quality control of MHC class I molecules in the early secretory pathway.

    PubMed

    Springer, Sebastian

    2015-06-01

    Folding and peptide binding of major histocompatibility complex (MHC) class I molecules have been thoroughly researched, but the mechanistic connection between these biochemical events and the progress of class I through the early secretory pathway is much less well understood. This review focuses on the question how the partially assembled forms of class I (which lack high-affinity peptide and/or the light chain beta-2 microglobulin) are retained inside the cell. Such investigations offer researchers exciting chances to understand the connections between class I structure, conformational dynamics, peptide binding kinetics and thermodynamics, intracellular transport, and antigen presentation.

  6. Characterization and evolution of MHC class II B genes in Ardeid birds.

    PubMed

    Li, Li; Zhou, Xiaopin; Chen, Xiaolin

    2011-06-01

    Major histocompatibility complex (MHC) is a multi-gene family that is very suitable to investigate a wide range of open questions in evolutionary ecology. In this study, we characterized two expressed MHC class II B genes (DAB1 and DAB2) in the Grey Heron (Aves: Ardea cinerea). We further developed the primer pairs to amplify and sequence two MHC class II B loci in ten ardeid birds. Phylogenetic analysis revealed that different parts of the genes showed different evolutionary patterns. The exon 2 sequences tended to cluster two gene-specific lineages. In each lineage, exon 2 sequences from several species showed closer relationships than sequences within species, and two shared identical alleles were found between species (Egretta sacra and Nycticorax nycticorax; Egretta garzetta and Bubulcus ibis), supporting the hypothesis of trans-species polymorphism. In contrast, the species-specific intron 2 plus partial exon 3 tree suggested that DAB1 and DAB2 were subject to concerted evolution. GENECONV analyses showed the gene exchange played an important role in the ardeid MHC evolution.

  7. The first step of peptide selection in antigen presentation by MHC class I molecules

    PubMed Central

    Garstka, Malgorzata A.; Fish, Alexander; Celie, Patrick H. N.; Joosten, Robbie P.; Janssen, George M. C.; Berlin, Ilana; Hoppes, Rieuwert; Stadnik, Magda; Janssen, Lennert; Ovaa, Huib; van Veelen, Peter A.; Perrakis, Anastassis; Neefjes, Jacques

    2015-01-01

    MHC class I molecules present a variable but limited repertoire of antigenic peptides for T-cell recognition. Understanding how peptide selection is achieved requires mechanistic insights into the interactions between the MHC I and candidate peptides. We find that, at first encounter, MHC I H-2Kb considers a wide range of peptides, including those with expanded N termini and unfitting anchor residues. Discrimination occurs in the second step, when noncanonical peptides dissociate with faster exchange rates. This second step exhibits remarkable temperature sensitivity, as illustrated by numerous noncanonical peptides presented by H-2Kb in cells cultured at 26 °C relative to 37 °C. Crystallographic analyses of H-2Kb–peptide complexes suggest that a conformational adaptation of H-2Kb drives the decisive step in peptide selection. We propose that MHC class I molecules consider initially a large peptide pool, subsequently refined by a temperature-sensitive induced-fit mechanism to retain the canonical peptide repertoire. PMID:25605945

  8. Bap29/31 influences the intracellular traffic of MHC class I molecules.

    PubMed

    Paquet, Marie-Eve; Cohen-Doyle, Myrna; Shore, Gordon C; Williams, David B

    2004-06-15

    In this study, we examine the role of the putative cargo receptor B cell-associated protein (Bap)29/31 in the export of MHC class I molecules out of the endoplasmic reticulum (ER). We show that Bap31 binds to two allotypes of mouse class I molecules, with the interaction initiated at the time of H chain association with beta(2)-microglobulin and maintained until the class I molecule has left the ER. We also show that Bap31 is part of the peptide-loading complex, although is not required for its formation. Bap31 binds not only to class I molecules, but can bind to tapasin in the absence of class I. Consistent with an important role in recruiting class I molecules to transport vesicles, we show that in the absence of Bap29/31, there is a loss of class I colocalization with mSec31 (p137), a component of mammalian coat protein complex II coats. This observation is also associated with a delay in class I traffic from ER to Golgi. Our results are consistent with the view that class I molecules are largely recruited to ER exit sites by Bap29/31, and that Bap29/31 is a cargo receptor for MHC class I molecules.

  9. The common marmoset: a new world primate species with limited Mhc class II variability.

    PubMed

    Antunes, S G; de Groot, N G; Brok, H; Doxiadis, G; Menezes, A A; Otting, N; Bontrop, R E

    1998-09-29

    The common marmoset (Callithrix jacchus) is a New World primate species that is highly susceptible to fatal infections caused by various strains of bacteria. We present here a first step in the molecular characterization of the common marmoset's Mhc class II genes by nucleotide sequence analysis of the polymorphic exon 2 segments. For this study, genetic material was obtained from animals bred in captivity as well as in the wild. The results demonstrate that the common marmoset has, like other primates, apparently functional Mhc-DR and -DQ regions, but the Mhc-DP region has been inactivated. At the -DR and -DQ loci, only a limited number of lineages were detected. On the basis of the number of alleles found, the -DQA and -B loci appear to be oligomorphic, whereas only a moderate degree of polymorphism was observed for two of three Mhc-DRB loci. The contact residues in the peptide-binding site of the Caja-DRB1*03 lineage members are highly conserved, whereas the -DRB*W16 lineage members show more divergence in that respect. The latter locus encodes five oligomorphic lineages whose members are not observed in any other primate species studied, suggesting rapid evolution, as illustrated by frequent exchange of polymorphic motifs. All common marmosets tested were found to share one monomorphic type of Caja-DRB*W12 allele probably encoded by a separate locus. Common marmosets apparently lack haplotype polymorphism because the number of Caja-DRB loci present per haplotype appears to be constant. Despite this, however, an unexpectedly high number of allelic combinations are observed at the haplotypic level, suggesting that Caja-DRB alleles are exchanged frequently between chromosomes by recombination, promoting an optimal distribution of limited Mhc polymorphisms among individuals of a given population. This peculiar genetic make up, in combination with the limited variability of the major histocompatability complex class II repertoire, may contribute to the common

  10. Decreased monocyte class II MHC expression following major abdominal surgery in children is related to operative stress.

    PubMed

    McHoney, M; Klein, N J; Eaton, S; Pierro, A

    2006-04-01

    Monocyte class II major histocompatibility complex (MHC) expression is necessary for antigen presentation and stimulation of T-cells. The aim of this study was to correlate monocyte class II MHC response to operative stress in children and the possible influence of cytokines in the postoperative period. We studied 21 children undergoing elective abdominal surgery. Operative stress score (OSS) was calculated. Monocyte class II MHC expression was measured preoperatively, immediately after surgery, 24 and 48 h postoperatively, using flow cytometry. Class II MHC is expressed as mean fluorescence intensity (MFI) of monocytes expressing MHC (mean +/- SD). Cytokine levels (interleukins 1ra, 6, and 10, and tumor necrosis factor-alpha) were also measured. Data between time points were compared using repeated measures ANOVA. There was an immediate postoperative decrease in class II MHC expression, with lowest levels 24 h postoperatively (preoperative 50 +/- 23.6, 24 h 18.2 +/- 9.4, P < 0.0001 vs. preoperative). At 48 h there was partial recovery in class II MHC, but levels were still significantly lower than preoperative (23.9 +/- 11.1, P < 0.001). The degree of monocyte depression was related to the magnitude of operative stress. Patients who had OSS <10 displayed some recovery in expression at 48 h 25.5 +/- 11.1), whereas in patients with OSS > or = 10 (severe surgical stress), expression further decreased at 48 h (MFI 14.0 +/- 0.1). There was an elevation of interleukin-1ra in the immediate postoperative period in both groups. There was no elevation in the other cytokines. Abdominal surgery in children decreases monocyte MHC expression. Class II MHC depression was related to magnitude of surgical trauma, implying that more severe immuneparesis follows surgery of greater magnitude. This may predispose to postoperative infection.

  11. Tumor-specific CD4+ T cells eradicate myeloma cells genetically deficient in MHC class II display

    PubMed Central

    Tveita, Anders; Fauskanger, Marte; Bogen, Bjarne; Haabeth, Ole Audun Werner

    2016-01-01

    CD4+ T cells have been shown to reject tumor cells with no detectable expression of major histocompatibility complex class II (MHC II). However, under certain circumstances, induction of ectopic MHC II expression on tumor cells has been reported. To confirm that CD4+ T cell-mediated anti-tumor immunity can be successful in the complete absence of antigen display on the tumor cells themselves, we eliminated MHC II on tumor cells using CRISPR/Cas9. Our results demonstrate that ablation of the relevant MHC II (I-Ed) in multiple myeloma cells (MOPC315) does not hinder rejection by tumor-specific CD4+ T cells. These findings provide conclusive evidence that CD4+ T cells specific for tumor antigens can eliminate malignant cells in the absence of endogenous MHC class II expression on the tumor cells. This occurs through antigen uptake and indirect presentation on tumor-infiltrating macrophages. PMID:27626487

  12. MHC class II B diversity in blue tits: a preliminary study

    PubMed Central

    Aguilar, Juan Rivero-de; Schut, Elske; Merino, Santiago; Martínez, Javier; Komdeur, Jan; Westerdahl, Helena

    2013-01-01

    In this study, we partly characterize major histocompatibility complex (MHC) class II B in the blue tit (Cyanistes caeruleus). A total of 22 individuals from three different European locations: Spain, The Netherlands, and Sweden were screened for MHC allelic diversity. The MHC genes were investigated using both PCR-based methods and unamplified genomic DNA with restriction fragment length polymorphism (RFLP) and southern blots. A total of 13 different exon 2 sequences were obtained independently from DNA and/or RNA, thus confirming gene transcription and likely functionality of the genes. Nine out of 13 alleles were found in more than one country, and two alleles appeared in all countries. Positive selection was detected in the region coding for the peptide binding region (PBR). A maximum of three alleles per individual was detected by sequencing and the RFLP pattern consisted of 4–7 fragments, indicating a minimum number of 2–4 loci per individual. A phylogenetic analysis, demonstrated that the blue tit sequences are divergent compared to sequences from other passerines resembling a different MHC lineage than those possessed by most passerines studied to date. PMID:23919136

  13. Induction of the rainbow trout MHC class I pathway during acute IHNV infection.

    PubMed

    Hansen, John D; La Patra, Scott

    2002-12-01

    Interferons are essential for establishing cytotoxic T-lymphocyte immunity against viral pathogens through different mechanisms including the modulation of antigen presentation to T-cell subsets. At the present time, interferons have yet to be isolated from teleost fish. We have developed a salmonid model to examine whether MHC gene regulation is modulated during acute viral infection in trout, an event attributable to interferons in mammals. During peak infection with infectious hematopoietic necrosis virus, induction of STAT-1, PSMB9A and ABCB2 mRNA was evident in all tissues within infected fish, as compared with controls. In addition, MHC class Ia and beta(2) microglobulin (beta(2)m) transcript levels were enhanced within the experimental group but surprisingly, splenic and pronephric class IIB mRNA expression was virtually absent. A time-course study looking at 24, 72 and 192 h post-infection was then performed to determine the overall kinetics of this response. STAT-1 and PSMB9A message levels increased early during the immune response and remain at relatively high levels until the final time point. MHC class Ia expression is not consistently upregulated until midway in the response. MHC class IIB transcripts are downregulated by 72 h in the spleen and pronephros and then partially restored by 192 h. Finally, analysis of the putative promoter regions for PSMB9A and ABCB2 identified interferon (IFN) regulatory factory (IRF-1) and INF-gamma (GAS) activation sites that may be involved in the regulation of these genes during viral infection.

  14. Expression of rat class I major histocompatibility complex (MHC) alloantigens and hepatocytes and hepatoma cells

    SciTech Connect

    Hunt, J.M.; Desai, P.A.; Chakraborty, S.

    1986-03-05

    Altered expression of Class I MHC alloantigens has been reported for murine tumors, and may be associated with the tumorigenic phenotype of tumor cells. To characterize MHC Class I alloantigen expression on a chemically-induced transplantable rat hepatoma cell line, 17X, derived from a (WF x F344) F/sub 1/ rat, polyvalent anti-F344 and anti-WF rat alloantisera were first used to immunoprecipitate the rat RT1.A Class I MHC alloantigens expressed on primary (WF x F344) F/sub 1/ hepatocyptes in short-term monolayer cultures. Two-dimensional isoelectric focusing and SDS-PAGE of immunoprecipitates from /sup 35/S-methionine-labeled (WF x F344) F/sub 1/ hepatocytes clearly resolved the RT1.A/sup u/ (WF) and RT1.A/sup LvI/ (F344) parental alloantigens. Identical radiolabeling and immunoprecipitation failed to detect either parental alloantigen on the 17X hepatoma cells. However, indirect immunofluorescence and immunoblot analyses demonstrated the presence of parental alloantigens on the 17X cells. Immunization of F344 rats but not of WF rats with 17X cells resulted in antibodies cytotoxic for normal (WF X F344) F/sub 1/ spleen cells in the presence of complement. These findings indicate that a combination of detection techniques will be necessary to characterize altered alloantigen expression on rat hepatoma cells.

  15. A family of MHC class I-like genes located in the vicinity of the mouse leukocyte receptor complex

    PubMed Central

    Kasahara, Masanori; Watanabe, Yutaka; Sumasu, Motoko; Nagata, Taeko

    2002-01-01

    Some members of the major histocompatibility complex (MHC) class I gene family are encoded outside the MHC. Here we describe a family of mouse class I-like genes mapping to the vicinity of the leukocyte receptor complex (LRC) on chromosome 7. This family, which we call Mill (MHC class I-like located near the LRC), has two members designated Mill1 and Mill2. Both genes are predicted to encode membrane glycoproteins with domain organization essentially similar to that of MHC class I heavy chains. The following features of Mill are noteworthy. (i) The deduced MILL proteins lack most of the residues known to be involved in the docking of peptides in classical MHC class I molecules. (ii) Among the known members of the class I gene family, MILL1 and MILL2 are related most closely to MICA/MICB encoded in the human MHC. (iii) Unlike all other known members of the class I gene family, Mill1 and Mill2 have an exon between those coding for the signal peptide and the α1 domain. (iv) Mill1 has a more restricted expression profile than Mill2. (v) The gene orthologous to Mill1 or Mill2 apparently is absent in the human. (vi) Mill1 and Mill2 show a limited degree of polymorphism in laboratory mice. The observation that the Mill family is related most closely to the MIC family, together with its apparent absence in the human, suggests its involvement in innate immunity. PMID:12370446

  16. The oxidoreductase ERp57 efficiently reduces partially folded in preference to fully folded MHC class I molecules

    PubMed Central

    Antoniou, Antony N.; Ford, Stuart; Alphey, Magnus; Osborne, Andrew; Elliott, Tim; Powis, Simon J.

    2002-01-01

    The oxidoreductase ERp57 is an integral component of the peptide loading complex of major histocompatibility complex (MHC) class I molecules, formed during their chaperone-assisted assembly in the endoplasmic reticulum. Misfolded MHC class I molecules or those denied suitable peptides are retrotranslocated and degraded in the cytosol. The presence of ERp57 during class I assembly suggests it may be involved in the reduction of intrachain disulfides prior to retrotranslocation. We have studied the ability of ERp57 to reduce MHC class I molecules in vitro. Recombinant ERp57 specifically reduced partially folded MHC class I molecules, whereas it had little or no effect on folded and peptide-loaded MHC class I molecules. Reductase activity was associated with cysteines at positions 56 and 405 of ERp57, the N-terminal residues of the active CXXC motifs. Our data suggest that the reductase activity of ERp57 may be involved during the unfolding of MHC class I molecules, leading to targeting for degradation. PMID:12032078

  17. Intracellular recycling and cross-presentation by MHC class I molecules.

    PubMed

    van Endert, Peter

    2016-07-01

    Cross-presentation of internalized antigens by dendritic cells requires efficient delivery of Major Histocompatibility Complex (MHC) class I molecules to peptide-loading compartments. Strong evidence suggests that such loading can occur outside of the endoplasmic reticulum; however, the trafficking pathways and sources of class I molecules involved are poorly understood. Examination of non-professional, non-phagocytic cells has revealed a clathrin-independent, Arf6-dependent recycling pathway likely traveled by internalized optimally loaded (closed) class I molecules. Some closed and all open MHC class I molecules travel to late endosomes to be degraded but might also partly be re-loaded with peptides and recycled. Studies of viral interference revealed pathways in which class I molecules are directed to degradation in lysosomes upon ubiquitination at the surface, or upon AP-1 and HIV-nef-dependent misrouting from the Golgi network to lysosomes. While many observations made in non-professional cells remain to be re-examined in dendritic cells, available evidence suggests that both recycling and neo-synthesized class I molecules can be loaded with cross-presented peptides. Recycling molecules can be recruited to phagosomes triggered by innate signals such as TLR4 ligands, and may therefore specialize in loading with phagocytosed antigens. In contrast, AP-1-dependent accumulation at, or trafficking through, a Golgi compartment of newly synthesized molecules appears to be important for cross-presentation of soluble proteins and possibly of long peptides that are processed in the so-called vacuolar pathway. However, significant cell biological work will be required to confirm this or any other model and to integrate knowledge on MHC class I biochemistry and trafficking in models of CD8(+) T-cell priming by dendritic cells.

  18. Negative regulation by HLA-DO of MHC class II-restricted antigen processing.

    PubMed

    Denzin, L K; Sant'Angelo, D B; Hammond, C; Surman, M J; Cresswell, P

    1997-10-03

    HLA-DM is a major histocompatibility complex (MHC) class II-like molecule that facilitates antigen processing by catalyzing the exchange of invariant chain-derived peptides (CLIP) from class II molecules for antigenic peptides. HLA-DO is a second class II-like molecule that physically associates with HLA-DM in B cells. HLA-DO was shown to block HLA-DM function. Purified HLA-DM-DO complexes could not promote peptide exchange in vitro. Expression of HLA-DO in a class II+ and DM+, DO- human T cell line caused the accumulation of class II-CLIP complexes, indicating that HLA-DO blocked DM function in vivo and suggesting that HLA-DO is an important modulator of class II-restricted antigen processing.

  19. DPA1*02012: A DPA1*0201-related Mhc class II allele in West Africa

    SciTech Connect

    Meyer, C.G.; May, J.; Spauke, D.; Schnittger, L.

    1994-12-31

    DNA techniques such as sequence-specific oligonucleotide probe (SSOP) hybridizations, restriction-fragment length polymorphism (RFLP) analyses, and DNA sequencing have greatly supported the characterization of Mhc class II allelic polymorphism. Here the authors describe a DPA 1 allele which has been identified in two male individuals from Liberia and Benin, West Africa, during a survey study on Mhc class II associations with the different manifestations after infection with Onchocerca volvulus. 4 refs., 1 fig.

  20. Full-length novel MHC class I allele discovery by next-generation sequencing: two platforms are better than one.

    PubMed

    Dudley, Dawn M; Karl, Julie A; Creager, Hannah M; Bohn, Patrick S; Wiseman, Roger W; O'Connor, David H

    2014-01-01

    Deep sequencing has revolutionized major histocompatibility complex (MHC) class I analysis of nonhuman primates by enabling high-throughput, economical, and comprehensive genotyping. Full-length MHC class I cDNA sequences, which are required to generate reagents such as MHC-peptide tetramers, cannot be directly obtained by short read deep sequencing. We combined data from two next-generation sequencing platforms to discover novel full-length MHC class I mRNA/cDNA transcripts in Chinese rhesus macaques. We first genotyped macaques by Roche/454 pyrosequencing using a 530-bp amplicon spanning the densely polymorphic exons 2 through 4 of the MHC class I loci that encode the peptide-binding region. We then mapped short paired-end 250 bp Illumina sequence reads spanning the full-length transcript to each 530-bp amplicon at high stringency and used paired-end information to reconstruct full-length allele sequences. We characterized 65 full-length sequences from six Chinese rhesus macaques. Overall, approximately 70 % of the alleles distinguished in these six animals contained new sequence information, including 29 novel transcripts. The flexibility of this approach should make full-length MHC class I allele genotyping accessible for any nonhuman primate population of interest. We are currently optimizing this method for full-length characterization of other highly polymorphic, duplicated loci such as the MHC class II DRB and killer immunoglobulin-like receptors. We anticipate that this method will facilitate rapid expansion and near completion of sequence libraries of polymorphic loci, such as MHC class I, within a few years.

  1. Expression levels of MHC class I molecules are inversely correlated with promiscuity of peptide binding

    PubMed Central

    Chappell, Paul E; Meziane, El Kahina; Harrison, Michael; Magiera, Łukasz; Hermann, Clemens; Mears, Laura; Wrobel, Antoni G; Durant, Charlotte; Nielsen, Lise Lotte; Buus, Søren; Ternette, Nicola; Mwangi, William; Butter, Colin; Nair, Venugopal; Ahyee, Trudy; Duggleby, Richard; Madrigal, Alejandro; Roversi, Pietro; Lea, Susan M; Kaufman, Jim

    2015-01-01

    Highly polymorphic major histocompatibility complex (MHC) molecules are at the heart of adaptive immune responses, playing crucial roles in many kinds of disease and in vaccination. We report that breadth of peptide presentation and level of cell surface expression of class I molecules are inversely correlated in both chickens and humans. This relationship correlates with protective responses against infectious pathogens including Marek's disease virus leading to lethal tumours in chickens and human immunodeficiency virus infection progressing to AIDS in humans. We propose that differences in peptide binding repertoire define two groups of MHC class I molecules strategically evolved as generalists and specialists for different modes of pathogen resistance. We suggest that differences in cell surface expression level ensure the development of optimal peripheral T cell responses. The inverse relationship of peptide repertoire and expression is evidently a fundamental property of MHC molecules, with ramifications extending beyond immunology and medicine to evolutionary biology and conservation. DOI: http://dx.doi.org/10.7554/eLife.05345.001 PMID:25860507

  2. MARCH1 down-regulation in IL-10-activated B cells increases MHC class II expression.

    PubMed

    Galbas, Tristan; Steimle, Viktor; Lapointe, Réjean; Ishido, Satoshi; Thibodeau, Jacques

    2012-07-01

    IL-10 is vastly studied for its anti-inflammatory properties on most immune cells. However, it has been reported that IL-10 activates B cells, up-regulates their MHC class II molecules and prevents apoptosis. As MARCH1 was shown to be responsible for the intracellular sequestration of MHC class II molecules in dendritic cells and monocytes in response to IL-10, we set out to clarify the role of this ubiquitin ligase in B cells. Here, we demonstrate in mice that splenic follicular B cells represent the major cell population that up-regulate MHC II molecules in the presence of IL-10. Activation of these cells through TLR4, CD40 or the IL-10 receptor caused the down-regulation of MARCH1 mRNA. Accordingly, B cells from MARCH1-deficient mice do not up-regulate I-A(b) in response to IL-10. In all, our results demonstrate that IL-10 can have opposite effects on MARCH1 regulation in different cell types.

  3. MHC class II genes in European wolves: a comparison with dogs.

    PubMed

    Seddon, Jennifer M; Ellegren, Hans

    2002-10-01

    The genome of the grey wolf, one of the most widely distributed land mammal species, has been subjected to both stochastic factors, including biogeographical subdivision and population fragmentation, and strong selection during the domestication of the dog. To explore the effects of drift and selection on the partitioning of MHC variation in the diversification of species, we present nine DQA, 10 DQB, and 17 DRB1 sequences of the second exon for European wolves and compare them with sequences of North American wolves and dogs. The relatively large number of class II alleles present in both European and North American wolves attests to their large historical population sizes, yet there are few alleles shared between these regions at DQB and DRB1. Similarly, the dog has an extensive array of class II MHC alleles, a consequence of a genetically diverse origin, but allelic overlap with wolves only at DQA. Although we might expect a progression from shared alleles to shared allelic lineages during differentiation, the partitioning of diversity between wolves and dogs at DQB and DRB1 differs from that at DQA. Furthermore, an extensive region of nucleotide sequence shared between DRB1 and DQB alleles and a shared motif suggests intergenic recombination may have contributed to MHC diversity in the Canidae.

  4. Genetic Contribution of MHC Class II Genes in Susceptibility to West Nile Virus Infection.

    PubMed

    Sarri, Constantina A; Markantoni, Maria; Stamatis, Costas; Papa, Anna; Tsakris, Athanasios; Pervanidou, Danai; Baka, Agoritsa; Politis, Constantina; Billinis, Charalambos; Hadjichristodoulou, Christos; Mamuris, Zissis

    2016-01-01

    WNV is a zoonotic neurotropic flavivirus that has recently emerged globally as a significant cause of viral encephalitis. The last five years, 624 incidents of WNV infection have been reported in Greece. The risk for severe WNV disease increases among immunosuppressed individuals implying thus the contribution of the MHC locus to the control of WNV infection. In order to investigate a possible association of MHC class II genes, especially HLA-DPA1, HLA-DQA1, HLA-DRB1, we examined 105 WNV patients, including 68 cases with neuroinvasive disease and 37 cases with mild clinical phenotype, collected during the period from 2010 to2013, and 100 control individuals selected form the Greek population. Typing was performed for exon 2 for all three genes. DQA1*01:01 was considered to be "protective" against WNV infection (25.4% vs 40.1%, P = 0.004) while DQA1*01:02 was associated with increased susceptibility (48.0% vs 32.1%, P = 0.003). Protection against neuroinvasion was associated with the presence of DRB1*11:02 (4.99% vs 0.0%, P = 0.018). DRB1*16:02 was also absent from the control cohort (P = 0.016). Three additional population control groups were used in order to validate our results. No statistically significant association with the disease was found for HLA-DPA alleles. The results of the present study provide some evidence that MHC class II is involved in the response to WNV infection, outlining infection "susceptibility" and "CNS-high-risk" candidates. Furthermore, three new alleles were identified while the frequency of all alleles in the study was compared with worldwide data. The characterization of the MHC locus could help to estimate the risk for severe WNV cases in a country.

  5. Genetic Contribution of MHC Class II Genes in Susceptibility to West Nile Virus Infection

    PubMed Central

    Sarri, Constantina A.; Markantoni, Maria; Stamatis, Costas; Papa, Anna; Tsakris, Athanasios; Pervanidou, Danai; Baka, Agoritsa; Politis, Constantina; Billinis, Charalambos; Hadjichristodoulou, Christos; Mamuris, Zissis

    2016-01-01

    WNV is a zoonotic neurotropic flavivirus that has recently emerged globally as a significant cause of viral encephalitis. The last five years, 624 incidents of WNV infection have been reported in Greece. The risk for severe WNV disease increases among immunosuppressed individuals implying thus the contribution of the MHC locus to the control of WNV infection. In order to investigate a possible association of MHC class II genes, especially HLA-DPA1, HLA-DQA1, HLA-DRB1, we examined 105 WNV patients, including 68 cases with neuroinvasive disease and 37 cases with mild clinical phenotype, collected during the period from 2010 to2013, and 100 control individuals selected form the Greek population. Typing was performed for exon 2 for all three genes. DQA1*01:01 was considered to be "protective" against WNV infection (25.4% vs 40.1%, P = 0.004) while DQA1*01:02 was associated with increased susceptibility (48.0% vs 32.1%, P = 0.003). Protection against neuroinvasion was associated with the presence of DRB1*11:02 (4.99% vs 0.0%, P = 0.018). DRB1*16:02 was also absent from the control cohort (P = 0.016). Three additional population control groups were used in order to validate our results. No statistically significant association with the disease was found for HLA-DPA alleles. The results of the present study provide some evidence that MHC class II is involved in the response to WNV infection, outlining infection "susceptibility" and "CNS-high-risk" candidates. Furthermore, three new alleles were identified while the frequency of all alleles in the study was compared with worldwide data. The characterization of the MHC locus could help to estimate the risk for severe WNV cases in a country. PMID:27812212

  6. Hyperexpression of interferon-gamma-induced MHC class II genes associated with reorganization of the cytoskeleton.

    PubMed Central

    Ulevitch, R. J.; Kline, L.; Schreiber, R. D.; Pingel, J.; Amaldi, I.; Reith, W.; Mach, B.

    1991-01-01

    Class I and class II major histocompatibility complex (MHC) gene products are key recognition units in the induction and regulation of the immune response. Expression of class I and class II may be constitutive or inducible by cytokines such as interferon-gamma (IFN-gamma). A key step in the induction of MHC genes is recognition of IFN-gamma by its membrane receptor. The work described here examines the regulation of the occupied IFN-gamma receptor by the cytoskeleton. To do this the authors have used the fungal metabolites dihydrocytochalasin B (DHCB) and cytochalasin D (CD), substances that bind to actin filaments and thereby disrupt the cytoskeleton. The authors have studied the effect of DHCB and CD on IFN-gamma-induced MHC gene expression in 143 B cells, a human osteosarcoma-derived cell line. Herein the authors demonstrate that alterations in the cytoskeleton induced by DHCB and CD can lead to increases in IFN-gamma-induced MHC gene expression. Dihydrocytochalasin B added up to 3 hours after IFN-gamma results in a threefold to sixfold increase in levels of class II mRNA while producing minimal enhancement of class I gene expression. In contrast, glyceraldehyde-3-phosphate dehydrogenase mRNA expression was unaltered by IFN-gamma or by the cytochalasins. The increased amount of class II mRNA can be accounted for by a concomitant increase in transcription rate of this gene. Studies using 125I-IFN-gamma demonstrate that the occupied IFN-gamma receptor associates with a Triton X-100 insoluble fraction of 143 B cells and that DHCB and CD markedly inhibit this association. The results described here provide evidence that is consistent with the hypothesis that the activity of the occupied IFN-gamma receptor may be modulated by interactions with the cytoskeleton of the cell. This receptor may be one of a group of plasma membrane receptors that are sensitive to the action of cytochalasins after ligand binding. Images Figure 1 Figure 2 PMID:1907805

  7. MHC class I molecules are enriched in caveolae but do not enter with simian virus 40.

    PubMed

    Anderson, H A; Chen, Y; Norkin, L C

    1998-06-01

    Simian virus 40 (SV40) binds to MHC class I molecules anywhere on the cell surface and then enters through caveolae. The fate of class I molecules after SV40 binding is not known. Sensitivity of 125I-surface-labelled class I molecules to papain cleavage was used to distinguish internalized class I molecules from class I molecules remaining at the cell surface. Whereas the caveolae-enriched membrane microdomain was found to also be enriched for class I molecules, no internalized papain-resistant 125I-surface-labelled class I molecules could be detected at any time in either control cells or in cells preadsorbed with saturating amounts of SV40. Instead, 125I-surface-labelled class I molecules, as well as preadsorbed 125I-labelled anti-class I antibodies, accumulated in the medium, coincident with the turnover of class I molecules at the cell surface. The class I heavy chains that accumulated in the medium were truncated and their release was specifically prevented by the metalloprotease inhibitor 1,10-phenanthroline. Thus, whereas class I molecules mediate SV40 binding, they do not appear to mediate SV40 entry.

  8. The opossum MHC genomic region revisited.

    PubMed

    Krasnec, Katina V; Sharp, Alana R; Williams, Tracey L; Miller, Robert D

    2015-04-01

    The gray short-tailed opossum Monodelphis domestica is one of the few marsupial species for which a high quality whole genome sequence is available and the major histocompatibility complex (MHC) region has been annotated. Previous analyses revealed only a single locus within the opossum MHC region, designated Modo-UA1, with the features expected for encoding a functionally classical class I α-chain. Nine other class I genes found within the MHC are highly divergent and have features usually associated with non-classical roles. The original annotation, however, was based on an early version of the opossum genome assembly. More recent analyses of allelic variation in individual opossums revealed too many Modo-UA1 sequences per individual to be accounted for by a single MHC class I locus found in the genome assembly. A reanalysis of a later generation assembly, MonDom5, revealed the presence of two additional loci, now designated Modo-UA3 and UA4, in a region that was expanded and more complete than in the earlier assembly. Modo-UA1, UA3, and UA4 are all transcribed, although Modo-UA4 transcripts are rarer. Modo-UA4 is also relatively non-polymorphic. Evidence presented support the accuracy of the later assembly and the existence of three related class I genes in the opossum, making opossums more typical of mammals and most tetrapods by having multiple apparent classical MHC class I loci.

  9. HLA-DM induces CLIP dissociation from MHC class II alpha beta dimers and facilitates peptide loading.

    PubMed

    Denzin, L K; Cresswell, P

    1995-07-14

    Human leukocyte antigen DM (HLA-DM) molecules are structurally related to classical MHC class II molecules and reside in the lysosome-like compartment where class II-restricted antigen processing is thought to occur. Mutant cell lines lacking HLA-DM are defective in antigen processing and accumulate class II molecules associated with a nested set of invariant chain-derived peptides (class II-associated invariant chain peptides, CLIP). Here we show that HLA-DM catalyzes the dissociation of CLIP from MHC class II-CLIP complexes in vitro and facilitates the binding of antigenic peptides. The reaction has an acidic pH optimum, consistent with its occurrence in a lysosome-like compartment in vivo. Antibody blocking experiments suggest that a transient interaction between HLA-DM and the MHC class II-CLIP complex is required.

  10. MHC class II-associated proteins in B-cell exosomes and potential functional implications for exosome biogenesis.

    PubMed

    Buschow, Sonja I; van Balkom, Bas W M; Aalberts, Marian; Heck, Albert J R; Wauben, Marca; Stoorvogel, Willem

    2010-01-01

    Professional antigen-presenting cells secrete major histocompatibility complex class II (MHC II) carrying exosomes with unclear physiological function(s). Exosomes are first generated as the intraluminal vesicles (ILVs) of a specific type of multivesicular body, and are then secreted by fusion of this compartment with the plasma membrane. We have previously shown that in contrast to the sorting of MHC II at lysosomally targeted multivesicular bodies, sorting of MHC II into exosomes does not rely on MHC II ubiquitination. In search for proteins that drive the incorporation of MHC II into exosomes or functionally discriminate exosomal from plasma membrane MHC II, we first analyzed the total proteome of highly purified B cell-derived exosomes using sensitive and accurate mass spectrometry (MS), and identified 539 proteins, including known and not previously identified constituents. Using quantitative MS, we then identified a small subset of proteins that were specifically co-immunoprecipitated with MHC II from detergent-solubilized exosomes. These include HSC71, HSP90, 14-3-3ɛ, CD20 and pyruvate kinase type M2 (PKM2), and we speculate on the functionality of their interaction with exosomal MHC II.

  11. The comings and goings of MHC class I molecules herald a new dawn in cross-presentation.

    PubMed

    Blander, J Magarian

    2016-07-01

    MHC class I (MHC-I) molecules are the centerpieces of cross-presentation. They are loaded with peptides derived from exogenous sources and displayed on the plasma membrane to communicate with CD8 T cells, relaying a message of tolerance or attack. The study of cross-presentation has been focused on the relative contributions of the vacuolar versus cytosolic pathways of antigen processing and the location where MHC-I molecules are loaded. While vacuolar processing generates peptides loaded onto vacuolar MHC-I molecules, how and where exogenous peptides generated by the proteasome and transported by TAP meet MHC-I molecules for loading has been a matter of debate. The source and trafficking of MHC-I molecules in dendritic cells have largely been ignored under the expectation that these molecules came from the Endoplasmic reticulum (ER) or the plasma membrane. New studies reveal a concentrated pool of MHC-I molecules in the endocytic recycling compartment (ERC). These pools are rapidly mobilized to phagosomes carrying microbial antigens, and in a signal-dependent manner under the control of Toll-like receptors. The phagosome becomes a dynamic hub receiving traffic from multiple sources, the ER-Golgi intermediate compartment for delivering the peptide-loading machinery and the ERC for deploying MHC-I molecules that alert CD8 T cells of infection.

  12. Structural and phylogenetic analysis of the MHC class I-like Fc receptor gene

    SciTech Connect

    Kandil, Eman; Ishibashi, Teruo; Kasahara, Masanori

    1995-06-01

    The intestinal epithelium of neonatal mice and rats expresses an Fc receptor that mediates selective uptake of IgG in mothers`milk. This receptor (FcRn), which helps newborn animals to acquire passive immunity, is an MHC class I-like heterodimer made up of a heavy chain and {beta}{sub 2}-microglobulin. In the present study, we determined the genomic structure of a mouse gene (FcRn) encoding the heavy of FcRn. The overall exon-intron organization of the Fcrn gene was similar to that of the Fcrn gene, thus providing structural evidence that Fcrn os a bona fide class I gene. The 5{prime}-flanking region of the Fcrn gene contained the binding motifs for two cytokine-inducible transcription factors, NF-IL6 and NF1. However, regulatory elements found in MHC class I genes (enhancer A, enhancer B, and the IFN response element) were absent. Phylogenetic tree analysis suggested that, like the MICA, AZGP1, and CD1 genes, the Fcrn gene diverged form MHC class I genes after the emergence of amphibians but before the split of placental and marsupial mammals. Consistent with this result, Southern blot analysis with a mouse Fcrn cDNA probe detected cross-hybridizing bands in various mammalian species and chickens. Sequence analysis of the Fcrn gene isolated from eight mouse strains showed that the membrane-distal domain of FcRn has at least three amino acid variants. The fact that Fcrn is a single copy gene indicates that it is expressed in both the neonatal intestine and the fetal yolk sac. 74 refs., 7 figs., 2 tabs.

  13. MHC class I-deficient metastatic tumor variants immunoselected by T lymphocytes originate from the coordinated downregulation of APM components.

    PubMed

    Garcia-Lora, Angel; Martinez, Marisol; Algarra, Ignacio; Gaforio, Jose Juan; Garrido, Federico

    2003-09-10

    Previous reports from our group indicated that the MHC class I phenotype of metastatic lung colonies produced by a mouse fibrosarcoma tumor clone (B9) were, depending on the immune status of the host, MHC class I negative in immunocompetent mice and MHC class I positive in immunodeficient athymic nude/nude mice. Now we report the identification of the molecular alterations responsible for the changes of MHC class I molecules in both situations. Metastatic nodes were analyzed for the mRNA level of H-2 class I and beta2-microglobulin genes, and several gene components of the major histocompatibility complex (MHC) class I antigen-processing machinery (APM). These included the genes coding for the low-molecular-weight proteins LMP2, LMP7, LMP10, the transporter associated with antigen processing (TAP-1, TAP-2), and calnexin, calreticulin, tapasin, PA-28-alpha, PA-28-beta, ERP-59 and ER-60. Analyses with RT-PCR showed that TAP-1, TAP2, LMP-2, LMP7, LMP10, tapasin and calnexin mRNA specific for these genes was absent in metastases produced in immunocompetent mice. In contrast, similar techniques with mRNA preparations obtained from metastatic nodes from immunodeficient mice showed that the mRNA expression level of these genes was highly positive. Interestingly, the MHC class I-positive or negative phenotypes of the metastatic colonies correlated with in vivo immunogenicity. H-2 positive metastasis grew more slowly than the H-2 negative ones when injected intrafootpat in syngeneic immunocompetent animals and were finally rejected. These results provide evidence of the role of T cells in immune surveillance against tumors and identify a mechanism targeted by antitumor T lymphocytes to generate MHC class I-negative tumor escape variants.

  14. MHC class II up-regulation and co-localization with Fas in experimental models of immune-mediated bone marrow failure

    PubMed Central

    Erie, Andrew J.; Samsel, Leigh; Takaku, Tomoiku; Desierto, Marie J.; Keyvanfar, Keyvan; McCoy, J. Philip; Young, Neal S.; Chen, Jichun

    2011-01-01

    Objective To test the hypothesis that gamma interferon (IFN-γ) promotes MHC class II expression on bone marrow (BM) cell targets that facilitates T cell-mediated BM destruction in immune-mediated BM failure. Materials and Methods Allogeneic lymph node (LN) cells were infused into MHC or minor histocompatibility antigen (minor-H) mismatched hosts to induce BM failure. MHC class II and Fas expression and cell apoptosis were analyzed by flow cytometry. MHC class II-Fas co-localization was detected by ImageStream Imaging Flow Cytometry and other cell-cell associations were visualized by confocal microscopy. T cell-mediated BM cell apoptosis and effects of IFN-γ on MHC class II-Fas co-localization on normal BM cells were studied using cell culture in vitro followed by conventional and imaging flow cytometry. Results BM failure animals had significantly up-regulated MHC class II expression on CD4−CD8−CD11b−CD45R− residual BM cells and significantly increased MHC class II-Fas co-localization on BM CD150+ and CD34+ hematopoietic cells. MHC class II+Fas+ BM cells were closely associated with CD4+ T cells in the BM of affected animals, and they were significantly more responsive to T-cell mediated cell apoptosis relative to MHC class II−Fas− BM cells. Infusion of IFN-γ-deficient LN cells into minor-H mismatched recipients resulted in no MHC class II-Fas up-regulation and no clinically overt BM failure. Treatment with recombinant IFN-γ significantly increased both MHC class II-Fas co-expression and co-localization on normal BM cells. Conclusion Elevation of the inflammatory cytokine IFN-γ stimulated MHC class II expression and MHC class II-Fas co-localization, which may facilitate T-cell mediated cell destruction. PMID:21635935

  15. Low MHC class II diversity in the Tasmanian devil (Sarcophilus harrisii).

    PubMed

    Cheng, Yuanyuan; Sanderson, Claire; Jones, Menna; Belov, Katherine

    2012-07-01

    The largest remaining carnivorous marsupial, the Tasmanian devil (Sarcophilus harrisii), is currently under threat of extinction due to a fatal contagious cancer-devil facial tumour disease. Low major histocompatibility complex (MHC) class I diversity is believed to have contributed to the transmission of the tumour allograft through devil populations. Here, we report low MHC class II variability in this species, with DA β chain genes (Saha-DAB1, 2 and 3) exhibiting very limited diversity and the sole α chain gene (Saha-DAA) monomorphic. Three, six and three alleles were found at Saha-DAB1, 2 and 3, respectively, with a predominant allele found at each locus. Heterozygosity at these three loci is low in the eastern population and modestly higher in northwestern individuals. The results are indicative of a selective sweep likely due to an infectious disease resulting in the fixation of selectively favoured alleles and depletion of genetic diversity at devil class II loci. Several attempts were made to isolate the other marsupial classical class II gene family, namely, DB, resulting in only one DBB pseudogene being found. These findings further support the view that this species has a compromised capacity to respond to pathogen evolution, emerging infectious diseases and environmental changes.

  16. Recognition of core and flanking amino acids of MHC class II-bound peptides by the T cell receptor.

    PubMed

    Sant'Angelo, Derek B; Robinson, Eve; Janeway, Charles A; Denzin, Lisa K

    2002-09-01

    CD4 T cells recognize peptides bound to major histocompatibility complex (MHC) class II molecules. Most MHC class II molecules have four binding pockets occupied by amino acids 1, 4, 6, and 9 of the minimal peptide epitope, while the residues at positions 2, 3, 5, 7, and 8 are available to interact with the T cell receptor (TCR). In addition MHC class II bound peptides have flanking residues situated outside of this peptide core. Here we demonstrate that the flanking residues of the conalbumin peptide bound to I-A(k) have no effect on recognition by the D10 TCR. To study the role of peptide flanks for recognition by a second TCR, we determined the MHC and TCR contacting amino acids of the I-A(b) bound Ealpha peptide. The Ealpha peptide is shown to bind I-A(b) using four alanines as anchor residues. TCR recognition of Ealpha peptides with altered flanking residues again suggested that, in general, no specific interactions occurred with the peptide flanks. However, using an HLA-DM-mediated technique to measure peptide binding to MHC class II molecules, we found that the peptide flanking residues contribute substantially to MHC binding.

  17. Dendritic cell preactivation impairs MHC class II presentation of vaccines and endogenous viral antigens

    PubMed Central

    Young, Louise J.; Wilson, Nicholas S.; Schnorrer, Petra; Mount, Adele; Lundie, Rachel J.; La Gruta, Nicole L.; Crabb, Brendan S.; Belz, Gabrielle T.; Heath, William R.; Villadangos, Jose A.

    2007-01-01

    When dendritic cells (DCs) encounter signals associated with infection or inflammation, they become activated and undergo maturation. Mature DCs are very efficient at presenting antigens captured in association with their activating signal but fail to present subsequently encountered antigens, at least in vitro. Such impairment of MHC class II (MHC II) antigen presentation has generally been thought to be a consequence of down-regulation of endocytosis, so it might be expected that antigens synthesized by the DCs themselves (for instance, viral antigens) would still be presented by mature DCs. Here, we show that DCs matured in vivo could still capture and process soluble antigens, but were unable to present peptides derived from these antigens. Furthermore, presentation of viral antigens synthesized by the DCs themselves was also severely impaired. Indeed, i.v. injection of pathogen mimics, which caused systemic DC activation in vivo, impaired the induction of CD4 T cell responses against subsequently encountered protein antigens. This immunosuppressed state could be reversed by adoptive transfer of DCs loaded exogenously with antigens, demonstrating that impairment of CD4 T cell responses was due to lack of antigen presentation rather than to overt suppression of T cell activation. The biochemical mechanism underlying this phenomenon was the down-regulation of MHC II–peptide complex formation that accompanied DC maturation. These observations have important implications for the design of prophylactic and therapeutic DC vaccines and contribute to the understanding of the mechanisms causing immunosuppression during systemic blood infections. PMID:17978177

  18. Bap31 enhances the endoplasmic reticulum export and quality control of human class I MHC molecules.

    PubMed

    Ladasky, John J; Boyle, Sarah; Seth, Malini; Li, Hewang; Pentcheva, Tsvetelina; Abe, Fumiyoshi; Steinberg, Steven J; Edidin, Michael

    2006-11-01

    The assembly of class I MHC molecules and their export from the endoplasmic reticulum (ER) is governed by chaperones and accessory proteins. We present evidence that the putative cargo receptor protein Bap31 participates in the transport and the quality control of human class I molecules. Transfection of the human adenocarcinoma cell line HeLa with yellow fluorescent protein-Bap31 chimeras increased surface levels of class I in a dose-dependent manner, by as much as 3.7-fold. The increase in surface class I resulted from an increase in the rate of export of newly synthesized class I molecules to the cell surface and from an increase in the stability of the exported molecules. We propose that Bap31 performs quality control on class I molecules in two distinct phases: first, by exporting peptide-loaded class I molecules to the ER/Golgi intermediate compartment, and second, by retrieving class I molecules that have lost peptides in the acidic post-ER environment. This function of Bap31 is conditional or redundant, because we find that Bap31 deficiency does not reduce surface class I levels. Overexpression of the Bap31 homolog, Bap29, decreases surface class levels in HeLa, indicating that it does not substitute for Bap31.

  19. How did variable NK-cell receptors and MHC class I ligands influence immunity, reproduction and human evolution?

    PubMed Central

    Parham, Peter; Moffett, Ashley

    2014-01-01

    Preface Natural killer (NK) cells have roles in immunity and reproduction that are controlled by variable receptors that recognize MHC class I molecules. The variable NK cell receptors found in humans are specific to simian primates, where they have progressively co-evolved with MHC class I molecules. The emergence of MHC-C in hominids drove the evolution of a system of MHC-C receptors that is most elaborate in chimpanzees. In contrast, the human system appears to have been subject to different and competing selection pressures that have acted on its immunological and reproductive functions. We suggest that this compromise facilitated development of the bigger brains that enabled archaic and modern humans to migrate out-of-Africa and populate other continents. PMID:23334245

  20. The common marmoset: A new world primate species with limited Mhc class II variability

    PubMed Central

    Antunes, Susana G.; de Groot, Natasja G.; Brok, Herbert; Doxiadis, Gaby; Menezes, Alexandre A. L.; Otting, Nel; Bontrop, Ronald E.

    1998-01-01

    The common marmoset (Callithrix jacchus) is a New World primate species that is highly susceptible to fatal infections caused by various strains of bacteria. We present here a first step in the molecular characterization of the common marmoset’s Mhc class II genes by nucleotide sequence analysis of the polymorphic exon 2 segments. For this study, genetic material was obtained from animals bred in captivity as well as in the wild. The results demonstrate that the common marmoset has, like other primates, apparently functional Mhc-DR and -DQ regions, but the Mhc-DP region has been inactivated. At the -DR and -DQ loci, only a limited number of lineages were detected. On the basis of the number of alleles found, the -DQA and -B loci appear to be oligomorphic, whereas only a moderate degree of polymorphism was observed for two of three Mhc-DRB loci. The contact residues in the peptide-binding site of the Caja-DRB1*03 lineage members are highly conserved, whereas the -DRB*W16 lineage members show more divergence in that respect. The latter locus encodes five oligomorphic lineages whose members are not observed in any other primate species studied, suggesting rapid evolution, as illustrated by frequent exchange of polymorphic motifs. All common marmosets tested were found to share one monomorphic type of Caja-DRB*W12 allele probably encoded by a separate locus. Common marmosets apparently lack haplotype polymorphism because the number of Caja-DRB loci present per haplotype appears to be constant. Despite this, however, an unexpectedly high number of allelic combinations are observed at the haplotypic level, suggesting that Caja-DRB alleles are exchanged frequently between chromosomes by recombination, promoting an optimal distribution of limited Mhc polymorphisms among individuals of a given population. This peculiar genetic make up, in combination with the limited variability of the major histocompatability complex class II repertoire, may contribute to the common

  1. Insight into the primordial MHC from studies in ectothermic vertebrates.

    PubMed

    Flajnik, M F; Ohta, Y; Namikawa-Yamada, C; Nonaka, M

    1999-02-01

    MHC classical class I and class II genes have been identified in representative species from all major jawed vertebrate taxa, the oldest group being the cartilaginous fish, whereas no class I/II genes of any type have been detected in animals from older taxa. Among ectothermic vertebrate classes, studies of MHC architecture have been done in cartilaginous fish (sharks), bony fish (several teleost species), and amphibians (the frog Xenopus). The Xenopus MHC contains class I, class II, and class III genes, demonstrating that all of these genes were linked in the ancestor of the tetrapods, but the gene order is not the same as that in mouse/man. Studies of polyploid Xenopus suggest that MHC genes can be differentially silenced when multiple copies are present; i.e. MHC 'subregions' can be silenced. Surprisingly, in all teleosts examined to date class I and class II genes are not linked. Likewise, class III genes like the complement genes factor B (Bf) and C4 are scattered throughout the genome of teleosts. However, the presumed classical class I genes are closely linked to the 'immune' proteasome genes, LMP2 and LMP7, and to the peptide-transporter genes (TAP), implying that a true 'class I region' exists in this group. A similar type of linkage group is found in chickens and perhaps Xenopus, and thus it may reveal the ancestral organization of class I-associated genes. In cartilaginous fish, classical and non-classical class I genes have been isolated from three shark species, and class II A and B chain genes from nurse sharks. Studies of MHC linkage in sharks are being carried out to provide further understanding of the putative primordial organization of MHC Segregation studies in one shark family point to linkage of classical class I and class II genes, suggesting that the non-linkage of these genes in teleosts is a derived characteristic.

  2. Translating DRiPs: MHC class I immunosurveillance of pathogens and tumors

    PubMed Central

    Antón, Luis C.; Yewdell, Jonathan W.

    2014-01-01

    MHC class I molecules display oligopeptides on the cell surface to enable T cell immunosurveillance of intracellular pathogens and tumors. Speed is of the essence in detecting viruses, which can complete a full replication cycle in just hours, whereas tumor detection is typically a finding-the-needle-in-the-haystack exercise. We review current evidence supporting a nonrandom, compartmentalized selection of peptidogenic substrates that focuses on rapidly degraded translation products as a main source of peptide precursors to optimize immunosurveillance of pathogens and tumors. PMID:24532645

  3. Selection, diversity and evolutionary patterns of the MHC class II DAB in free-ranging Neotropical marsupials

    PubMed Central

    Meyer-Lucht, Yvonne; Otten, Celine; Püttker, Thomas; Sommer, Simone

    2008-01-01

    Background Research on the genetic architecture and diversity of the MHC has focused mainly on eutherian mammals, birds and fish. So far, studies on model marsupials used in laboratory investigations indicated very little or even no variation in MHC class II genes. However, natural levels of diversity and selection are unknown in marsupials as studies on wild populations are virtually absent. We used two endemic South American mouse opossums, Gracilinanus microtarsus and Marmosops incanus, to investigate characteristic features of MHC selection. This study is the first investigation of MHC selection in free-ranging Neotropical marsupials. In addition, the evolutionary history of MHC lineages within the group of marsupials was examined. Results G. microtarsus showed extensive levels of MHC diversity within and among individuals as 47 MHC-DAB alleles and high levels of sequence divergence were detected at a minimum of four loci. Positively selected codon sites were identified, of which most were congruent with human antigen binding sites. The diversity in M. incanus was rather low with only eight observed alleles at presumably two loci. However, these alleles also revealed high sequence divergence. Again, positive selection was identified on specific codon sites, all congruent with human ABS and with positively selected sites observed in G. microtarsus. In a phylogenetic comparison alleles of M. incanus interspersed widely within alleles of G. microtarsus with four alleles being present in both species. Conclusion Our investigations revealed extensive MHC class II polymorphism in a natural marsupial population, contrary to previous assumptions. Furthermore, our study confirms for the first time in marsupials the presence of three characteristic features common at MHC loci of eutherian mammals, birds and fish: large allelic sequence divergence, positive selection on specific sites and trans-specific polymorphism. PMID:18534008

  4. Mapping and characterization of non-HLA multigene assemblages in the human MHC class I region

    SciTech Connect

    Venditti, C.P.; Harris, J.M.; Geraghty, D.E.

    1994-07-15

    The major histocompatibility complex (MHC) class I region has been shown to be associated with a variety of immune and nonimmune disorders. In an effort to initiate steps designed to identify the idiopathic hemochromatosis disease gene (HFE), the authors have cloned and mapped two expressed messages using probes from the HLA-H subregion that lie immediately distal to the HLA-A9 breakpoint. Although the cDNA clones identify distinct multifragment families that are dispersed throughout the MHC, the gene sequences from which the two cDNA clones derive map centromeric to the HLA-B locus and are absent from the genomes of higher nonhuman primates. This suggests that a syntenic coding segment arose within a highly polymorphic region (TNF to HLA-B interval) as the result of an insertion event following the emergence of Homo sapiens. An additional syntenic cluster exists within a peak of linkage disequilibrium with the HFE gene and may define coding sequences that underlie the defect in genetic iron overload. These data generally support the concept that the class I region is potentially gene-rich and further highlight the possibility that these new coding sequences may play a role in the development of a variety of HLA-linked diseases. The observations presented suggest that interlocus exchanges have played a structural role in the genesis of the human class I region. 46 refs., 6 refs.

  5. Localization of type 1 diabetes susceptibility to the MHC class I genes HLA-B and HLA-A

    PubMed Central

    Nejentsev, Sergey; Howson, Joanna M. M.; Walker, Neil M.; Szeszko, Jeffrey; Field, Sarah F.; Stevens, Helen E.; Reynolds, Pamela; Hardy, Matthew; King, Erna; Masters, Jennifer; Hulme, John; Maier, Lisa M.; Smyth, Deborah; Bailey, Rebecca; Cooper, Jason D.; Ribas, Gloria; Campbell, R. Duncan; Clayton, David G.; Todd, John A.

    2009-01-01

    The major histocompatibility complex (MHC) on chromosome 6 is associated with susceptibility to more common diseases than any other region of the human genome, including almost all disorders classified as autoimmune. In type 1 diabetes the major genetic susceptibility determinants have been mapped to the MHC class II genes HLA-DQB1 and HLA-DRB1 (refs 1-3), but these genes cannot completely explain the association between type 1 diabetes and the MHC region4-11. Owing to the region’s extreme gene density, the multiplicity of disease-associated alleles, strong associations between alleles, limited genotyping capability, and inadequate statistical approaches and sample sizes, which, and how many, loci within the MHC determine susceptibility remains unclear. Here, in several large type 1 diabetes data sets, we analyse a combined total of 1,729 polymorphisms, and apply statistical methods—recursive partitioning and regression—to pinpoint disease susceptibility to the MHC class I genes HLA-B and HLA-A (risk ratios>1.5; Pcombined=2.01×10-19 and 2.35×10-13, respectively) in addition to the established associations of the MHC class II genes. Other loci with smaller and/or rarer effects might also be involved, but to find these, future searches must take into account both the HLA class II and class I genes and use even larger samples. Taken together with previous studies4-8,10-16, we conclude that MHC-class-I-mediated events, principally involving HLA-B*39, contribute to the aetiology of type 1 diabetes. PMID:18004301

  6. MHC class II tetramers made from isolated recombinant α and β chains refolded with affinity-tagged peptides.

    PubMed

    Braendstrup, Peter; Justesen, Sune; Osterbye, Thomas; Nielsen, Lise Lotte Bruun; Mallone, Roberto; Vindeløv, Lars; Stryhn, Anette; Buus, Søren

    2013-01-01

    Targeting CD4+ T cells through their unique antigen-specific, MHC class II-restricted T cell receptor makes MHC class II tetramers an attractive strategy to identify, validate and manipulate these cells at the single cell level. Currently, generating class II tetramers is a specialized undertaking effectively limiting their use and emphasizing the need for improved methods of production. Using class II chains expressed individually in E. coli as versatile recombinant reagents, we have previously generated peptide-MHC class II monomers, but failed to generate functional class II tetramers. Adding a monomer purification principle based upon affinity-tagged peptides, we here provide a robust method to produce class II tetramers and demonstrate staining of antigen-specific CD4+ T cells. We also provide evidence that both MHC class II and T cell receptor molecules largely accept affinity-tagged peptides. As a general approach to class II tetramer generation, this method should support rational CD4+ T cell epitope discovery as well as enable specific monitoring and manipulation of CD4+ T cell responses.

  7. Population Based Assessment of MHC Class I Antigens Down Regulation as Markers of Increased Risk for Development and Progression of Breast Cancer from Benign Breast Lesions

    DTIC Science & Technology

    2007-01-01

    Manuscript attached: Appendix A- 2 C: EXPRESSION OF MHC CLASS I AND II EXPRESSION SIGNIFICANTLY DISCRIMINATES AMONG BENIGN, CARCINOMA IN SITU, AND...Tumor aggressiveness and MHC class I and II antigens in laryngeal and breast cancer. Semin Cancer Biol. 2 :47-54; 1991. 5. Sawtell, NM., DiPersio, L... 2 , 3). In breast lesions examined for expression of MHC class I, approximately half (51%) of carcinomas had an abnormally low content of HLA-A, -B

  8. A comparison of the antigen-presenting capabilities of class II MHC-expressing human lung epithelial and endothelial cells.

    PubMed Central

    Cunningham, A C; Zhang, J G; Moy, J V; Ali, S; Kirby, J A

    1997-01-01

    Human lung alveolar epithelial cells constitutively express class II major histocompatibility complex (MHC). Human lung microvascular endothelial and small airway epithelial cells can be induced to express class II MHC by stimulation with the pro-inflammatory cytokine interferon-gamma. The levels of class II MHC on lung epithelial and endothelial cells were comparable to those seen on an Epstein-Barr virus (EBV)-transformed B-cell line. However, the costimulatory molecules B7-1 and B7-2 were not expressed. The ability of the class II MHC expressing human lung parenchymal cells to present alloantigen to CD4+ T lymphocytes was investigated. Freshly isolated human alveolar epithelial cells (type II pneumocytes) and monolayers of interferon-gamma-stimulated small airway epithelial and lung microvascular endothelial cells were co-cultured with allogeneic CD4+ T lymphocytes and proliferation determined by [3H]thymidine incorporation. A clear difference was observed between effects of the epithelial and endothelial cells on CD4+ T-lymphocyte activation. Alveolar and small airway epithelial cells failed to stimulate the proliferation of allogeneic CD4+ T lymphocytes whereas lung microvascular endothelial cells did stimulate proliferation. This difference could not be explained by the levels of class II MHC or the lack of B7-1 and B7-2 solely. Microvascular endothelial cells, and not alveolar or small airway epithelial cells, possess B7-independent costimulatory pathways. PMID:9301537

  9. pRB is required for interferon-gamma-induction of the MHC class II abeta gene.

    PubMed

    Zhu, X; Pattenden, S; Bremner, R

    1999-09-02

    pRB is required for IFN-gamma-induction of MHC class II in human tumor cell lines, providing a potential link between tumor suppressors and the immune system. However, other genes, such as cyclin D1, show pRB-dependency only in tumor cells, so by analogy, pRB may not be necessary for cII-regulation in normal cells. Here, we demonstrate that induction of the mouse MHC class II I-A heterodimer is normal in RB+/+ mouse embryonic fibroblasts (MEFs), but deficient in RB-/- MEFs. Inducibility is restored in RB-/- MEFs stably transfected with wild type RB cDNA or infected with an adenovirus expressing pRB. Thus, involvement of pRB in MHC class II expression is conserved in the mouse and is not an aberrant feature of tumorigenic, aneuploid, human tumor cells. Although cII genes are generally induced in a coordinate fashion, suggesting a common mechanism, we found that pRB was specifically required for induction of the Abeta, but not Aalpha or other MHC cII genes including Ebeta, Ii and H2-Malpha. Finally, IFN-gamma-induction of class II transactivator (CIITA), was pRB-independent, suggesting that pRB works downstream of this master-regulator of MHC class II expression.

  10. Interaction of Bap31 and MHC class I molecules and their traffic out of the endoplasmic reticulum.

    PubMed

    Abe, Fumiyoshi; Van Prooyen, Nancy; Ladasky, John J; Edidin, Michael

    2009-04-15

    The endoplasmic reticulum (ER) protein Bap31 associates with nascent class I MHC molecules. It appears to mediate the export of class I MHC molecules from the ER and may also be involved in their quality control. In this study, we use Förster resonance energy transfer and quantitative fluorescence imaging to show that in human, HeLa cells, Bap31 clusters with MHC class I (HLA-A2) molecules in the ER, and traffics via export vesicles to the ER/Golgi intermediate compartment. Förster resonance energy transfer between Bap31 and HLA-A2 and forward traffic increases when MHC class I molecules are loaded with a pulse of peptide. The increased forward traffic is blocked by overexpression of Bap29, a partner protein for Bap31, which localizes to the ER. Thus, in HeLa cells, Bap31 is involved in the exit of peptide-loaded MHC class I from the ER, and its function is regulated by its interaction with its homologue, Bap29.

  11. Diverse repertoire of the MHC class II-peptide complexes is required for presentation of viral superantigens.

    PubMed

    Golovkina, T; Agafonova, Y; Kazansky, D; Chervonsky, A

    2001-02-15

    Among other features, peptides affect MHC class II molecules, causing changes in the binding of bacterial superantigens (b-Sag). Whether peptides can alter binding of viral superantigens (v-Sag) to MHC class II was not known. Here we addressed the question of whether mutations limiting the diversity of peptides bound by the MHC class II molecules influenced the presentation of v-Sag and, subsequently, the life cycle of the mouse mammary tumor virus (MMTV). T cells reactive to v-Sag were found in mice lacking DM molecules as well as in A(b)Ep-transgenic mice in which MHC class II binding grooves were predominantly occupied by an invariant chain fragment or Ealpha(52-68) peptide, respectively. APCs from the mutant mice failed to present v-Sag, as determined by the lack of Sag-specific T cell activation, Sag-induced T cell deletion, and by the aborted MMTV infection. In contrast, mice that express I-A(b) with a variety of bound peptides presented v-Sag and were susceptible to MMTV infection. Comparison of v-Sag and b-Sag presentation by the same mutant cells suggested that presentation of v-Sag had requirements similar to that for presentation of toxic shock syndrome toxin-1. Thus, MHC class II peptide repertoire is critical for recognition of v-Sag by the T cells and affects the outcome of infection with a retrovirus.

  12. Prediction of MHC class II binding affinity using SMM-align, a novel stabilization matrix alignment method

    PubMed Central

    Nielsen, Morten; Lundegaard, Claus; Lund, Ole

    2007-01-01

    Background Antigen presenting cells (APCs) sample the extra cellular space and present peptides from here to T helper cells, which can be activated if the peptides are of foreign origin. The peptides are presented on the surface of the cells in complex with major histocompatibility class II (MHC II) molecules. Identification of peptides that bind MHC II molecules is thus a key step in rational vaccine design and developing methods for accurate prediction of the peptide:MHC interactions play a central role in epitope discovery. The MHC class II binding groove is open at both ends making the correct alignment of a peptide in the binding groove a crucial part of identifying the core of an MHC class II binding motif. Here, we present a novel stabilization matrix alignment method, SMM-align, that allows for direct prediction of peptide:MHC binding affinities. The predictive performance of the method is validated on a large MHC class II benchmark data set covering 14 HLA-DR (human MHC) and three mouse H2-IA alleles. Results The predictive performance of the SMM-align method was demonstrated to be superior to that of the Gibbs sampler, TEPITOPE, SVRMHC, and MHCpred methods. Cross validation between peptide data set obtained from different sources demonstrated that direct incorporation of peptide length potentially results in over-fitting of the binding prediction method. Focusing on amino terminal peptide flanking residues (PFR), we demonstrate a consistent gain in predictive performance by favoring binding registers with a minimum PFR length of two amino acids. Visualizing the binding motif as obtained by the SMM-align and TEPITOPE methods highlights a series of fundamental discrepancies between the two predicted motifs. For the DRB1*1302 allele for instance, the TEPITOPE method favors basic amino acids at most anchor positions, whereas the SMM-align method identifies a preference for hydrophobic or neutral amino acids at the anchors. Conclusion The SMM-align method was

  13. MHC class I–associated peptides derive from selective regions of the human genome

    PubMed Central

    Pearson, Hillary; Granados, Diana Paola; Durette, Chantal; Bonneil, Eric; Courcelles, Mathieu; Rodenbrock, Anja; Laverdure, Jean-Philippe; Côté, Caroline; Thibault, Pierre

    2016-01-01

    MHC class I–associated peptides (MAPs) define the immune self for CD8+ T lymphocytes and are key targets of cancer immunosurveillance. Here, the goals of our work were to determine whether the entire set of protein-coding genes could generate MAPs and whether specific features influence the ability of discrete genes to generate MAPs. Using proteogenomics, we have identified 25,270 MAPs isolated from the B lymphocytes of 18 individuals who collectively expressed 27 high-frequency HLA-A,B allotypes. The entire MAP repertoire presented by these 27 allotypes covered only 10% of the exomic sequences expressed in B lymphocytes. Indeed, 41% of expressed protein-coding genes generated no MAPs, while 59% of genes generated up to 64 MAPs, often derived from adjacent regions and presented by different allotypes. We next identified several features of transcripts and proteins associated with efficient MAP production. From these data, we built a logistic regression model that predicts with good accuracy whether a gene generates MAPs. Our results show preferential selection of MAPs from a limited repertoire of proteins with distinctive features. The notion that the MHC class I immunopeptidome presents only a small fraction of the protein-coding genome for monitoring by the immune system has profound implications in autoimmunity and cancer immunology. PMID:27841757

  14. Oxidation matters: the ubiquitin proteasome system connects innate immune mechanisms with MHC class I antigen presentation.

    PubMed

    Warnatsch, Annika; Bergann, Theresa; Krüger, Elke

    2013-09-01

    During innate immune responses the delicate balance of protein synthesis, quality control and degradation is severely challenged by production of radicals and/or the massive synthesis of pathogen proteins. The regulated degradation of ubiquitin-tagged proteins by the ubiquitin proteasome system (UPS) represents one major pathway for the maintenance of cellular proteostasis and regulatory processes under these conditions. In addition, MHC class I antigen presentation is strictly dependent on an appropriate peptide supply by the UPS to efficiently prime CD8(+) T cells and to initiate an adaptive immune response. We here discuss recent efforts in defining the link between innate immune mechanisms like cytokine and ROS production, the induction of an efficient adaptive immune response and the specific involvement of the UPS therein. Cytokines and/or infections induce translation and the production of free radicals, which in turn confer oxidative damage to nascent as well as folded proteins. In parallel, the same signaling cascades are able to accelerate the protein turnover by the concomitantly induced ubiquitin conjugation and degradation of such damaged polypeptides by immunoproteasomes. The ability of immunoproteasomes to efficiently degrade such oxidant-damaged ubiquitylated proteins protects cells from accumulating toxic ubiquitin-rich aggregates. At the same time, this innate immune mechanism facilitates a sufficient peptide supply for MHC class I antigen presentation and connects it to initiation of adaptive immunity.

  15. Distinct Conformations of Ly49 Natural Killer Cell Receptors Mediate MHC Class I Recognition in Trans and Cis

    SciTech Connect

    Back, J.; Malchiodi, E; Cho, S; Scarpellino, L; Schneider, P; Kerzic, M; Mariuzza, R; Held, W

    2009-01-01

    Certain cell-surface receptors engage ligands expressed on juxtaposed cells and ligands on the same cell. The structural basis for trans versus cis binding is not known. Here, we showed that Ly49 natural killer (NK) cell receptors bound two MHC class I (MHC-I) molecules in trans when the two ligand-binding domains were backfolded onto the long stalk region. In contrast, dissociation of the ligand-binding domains from the stalk and their reorientation relative to the NK cell membrane allowed monovalent binding of MHC-I in cis. The distinct conformations (backfolded and extended) define the structural basis for cis-trans binding by Ly49 receptors and explain the divergent functional consequences of cis versus trans interactions. Further analyses identified specific stalk segments that were not required for MHC-I binding in trans but were essential for inhibitory receptor function. These data identify multiple distinct roles of stalk regions for receptor function.

  16. Trans-Species Polymorphism and Selection in the MHC Class II DRA Genes of Domestic Sheep

    PubMed Central

    Ballingall, Keith T.; Rocchi, Mara S.; McKeever, Declan J.; Wright, Frank

    2010-01-01

    Highly polymorphic genes with central roles in lymphocyte mediated immune surveillance are grouped together in the major histocompatibility complex (MHC) in higher vertebrates. Generally, across vertebrate species the class II MHC DRA gene is highly conserved with only limited allelic variation. Here however, we provide evidence of trans-species polymorphism at the DRA locus in domestic sheep (Ovis aries). We describe variation at the Ovar-DRA locus that is far in excess of anything described in other vertebrate species. The divergent DRA allele (Ovar-DRA*0201) differs from the sheep reference sequences by 20 nucleotides, 12 of which appear non-synonymous. Furthermore, DRA*0201 is paired with an equally divergent DRB1 allele (Ovar-DRB1*0901), which is consistent with an independent evolutionary history for the DR sub-region within this MHC haplotype. No recombination was observed between the divergent DRA and B genes in a range of breeds and typical levels of MHC class II DR protein expression were detected at the surface of leukocyte populations obtained from animals homozygous for the DRA*0201, DRB1*0901 haplotype. Bayesian phylogenetic analysis groups Ovar-DRA*0201 with DRA sequences derived from species within the Oryx and Alcelaphus genera rather than clustering with other ovine and caprine DRA alleles. Tests for Darwinian selection identified 10 positively selected sites on the branch leading to Ovar-DRA*0201, three of which are predicted to be associated with the binding of peptide antigen. As the Ovis, Oryx and Alcelaphus genera have not shared a common ancestor for over 30 million years, the DRA*0201 and DRB1*0901 allelic pair is likely to be of ancient origin and present in the founding population from which all contemporary domestic sheep breeds are derived. The conservation of the integrity of this unusual DR allelic pair suggests some selective advantage which is likely to be associated with the presentation of pathogen antigen to T-cells and the

  17. Trans-species polymorphism and selection in the MHC class II DRA genes of domestic sheep.

    PubMed

    Ballingall, Keith T; Rocchi, Mara S; McKeever, Declan J; Wright, Frank

    2010-06-30

    Highly polymorphic genes with central roles in lymphocyte mediated immune surveillance are grouped together in the major histocompatibility complex (MHC) in higher vertebrates. Generally, across vertebrate species the class II MHC DRA gene is highly conserved with only limited allelic variation. Here however, we provide evidence of trans-species polymorphism at the DRA locus in domestic sheep (Ovis aries). We describe variation at the Ovar-DRA locus that is far in excess of anything described in other vertebrate species. The divergent DRA allele (Ovar-DRA*0201) differs from the sheep reference sequences by 20 nucleotides, 12 of which appear non-synonymous. Furthermore, DRA*0201 is paired with an equally divergent DRB1 allele (Ovar-DRB1*0901), which is consistent with an independent evolutionary history for the DR sub-region within this MHC haplotype. No recombination was observed between the divergent DRA and B genes in a range of breeds and typical levels of MHC class II DR protein expression were detected at the surface of leukocyte populations obtained from animals homozygous for the DRA*0201, DRB1*0901 haplotype. Bayesian phylogenetic analysis groups Ovar-DRA*0201 with DRA sequences derived from species within the Oryx and Alcelaphus genera rather than clustering with other ovine and caprine DRA alleles. Tests for Darwinian selection identified 10 positively selected sites on the branch leading to Ovar-DRA*0201, three of which are predicted to be associated with the binding of peptide antigen. As the Ovis, Oryx and Alcelaphus genera have not shared a common ancestor for over 30 million years, the DRA*0201 and DRB1*0901 allelic pair is likely to be of ancient origin and present in the founding population from which all contemporary domestic sheep breeds are derived. The conservation of the integrity of this unusual DR allelic pair suggests some selective advantage which is likely to be associated with the presentation of pathogen antigen to T-cells and the

  18. Genomic sequence analysis of the MHC class I G/F segment in common marmoset (Callithrix jacchus).

    PubMed

    Kono, Azumi; Brameier, Markus; Roos, Christian; Suzuki, Shingo; Shigenari, Atsuko; Kametani, Yoshie; Kitaura, Kazutaka; Matsutani, Takaji; Suzuki, Ryuji; Inoko, Hidetoshi; Walter, Lutz; Shiina, Takashi

    2014-04-01

    The common marmoset (Callithrix jacchus) is a New World monkey that is used frequently as a model for various human diseases. However, detailed knowledge about the MHC is still lacking. In this study, we sequenced and annotated a total of 854 kb of the common marmoset MHC region that corresponds to the HLA-A/G/F segment (Caja-G/F) between the Caja-G1 and RNF39 genes. The sequenced region contains 19 MHC class I genes, of which 14 are of the MHC-G (Caja-G) type, and 5 are of the MHC-F (Caja-F) type. Six putatively functional Caja-G and Caja-F genes (Caja-G1, Caja-G3, Caja-G7, Caja-G12, Caja-G13, and Caja-F4), 13 pseudogenes related either to Caja-G or Caja-F, three non-MHC genes (ZNRD1, PPPIR11, and RNF39), two miscRNA genes (ZNRD1-AS1 and HCG8), and one non-MHC pseudogene (ETF1P1) were identified. Phylogenetic analysis suggests segmental duplications of units consisting of basically five (four Caja-G and one Caja-F) MHC class I genes, with subsequent expansion/deletion of genes. A similar genomic organization of the Caja-G/F segment has not been observed in catarrhine primates, indicating that this genomic segment was formed in New World monkeys after the split of New World and Old World monkeys.

  19. Simian virus 40 infection via MHC class I molecules and caveolae.

    PubMed

    Norkin, L C

    1999-04-01

    MHC class I molecules are a necessary component of the cell surface receptor for simian virus 40 (SV40). After binding to class I molecules, SV40 enters cells via a unique endocytic pathway that involves caveolae, rather than clathrin-coated pits. This pathway is dependent on a transmembrane signal that SV40 transmits from the cell surface. Furthermore, it delivers SV40 to the endoplasmic reticulum, rather than to the endosomal/lysosomal compartment, which is the usual target for endocytic traffic. The glycosphingolipid and cholesterol-enriched plasma membrane domains that contain caveolae are also enriched for class I molecules, relative to whole plasma membrane. Nevertheless, although class I molecules bind SV40, they do not enter with SV40, nor do they enter spontaneously into uninfected SV40 host cells. Instead, they are shed from the cell surface by the activity of a metalloprotease. These results imply the existence of a putative secondary receptor for SV40 that might mediate SV40 entry. It is not yet clear whether class I molecules are active in transmitting the SV40 signal. Monoclonal antibodies against class I molecules also induce a signal in the SV40 host cells. However, the antibody-induced signal is mediated by mitogen-activated protein kinase (MAP kinase), whereas the SV40 signal is independent of MAP kinase.

  20. Extraordinary MHC class II B diversity in a non-passerine, wild bird: the Eurasian Coot Fulica atra (Aves: Rallidae)

    PubMed Central

    Alcaide, Miguel; Muñoz, Joaquin; Martínez-de la Puente, Josué; Soriguer, Ramón; Figuerola, Jordi

    2014-01-01

    The major histocompatibility complex (MHC) hosts the most polymorphic genes ever described in vertebrates. The MHC triggers the adaptive branch of the immune response, and its extraordinary variability is considered an evolutionary consequence of pathogen pressure. The last few years have witnessed the characterization of the MHC multigene family in a large diversity of bird species, unraveling important differences in its polymorphism, complexity, and evolution. Here, we characterize the first MHC class II B sequences isolated from a Rallidae species, the Eurasian Coot Fulica atra. A next-generation sequencing approach revealed up to 265 alleles that translated into 251 different amino acid sequences (β chain, exon 2) in 902 individuals. Bayesian inference identified up to 19 codons within the presumptive peptide-binding region showing pervasive evidence of positive, diversifying selection. Our analyses also detected a significant excess of high-frequency segregating sites (average Tajima's D = 2.36, P < 0.05), indicative of balancing selection. We found one to six different alleles per individual, consistent with the occurrence of at least three MHC class II B gene duplicates. However, the genotypes comprised of three alleles were by far the most abundant in the population investigated (49.4%), followed by those with two (29.6%) and four (17.5%) alleles. We suggest that these proportions are in agreement with the segregation of MHC haplotypes differing in gene copy number. The most widespread segregating haplotypes, according to our findings, would contain one single gene or two genes. The MHC class II of the Eurasian Coot is a valuable system to investigate the evolutionary implications of gene copy variation and extensive variability, the greatest ever found, to the best of our knowledge, in a wild population of a non-passerine bird. PMID:24683452

  1. Extraordinary MHC class II B diversity in a non-passerine, wild bird: the Eurasian Coot Fulica atra (Aves: Rallidae).

    PubMed

    Alcaide, Miguel; Muñoz, Joaquin; Martínez-de la Puente, Josué; Soriguer, Ramón; Figuerola, Jordi

    2014-03-01

    The major histocompatibility complex (MHC) hosts the most polymorphic genes ever described in vertebrates. The MHC triggers the adaptive branch of the immune response, and its extraordinary variability is considered an evolutionary consequence of pathogen pressure. The last few years have witnessed the characterization of the MHC multigene family in a large diversity of bird species, unraveling important differences in its polymorphism, complexity, and evolution. Here, we characterize the first MHC class II B sequences isolated from a Rallidae species, the Eurasian Coot Fulica atra. A next-generation sequencing approach revealed up to 265 alleles that translated into 251 different amino acid sequences (β chain, exon 2) in 902 individuals. Bayesian inference identified up to 19 codons within the presumptive peptide-binding region showing pervasive evidence of positive, diversifying selection. Our analyses also detected a significant excess of high-frequency segregating sites (average Tajima's D = 2.36, P < 0.05), indicative of balancing selection. We found one to six different alleles per individual, consistent with the occurrence of at least three MHC class II B gene duplicates. However, the genotypes comprised of three alleles were by far the most abundant in the population investigated (49.4%), followed by those with two (29.6%) and four (17.5%) alleles. We suggest that these proportions are in agreement with the segregation of MHC haplotypes differing in gene copy number. The most widespread segregating haplotypes, according to our findings, would contain one single gene or two genes. The MHC class II of the Eurasian Coot is a valuable system to investigate the evolutionary implications of gene copy variation and extensive variability, the greatest ever found, to the best of our knowledge, in a wild population of a non-passerine bird.

  2. High levels of MHC class II allelic diversity in lake trout from Lake Superior

    USGS Publications Warehouse

    Dorschner, M.O.; Duris, T.; Bronte, C.R.; Burnham-Curtis, M. K.; Phillips, R.B.

    2000-01-01

    Sequence variation in a 216 bp portion of the major histocompatibility complex (MHC) II B1 domain was examined in 74 individual lake trout (Salvelinus namaycush) from different locations in Lake Superior. Forty-three alleles were obtained which encoded 71-72 amino acids of the mature protein. These sequences were compared with previous data obtained from five Pacific salmon species and Atlantic salmon using the same primers. Although all of the lake trout alleles clustered together in the neighbor-joining analysis of amino acid sequences, one amino acid allelic lineage was shared with Atlantic salmon (Salmo salar), a species in another genus which probably diverged from Salvelinus more than 10-20 million years ago. As shown previously in other salmonids, the level of nonsynonymous nucleotide substitution (d(N)) exceeded the level of synonymous substitution (d(S)). The level of nucleotide diversity at the MHC class II B1 locus was considerably higher in lake trout than in the Pacific salmon (genus Oncorhynchus). These results are consistent with the hypothesis that lake trout colonized Lake Superior from more than one refuge following the Wisconsin glaciation. Recent population bottlenecks may have reduced nucleotide diversity in Pacific salmon populations.

  3. Recombination hotspots rather than population history dominate linkage disequilibrium in the MHC class II region.

    PubMed

    Kauppi, Liisa; Sajantila, Antti; Jeffreys, Alec J

    2003-01-01

    Recombination, demographic history, drift and selection influence the extent of linkage disequilibrium (LD) in the human genome, but their relative contributions remain unclear. To investigate the effect of meiotic recombination versus population history on LD, three populations with different demographic histories (UK north Europeans, Saami and Zimbabweans) were genotyped for high-frequency single-nucleotide polymorphisms (SNPs) across a 75 kb DNA segment of the MHC class II region. This region spans three well-characterized recombination hotspots and a 60 kb long LD block. Despite a high level of underlying haplotype diversity and considerable divergence in haplotype composition between populations, all three populations showed very similar patterns of LD. Surprisingly, the entire 60 kb LD block was present even in Africans, although it was relatively difficult to detect owing to a systematic deficiency of high frequency SNPs. In contrast, DNA within recombination hotspots did not show this low nucleotide diversity in Africans. Thus, while population history has some influence on LD, our findings suggest that recombination hotspots play a major global role in shaping LD patterns as well as helping to maintain localized SNP diversity in this region of the MHC.

  4. Sequence analysis of the MHC class II DPB1 gene in chimpanzees (Pan troglodytes).

    PubMed

    Bak, E-J; Ishii, Y; Omatsu, T; Kyuwa, S; Hayasaka, I; Yoshikawa, Y

    2005-06-01

    The diversity of the MHC class II region in non-human primates is a focus of biomedical research because this region plays a crucial role in the recognition of antigens in the immune system. In particular, the chimpanzee [Pan troglodytes (Patr)], which belongs to the superfamily Hominoidea, has been used as a human model for the study of diseases such as human hepatitis C virus (HCV), human hepatitis B virus (HBV) and human immunodeficiency virus (HIV) infections, to which only humans and chimpanzees are susceptible. In the present study, polymorphisms of the MHC-DPB1 gene (Patr-DPB1) in a chimpanzee colony in Japan were examined using a stepwise polymerase chain reaction (PCR) technique. In order to design a suitable primer pair which would amplify exon 2 of the Patr-DPB1 gene, a fragment of approximately 8 kb from exon 1 to exon 3 was amplified from chimpanzee genomic DNA. After designing a 500-bp primer pair at the 3' region of intron 1 and the 5' region of intron 2, analysis of DPB1 exon 2 alleles of each chimpanzee was carried out. Twenty-two chimpanzees were used in our study, and we identified seven alleles by sequence analysis on the Patr-DPB1 gene, including one new allele. The obtained nucleotide sequence patterns suggest that Patr-DPB1 alleles emerge by genetic variations such as the exchange of sequence motifs and the accumulation of point mutations.

  5. Viral infection transiently reverses activation receptor-mediated NK cell hyporesponsiveness in an MHC class I-independent mechanism.

    PubMed

    Mazumdar, Budhaditya; Bolanos, Fred D; Tripathy, Sandeep K

    2013-05-01

    Continuous engagement of the Ly49H activating receptor with its ligand (m157) in a transgenic mouse expressing m157 (m157-Tg) results in hyporesponsiveness of Ly49H(+) NK cells. The same interaction, during murine cytomegalovirus (MCMV) infection, leads to activation of Ly49H(+) NK cells. MCMV infection results in decreased MHC class I (MHC-I) expression on the infected cell as well as inflammatory responses, both of which do not take place in the uninfected m157-Tg mouse, potentially allowing for activation of NK cells in the context of MCMV infection. In this study, we demonstrated that viral infection transiently reverses activation receptor-mediated NK cell hyporesponsiveness in an MHC-I-independent mechanism. Furthermore, Ly49H(+) NK cells in an MHC-I-deficient environment remained hyporesponsive in the context of m157 expression, even when mature WT splenocytes were transferred into m157-Tg mice in an MHC-I-deficient environment. However, the administration of cytokines TNF-α, IL-12, and IFN-β resulted in a partial recovery from activation receptor-induced hyporesponsiveness. Thus, the release of the aforementioned cytokines during MCMV infection and not the downregulation of MHC-I expression appears to be responsible for partial resolution of Ly49H receptor-induced NK cell hyporesponsiveness.

  6. Genetic characterization of MHC class II DQB exon 2 variants in gayal (Bos frontalis).

    PubMed

    Sun, Yongke; Xi, Dongmei; Li, Guozhi; Hao, Tiantian; Chen, Yuhan; Yang, Yuai

    2014-09-03

    In the present study, exon 2 of major histocompatibility complex (MHC) class II DQB gene from 39 gayals (Bos frontalis) was isolated, characterized and compared with previously reported patterns for other bovidae. It was revealed by sequence analyses that there are 36 DQB exon 2 variants among 39 gayals. These variants exhibited a high degree of nucleotide and amino acid substitutions with most amino acid variations occurring at positions forming the peptide-binding sites (PBS). The DQB loci were analysed for patterns of synonymous (dS) and non-synonymous (dN) substitution. The gayals were observed to be under strong balancing selection in the DQB exon 2 PBS (dN = 0.094, P = 0.001). It appears that this variability among gayals could confer the ability to mount immune responses to a wide variety of peptides or pathogens.

  7. Genetic characterization of MHC class II DQB exon 2 variants in gayal (Bos frontalis)

    PubMed Central

    Sun, Yongke; Xi, Dongmei; Li, Guozhi; Hao, Tiantian; Chen, Yuhan; Yang, Yuai

    2014-01-01

    In the present study, exon 2 of major histocompatibility complex (MHC) class II DQB gene from 39 gayals (Bos frontalis) was isolated, characterized and compared with previously reported patterns for other bovidae. It was revealed by sequence analyses that there are 36 DQB exon 2 variants among 39 gayals. These variants exhibited a high degree of nucleotide and amino acid substitutions with most amino acid variations occurring at positions forming the peptide-binding sites (PBS). The DQB loci were analysed for patterns of synonymous (d S) and non-synonymous (d N) substitution. The gayals were observed to be under strong balancing selection in the DQB exon 2 PBS (d N = 0.094, P = 0.001). It appears that this variability among gayals could confer the ability to mount immune responses to a wide variety of peptides or pathogens. PMID:26019566

  8. Exposing the Specific Roles of the Invariant Chain Isoforms in Shaping the MHC Class II Peptidome.

    PubMed

    Fortin, Jean-Simon; Cloutier, Maryse; Thibodeau, Jacques

    2013-12-13

    The peptide repertoire (peptidome) associated with MHC class II molecules (MHCIIs) is influenced by the polymorphic nature of the peptide binding groove but also by cell-intrinsic factors. The invariant chain (Ii) chaperones MHCIIs, affecting their folding and trafficking. Recent discoveries relating to Ii functions have provided insights as to how it edits the MHCII peptidome. In humans, the Ii gene encodes four different isoforms for which structure-function analyses have highlighted common properties but also some non-redundant roles. Another layer of complexity arises from the fact that Ii heterotrimerizes, a characteristic that has the potential to affect the maturation of associated MHCIIs in many different ways, depending on the isoform combinations. Here, we emphasize the peptide editing properties of Ii and discuss the impact of the various isoforms on the MHCII peptidome.

  9. Tracking antigen-specific CD8⁺ T cells using MHC class I multimers.

    PubMed

    Alanio, Cécile; Bouvier, Isabelle; Jusforgues-Saklani, Hélène; Albert, Matthew L

    2013-01-01

    The tracking of epitope-specific T cells is a useful approach for the study of adaptive immune responses. This protocol describes how Major Histocompatibility Complex Class I (MHC-I) multimers can be used to stain, enrich, and enumerate (rare) populations of CD8(+) T cells specific for a given antigen. It provides the detailed steps for multimer labeling, magnetic enrichment, and cytometric analysis. Additionally, it provides informations for multiplexing experiments in order to achieve simultaneous detection of multiple antigenic specificities, and strategies for coupling the protocol with functional assays (e.g., intracellular cytokine staining). Future developments in cytometric systems (e.g., mass spectroscopy-based cytometry) and gene expression studies (e.g., single cell PCR) will extend these approaches and provide an unprecedented assessment of the immune repertoire.

  10. Efficient vaccine against pandemic influenza: combining DNA vaccination and targeted delivery to MHC class II molecules.

    PubMed

    Grødeland, Gunnveig; Bogen, Bjarne

    2015-06-01

    There are two major limitations to vaccine preparedness in the event of devastating influenza pandemics: the time needed to generate a vaccine and rapid generation of sufficient amounts. DNA vaccination could represent a solution to these problems, but efficacy needs to be enhanced. In a separate line of research, it has been established that targeting of vaccine molecules to antigen-presenting cells enhances immune responses. We have combined the two principles by constructing DNA vaccines that encode bivalent fusion proteins; these target hemagglutinin to MHC class II molecules on antigen-presenting cells. Such DNA vaccines rapidly induce hemagglutinin-specific antibodies and T cell responses in immunized mice. Responses are long-lasting and protect mice against challenge with influenza virus. In a pandemic situation, targeted DNA vaccines could be produced and tested within a month. The novel DNA vaccines could represent a solution to pandemic preparedness in the advent of novel influenza pandemics.

  11. Ectopic expression of HLA-DO in mouse dendritic cells diminishes MHC class II antigen presentation.

    PubMed

    Fallas, Jennifer L; Tobin, Helen M; Lou, Olivia; Guo, Donglin; Sant'Angelo, Derek B; Denzin, Lisa K

    2004-08-01

    The MHC class II-like molecule HLA-DM (DM) (H-2M in mice) catalyzes the exchange of CLIP for antigenic peptides in the endosomes of APCs. HLA-DO (DO) (H-2O in mice) is another class II-like molecule that is expressed in B cells, but not in other APCs. Studies have shown that DO impairs or modifies the peptide exchange activity of DM. To further evaluate the role of DO in Ag processing and presentation, we generated transgenic mice that expressed the human HLA-DOA and HLA-DOB genes under the control of a dendritic cell (DC)-specific promoter. Our analyses of DCs from these mice showed that as DO levels increased, cell surface levels of A(b)-CLIP also increased while class II-peptide levels decreased. The presentation of some, but not all, exogenous Ags to T cells or T hybridomas was significantly inhibited by DO. Surprisingly, H-2M accumulated in DO-expressing DCs and B cells, suggesting that H-2O/DO prolongs the half-life of H-2M. Overall, our studies showed that DO expression impaired H-2M function, resulting in Ag-specific down-modulation of class II Ag processing and presentation.

  12. Mutant MHC class II epitopes drive therapeutic immune responses to cancer

    PubMed Central

    Kreiter, Sebastian; Vormehr, Mathias; van de Roemer, Niels; Diken, Mustafa; Löwer, Martin; Diekmann, Jan; Boegel, Sebastian; Schrörs, Barbara; Vascotto, Fulvia; Castle, John C.; Tadmor, Arbel D.; Schoenberger, Stephen P.; Huber, Christoph; Türeci, Özlem; Sahin, Ugur

    2016-01-01

    Tumour-specific mutations are ideal targets for cancer immunotherapy as they lack expression in healthy tissues and can potentially be recognized as neo-antigens by the mature T-cell repertoire. Their systematic targeting by vaccine approaches, however, has been hampered by the fact that every patient’s tumour possesses a unique set of mutations (‘the mutanome’) that must first be identified. Recently, we proposed a personalized immunotherapy approach to target the full spectrum of a patient’s individual tumour-specific mutations1. Here we show in three independent murine tumour models that a considerable fraction of non-synonymous cancer mutations is immunogenic and that, unexpectedly, the majority of the immunogenic mutanome is recognized by CD4+ T cells. Vaccination with such CD4+ immunogenic mutations confers strong antitumour activity. Encouraged by these findings, we established a process by which mutations identified by exome sequencing could be selected as vaccine targets solely through bioinformatic prioritization on the basis of their expression levels and major histocompatibility complex (MHC) class II-binding capacity for rapid production as synthetic poly-neo-epitope messenger RNA vaccines. We show that vaccination with such polytope mRNA vaccines induces potent tumour control and complete rejection of established aggressively growing tumours in mice. Moreover, we demonstrate that CD4+ T cell neo-epitope vaccination reshapes the tumour microenvironment and induces cytotoxic T lymphocyte responses against an independent immunodominant antigen in mice, indicating orchestration of antigen spread. Finally, we demonstrate an abundance of mutations predicted to bind to MHC class II in human cancers as well by employing the same predictive algorithm on corresponding human cancer types. Thus, the tailored immunotherapy approach introduced here may be regarded as a universally applicable blueprint for comprehensive exploitation of the substantial neo

  13. Chemotherapy, IL-12 gene therapy and combined adjuvant therapy of HPV 16-associated MHC class I-proficient and -deficient tumours.

    PubMed

    Indrová, Marie; Bieblová, Jana; Jandlová, Tána; Vonka, Vladimír; Pajtasz-Piasecka, Elzbieta; Reinis, Milan

    2006-01-01

    Moderately immunogenic HPV 16-associated murine tumour cell line mimicking human HPV 16-associated neoplasms TC-1 (MHC class I(+)) and its variants, TC-1/P3C10 and TC-1/A9, with a marked down-regulation of MHC I molecules, were used to examine the effect of local interleukin 12 (IL-12) gene therapy for the treatment of early tumour transplants and minimal residual tumour disease obtained after cytoreductive chemotherapy (CMRTD). Experiments were designed to examine whether down-regulation of MHC class I molecules plays a role during chemotherapy and gene therapy of early tumour transplants. It was found that peritumoral administration of IL-12-producing tumour cell vaccines (single dose, day 8 after tumour cell administration) inhibited the growth of both TC-1 (MHC class I positive) tumours and their MHC class I-deficient variants. To investigate the antitumour effects in a clinically relevant setting, IL-12 gene therapy was utilised for the treatment of minimal residual tumour disease after cytoreductive chemotherapy. Intra-peritoneal treatment of tumour-bearing mice with ifosfamide derivative, CBM-4A, produced a significant tumour-inhibitory effect. This treatment was followed by peritumoral s.c. administration of genetically modified TC-1 (MHC class I positive) or MK16/I/IIIABC (MHC class I negative) vaccines producing IL-12 (single dose, day 7 after chemotherapy) or with recombinant interleukin 12 (rIL-12) in two cycles of 5 daily doses (days 8-19) after chemotherapy. This combined therapy significantly inhibited the growth of TC-1 and TC-1/A9 (MHC class I-) tumours. When the combined therapy of TC-1 (MHC class I positive) tumours was followed by peritumoral administration of bone marrow dendritic cell (BMDC) vaccines, the IL-12-mediated inhibitory effect was significantly boosted. In the next set of experiments, the impacts of chemotherapy and IL-12 adjuvant therapy on MHC class I surface expression were assessed. Chemotherapy and gene therapy of tumours led

  14. Linkage relationships in the bovine MHC region. High recombination frequency between class II subregions.

    PubMed

    Andersson, L; Lundén, A; Sigurdardottir, S; Davies, C J; Rask, L

    1988-01-01

    Class II genes of the bovine major histocompatibility complex (MHC) have been investigated by Southern blot analysis using human DNA probes. Previous studies revealed the presence of bovine DO beta, DQ alpha, DQ beta, DR alpha, and DR beta genes, and restriction fragment length polymorphisms for each of these genes were documented. In the present study, the presence of three additional class II genes, designated DZ alpha, DY alpha, and DY beta, are reported. DZ alpha was assumed to correspond to the human DZ alpha gene while the other two were designated DY because their relationship to human class II genes could not be firmly established. The linkage relationships among bovine class II genes and two additional loci, TCP1B and C4, were investigated by family segregation analysis and analysis of linkage disequilibrium. The results clearly indicated that all these loci belong to the same linkage group. This linkage group is divided into two subregions separated by a fairly high recombination frequency. One region includes the C4, DQ alpha, DQ beta, DR alpha, and DR beta loci and the other one is composed of the DO beta, DY alpha, DY beta, and TCP1B loci. No recombinant was observed within any of these subregions and there was a strong or fairly strong linkage disequilibrium between loci within groups. In contrast, as many as five recombinants among three different families were detected in the interval between these subregions giving a recombination frequency estimate of 0.17 +/- 0.07. The fairly high recombination frequency observed between class II genes in cattle is strikingly different from the corresponding recombination estimates in man and mouse. The finding implies either a much larger molecular distance between some of the bovine class II genes or alternatively the presence of a recombinational "hot spot" in the bovine class II region.

  15. Upregulation of MHC class I in transgenic mice results in reduced force-generating capacity in slow-twitch muscle.

    PubMed

    Salomonsson, Stina; Grundtman, Cecilia; Zhang, Shi-Jin; Lanner, Johanna T; Li, Charles; Katz, Abram; Wedderburn, Lucy R; Nagaraju, Kanneboyina; Lundberg, Ingrid E; Westerblad, Håkan

    2009-05-01

    Expression of major histocompatibility complex (MHC) class I in skeletal muscle fibers is an early and consistent finding in inflammatory myopathies. To test if MHC class I has a primary role in muscle impairment, we used transgenic mice with inducible overexpression of MHC class I in their skeletal muscle cells. Contractile function was studied in isolated extensor digitorum longus (EDL, fast-twitch) and soleus (slow-twitch) muscles. We found that EDL was smaller, whereas soleus muscle was slightly larger. Both muscles generated less absolute force in myopathic compared with control mice; however, when force was expressed per cross-sectional area, only soleus muscle generated less force. Inflammation was markedly increased, but no changes were found in the activities of key mitochondrial and glycogenolytic enzymes in myopathic mice. The induction of MHC class I results in muscle atrophy and an intrinsic decrease in force-generation capacity. These observations may have important implications for our understanding of the pathophysiological processes of muscle weakness seen in inflammatory myopathies. Muscle Nerve, 2008.

  16. Presence of specific MHC Class II expressed alleles associates with clinical disease in ovine progressive pneumonia virus (OPPV) infected sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A genetic tool hypothesized to predict which OPPV infected sheep will progress to debilitating clinical disease is MHC Class II Ovis aries (Ovar)-DRB1. Previously, fifteen Ovar-DRB1 beta 1 expressed alleles were identified in a ewe-lamb flock of 32 originating from an Idaho flock using RT-PCR, clon...

  17. MHC class II genes in the European badger (Meles meles): characterization, patterns of variation, and transcription analysis.

    PubMed

    Sin, Yung Wa; Dugdale, Hannah L; Newman, Chris; Macdonald, David W; Burke, Terry

    2012-04-01

    The major histocompatibility complex (MHC) comprises many genes, some of which are polymorphic with numerous alleles. Sequence variation among alleles is most pronounced in exon 2 of the class II genes, which encodes the α1 and β1 domains that form the antigen-binding site (ABS) for the presentation of peptides. The MHC thus plays an important role in pathogen defense. European badgers (Meles meles) are a good species in which to study the MHC, as they harbor a variety of pathogens. We present the first characterization of MHC class II genes, isolated from genomic DNA (gDNA) and complementary DNA (cDNA), in the European badger. Examination of seven individuals revealed four DRB, two DQB, two DQA, and two DRA putatively functional gDNA sequences. All of these sequences, except DRA, exhibited high variability in exon 2; DRB had the highest variability. The ABS codons demonstrated high variability, due potentially to balancing selection, while non-ABS codons had lower variability. Positively selected sites were detected in DRB and DQA. Phylogenetic analysis demonstrated trans-species polymorphism of class II genes. Comparison with cDNA from whole blood revealed that only DRB had a transcription pattern reflecting the alleles that were present in the gDNA, while the other three genes had disparities between gDNA and cDNA. Only one sequence was transcribed, even though two gDNA sequences were present, from each of both DQB and DRA. Our characterization of badger MHC sequences forms a basis for further studies of MHC variability, mate choice, and pathogen resistance in this, and other, species.

  18. MHC class I genes in a New World primate, the cotton-top tamarin (Saguinus oedipus), have evolved by an active process of loci turnover.

    PubMed

    Cadavid, L F; Mejía, B E; Watkins, D I

    1999-03-01

    Lymphocytes of a New World primate, the cotton-top tamarin (Saguinus oedipus), express classical G-related major histocompatibility complex (MHC) class I molecules with unusually limited polymorphism and variability. Three G-related loci, an F locus, an E locus, and two pseudogenes (So-N1 and So-N3) have been identified by cDNA library screening and extensive PCR analysis of both cDNA and genomic DNA from the cotton-top tamarin. Furthermore, each genus of the subfamily Callitrichinae (tamarins and marmosets) appears to express its own unique set of MHC class I genes, likely due to a rapid turnover of loci. The rapid emergence of unique MHC class I genes in the Callitrichinae genera, resulting from an active process of duplication and inactivation of loci, may account for the limited diversity of the MHC class I genes in the cotton-top tamarin. To determine the nature of the entire complement of MHC class I genes in the cotton-top tamarin, we synthesized a genomic DNA library and screened it with MHC class I-specific probes. We isolated nine new MHC class I pseudogenes from this library. These newly isolated tamarin G-related MHC class I pseudogenes are not closely related to any of their functional counterparts in the tamarin, suggesting that they do not share a recent common ancestral gene with the tamarin's currently expressed MHC class I loci. In addition, these tamarin sequences display a high rate of nonsynonymous substitutions in their putative peptide binding region. This indicates that the genes from which they have derived were likely subject to positive selection and, therefore, were once functional. Our data support the notion that an extremely high rate of loci turnover is largely responsible for the limited diversity of the MHC class I genes in the cotton-top tamarin.

  19. In silico designing breast cancer peptide vaccine for binding to MHC class I and II: A molecular docking study.

    PubMed

    Mahdavi, Manijeh; Moreau, Violaine

    2016-12-01

    Antigenic peptides or cancer peptide vaccines can be directly delivered to cancer patients to produce immunologic responses against cancer cells. Specifically, designed peptides can associate with Major Histocompatibility Complex (MHC) class I or II molecules on the cell surface of antigen presenting cells activating anti-tumor effector mechanisms by triggering helper T cell (Th) or cytotoxic T cells (CTL). In general, high binding to MHCs approximately correlates with in vivo immunogenicity. Consequently, a molecular docking technique was run on a library of novel discontinuous peptides predicted by PEPOP from Human epidermal growth factor receptor 2 (HER2 ECD) subdomain III. This technique is expected to improve the prediction accuracy in order to identify the best MHC class I and II binder peptides. Molecular docking analysis through GOLD identified the peptide 1412 as the best MHC binder peptide to both MHC class I and II molecules used in the study. The GOLD results predicted HLA-DR4, HLA-DP2 and TCR as the most often targeted receptors by the peptide 1412. These findings, based on bioinformatics analyses, can be exploited in further experimental analyses in vaccine design and cancer therapy to find possible proper approaches providing beneficial effects.

  20. Structural Mechanism of ER Retrieval of MHC Class I by Cowpox

    PubMed Central

    McCoy, William H.; Wang, Xiaoli; Yokoyama, Wayne M.; Hansen, Ted H.; Fremont, Daved H.

    2012-01-01

    One of the hallmarks of viral immune evasion is the capacity to disrupt major histocompatibility complex class I (MHCI) antigen presentation to evade T-cell detection. Cowpox virus encoded protein CPXV203 blocks MHCI surface expression by exploiting the KDEL-receptor recycling pathway, and here we show that CPXV203 directly binds a wide array of fully assembled MHCI proteins, both classical and non-classical. Further, the stability of CPXV203/MHCI complexes is highly pH dependent, with dramatically increased affinities at the lower pH of the Golgi relative to the endoplasmic reticulum (ER). Crystallographic studies reveal that CPXV203 adopts a beta-sandwich fold similar to poxvirus chemokine binding proteins, and binds the same highly conserved MHCI determinants located under the peptide-binding platform that tapasin, CD8, and natural killer (NK)-receptors engage. Mutagenesis of the CPXV203/MHCI interface identified the importance of two CPXV203 His residues that confer low pH stabilization of the complex and are critical to ER retrieval of MHCI. These studies clarify mechanistically how CPXV203 coordinates with other cowpox proteins to thwart antigen presentation. PMID:23209377

  1. Does the parasite-mediated selection drive the MHC class IIB diversity in wild populations of European chub (Squalius cephalus)?

    PubMed

    Seifertová, Mária; Jarkovský, Jiří; Šimková, Andrea

    2016-04-01

    The genes of major histocompatibility complex (MHC) provide an excellent opportunity to study host-parasite relationships because they are expected to evolve in response to parasites and variation in parasite communities. In this study, we investigated the potential role of parasite-mediated selection acting on MHC class IIB (DAB) genes in European chub (Squalius cephalus) natural populations. We found significant differences between populations in metazoan parasites, neutral and adaptive genetic diversities. The analyses based on pairwise data revealed that populations with dissimilar MHC allelic profiles were geographically distant populations with significantly different diversity in microsatellites and a dissimilar composition of parasite communities. The results from the generalized estimating equations method (GEE) on the level of individuals revealed that metazoan parasite load in European chub was influenced by the diversity of DAB alleles as well as by the diversity of neutral genetic markers and host traits reflecting condition and immunocompetence. The multivariate co-inertia analysis showed specific associations between DAB alleles and parasite species. DAB1-like alleles were more involved in associations with ectoparasites, while DAB3-like alleles were positively associated with endoparasites which could suggest potential differences between DAB genes caused by different selection pressure. Our study revealed that parasite-mediated selection is not the only variable affecting MHC diversity in European chub; however, we strongly support the role of neutral processes as the main driver of DAB diversity across populations. In addition, our study contributes to the understanding of the evolution of MHC genes in wild living fish.

  2. The class I myosin Myo1e regulates TLR4-triggered macrophage spreading, chemokine release and antigen presentation via MHC class II

    PubMed Central

    Wenzel, Jens; Ouderkirk, Jessica L.; Krendel, Mira; Lang, Roland

    2014-01-01

    TLR-mediated recognition of microbial danger induces substantial changes in macrophage migration, adherence and phagocytosis. Recently, we described the LPS-regulated phosphorylation of many cytoskeleton-associated proteins by phosphoproteomics. The functional role of these cytoskeletal and motor proteins in innate immune cell responses is largely unexplored. Here, we first identified both long-tailed class I myosins Myo1e and Myo1f as important contributors to LPS-triggered macrophage spreading. Mouse bone marrow-derived macrophages and dendritic cells (DCs) deficient in Myo1e selectively secreted increased amounts of the chemokine CCL2. In addition, the cell surface expression of MHC class II (MHC-II) on both cell types was reduced in the absence of Myo1e. However, transcriptional changes in CCL2 and MHC-II were not observed in the absence of Myo1e, indicating that Myo1e regulates specific intracellular transport processes. The capacity of macrophages and DCs lacking Myo1e to stimulate antigen-specific CD4+ T-cell proliferation was impaired, consistent with the reduced MHC-II surface protein levels. Surprisingly, in Myo1e-deficient DCs, the proteolytic cleavage of endocytosed antigen was also increased. Together, our results provide evidence for a non-redundant function of the motor protein Myo1e in the regulation of TLR4-controlled, cytoskeleton-associated functional properties of macrophages and DCs, and in induction of a full MHC-II-restricted adaptive immune response. PMID:25263281

  3. MHC Class I Expression by Donor Hematopoietic Stem Cells Is Required to Prevent NK Cell Attack in Allogeneic, but Not Syngeneic Recipient Mice.

    PubMed

    Hirata, Yuichi; Li, Hao-Wei; Takahashi, Kazuko; Ishii, Hiroshi; Sykes, Megan; Fujisaki, Joji

    2015-01-01

    NK cells resist engraftment of syngeneic and allogeneic bone marrow (BM) cells lacking major histocompatibility (MHC) class I molecules, suggesting a critical role for donor MHC class I molecules in preventing NK cell attack against donor hematopoietic stem and progenitor cells (HSPCs), and their derivatives. However, using high-resolution in vivo imaging, we demonstrated here that syngeneic MHC class I knockout (KO) donor HSPCs persist with the same survival frequencies as wild-type donor HSPCs. In contrast, syngeneic MHC class I KO differentiated hematopoietic cells and allogeneic MHC class I KO HSPCs were rejected in a manner that was significantly inhibited by NK cell depletion. In vivo time-lapse imaging demonstrated that mice receiving allogeneic MHC class I KO HSPCs showed a significant increase in NK cell motility and proliferation as well as frequencies of NK cell contact with and killing of HSPCs as compared to mice receiving wild-type HSPCs. The data indicate that donor MHC class I molecules are required to prevent NK cell-mediated rejection of syngeneic differentiated cells and allogeneic HSPCs, but not of syngeneic HSPCs.

  4. MHC Class I Expression by Donor Hematopoietic Stem Cells Is Required to Prevent NK Cell Attack in Allogeneic, but Not Syngeneic Recipient Mice

    PubMed Central

    Hirata, Yuichi; Li, Hao-Wei; Takahashi, Kazuko; Ishii, Hiroshi; Sykes, Megan; Fujisaki, Joji

    2015-01-01

    NK cells resist engraftment of syngeneic and allogeneic bone marrow (BM) cells lacking major histocompatibility (MHC) class I molecules, suggesting a critical role for donor MHC class I molecules in preventing NK cell attack against donor hematopoietic stem and progenitor cells (HSPCs), and their derivatives. However, using high-resolution in vivo imaging, we demonstrated here that syngeneic MHC class I knockout (KO) donor HSPCs persist with the same survival frequencies as wild-type donor HSPCs. In contrast, syngeneic MHC class I KO differentiated hematopoietic cells and allogeneic MHC class I KO HSPCs were rejected in a manner that was significantly inhibited by NK cell depletion. In vivo time-lapse imaging demonstrated that mice receiving allogeneic MHC class I KO HSPCs showed a significant increase in NK cell motility and proliferation as well as frequencies of NK cell contact with and killing of HSPCs as compared to mice receiving wild-type HSPCs. The data indicate that donor MHC class I molecules are required to prevent NK cell-mediated rejection of syngeneic differentiated cells and allogeneic HSPCs, but not of syngeneic HSPCs. PMID:26544200

  5. MHC class-I-restricted CD8 T cells play a protective role during primary Salmonella infection.

    PubMed

    Lee, Seung-Joo; Dunmire, Samantha; McSorley, Stephen J

    2012-12-17

    Protective immunity against Salmonella infection is known to require CD4 Th1 cells and B cells, but the role of MHC class-I-restricted CD8 T cells is less clear. Previous studies have suggested that CD8 T cells participate in secondary, but not primary, bacterial clearance. However, these studies have used experimental models that are difficult to interpret and do not clearly isolate the role of MHC class-I-restricted CD8 T cells from other cell populations. Here, we examined the role of class-I-restricted T cells in protection against Salmonella infection using mice lacking all classical MHC class-Ia molecules, perforin, or granzyme B. Immunized K(b)D(b)-, perforin-, granzyme B-, or perforin/granzyme B-deficient mice were able to resolve secondary infection with virulent Salmonella, demonstrating that class-I-restricted CTLs are not required for acquired immunity. However, during primary infection with attenuated bacteria, bacterial clearance was delayed in each of these mouse strains when compared to wild-type mice. Taken together, these data demonstrate that CD8 T cells are not required for acquired immunity to Salmonella, but can play a protective role in resolving primary infection with attenuated bacteria.

  6. A single nomenclature and associated database for alleles at the MHC class II DRB1 locus of sheep: IPD-MHC-OLA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of standardised nomenclatures with associated databases containing reference sequences for alleles at polymorphic loci within the Major Histocompatibility Complex (MHC) has been facilitated by the development of the Immuno Polymorphism Database (IPD-MHC). Recently, included within I...

  7. Molecular cloning and characterization of sea bass (Dicentrarchus labrax, L.) MHC class I heavy chain and β2-microglobulin.

    PubMed

    Pinto, Rute D; Randelli, Elisa; Buonocore, Francesco; Pereira, Pedro J B; dos Santos, Nuno M S

    2013-03-01

    In this work, the gene and cDNA of sea bass (Dicentrarchus labrax) β2-microglobulin (Dila-β2m) and several cDNAs of MHC class I heavy chain (Dila-UA) were characterized. While Dila-β2m is single-copy, numerous Dila-UA transcripts were identified per individual with variability at the peptide-binding domain (PBD), but also with unexpected diversity from the connective peptide (CP) through the 3' untranslated region (UTR). Phylogenetic analysis segregates Dila-β2m and Dila-UA into each subfamily cluster, placing them in the fish class and branching Dila-MHC-I with lineage U. The α1 domains resemble those of the recently proposed L1 trans-species lineage. Although no Dila-specific α1, α2 or α3 sub-lineages could be observed, two highly distinct sub-lineages were identified at the CP/TM/CYT regions. The three-dimensional homology model of sea bass MHC-I complex is consistent with other characterized vertebrate structures. Furthermore, basal tissue-specific expression profiles were determined for both molecules, and expression of β2m was evaluated after poly I:C stimulus. Results suggest these molecules are orthologues of other β2m and teleost classical MHC-I and their basic structure is evolutionarily conserved, providing relevant information for further studies on antigen presentation in this fish species.

  8. Intrasequence GFP in class I MHC molecules, a rigid probe for fluorescence anisotropy measurements of the membrane environment.

    PubMed

    Rocheleau, Jonathan V; Edidin, Michael; Piston, David W

    2003-06-01

    Fluorescence anisotropy measurements can elucidate the microenvironment of a membrane protein in terms of its rotational diffusion, interactions, and proximity to other proteins. However, use of this approach requires a fluorescent probe that is rigidly attached to the protein of interest. Here we describe the use of one such probe, a green fluorescent protein (GFP) expressed and rigidly held within the amino acid sequence of a major histocompatibility complex (MHC) class I molecule, H2L(d). We contrast the anisotropy of this GFP-tagged MHC molecule, H2L(d)GFPout, with that of an H2L(d) that was GFP-tagged at its C-terminus, H2L(d)GFPin. Both molecules fold properly, reach the cell surface, and are recognized by specific antibodies and T-cell receptors. We found that polarized fluorescence images of H2L(d)GFPout in plasma membrane blebs show intensity variations that depend on the relative orientation of the polarizers and the membrane normal, thus demonstrating that the GFP is oriented with respect to the membrane. These variations were not seen for H2L(d)GFPin. Before transport to the membrane surface, MHC class I associates with the transporter associated with antigen processing complex in the endoplasmic reticulum. The intensity-dependent steady-state anisotropy in the ER of H2L(d)GFPout was consistent with FRET homotransfer, which indicates that a significant fraction of these molecules were clustered. After MCMV-peptide loading, which supplies antigenic peptide to the MHC class I releasing it from the antigen processing complex, the anisotropy of H2L(d)GFPout was independent of intensity, suggesting that the MHC proteins were no longer clustered. These results demonstrate the feasibility and usefulness of a GFP moiety rigidly attached to the protein of interest as a probe for molecular motion and proximity in cell membranes.

  9. Paternal MHC expression on mouse trophoblast affects uterine vascularization and fetal growth.

    PubMed

    Madeja, Zofia; Yadi, Hakim; Apps, Richard; Boulenouar, Selma; Roper, Stephen J; Gardner, Lucy; Moffett, Ashley; Colucci, Francesco; Hemberger, Myriam

    2011-03-08

    The mammalian fetus represents a semiallograft within the maternal uterus yet is not rejected. This situation is particularly pronounced in species with a hemochorial type of placentation, such as humans and rodents, where maternal tissues and blood are in direct contact with fetal trophoblast and thus potentially with paternal antigens. The main polymorphic antigens responsible for graft rejection are MHC antigens. In humans the trophoblast cells invading into the decidua have a unique pattern of MHC class I expression characterized by both classical (HLA-C) and nonclassical (HLA-G and HLA-E) molecules. Whether such an unusual MHC repertoire on the surface of trophoblast is a conserved feature between species with hemochorial placentation has not been resolved. Here we demonstrate, using a range of methods, that C57BL/6 mouse trophoblast predominantly expresses only one MHC class I antigen, H2-K, at the cell surface of giant cells but lacks expression of nonclassical MHC molecules. Antigenic disparity between parental MHCs affects trophoblast-induced transformation of the uterine vasculature and, consequently, placental and fetal gowth. Maternal uterine blood vessels were more dilated, allowing for increased blood supply, in certain combinations of maternal and paternal MHC haplotypes, and these allogeneic fetuses and placentas were heavier at term compared with syngeneic controls. Thus, maternal-fetal immune interactions are instrumental to optimize reproductive success. This cross-talk has important implications for human disorders of pregnancy, such as preeclampsia and fetal growth restriction.

  10. Comparative molecular dynamics analysis of tapasin-dependent and -independent MHC class I alleles.

    SciTech Connect

    Sieker, Florian; Springer, Sebastian; Zacharias, Martin W.

    2007-02-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. MHC class I molecules load antigenic peptides in the endoplasmic reticulum and present them at the cell surface. Efficiency of peptide loading depends on the class I allele and can involve interaction with tapasin and other proteins of the loading complex. Allele HLA-B*4402 (Asp at position 116) depends on tapasin for efficient peptide loading, whereas HLA-B*4405 (identical to B*4402 except for Tyr116) can efficiently load peptides in the absence of tapasin. Both alleles adopt very similar structures in the presence of the same peptide. Comparative unrestrained molecular dynamics simulations on the 1/2 peptide binding domains performed in the presence of bound peptides resulted in structures in close agreement with experiments for both alleles. In the absence of peptides, allele-specific conformational changes occurred in the first segment of the 2-helix that flanks the peptide C-terminal binding region (F-pocket) and contacts residue 116. This segment is also close to the proposed tapasin contact region. For B*4402, a shift toward an altered F-pocket structure deviating significantly from the bound form was observed. Subsequent free energy simulations on induced F-pocket opening in B*4402 confirmed a conformation that deviated significantly from the bound structure. For B*4405, a free energy minimum close to the bound structure was found. The simulations suggest that B*4405 has a greater tendency to adopt a peptide receptive conformation in the absence of peptide, allowing tapasin-independent peptide loading. A possible role of tapasin could be the stabilization of a peptide-receptive class I conformation for HLA-B*4402 and other tapasin-dependent alleles.

  11. CDw78 defines MHC class II-peptide complexes that require Ii chain-dependent lysosomal trafficking, not localization to a specific tetraspanin membrane microdomain.

    PubMed

    Poloso, Neil J; Denzin, Lisa K; Roche, Paul A

    2006-10-15

    MHC class II molecules (MHC-II) associate with detergent-resistant membrane microdomains, termed lipid rafts, which affects the function of these molecules during Ag presentation to CD4+ T cells. Recently, it has been proposed that MHC-II also associates with another type of membrane microdomain, termed tetraspan microdomains. These microdomains are defined by association of molecules to a family of proteins that contain four-transmembrane regions, called tetraspanins. It has been suggested that MHC-II associated with tetraspanins are selectively identified by a mAb to a MHC-II determinant, CDw78. In this report, we have re-examined this issue of CDw78 expression and MHC-II-association with tetraspanins in human dendritic cells, a variety of human B cell lines, and MHC-II-expressing HeLa cells. We find no correlation between the expression of CDw78 and the expression of tetraspanins CD81, CD82, CD53, CD9, and CD37. Furthermore, we find that the relative amount of tetraspanins bound to CDw78-reactive MHC-II is indistinguishable from the amount bound to peptide-loaded MHC-II. We found that expression of CDw78 required coexpression of MHC-II together with its chaperone Ii chain. In addition, analysis of a panel of MHC-II-expressing B cell lines revealed that different alleles of HLA-DR express different amounts of CDw78 reactivity. We conclude that CDw78 defines a conformation of MHC-II bound to peptides that are acquired through trafficking to lysosomal Ag-processing compartments and not MHC-II-associated with tetraspanins.

  12. Comparative genome analysis of the major histocompatibility complex (MHC) class I B/C segments in primates elucidated by genomic sequencing in common marmoset (Callithrix jacchus).

    PubMed

    Shiina, Takashi; Kono, Azumi; Westphal, Nico; Suzuki, Shingo; Hosomichi, Kazuyoshi; Kita, Yuki F; Roos, Christian; Inoko, Hidetoshi; Walter, Lutz

    2011-08-01

    Common marmoset monkeys (Callithrix jacchus) have emerged as important animal models for biomedical research, necessitating a more extensive characterization of their major histocompatibility complex (MHC) region. However, the genomic information of the marmoset MHC (Caja) is still lacking. The MHC-B/C segment represents the most diverse MHC region among primates. Therefore, in this paper, to elucidate the detailed gene organization and evolutionary processes of the Caja class I B (Caja-B) segment, we determined two parts of the Caja-B sequences with 1,079 kb in total, ranging from H6orf15 to BAT1 and compared the structure and phylogeny with that of other primates. This segment contains 54 genes in total, nine Caja-B genes (Caja-B1 to Caja-B9), two MIC genes (MIC1 and MIC2), eight non-MHC genes, two non-coding genes, and 33 non-MHC pseudogenes that have not been observed in other primate MHC-B/C segments. Caja-B3, Caja-B4, and Caja-B7 encode proper MHC class I proteins according to amino acid structural characteristics. Phylogenetic relationships based on 48 MHC-I nucleotide sequences in primates suggested (1) species-specific divergence for Caja, Mamu, and HLA/Patr/Gogo lineages, (2) independent generation of the "seven coding exon" type MHC-B genes in Mamu and HLA/Patr/Gogo lineages from an ancestral "eight coding exon" type MHC-I gene, (3) parallel correlation with the long and short segmental duplication unit length in Caja and Mamu lineages. These findings indicate that the MHC-B/C segment has been under permanent selective pressure in the evolution of primates.

  13. Aberrant MHC class II expression in mouse joints leads to arthritis with extraarticular manifestations similar to rheumatoid arthritis

    PubMed Central

    Kanazawa, Satoshi; Ota, Shusuke; Sekine, Chiyoko; Tada, Toyohiro; Otsuka, Takanobu; Okamoto, Takashi; Sønderstrup, Grete; Peterlin, B. Matija

    2006-01-01

    Genetic susceptibility to rheumatoid arthritis (RA) is associated with certain MHC class II molecules. To clarify the role of these determinants in RA, we generated the D1CC transgenic mouse that expressed genes involved in antigen processing and presentation by the MHC class II pathway in joints. The class II transactivator, which was transcribed from the rat collagen type II promoter and enhancer, directed the expression of these genes. In D1CC mice congenic for the H-2q (DBA/1) background, small amounts of bovine collagen type II in adjuvant induced reproducibly an inflammatory arthritis resembling RA. Importantly, these stimuli had no effect in DBA/1 mice. Eighty-nine percent of D1CC mice developed chronic disease with joint swelling, redness, and heat in association with synovial proliferation as well as pannus formation and mononuclear infiltration of synovial membranes. Granulomatous lesions resembling rheumatoid nodules and interstitial pneumonitis also were observed. As in patients with RA, anticyclic citrullinated peptide antibodies were detected during the inflammatory stage. Finally, joints in D1CC mice displayed juxtaarticular demineralization, severe joint space narrowing, and erosions, which led to ankylosis, but without the appearance of osteophytes. Thus, aberrant expression of MHC class II in joints facilitates the development of severe erosive inflammatory polyarthritis, which is very similar to RA. PMID:16980409

  14. Experimental hemochromatosis due to MHC class I HFE deficiency: Immune status and iron metabolism

    PubMed Central

    Bahram, Seiamak; Gilfillan, Susan; Kühn, Lukas C.; Moret, Rémy; Schulze, Johannes B.; Lebeau, Annette; Schümann, Klaus

    1999-01-01

    The puzzling linkage between genetic hemochromatosis and histocompatibility loci became even more so when the gene involved, HFE, was identified. Indeed, within the well defined, mainly peptide-binding, MHC class I family of molecules, HFE seems to perform an unusual yet essential function. As yet, our understanding of HFE function in iron homeostasis is only partial; an even more open question is its possible role in the immune system. To advance on both of these avenues, we report the deletion of HFE α1 and α2 putative ligand binding domains in vivo. HFE-deficient animals were analyzed for a comprehensive set of metabolic and immune parameters. Faithfully mimicking human hemochromatosis, mice homozygous for this deletion develop iron overload, characterized by a higher plasma iron content and a raised transferrin saturation as well as an elevated hepatic iron load. The primary defect could, indeed, be traced to an augmented duodenal iron absorption. In parallel, measurement of the gut mucosal iron content as well as iron regulatory proteins allows a more informed evaluation of various hypotheses regarding the precise role of HFE in iron homeostasis. Finally, an extensive phenotyping of primary and secondary lymphoid organs including the gut provides no compelling evidence for an obvious immune-linked function for HFE. PMID:10557317

  15. Allelic diversity at MHC class II DQ loci in buffalo (Bubalus bubalis): evidence for duplication.

    PubMed

    Niranjan, Saket K; Deb, Sitangsu M; Kumar, Subodh; Mitra, Abhijit; Sharma, Arjava; Sakaram, Durgam; Naskar, Soumen; Sharma, Deepak; Sharma, Sita R

    2010-12-01

    The genetic diversity of MHC class II DQ genes was investigated in riverine buffalo (Bubalus bubalis) by PCR-RFLP and sequencing. Highly variable regions (exons 2-3) of DQ genes were amplified from 152 buffaloes and genotyped by PCR-RFLP. Alleles identified by differential restriction patterns were sequenced for the characterization. PCR-RFLP was a rapid method to discriminate between DQA1 and duplicated DQA2 genes in buffalo, however, the method appeared to be inadequate for determining the more complicated DQB genotypes. A total of 7 and 10 alleles were identified for DQA and DQB loci, respectively. Nucleotide as well as amino acid variations among DQ alleles particularly at peptide binding regions were high. Such variations were as expected higher in DQB than DQA alleles. The phylogenetic analysis for both genes revealed the grouping of alleles into two major sub-groups with higher genetic divergence. High divergence among DQ allelic families and the isolation of two diverse DQA and DQB sequences from individual samples indicated duplication of DQ loci was similar in buffalo to other ruminants.

  16. Cell surface display of functional human MHC class II proteins: yeast display versus insect cell display

    PubMed Central

    Wen, Fei; Sethi, Dhruv K.; Wucherpfennig, Kai W.; Zhao, Huimin

    2011-01-01

    Reliable and robust systems for engineering functional major histocompatibility complex class II (MHCII) proteins have proved elusive. Availability of such systems would enable the engineering of peptide-MHCII (pMHCII) complexes for therapeutic and diagnostic applications. In this paper, we have developed a system based on insect cell surface display that allows functional expression of heterodimeric DR2 molecules with or without a covalently bound human myelin basic protein (MBP) peptide, which is amenable to directed evolution of DR2–MBP variants with improved T cell receptor (TCR)-binding affinity. This study represents the first example of functional display of human pMHCII complexes on insect cell surface. In the process of developing this pMHCII engineering system, we have also explored the potential of using yeast surface display for the same application. Our data suggest that yeast display is a useful system for analysis and engineering of peptide binding of MHCII proteins, but not suitable for directed evolution of pMHC complexes that bind with low affinity to self-reactive TCRs. PMID:21752831

  17. Translational diffusion of individual class II MHC membrane proteins in cells.

    PubMed Central

    Vrljic, Marija; Nishimura, Stefanie Y; Brasselet, Sophie; Moerner, W E; McConnell, Harden M

    2002-01-01

    Single-molecule epifluorescence microscopy was used to observe the translational motion of GPI-linked and native I-E(k) class II MHC membrane proteins in the plasma membrane of CHO cells. The purpose of the study was to look for deviations from Brownian diffusion that might arise from barriers to this motion. Detergent extraction had suggested that these proteins may be confined to lipid microdomains in the plasma membrane. The individual I-E(k) proteins were visualized with a Cy5-labeled peptide that binds to a specific extracytoplasmic site common to both proteins. Single-molecule trajectories were used to compute a radial distribution of displacements, yielding average diffusion coefficients equal to 0.22 (GPI-linked I-E(k)) and 0.18 microm(2)/s (native I-E(k)). The relative diffusion of pairs of proteins was also studied for intermolecular separations in the range 0.3-1.0 microm, to distinguish between free diffusion of a protein molecule and diffusion of proteins restricted to a rapidly diffusing small domain. Both analyses show that motion is predominantly Brownian. This study finds no strong evidence for significant confinement of either GPI-linked or native I-E(k) in the plasma membrane of CHO cells. PMID:12414700

  18. HLA-DO as the Optimizer of Epitope Selection for MHC Class II Antigen Presentation

    PubMed Central

    Poluektov, Yuri O.; Kim, AeRyon; Hartman, Isamu Z.; Sadegh-Nasseri, Scheherazade

    2013-01-01

    Processing of antigens for presentation to helper T cells by MHC class II involves HLA-DM (DM) and HLA-DO (DO) accessory molecules. A mechanistic understanding of DO in this process has been missing. The leading model on its function proposes that DO inhibits the effects of DM. To directly study DO functions, we designed a recombinant soluble DO and expressed it in insect cells. The kinetics of binding and dissociation of several peptides to HLA-DR1 (DR1) molecules in the presence of DM and DO were measured. We found that DO reduced binding of DR1 to some peptides, and enhanced the binding of some other peptides to DR1. Interestingly, these enhancing and reducing effects were observed in the presence, or absence, of DM. We found that peptides that were negatively affected by DO were DM-sensitive, whereas peptides that were enhanced by DO were DM-resistant. The positive and negative effects of DO could only be measured on binding kinetics as peptide dissociation kinetics were not affected by DO. Using Surface Plasmon Resonance, we demonstrate direct binding of DO to a peptide-receptive, but not a closed conformation of DR1. We propose that DO imposes another layer of control on epitope selection during antigen processing. PMID:23951115

  19. [Cloning and expression of MHC class I chain-related gene A in E. coli].

    PubMed

    He, Yan-Ming; Tao, Su-Dan; Ying, Yan-Ling; Zhu, Fa-Ming; Lü, Hang-Jun; Yan, Li-Xing

    2010-10-01

    In order to construct prokaryotic expression system of MHC classI chain-related gene A (mica) and purify MICA protein, RNAs were extracted from the peripheral blood samples and mica cDNA fragments were obtained by RT-PCR method. The cDNA for mica was ligated with cloning vector by TOPO method. The recombinant cloning vector and prokaryotic expression vector pET-28a were digested by two restriction enzymes and ligated to construct pET-28a-MICA recombinant expression vector, then the pET-28a-MICA vector was transformed and expressed in E. coli BL21 DE3. The recombinant protein was purified by Ni-NTA Spin method. The results showed that the recombinant MICA protein expressed with soluble form in host with pET-28a-MICA vector after IPTG induction. The recombinant target protein was obtained by Ni-NTA spin purification. In conclusion, this study has constructed prokaryotic expression system of mica gene and has purified MICA protein which would help to explore the interaction between MICA and transplantation immunology.

  20. Ubiquitin-mediated fluctuations in MHC class II facilitate efficient germinal center B cell responses

    PubMed Central

    McGowan, Simon J.; Ersching, Jonatan; Ishido, Satoshi; Victora, Gabriel D.; Shin, Jeoung-Sook

    2016-01-01

    Antibody affinity maturation occurs in germinal centers (GCs) through iterative rounds of somatic hypermutation and selection. Selection involves B cells competing for T cell help based on the amount of antigen they capture and present on their MHC class II (MHCII) proteins. How GC B cells are able to rapidly and repeatedly transition between mutating their B cell receptor genes and then being selected shortly after is not known. We report that MHCII surface levels and degradation are dynamically regulated in GC B cells. Through ectopic expression of a photoconvertible MHCII-mKikGR chimeric gene, we found that individual GC B cells differed in the rates of MHCII protein turnover. Fluctuations in surface MHCII levels were dependent on ubiquitination and the E3 ligase March1. Increases in March1 expression in centroblasts correlated with decreases in surface MHCII levels, whereas CD83 expression in centrocytes helped to stabilize MHCII at that stage. Defects in MHCII ubiquitination caused GC B cells to accumulate greater amounts of a specific peptide–MHCII (pMHCII), suggesting that MHCII turnover facilitates the replacement of old complexes. We propose that pMHCII complexes are periodically targeted for degradation in centroblasts to favor the presentation of recently acquired antigens, thereby promoting the fidelity and efficiency of selection. PMID:27162138

  1. A novel HURRAH protocol reveals high numbers of monomorphic MHC class II loci and two asymmetric multi-locus haplotypes in the Père David's deer.

    PubMed

    Wan, Qiu-Hong; Zhang, Pei; Ni, Xiao-Wei; Wu, Hai-Long; Chen, Yi-Yan; Kuang, Ye-Ye; Ge, Yun-Fa; Fang, Sheng-Guo

    2011-01-18

    The Père David's deer is a highly inbred, but recovered, species, making it interesting to consider their adaptive molecular evolution from an immunological perspective. Prior to this study, genomic sequencing was the only method for isolating all functional MHC genes within a certain species. Here, we report a novel protocol for isolating MHC class II loci from a species, and its use to investigate the adaptive evolution of this endangered deer at the level of multi-locus haplotypes. This protocol was designated "HURRAH" based on its various steps and used to estimate the total number of MHC class II loci. We confirmed the validity of this novel protocol in the giant panda and then used it to examine the Père David's deer. Our results revealed that the Père David's deer possesses nine MHC class II loci and therefore has more functional MHC class II loci than the eight genome-sequenced mammals for which full MHC data are currently available. This could potentially account at least in part for the strong survival ability of this species in the face of severe bottlenecking. The results from the HURRAH protocol also revealed that: (1) All of the identified MHC class II loci were monomorphic at their antigen-binding regions, although DRA was dimorphic at its cytoplasmic tail; and (2) these genes constituted two asymmetric functional MHC class II multi-locus haplotypes: DRA1*01 ∼ DRB1 ∼ DRB3 ∼ DQA1 ∼ DQB2 (H1) and DRA1*02 ∼ DRB2 ∼ DRB4 ∼ DQA2 ∼ DQB1 (H2). The latter finding indicates that the current members of the deer species have lost the powerful ancestral MHC class II haplotypes of nine or more loci, and have instead fixed two relatively weak haplotypes containing five genes. As a result, the Père David's deer are currently at risk for increased susceptibility to infectious pathogens.

  2. P2X7 Receptor Activation Impairs Exogenous MHC Class I Oligopeptides Presentation in Antigen Presenting Cells

    PubMed Central

    Baroja-Mazo, Alberto; Barberà-Cremades, Maria; Pelegrín, Pablo

    2013-01-01

    Major histocompatibility complex class I (MHC I) on antigen presenting cells (APCs) is a potent molecule to activate CD8+ T cells and initiate immunity. P2X7 receptors (P2X7Rs) are present on the plasma membrane of APCs to sense the extracellular danger signal adenosine-5′-triphosphate (ATP). P2X7R activates the inflammasome and the release of IL-1β in macrophages and other immune cells to initiate the inflammatory response. Here we show that P2X7R stimulation by ATP in APCs decreased the amount of MHC I at the plasma membrane. Specific antagonism or genetic ablation of P2X7R inhibited the effects of ATP on levels of cellular MHC I. Furthermore, P2X7R stimulation was able to inhibit activation of CD8+ T cells via specific MHC I-oligopeptide complexes. Our study suggests that P2X7R activation on APCs is a novel inhibitor of adaptive CD8+ T cell immunity. PMID:23940597

  3. Self-adjuvanted nanovaccine for cancer immunotherapy: Role of lysosomal rupture-induced ROS in MHC class I antigen presentation.

    PubMed

    Wang, Ce; Li, Ping; Liu, Lanlan; Pan, Hong; Li, Hongchang; Cai, Lintao; Ma, Yifan

    2016-02-01

    MHC class I (MHC I) antigen presentation of exogenous antigens (so called "cross presentation") is a central mechanism of CD8(+) cytotoxic T lymphocyte (CTL) responses essential for successful vaccine-based cancer immunotherapy. The present study constructed amphiphilic pH-sensitive galactosyl dextran-retinal (GDR) nanogels for cancer vaccine delivery, in which dextran was conjugated with all-trans retinal (a metabolite of vitamin A) through a pH-sensitive hydrazone bond, followed by galactosylation to acquire dendritic cell (DC)-targeting ability. Our results showed that pH-sensitive GDR nanogel was a self-adjuvanted vaccine carrier that not only promoted DC maturation through activating retinoic acid receptor (RAR) signaling, but also facilitated antigen uptake and cytosolic antigen release in DCs. Furthermore, pH-sensitive GDR nanogel effectively augmented MHC I antigen presentation and evoked potent anti-cancer immune responses in vivo. More importantly, we first reported that nanoparticle-triggered lysosome rupture could directly induce ROS production in DCs, which was found to be essential for augmenting proteasome activity and downstream MHC I antigen presentation. Hence, DC-targeted pH-sensitive GDR nanogels could be a potent delivery system for cancer vaccine development. Triggering lyososomal rupture in DCs with pH-sensitive nanoparticles might be a plausible strategy to elevate intracellular ROS production for promoting antigen cross presentation, thereby improving cancer vaccine efficacy.

  4. Translating DRiPs: progress in understanding viral and cellular sources of MHC class I peptide ligands

    PubMed Central

    Dolan, Brian P.; Bennink, Jack R.

    2012-01-01

    It has been 15 years since we proposed the defective ribosomal product (DRiP) hypothesis to explain the rapid presentation of viral peptides by MHC class I molecules on the surface of infected cells. Here, we review the evidence for the contribution of DRiPs to antigen processing, pointing to the uncertainties regarding the physical nature of DRiPs, and emphasizing recent findings suggesting that peptide generation is a specialized process involving compartmentalized translation. PMID:21416150

  5. Metastatic MHC class I-negative mouse cells derived by transformation with human papillomavirus type 16

    PubMed Central

    Šmahel, M; Sobotková, E; Bubeník, J; Šímová, J; Žák, R; Ludvíková, V; Hájková, R; Kovařík, J; Jelínek, F; Povýšil, C; Marinov, J; Vonka, V

    2001-01-01

    In the endeavour to develop a model for studying gene therapy of cancers associated with human papillomaviruses (HPVs), mouse cells were transformed with the HPV type 16 (HPV16) and activated H-ras oncogenes. This was done by contransfection of plasmid p16HHMo, carrying the HPV16 E6/E7 oncogenes, and plasmid pEJ6.6, carrying the gene coding for human H-ras oncoprotein activated by G12V mutation, into secondary C57BL/6 mouse kidney cells. An oncogenic cell line, designated MK16/1/IIIABC, was derived. The epithelial origin of the cells was confirmed by their expression of cytokeratins. No MHC class I and class II molecules were detected on the surface of MK16/1/IIIABC cells. Spontaneous metastases were observed in lymphatic nodes and lungs after prolonged growth of MK16/1/IIIABC-induced subcutaneous tumours. Lethally irradiated MK16/1/IIIABC cells induced protection against challenge with 105homologous cells, but not against a higher cell dose (5 × 105). Plasmids p16HHMo and pEJ6.6 were also used for preventive immunization of mice. In comparison with a control group injected with pBR322, they exhibited moderate protection, in terms of prolonged survival, against MK16/1/IIIABC challenge (P< 0.03). These data suggest that MK16/1/IIIABC cells may serve as a model for studying immune reactions against HPV16-associated human tumours. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11225590

  6. Insights into MHC class I peptide loading from the structure of the tapasin/ERp57 heterodimer

    PubMed Central

    Dong, Gang; Wearsch, Pamela A.; Peaper, David R.; Cresswell, Peter; Reinisch, Karin M.

    2009-01-01

    SUMMARY Tapasin is a glycoprotein critical for loading Major Histocompatibility Complex (MHC) class I molecules with high affinity peptides. It functions within the multimeric peptide-loading complex (PLC) as a disulfide-linked, stable heterodimer with the thiol oxidoreductase ERp57, and this covalent interaction is required to support optimal PLC activity. Here we present the 2.6 Å resolution structure of the tapasin/ERp57 core of the PLC. The structure reveals the basis for the stable dimerization of tapasin and ERp57 and provides the first example of a protein disulfide isomerase family member interacting with a substrate. Mutational analysis identified a conserved surface on tapasin that interacts with MHC class I molecules and is critical for the peptide loading and editing function of the tapasin-ERp57 heterodimer. By combining the tapasin/ERp57 structure with those of other defined PLC components we present a molecular model that illuminates the processes involved in MHC class I peptide loading. PMID:19119025

  7. Autophagy and proteasome interconnect to coordinate cross-presentation through MHC class I pathway in B cells.

    PubMed

    Dasari, Vijayendra; Rehan, Sweera; Tey, Siok-Keen; Smyth, Mark J; Smith, Corey; Khanna, Rajiv

    2016-11-01

    Cross-presentation of exogenous protein antigens by B cells through the major histocompatibility complex (MHC) class I pathway in lymphoid malignancies, and transplant setting has been recognised as an important mediator of immune pathogenesis and T cell-mediated immune regulation. However, the precise mechanism of cross-presentation of exogenous antigens in B cells has remained unresolved. Here we have delineated a novel pathway for cross-presentation in B cells, which involves synergistic cooperation of the proteasome and autophagy. After endocytosis, protein antigen is processed through an autophagy- and proteasome-dependent pathway and CD8(+) T-cell epitopes are loaded onto MHC class I molecules within the autophagolysomal compartment rather than the conventional secretory pathway, which requires transporters associated with antigen processing-dependent transport. Interestingly, this cross-presentation was critically dependent on valosin-containing protein (VCP)/p97 ATPase through its participation in autophagy. Loss of VCP/p97 ATPase was coincident with accumulation of LC3-II and marked reduction in antigen presentation. These observations provide unique insight on how the autophagy and proteasomal degradation systems interconnect to coordinate MHC class I-restricted cross-presentation in B cells.

  8. PPE38 Protein of Mycobacterium tuberculosis Inhibits Macrophage MHC Class I Expression and Dampens CD8+ T Cell Responses

    PubMed Central

    Meng, Lu; Tong, Jingfeng; Wang, Hui; Tao, Chengwu; Wang, Qinglan; Niu, Chen; Zhang, Xiaoming; Gao, Qian

    2017-01-01

    Suppression of CD8+ T cell activation is a critical mechanism used by Mycobacterium tuberculosis (MTB) to escape protective host immune responses. PPE38 belongs to the unique PPE family of MTB and in our previous study, PPE38 protein was speculated to participate in manipulating macrophage MHC class I pathway. To test this hypothesis, the function of mycobacterial PPE38 protein was assessed here using macrophage and mouse infection models. Decreased amount of MHC class I was observed on the surface of macrophages infected with PPE38-expressing mycobacteria. The transcript of genes encoding MHC class I was also inhibited by PPE38. After infection of C57BL/6 mice with Mycobacterium smegmatis expressing PPE38 (Msmeg-PPE38), decreased number of CD8+ T cells was found in spleen, liver, and lungs through immunohistochemical analysis, comparing to the control strain harboring empty vector (Msmeg-V). Consistently, flow cytometry assay showed that fewer effector/memory CD8+ T cells (CD44highCD62Llow) were activated in spleen from Msmeg-PPE38 infected mice. Moreover, Msmeg-PPE38 confers a growth advantage over Msmeg-V in C57BL/6 mice, indicating an effect of PPE38 to favor mycobacterial persistence in vivo. Overall, this study shows a unique biological function of PPE38 protein to facilitate mycobacteria to escape host immunity, and provides hints for TB vaccine development. PMID:28348981

  9. Insights into MHC class I peptide loading from the structure of the Tapasin-ERp57 thiol oxidoreductase heterodimer

    SciTech Connect

    Dong, G.; Wearsch, P.A.; Peaper, D.R.; Cresswell, P.; Reinisch, K.M.

    2009-03-02

    Tapasin is a glycoprotein critical for loading major histocompatibility complex (MHC) class I molecules with high-affinity peptides. It functions within the multimeric peptide-loading complex (PLC) as a disulfide-linked, stable heterodimer with the thiol oxidoreductase ERp57, and this covalent interaction is required to support optimal PLC activity. Here, we present the 2.6 {angstrom} resolution structure of the tapasin-ERp57 core of the PLC. The structure revealed that tapasin interacts with both ERp57 catalytic domains, accounting for the stability of the heterodimer, and provided an example of a protein disulfide isomerase family member interacting with substrate. Mutational analysis identified a conserved surface on tapasin that interacted with MHC class I molecules and was critical for peptide loading and editing functions of the tapasin-ERp57 heterodimer. By combining the tapasin-ERp57 structure with those of other defined PLC components, we present a molecular model that illuminates the processes involved in MHC class I peptide loading.

  10. Semi-empirical quantum evaluation of peptide - MHC class II binding

    NASA Astrophysics Data System (ADS)

    González, Ronald; Suárez, Carlos F.; Bohórquez, Hugo J.; Patarroyo, Manuel A.; Patarroyo, Manuel E.

    2017-01-01

    Peptide presentation by the major histocompatibility complex (MHC) is a key process for triggering a specific immune response. Studying peptide-MHC (pMHC) binding from a structural-based approach has potential for reducing the costs of investigation into vaccine development. This study involved using two semi-empirical quantum chemistry methods (PM7 and FMO-DFTB) for computing the binding energies of peptides bonded to HLA-DR1 and HLA-DR2. We found that key stabilising water molecules involved in the peptide binding mechanism were required for finding high correlation with IC50 experimental values. Our proposal is computationally non-intensive, and is a reliable alternative for studying pMHC binding interactions.

  11. Modulation of MHC class II transport and lysosome distribution by macrophage-colony stimulating factor in human dendritic cells derived from monocytes.

    PubMed

    Baron, C; Raposo, G; Scholl, S M; Bausinger, H; Tenza, D; Bohbot, A; Pouillart, P; Goud, B; Hanau, D; Salamero, J

    2001-03-01

    The macrophage-colony stimulating factor (M-CSF) has been already shown to affect the function of dendritic cells (DC). Therefore, the differentiation of dendritic cells into macrophages (M(PHI)) might represent a pathway which could inhibit the immune response initiated by DC. Because Major Histocompatibility Complex class II molecules (MHC-II) are crucial for DC function, we asked whether M-CSF may influence the intracellular transport of MHC-II in monocyte derived DC. We found that, at early stages, M-CSF induced first a rapid redistribution of MHC-II from the MHC-II containing compartments (MIIC) to the plasma membrane and second an increase in MHC-II synthesis as observed with LPS or TNF-(alpha). These processes were associated with the sorting of MHC-II from lysosomal membranes which underwent a drastic structural reorganization. However, in contrast to tumor necrosis factor (TNF)-(alpha) or lipopolysaccharide (LPS), M-CSF neither potentiated the allostimulatory function of DC nor allowed the stabilization of MHC-II at the cell surface, but rather increased MHC-II turnover. We conclude that the rapid modulation of MHC-II transport and distribution may participate in the inhibitory effect of M-CSF on DC function and differentiation.

  12. Signal peptide-dependent inhibition of MHC class I heavy chain translation by rhesus cytomegalovirus.

    PubMed

    Powers, Colin J; Früh, Klaus

    2008-10-03

    The US2-11 region of human and rhesus cytomegalovirus encodes a conserved family of glycoproteins that inhibit MHC-I assembly with viral peptides, thus preventing cytotoxic T cell recognition. Since HCMV lacking US2-11 is no longer able to block assembly and transport of MHC-I, we examined whether this is also observed for RhCMV lacking the corresponding region. Unexpectedly, recombinant RhCMV lacking US2-11 was still able to inhibit MHC-I expression in infected fibroblasts, suggesting the presence of an additional MHC-I evasion mechanism. Progressive deletion analysis of RhCMV-specific genomic regions revealed that MHC-I expression is fully restored upon additional deletion of rh178. The protein encoded by this RhCMV-specific open reading frame is anchored in the endoplasmic reticulum membrane. In the presence of rh178, RhCMV prevented MHC-I heavy chain (HC) expression, but did not inhibit mRNA transcription or association of HC mRNA with translating ribosomes. Proteasome inhibitors stabilized a HC degradation intermediate in the absence of rh178, but not in its presence, suggesting that rh178 prevents completion of HC translation. This interference was signal sequence-dependent since replacing the signal peptide with that of CD4 or murine HC rendered human HCs resistant to rh178. We have identified an inhibitor of antigen presentation encoded by rhesus cytomegalovirus unique in both its lack of homology to any other known protein and in its mechanism of action. By preventing signal sequence-dependent HC translocation, rh178 acts prior to US2, US3 and US11 which attack MHC-I proteins after protein synthesis is completed. Rh178 is the first viral protein known to interfere at this step of the MHC-I pathway, thus taking advantage of the conserved nature of HC leader peptides, and represents a new mechanism of translational interference.

  13. Association of HLA-A and Non-Classical HLA Class I Alleles

    PubMed Central

    Carlini, Federico; Ferreira, Virginia; Buhler, Stéphane; Tous, Audrey; Eliaou, Jean-François; René, Céline; Chiaroni, Jacques; Picard, Christophe; Di Cristofaro, Julie

    2016-01-01

    The HLA-A locus is surrounded by HLA class Ib genes: HLA-E, HLA-H, HLA-G and HLA-F. HLA class Ib molecules are involved in immuno-modulation with a central role for HLA-G and HLA-E, an emerging role for HLA-F and a yet unknown function for HLA-H. Thus, the principal objective of this study was to describe the main allelic associations between HLA-A and HLA-H, -G, -F and -E. Therefore, HLA-A, -E, -G, -H and -F coding polymorphisms, as well as HLA-G UnTranslated Region haplotypes (referred to as HLA-G UTRs), were explored in 191 voluntary blood donors. Allelic frequencies, Global Linkage Disequilibrium (GLD), Linkage Disequilibrium (LD) for specific pairs of alleles and two-loci haplotype frequencies were estimated. We showed that HLA-A, HLA-H, HLA-F, HLA-G and HLA-G UTRs were all in highly significant pairwise GLD, in contrast to HLA-E. Moreover, HLA-A displayed restricted associations with HLA-G UTR and HLA-H. We also confirmed several associations that were previously found to have a negative impact on transplantation outcome. In summary, our results suggest complex functional and clinical implications of the HLA-A genetic region. PMID:27701438

  14. Patterns of genetic differentiation at MHC class I genes and microsatellites identify conservation units in the giant panda

    PubMed Central

    2013-01-01

    Background Evaluating patterns of genetic variation is important to identify conservation units (i.e., evolutionarily significant units [ESUs], management units [MUs], and adaptive units [AUs]) in endangered species. While neutral markers could be used to infer population history, their application in the estimation of adaptive variation is limited. The capacity to adapt to various environments is vital for the long-term survival of endangered species. Hence, analysis of adaptive loci, such as the major histocompatibility complex (MHC) genes, is critical for conservation genetics studies. Here, we investigated 4 classical MHC class I genes (Aime-C, Aime-F, Aime-I, and Aime-L) and 8 microsatellites to infer patterns of genetic variation in the giant panda (Ailuropoda melanoleuca) and to further define conservation units. Results Overall, we identified 24 haplotypes (9 for Aime-C, 1 for Aime-F, 7 for Aime-I, and 7 for Aime-L) from 218 individuals obtained from 6 populations of giant panda. We found that the Xiaoxiangling population had the highest genetic variation at microsatellites among the 6 giant panda populations and higher genetic variation at Aime-MHC class I genes than other larger populations (Qinling, Qionglai, and Minshan populations). Differentiation index (FST)-based phylogenetic and Bayesian clustering analyses for Aime-MHC-I and microsatellite loci both supported that most populations were highly differentiated. The Qinling population was the most genetically differentiated. Conclusions The giant panda showed a relatively higher level of genetic diversity at MHC class I genes compared with endangered felids. Using all of the loci, we found that the 6 giant panda populations fell into 2 ESUs: Qinling and non-Qinling populations. We defined 3 MUs based on microsatellites: Qinling, Minshan-Qionglai, and Daxiangling-Xiaoxiangling-Liangshan. We also recommended 3 possible AUs based on MHC loci: Qinling, Minshan-Qionglai, and Daxiangling

  15. Characterization of the Antigen Processing Machinery and Endogenous Peptide Presentation of a Bat MHC Class I Molecule.

    PubMed

    Wynne, James W; Woon, Amanda P; Dudek, Nadine L; Croft, Nathan P; Ng, Justin H J; Baker, Michelle L; Wang, Lin-Fa; Purcell, Anthony W

    2016-06-01

    Bats are a major reservoir of emerging and re-emerging infectious diseases, including severe acute respiratory syndrome-like coronaviruses, henipaviruses, and Ebola virus. Although highly pathogenic to their spillover hosts, bats harbor these viruses, and a large number of other viruses, with little or no clinical signs of disease. How bats asymptomatically coexist with these viruses is unknown. In particular, little is known about bat adaptive immunity, and the presence of functional MHC molecules is mostly inferred from recently described genomes. In this study, we used an affinity purification/mass spectrometry approach to demonstrate that a bat MHC class I molecule, Ptal-N*01:01, binds antigenic peptides and associates with peptide-loading complex components. We identified several bat MHC class I-binding partners, including calnexin, calreticulin, protein disulfide isomerase A3, tapasin, TAP1, and TAP2. Additionally, endogenous peptide ligands isolated from Ptal-N*01:01 displayed a relatively broad length distribution and an unusual preference for a C-terminal proline residue. Finally, we demonstrate that this preference for C-terminal proline residues was observed in Hendra virus-derived peptides presented by Ptal-N*01:01 on the surface of infected cells. To our knowledge, this is the first study to identify endogenous and viral MHC class I ligands for any bat species and, as such, provides an important avenue for monitoring and development of vaccines against major bat-borne viruses both in the reservoir and spillover hosts. Additionally, it will provide a foundation to understand the role of adaptive immunity in bat antiviral responses.

  16. Distribution of CD163-positive cell and MHC class II-positive cell in the normal equine uveal tract

    PubMed Central

    SANO, Yuto; MATSUDA, Kazuya; OKAMOTO, Minoru; TAKEHANA, Kazushige; HIRAYAMA, Kazuko; TANIYAMA, Hiroyuki

    2015-01-01

    Antigen-presenting cells (APCs) in the uveal tract participate in ocular immunity including immune homeostasis and the pathogenesis of uveitis. In horses, although uveitis is the most common ocular disorder, little is known about ocular immunity, such as the distribution of APCs. In this study, we investigated the distribution of CD163-positive and MHC II-positive cells in the normal equine uveal tract using an immunofluorescence technique. Eleven eyes from 10 Thoroughbred horses aged 1 to 24 years old were used. Indirect immunofluorescence was performed using the primary antibodies CD163, MHC class II (MHC II) and CD20. To demonstrate the site of their greatest distribution, positive cells were manually counted in 3 different parts of the uveal tract (ciliary body, iris and choroid), and their average number was assessed by statistical analysis. The distribution of pleomorphic CD163- and MHC II-expressed cells was detected throughout the equine uveal tract, but no CD20-expressed cells were detected. The statistical analysis demonstrated the distribution of CD163- and MHC II-positive cells focusing on the ciliary body. These results demonstrated that the ciliary body is the largest site of their distribution in the normal equine uveal tract, and the ciliary body is considered to play important roles in uveal and/or ocular immune homeostasis. The data provided in this study will help further understanding of equine ocular immunity in the normal state and might be beneficial for understanding of mechanisms of ocular disorders, such as equine uveitis. PMID:26537548

  17. Bacterial Superantigens Promote Acute Nasopharyngeal Infection by Streptococcus pyogenes in a Human MHC Class II-Dependent Manner

    PubMed Central

    Kasper, Katherine J.; Zeppa, Joseph J.; Wakabayashi, Adrienne T.; Xu, Stacey X.; Mazzuca, Delfina M.; Welch, Ian; Baroja, Miren L.; Kotb, Malak; Cairns, Ewa; Cleary, P. Patrick; Haeryfar, S. M. Mansour; McCormick, John K.

    2014-01-01

    Establishing the genetic determinants of niche adaptation by microbial pathogens to specific hosts is important for the management and control of infectious disease. Streptococcus pyogenes is a globally prominent human-specific bacterial pathogen that secretes superantigens (SAgs) as ‘trademark’ virulence factors. SAgs function to force the activation of T lymphocytes through direct binding to lateral surfaces of T cell receptors and class II major histocompatibility complex (MHC-II) molecules. S. pyogenes invariably encodes multiple SAgs, often within putative mobile genetic elements, and although SAgs are documented virulence factors for diseases such as scarlet fever and the streptococcal toxic shock syndrome (STSS), how these exotoxins contribute to the fitness and evolution of S. pyogenes is unknown. Here we show that acute infection in the nasopharynx is dependent upon both bacterial SAgs and host MHC-II molecules. S. pyogenes was rapidly cleared from the nasal cavity of wild-type C57BL/6 (B6) mice, whereas infection was enhanced up to ∼10,000-fold in B6 mice that express human MHC-II. This phenotype required the SpeA superantigen, and vaccination with an MHC –II binding mutant toxoid of SpeA dramatically inhibited infection. Our findings indicate that streptococcal SAgs are critical for the establishment of nasopharyngeal infection, thus providing an explanation as to why S. pyogenes produces these potent toxins. This work also highlights that SAg redundancy exists to avoid host anti-SAg humoral immune responses and to potentially overcome host MHC-II polymorphisms. PMID:24875883

  18. Human epidermal Langerhans cells cointernalize by receptor-mediated endocytosis "nonclassical" major histocompatibility complex class I molecules (T6 antigens) and class II molecules (HLA-DR antigens).

    PubMed Central

    Hanau, D; Fabre, M; Schmitt, D A; Garaud, J C; Pauly, G; Tongio, M M; Mayer, S; Cazenave, J P

    1987-01-01

    HLA-DR and T6 surface antigens are expressed only by Langerhans cells and indeterminate cells in normal human epidermis. We have previously demonstrated that T6 antigens are internalized in Langerhans cells and indeterminate cells by receptor-mediated endocytosis. This process is induced by the binding of BL6, a monoclonal antibody directed against T6 antigens. In the present study, using a monoclonal antibody directed against HLA-DR antigens, on human epidermal cells in suspension, we show that the surface HLA-DR antigens are also internalized by receptor-mediated endocytosis in Langerhans and indeterminate cells. Moreover, using immunogold double labeling, we demonstrate that T6 and HLA-DR antigens are internalized through common coated regions of the membrane of Langerhans or indeterminate cells. The receptor-mediated endocytosis that is induced involves coated pits and vesicles, receptosomes, lysosomes, and also, in Langerhans cells, the Birbeck granules. Thus, T6 antigens, which are considered to be "unusual" or "nonclassical" major histocompatibility complex class I molecules, and the major histocompatibility complex class II molecules, HLA-DR, are internalized in Langerhans and indeterminate cells through common receptor-mediated endocytosis organelles. Images PMID:3106979

  19. Characterization of bovine MHC class II DRB3 diversity in South American Holstein cattle populations.

    PubMed

    Takeshima, S-N; Giovambattista, G; Okimoto, N; Matsumoto, Y; Rogberg-Muñoz, A; Acosta, T J; Onuma, M; Aida, Y

    2015-12-01

    Holstein cattle dominate the global milk production industry because of their outstanding milk production, however, this breed is susceptible to tropical endemic pathogens and suffers from heat stress and thus fewer Holstein populations are raised in tropical areas. The bovine major histocompatibility complex (BoLA)-DRB3 class II gene is used as a marker for disease and immunological traits, and its polymorphism has been studied extensively in Holstein cattle from temperate and cold regions. We studied the genetic diversity of the BoLA-DRB3 gene in South American Holstein populations to determine whether tropical populations have diverged from those bred in temperate and cold regions by selection and/or crossbreeding with local native breeds. We specifically studied Exon 2 of this gene from 855 South American Holstein individuals by a polymerase chain reaction (PCR) sequence-based typing method. We found a high degree of gene diversity at the allelic (Na > 20 and He > 0.87) and molecular (π > 0.080) levels, but a low degree of population structure (FST = 0.009215). A principal components analysis and tree showed that the Bolivian subtropical population had the largest genetic divergence compared with Holsteins bred in temperate or cold regions, and that this population was closely related to Bolivian Creole cattle. Our results suggest that Holstein genetic divergence can be explained by selection and/or gene introgression from local germplasms. This is the first examination of BoLA-DRB3 in Holsteins adapted to tropical environments, and contributes to an ongoing effort to catalog bovine MHC allele frequencies by breed and location.

  20. Human cytomegalovirus alters localization of MHC class II and dendrite morphology in mature Langerhans cells.

    PubMed

    Lee, Andrew W; Hertel, Laura; Louie, Ryan K; Burster, Timo; Lacaille, Vashti; Pashine, Achal; Abate, Davide A; Mocarski, Edward S; Mellins, Elizabeth D

    2006-09-15

    Hemopoietic stem cell-derived mature Langerhans-type dendritic cells (LC) are susceptible to productive infection by human CMV (HCMV). To investigate the impact of infection on this cell type, we examined HLA-DR biosynthesis and trafficking in mature LC cultures exposed to HCMV. We found decreased surface HLA-DR levels in viral Ag-positive as well as in Ag-negative mature LC. Inhibition of HLA-DR was independent of expression of unique short US2-US11 region gene products by HCMV. Indeed, exposure to UV-inactivated virus, but not to conditioned medium from infected cells, was sufficient to reduce HLA-DR on mature LC, implicating particle binding/penetration in this effect. Reduced surface levels reflected an altered distribution of HLA-DR because total cellular HLA-DR was not diminished. Accumulation of HLA-DR was not explained by altered cathepsin S activity. Mature, peptide-loaded HLA-DR molecules were retained within cells, as assessed by the proportion of SDS-stable HLA-DR dimers. A block in egress was implicated, as endocytosis of surface HLA-DR was not increased. Immunofluorescence microscopy corroborated the intracellular retention of HLA-DR and revealed markedly fewer HLA-DR-positive dendritic projections in infected mature LC. Unexpectedly, light microscopic analyses showed a dramatic loss of the dendrites themselves and immunofluorescence revealed that cytoskeletal elements crucial for the formation and maintenance of dendrites are disrupted in viral Ag-positive cells. Consistent with these dendrite effects, HCMV-infected mature LC exhibit markedly reduced chemotaxis in response to lymphoid chemokines. Thus, HCMV impedes MHC class II molecule trafficking, dendritic projections, and migration of mature LC. These changes likely contribute to the reduced activation of CD4+ T cells by HCMV-infected mature LC.

  1. MMTV superantigens coerce an unconventional topology between the TCR and MHC class II.

    PubMed

    Fortin, Jean-Simon; Genève, Laetitia; Gauthier, Catherine; Shoukry, Naglaa H; Azar, Georges A; Younes, Souheil; Yassine-Diab, Bader; Sékaly, Rafick-Pierre; Fremont, Daved H; Thibodeau, Jacques

    2014-02-15

    Mouse mammary tumor virus superantigens (vSAGs) are notorious for defying structural characterization, and a consensus has yet to be reached regarding their ability to bridge the TCR to MHC class II (MHCII). In this study, we determined the topology of the T cell signaling complex by examining the respective relation of vSAG7 with the MHCII molecule, MHCII-associated peptide, and TCR. We used covalently linked peptide/MHCII complexes to demonstrate that vSAG presentation is tolerant to variation in the protruding side chains of the peptide, but can be sensitive to the nature of the protruding N-terminal extension. An original approach in which vSAG was covalently linked to either MHCII chain confirmed that vSAG binds outside the peptide binding groove. Also, whereas the C-terminal vSAG segment binds to the MHCII α-chain in a conformation-sensitive manner, the membrane-proximal N-terminal domain binds the β-chain. Because both moieties of the mature vSAG remain noncovalently associated after processing, our results suggest that vSAG crosslinks MHCII molecules. Comparing different T cell hybridomas, we identified key residues on the MHCII α-chain that are differentially recognized by the CDR3β when engaged by vSAG. Finally, we show that the highly conserved tyrosine residue found in the vSAg TGXY motif is required for T cell activation. Our results reveal a novel SAG/MHCII/TCR architecture in which vSAGs coerce a near-canonical docking between MHCII and TCR that allows eschewing of traditional CDR3 binding with the associated peptide in favor of MHCII α-chain binding. Our findings highlight the plasticity of the TCR CDRs.

  2. Evolutionary origins of retroposon lineages of Mhc class II Ab alleles.

    PubMed

    Lu, C C; Ye, Y; She, J X; Bonhomme, F; Wakeland, E K

    1996-01-01

    Major histocompatibility complex (Mhc) class II Ab genes have evolved into three distinct lineages. While lineage 2 alleles differ from lineage 1 alleles by the insertion of a retroposon in intron 2, the basis for the extremely large intron 2 in lineage 3 alleles has heretofore been undetermined. In this report, we demonstrate by nucleotide sequencing that the genomic sequences of prototypic alleles from all three lineages diverge significantly and that lineage 3 is derived from lineage 2 by two insertional events in intron 2. One insert, composed of a member of B1 short interspersed repetitive elements (SINEs), occurs 508 base pairs (bp) 3' of exon 2, and the other, 1141 bp 3' of exon 2 within the retroposon that distinguishes lineage 2 from lineage 1. To assess the evolutionary stability of these lineages and the extent of ancestral polymorphisms of Ab within Mus species, we extended our restriction site polymorphism analysis to include 86 alleles from 120 independently derived H2 haplotypes from 12 separate species and subspecies of Mus. A phylogenetic tree revealing the relationships of these Ab alleles with respect to restriction site polymorphisms, but excluding the retroposon insertions, demonstrated that these lineages have distinctive genomic structures beyond the retroposon polymorphisms. In summary, these mouse Ab genes were produced from successive retroposon insertion events. Lineage 1 and 2 were detected in a variety of Mus species, including Mus caroli, indicating that these lineages diverged more than 2 million years ago. Lineage 3 alleles were found only in the Mus musculus subspecies, suggesting that it diverged from lineage 2 more recently. These results indicate that all three lineages of Ab have persisted through several speciation events in the genus Mus.

  3. Molecular characterization of MHC class II in a nonmodel anuran species, the fire-bellied toad Bombina bombina.

    PubMed

    Hauswaldt, J Susanne; Stuckas, H; Pfautsch, S; Tiedemann, R

    2007-06-01

    While the anuran Xenopus comprises one of the best characterized nonmammalian taxa regarding the major histocompatibility complex (MHC), the organization of this gene complex has never been studied in other anurans, and information on amphibian MHC (other than Xenopus) is generally very scarce. Here, we describe the characterization of the first MHC class II B cDNA sequences from a nonmodel anuran species, the European fire-bellied toad (Bombina bombina). We isolated two transcript sequences differing substantially in amino acid composition and length within the beta2 domain. To investigate the variability of the peptide binding region in this species, we sequenced a 158-bp large fragment from wild B. bombina (n = 20) and identified eight distinct alleles. All substitutions but one were nonsynonymous, and many of the highly polymorphic sites corresponded with amino acid positions known to be involved in antigen binding. The level of variation we found in B. bombina was similar compared to that previously found in a comparable sample of a wild urodelan species, Ambystoma tigrinum, and to that found in Xenopus laevis. Based on the cDNA data and the individual's allelic diversity, we conclude that Bombina possesses at least two class II B loci. With our new beta1 primers, we were able to generate sequences in other species of anurans. We provide here a first phylogenetic analysis of this gene in amphibians.

  4. MHC class II variation in the endangered European mink Mustela lutreola (L. 1761)--consequences for species conservation.

    PubMed

    Becker, L; Nieberg, C; Jahreis, K; Peters, E

    2009-04-01

    The polymorphic major histocompatibility complex (MHC) has gained a specific relevance in pathogen resistance and mate choice. Particularly the antigen-binding site (ABS), encoded by exon 2 of the DRB class II gene, exhibits numerous alleles and extensive sequence variations between alleles. A lack of MHC variability has attributed to instances such as bottleneck effects or relaxed selection pressure and has a certain impact on the long-term viability of the species concerned. As a result of seriously decreased population density during the last century, the current population of the endangered European mink (Mustela lutreola, L. 1761) has suffered from geographic isolation. In this study, we amplified a partial sequence of the MHC class II DRB exon 2 (229 bp), assessed the degree of genetic variation and compared the variability with those of other Mustelidae. As a result, nine alleles were detected in 20 investigated individuals, which differ from each other by four to 25 nucleotide substitutions (two to 11 amino acid substitutions). Whilst an equal ratio for synonymous and non-synonymous substitutions was found inside the ABS, synonymous substitutions were significantly higher than non-synonymous substitutions in the non-ABS region. Results might indicate that no positive selection exists within the ex situ population of M. lutreola, at least in the analysed fragment. In addition, phylogenetic analyses support the trans-species model of evolution.

  5. Human cytomegalovirus decreases constitutive transcription of MHC class II genes in mature Langerhans cells by reducing CIITA transcript levels.

    PubMed

    Lee, Andrew W; Wang, Nan; Hornell, Tara M C; Harding, James J; Deshpande, Chetan; Hertel, Laura; Lacaille, Vashti; Pashine, Achal; Macaubas, Claudia; Mocarski, Edward S; Mellins, Elizabeth D

    2011-05-01

    Human cytomegalovirus (HCMV) productively infects CD34(+) progenitor-derived, mature Langerhans-type dendritic cells (matLC) and reduces surface expression of MHC class II complexes (MHC II) by increasing intracellular retention of these molecules. To determine whether HCMV also inhibits MHC II expression by other mechanisms, we assessed mRNA levels of the class II transcriptional regulator, CIITA, and several of its target genes in infected matLC. Levels of CIITA, HLA-DRA (DRA) and DRB transcripts, and new DR protein synthesis were compared in mock-infected and HCMV-infected cells by quantitative PCR and pulse-chase immunoprecipitation analyses, respectively. CIITA mRNA levels were significantly lower in HCMV-infected matLC as compared to mock-infected cells. When assessed in the presence of Actinomycin D, the stability of CIITA transcripts was not diminished by HCMV. Analysis of promoter-specific CIITA isoforms revealed that types I, III and IV all were decreased by HCMV, a result that differs from changes after incubation of these cells with lipopolysaccharide (LPS). Exposure to UV-inactivated virus failed to reduce CIITA mRNA levels, implicating de novo viral gene expression in this effect. HCMV-infected matLC also expressed lower levels of DR transcripts and reduced DR protein synthesis rates compared to mock-infected matLC. In summary, we demonstrate that HCMV infection of a human dendritic cell subset inhibits constitutive CIITA expression, most likely at the transcriptional level, resulting in reduced MHC II biosynthesis. We suggest this represents a new mechanism of modulation of mature LC by HCMV.

  6. Evolution of Mhc Class i Complex Region with Special Reference to Fragmentary Line Sequences

    NASA Astrophysics Data System (ADS)

    Tateno, Yoshio; Fukami-Kobayashi, Kaoru; Inoko, Hidetoshi

    2008-03-01

    We reviewed the origin and evolution of the two pairs of immune genes, (MHC-B and MHC-C) and (MICA and MICB) in man, chimpanzee and rhesus monkey based mainly on our previous work. Since those genes were well known to have been subject to strong natural selection in evolution, they themselves were not suitable for our study. We thus took another approach to use fragmented and nonfunctional LINEs that had coevolved with the two pairs in the same genomic fragments. Our results showed that MHC-B and MHC-C duplicated about 22 Mry (million years) ago, and MICA and MICB duplicated about 14 Myr ago. Interestingly, rhesus monkey was found not to have either pair but many repeats similar to MHC-B. Therefore, we estimated the divergence time of the monkey, and found that it diverged out from a common ancestor of man and chimpanzee about 30 Myr ago. The divergence time was consistent with the duplication times of the two pairs of immune genes. Based on our results we would predict that orangutan and gorilla also have the two pairs, because the both primate species are considered to have diverged less than 14 Myr ago.

  7. Repression of MHC class I transcription by HPV16E7 through interaction with a putative RXR{beta} motif and NF-{kappa}B cytoplasmic sequestration

    SciTech Connect

    Li, Hui; Zhan, TaiLan; Li, Chang; Liu, Mugen; Wang, Qing K.

    2009-10-16

    Down-regulation of transcription of the MHC class I genes in HPV16 tumorigenic cells is partly due to HPV16E7 associated with the MHC class I promoter and repressed chromatin activation. In this study, we further demonstrated that HPV16E7 is physically associated with a putative RXR{beta} binding motif (GGTCA) of the proximal promoter of the MHC class I genes by using reporter transcriptional assays and chromatin immunoprecipitation assays. Our data also provide evidence that HPV16E7 inhibits TNF-{alpha}-induced up-regulation of MHC class I transcription by impaired nuclear translocation of NF-{kappa}B. More importantly, CaSki tumor cells treated with TSA and transfected with the constitutively active mutant form of IKK-{alpha} (which can activate NF-{kappa}B directly) showed a maximal level of up-regulation of MHC-I expression. Taken together, our results suggest that HPV16E7 may employ two independent mechanisms to ensure that either the constitutive or inducible transcription of MHC class I genes is down-regulated.

  8. Major histocompatibility complex class II (MHC II) expression during the development of human fetal cerebral occipital lobe, cerebellum, and hematopoietic organs.

    PubMed

    Wierzba-Bobrowicz, T; Kosno-Kruszewska, E; Gwiazda, E; Lechowicz, W

    2000-01-01

    In adults, under physiological conditions proteins of the major histocompatibility complex, class II (MHC II) molecules are synthesized and then presented on the surface of the cells known under a common name as antigen presenting cells (APCs). Dendritic cells (DCs), microglia, macrophages, ameboid microglia and lymphocytes B are qualified as APCs. The aim of present study was to evaluate the expression of MHC II molecules in the central nervous system (CNS) and hematopoietic organs during the fetal development. Observations were made on the cerebral occipital lobe, cerebellum, thymus, spleen and liver of 30 normal human fetuses, between 11 and 22 week of gestation (GW). Histological, histochemical and immunohistochemical techniques were used to identify cells with expression of MHC II molecules. In the brain, MHC II molecules were detected on macrophages/ameboid microglia in meninges, choroid plexus and single cells of ramified microglia in deeper layers of the cortex and white matter. In the other organs besides macrophages and dendritic cells, MHC II molecules were also immunopositive in thymic epithelial cells, and in the spleen and liver also in other cells of stroma and lobule. The expression of MHC II molecules on so extensive population of cells, at an early stage of the fetal development, may evidence their significant involvement in histogenesis and morphogenesis. It seems that in adults the complex of MHC II with protein is originated from the foreign antigen. On the contrary, during normal fetal development the complex of MHC II with protein origins most probably from the fetus own structures.

  9. Quantum chemical analysis explains hemagglutinin peptide-MHC Class II molecule HLA-DRbeta1*0101 interactions.

    PubMed

    Cárdenas, Constanza; Villaveces, José Luis; Bohórquez, Hugo; Llanos, Eugenio; Suárez, Carlos; Obregón, Mateo; Patarroyo, Manuel Elkin

    2004-10-29

    We present a new method to explore interactions between peptides and major histocompatibility complex (MHC) molecules using the resultant vector of the three principal multipole terms of the electrostatic field expansion. Being that molecular interactions are driven by electrostatic interactions, we applied quantum chemistry methods to better understand variations in the electrostatic field of the MHC Class II HLA-DRbeta1*0101-HA complex. Multipole terms were studied, finding strong alterations of the field in Pocket 1 of this MHC molecule, and weak variations in other pockets, with Pocket 1>Pocket 4>Pocket 9 approximately Pocket 7>Pocket 6. Variations produced by "ideal" amino acids and by other occupying amino acids were compared. Two types of interactions were found in all pockets: a strong unspecific one (global interaction) and a weak specific interaction (differential interaction). Interactions in Pocket 1, the dominant pocket for this allele, are driven mainly by the quadrupole term, confirming the idea that aromatic rings are important in these interactions. Multipolar analysis is in agreement with experimental results, suggesting quantum chemistry methods as an adequate methodology to understand these interactions.

  10. Genetic variation of the major histocompatibility complex (MHC class II B gene) in the threatened Hume's pheasant, Syrmaticus humiae.

    PubMed

    Chen, Weicai; Bei, Yongjian; Li, Hanhua

    2015-01-01

    Major histocompatibility complex (MHC) genes are the most polymorphic genes in vertebrates and encode molecules that play a crucial role in pathogen resistance. As a result of their diversity, they have received much attention in the fields of evolutionary and conservation biology. Here, we described the genetic variation of MHC class II B (MHCIIB) exon 2 in a wild population of Hume's pheasant (Syrmaticus humiae), which has suffered a dramatic decline in population over the last three decades across its ranges in the face of heavy exploitation and habitat loss. Twenty-four distinct alleles were found in 73 S. humiae specimens. We found seven shared alleles among four geographical groups as well as six rare MHCIIB alleles. Most individuals displayed between one to five alleles, suggesting that there are at least three MHCIIB loci of the Hume's pheasant. The dN ⁄ dS ratio at putative antigen-binding sites (ABS) was significantly greater than one, indicating balancing selection is acting on MHCIIB exon 2. Additionally, recombination and gene conversion contributed to generating MHCIIB diversity in the Hume's pheasant. One to three recombination events and seventy-five significant gene conversion events were observed within the Hume's pheasant MHCIIB loci. The phylogenetic tree and network analysis revealed that the Hume's pheasant alleles do not cluster together, but are scattered through the tree or network indicating a trans-species evolutionary mode. These findings revealed the evolution of the Hume's pheasant MHC after suffering extreme habitat fragmentation.

  11. Structural Basis for the Presentation of Tumor-Associated MHC Class II-Restricted Phosphopeptides to CD4+ T Cells

    SciTech Connect

    Li, Y.; Depontieu, F; Sidney, J; Salay, T; Engelhard, V; Hunt, D; Sette, A; Topalian, S; Mariuzza, R

    2010-01-01

    Dysregulated protein phosphorylation is a hallmark of malignant transformation. Transformation can generate major histocompatibility complex (MHC)-bound phosphopeptides that are differentially displayed on tumor cells for specific recognition by T cells. To understand how phosphorylation alters the antigenic identity of self-peptides and how MHC class II molecules present phosphopeptides for CD4{sup +} T-cell recognition, we determined the crystal structure of a phosphopeptide derived from melanoma antigen recognized by T cells-1 (pMART-1), selectively expressed by human melanomas, in complex with HLA-DR1. The structure revealed that the phosphate moiety attached to the serine residue at position P5 of pMART-1 is available for direct interactions with T-cell receptor (TCR) and that the peptide N-terminus adopts an unusual conformation orienting it toward TCR. This structure, combined with measurements of peptide affinity for HLA-DR1 and of peptide-MHC recognition by pMART-1-specific T cells, suggests that TCR recognition is focused on the N-terminal portion of pMART-1. This recognition mode appears to be distinct from that of foreign antigen complexes but is remarkably reminiscent of the way autoreactive TCRs engage self- or altered self-peptides, consistent with the tolerogenic nature of tumor-host immune interactions.

  12. Conformational lability in the class II MHC 310 helix and adjacent extended strand dictate HLA-DM susceptibility and peptide exchange

    PubMed Central

    Painter, Corrie A.; Negroni, Maria P.; Kellersberger, Katherine A.; Zavala-Ruiz, Zarixia; Evans, James E.; Stern, Lawrence J.

    2011-01-01

    HLA-DM is required for efficient peptide exchange on class II MHC molecules, but its mechanism of action is controversial. We trapped an intermediate state of class II MHC HLA-DR1 by substitution of αF54, resulting in a protein with increased HLA-DM binding affinity, weakened MHC-peptide hydrogen bonding as measured by hydrogen-deuterium exchange mass spectrometry, and increased susceptibility to DM-mediated peptide exchange. Structural analysis revealed a set of concerted conformational alterations at the N-terminal end of the peptide-binding site. These results suggest that interaction with HLA-DM is driven by a conformational change of the MHC II protein in the region of the α-subunit 310 helix and adjacent extended strand region, and provide a model for the mechanism of DM-mediated peptide exchange. PMID:22084083

  13. Conformational lability in the class II MHC 310 helix and adjacent extended strand dictate HLA-DM susceptibility and peptide exchange.

    PubMed

    Painter, Corrie A; Negroni, Maria P; Kellersberger, Katherine A; Zavala-Ruiz, Zarixia; Evans, James E; Stern, Lawrence J

    2011-11-29

    HLA-DM is required for efficient peptide exchange on class II MHC molecules, but its mechanism of action is controversial. We trapped an intermediate state of class II MHC HLA-DR1 by substitution of αF54, resulting in a protein with increased HLA-DM binding affinity, weakened MHC-peptide hydrogen bonding as measured by hydrogen-deuterium exchange mass spectrometry, and increased susceptibility to DM-mediated peptide exchange. Structural analysis revealed a set of concerted conformational alterations at the N-terminal end of the peptide-binding site. These results suggest that interaction with HLA-DM is driven by a conformational change of the MHC II protein in the region of the α-subunit 3(10) helix and adjacent extended strand region, and provide a model for the mechanism of DM-mediated peptide exchange.

  14. A non-canonical ESCRT pathway, including histidine domain phosphotyrosine phosphatase (HD-PTP), is used for down-regulation of virally ubiquitinated MHC class I.

    PubMed

    Parkinson, Michael D J; Piper, Siân C; Bright, Nicholas A; Evans, Jennifer L; Boname, Jessica M; Bowers, Katherine; Lehner, Paul J; Luzio, J Paul

    2015-10-01

    The Kaposi's sarcoma-associated herpes virus (KSHV) K3 viral gene product effectively down-regulates cell surface MHC class I. K3 is an E3 ubiquitin ligase that promotes Lys(63)-linked polyubiquitination of MHC class I, providing the signal for clathrin-mediated endocytosis. Endocytosis is followed by sorting into the intralumenal vesicles (ILVs) of multivesicular bodies (MVBs) and eventual delivery to lysosomes. The sorting of MHC class I into MVBs requires many individual proteins of the four endosomal sorting complexes required for transport (ESCRTs). In HeLa cells expressing the KSHV K3 ubiquitin ligase, the effect of RNAi-mediated depletion of individual proteins of the ESCRT-0 and ESCRT-I complexes and three ESCRT-III proteins showed that these are required to down-regulate MHC class I. However, depletion of proteins of the ESCRT-II complex or of the ESCRT-III protein, VPS20 (vacuolar protein sorting 20)/CHMP6 (charged MVB protein 6), failed to prevent the loss of MHC class I from the cell surface. Depletion of histidine domain phosphotyrosine phosphatase (HD-PTP) resulted in an increase in the cell surface concentration of MHC class I in HeLa cells expressing the KSHV K3 ubiquitin ligase. Rescue experiments with wild-type (WT) and mutant HD-PTP supported the conclusion that HD-PTP acts as an alternative to ESCRT-II and VPS20/CHMP6 as a link between the ESCRT-I and those ESCRT-III protein(s) necessary for ILV formation. Thus, the down-regulation of cell surface MHC class I, polyubiquitinated by the KSHV K3 ubiquitin ligase, does not employ the canonical ESCRT pathway, but instead utilizes an alternative pathway in which HD-PTP replaces ESCRT-II and VPS20/CHMP6.

  15. Productive association between MHC class I and tapasin requires the tapasin transmembrane/cytosolic region and the tapasin C-terminal Ig-like domain

    PubMed Central

    Simone, Laura C.; Georgesen, Corey J.; Simone, Peter D.; Wang, Xiaojian; Solheim, Joyce C.

    2011-01-01

    The current model of antigen assembly with major histocompatibility complex (MHC) class I molecules posits that interactions between the tapasin N-terminal immunoglobulin (Ig)-like domain and the MHC class I peptide-binding groove permit tapasin to regulate antigen selection. Much less is known regarding interactions that might involve the tapasin C-terminal Ig-like domain. Additionally, the tapasin transmembrane/cytoplasmic region enables tapasin to bridge the MHC class I molecule to the transporter associated with antigen processing (TAP). In this investigation, we made use of two tapasin mutants to determine the relative contribution of the tapasin C-terminal Ig-like domain and the tapasin transmembrane/cytoplasmic region to the assembly of MHC class I molecules. Deletion of a loop within the tapasin C-terminal Ig-like domain (Δ334-342) prevented tapasin association with the MHC class I molecule Kd. Although tapasin Δ334-342 did not increase the efficiency of Kd folding, Kd surface expression was enhanced on cells expressing this mutant relative to tapasin-deficient cells. In contrast to tapasin Δ334-342, a soluble tapasin mutant lacking the transmembrane/cytoplasmic region retained the ability to bind to Kd molecules, but did not facilitate Kd surface expression. Furthermore, when soluble tapasin and tapasin Δ334-342 were co-expressed, soluble tapasin had a dominant negative effect on the folding and surface expression of not only Kd, but also Db and Kb. In addition, our molecular modeling of the MHC class I-tapasin interface revealed novel potential interactions involving tapasin residues 334-342. Together, these findings demonstrate that the tapasin C-terminal and transmembrane/cytoplasmic regions are critical to tapasin's capacity to associate effectively with the MHC class I molecule. PMID:22169163

  16. The Epstein-Barr Virus G-Protein-Coupled Receptor Contributes to Immune Evasion by Targeting MHC Class I Molecules for Degradation

    PubMed Central

    Zuo, Jianmin; Currin, Andrew; Griffin, Bryan D.; Shannon-Lowe, Claire; Thomas, Wendy A.; Ressing, Maaike E.; Wiertz, Emmanuel J. H. J.; Rowe, Martin

    2009-01-01

    Epstein-Barr virus (EBV) is a human herpesvirus that persists as a largely subclinical infection in the vast majority of adults worldwide. Recent evidence indicates that an important component of the persistence strategy involves active interference with the MHC class I antigen processing pathway during the lytic replication cycle. We have now identified a novel role for the lytic cycle gene, BILF1, which encodes a glycoprotein with the properties of a constitutive signaling G-protein-coupled receptor (GPCR). BILF1 reduced the levels of MHC class I at the cell surface and inhibited CD8+ T cell recognition of endogenous target antigens. The underlying mechanism involves physical association of BILF1 with MHC class I molecules, an increased turnover from the cell surface, and enhanced degradation via lysosomal proteases. The BILF1 protein of the closely related CeHV15 γ1-herpesvirus of the Rhesus Old World primate (80% amino acid sequence identity) downregulated surface MHC class I similarly to EBV BILF1. Amongst the human herpesviruses, the GPCR encoded by the ORF74 of the KSHV γ2-herpesvirus is most closely related to EBV BILF1 (15% amino acid sequence identity) but did not affect levels of surface MHC class I. An engineered mutant of BILF1 that was unable to activate G protein signaling pathways retained the ability to downregulate MHC class I, indicating that the immune-modulating and GPCR-signaling properties are two distinct functions of BILF1. These findings extend our understanding of the normal biology of an important human pathogen. The discovery of a third EBV lytic cycle gene that cooperates to interfere with MHC class I antigen processing underscores the importance of the need for EBV to be able to evade CD8+ T cell responses during the lytic replication cycle, at a time when such a large number of potential viral targets are expressed. PMID:19119421

  17. Isolation and characterization of a MHC class II DRB locus in the European water vole (Arvicola terrestris).

    PubMed

    Oliver, Matthew K; Piertney, Stuart B

    2006-06-01

    In so-called model species, such as human and mouse, genes of the major histocompatibility complex (MHC) are characterized by extremely high levels of polymorphism, and it is considered that such diversity is maintained by balancing selection. ;There is now a recognized need to expand studies into nonmodel species to examine whether high MHC diversity is mirrored in natural populations, and to determine the ecological, ethological, and evolutionary processes that underpin balancing selection. To address such issues, a necessary prerequisite is the ability to characterize diversity at a single, expressed, polymorphic MHC locus on which selection may be acting. Here, we provide the first description of allelic diversity at exon 2 of an MHC class II DRB locus in the European water vole (Arvicola terrestris), characterize variation across four natural populations, and test whether the patterns of variation are consistent with the effects of balancing selection. Using single-strand conformation polymorphism analysis and subsequent DNA sequencing of gel excisions, five DRB alleles were resolved, each with a unique amino acid sequence, among 100 individuals from four geographically distinct populations. Reverse transcription polymerase chain reaction confirmed that the alleles were products from an expressed locus. Intra-allelic amino acid differences were high (10.5-33.3%), and the nonsynonymous substitution rate exceeded the synonymous substitution rate for the functional peptide-binding region (d (N):d (S)=3.91 and P<0.005). Phylogenetic comparison of resolved alleles with closely related homologues indicated that each allele represented a unique lineage preserved across speciation events. These results indicate that balancing selection has maintained diversity of DRB allelic lineages and amino acid function over evolutionary time scales, but may be less effective at preserving alleles in contemporary populations where stochastic microevolutionary processes may

  18. Non-neutral evolution and reciprocal monophyly of two expressed Mhc class II B genes in Leach's storm-petrel.

    PubMed

    Dearborn, Donald C; Gager, Andrea B; Gilmour, Morgan E; McArthur, Andrew G; Hinerfeld, Douglas A; Mauck, Robert A

    2015-02-01

    The major histocompatibility complex (Mhc) is subject to pathogen-mediated balancing selection and can link natural selection with mate choice. We characterized two Mhc class II B loci in Leach's storm-petrel, Oceanodroma leucorhoa, focusing on exon 2 which encodes the portion of the protein that binds pathogen peptides. We amplified and sequenced exon 2 with locus-specific nested PCR and Illumina MiSeq using individually barcoded primers. Repeat genotyping of 78 single-locus genotypes produced identical results in 77 cases (98.7%). Sequencing of messenger RNA (mRNA) from three birds confirmed expression of both loci, consistent with the observed absence of stop codons or frameshifts in all alleles. In 48 birds, we found 9 and 12 alleles at the two loci, respectively, and all 21 alleles translated to unique amino acid sequences. Unlike many studies of duplicated Mhc genes, alleles of the two loci clustered into monophyletic groups. Consistent with this phylogenetic result, interlocus gene conversion appears to have affected only two short fragments of the exon. As predicted under a paradigm of pathogen-mediated selection, comparison of synonymous and non-synonymous substitution rates found evidence of a history of positive selection at putative peptide binding sites. Overall, the results suggest that the gene duplication event leading to these two loci is not recent and that point mutations and positive selection on the peptide binding sites may be the predominant forces acting on these genes. Characterization of these loci sets the stage for population-level work on the evolutionary ecology of Mhc in this species.

  19. Conserved 33-kb haplotype in the MHC class III region regulates chronic arthritis

    PubMed Central

    Yau, Anthony C. Y.; Tuncel, Jonatan; Norin, Ulrika; Houtman, Miranda; Padyukov, Leonid; Holmdahl, Rikard

    2016-01-01

    Genome-wide association studies have revealed many genetic loci associated with complex autoimmune diseases. In rheumatoid arthritis (RA), the MHC gene HLA-DRB1 is the strongest candidate predicting disease development. It has been suggested that other immune-regulating genes in the MHC contribute to the disease risk, but this contribution has been difficult to show because of the strong linkage disequilibrium within the MHC. We isolated genomic regions in the form of congenic fragments in rats to test whether there are additional susceptibility loci in the MHC. By both congenic mapping in inbred strains and SNP typing in wild rats, we identified a conserved, 33-kb large haplotype Ltab-Ncr3 in the MHC-III region, which regulates the onset, severity, and chronicity of arthritis. The Ltab-Ncr3 haplotype consists of five polymorphic immunoregulatory genes: Lta (lymphotoxin-α), Tnf, Ltb (lymphotoxin-β), Lst1 (leukocyte-specific transcript 1), and Ncr3 (natural cytotoxicity-triggering receptor 3). Significant correlation in the expression of the Ltab-Ncr3 genes suggests that interaction of these genes may be important in keeping these genes clustered together as a conserved haplotype. We studied the arthritis association and the spliceo-transcriptome of four different Ltab-Ncr3 haplotypes and showed that higher Ltb and Ncr3 expression, lower Lst1 expression, and the expression of a shorter splice variant of Lst1 correlate with reduced arthritis severity in rats. Interestingly, patients with mild RA also showed higher NCR3 expression and lower LST1 expression than patients with severe RA. These data demonstrate the importance of a conserved haplotype in the regulation of complex diseases such as arthritis. PMID:27303036

  20. Characterization of MHC class IIB for four endangered Australian freshwater fishes obtained from ecologically divergent populations.

    PubMed

    Bracamonte, Seraina E; Smith, Steve; Hammer, Michael; Pavey, Scott A; Sunnucks, Paul; Beheregaray, Luciano B

    2015-10-01

    Genetic diversity is an essential aspect of species viability, and assessments of neutral genetic diversity are regularly implemented in captive breeding and conservation programs. Despite their importance, information from adaptive markers is rarely included in such programs. A promising marker of significance in fitness and adaptive potential is the major histocompatibility complex (MHC), a key component of the adaptive immune system. Populations of Australian freshwater fishes are generally declining in numbers due to human impacts and the introduction of exotic species, a scenario of particular concern for members of the family Percichthyidae, several of which are listed as nationally vulnerable or endangered, and hence subject to management plans, captive breeding, and restoration plans. We used a next-generation sequencing approach to characterize the MHC IIB locus and provide a conservative description of its levels of diversity in four endangered percichthyids: Gadopsis marmoratus, Macquaria australasica, Nannoperca australis, and Nannoperca obscura. Evidence is presented for a duplicated MHC IIB locus, positively selected sites and recombination of MHC alleles. Relatively moderate levels of diversity were detected in the four species, as well as in different ecotypes within each species. Phylogenetic analyses revealed genus specific clustering of alleles and no allele sharing among species. There were also no shared alleles observed between two ecotypes within G. marmoratus and within M. australasica, which might be indicative of ecologically-driven divergence and/or long divergence times. This represents the first characterization and assessment of MHC diversity for Percichthyidae, and also for Australian freshwater fishes in general, providing key genetic resources for a vertebrate group of increasing conservation concern.

  1. The expression pattern of classical MHC class I molecules in the development of mouse central nervous system.

    PubMed

    Liu, Jiane; Shen, Yuqing; Li, Mingli; Shi, Qian; Zhang, Aifeng; Miao, Fengqin; Liu, Junhua; Wu, Xiaojing; He, Youji; Zhang, Jianqiong

    2013-02-01

    Classical major histocompatibility complex (MHC) class I, first identified in the immune system, is also expressed in the developing and adult central nervous system (CNS). Although the MHC class I molecules have been found to be expressed in the CNS of different species, a necessary step to elucidate the temporal and spatial expression patterns of MHC class I molecules in the brain development has never been taken. Frozen sections were made from the brains of embryonic and postnatal C57BL/6 J mice, and the expression of H-2D(b) mRNA was examined by in situ hybridization. Immunofluorescence was also performed to define the cell types that express H2-D(b) in P15 mice. At E10.5, the earliest stage we examined, H2-D(b) was expressed in neuroepithelium of the brain vesicles. From E12.5 to P0, H2-D(b) expression was mainly located at cerebral cortex, neuroepithelium of the lateral ventricle, neuroepithelium of aquaeductus and developing cerebellum. From P4 to adult, H2-D(b) mRNA was detected at olfactory bulb, hippocampus, cerebellum and some nerve nuclei. The major cell types expressing H-2D(b) in P15 hippocampus, cerebral cortex and olfactory bulb were neuron. H2-K(b) signal paralleled that of H2-D(b) and the expression levels of the two molecules were comparable throughout the brain. The investigation of the expression pattern of H-2D(b) at both embryonic and postnatal stages is important for further understanding the physiological and pathological roles of H2-D(b) in the developing CNS.

  2. Codominance of TLR2-dependent and TLR2-independent modulation of MHC class II in Mycobacterium tuberculosis infection in vivo.

    PubMed

    Kincaid, Eleanor Z; Wolf, Andrea J; Desvignes, Ludovic; Mahapatra, Sebabrata; Crick, Dean C; Brennan, Patrick J; Pavelka, Martin S; Ernst, Joel D

    2007-09-01

    Mycobacterium tuberculosis is an exceptionally successful human pathogen. A major component of this success is the ability of the bacteria to infect immunocompetent individuals and to evade eradication by an adaptive immune response that includes production of the macrophage-activating cytokine, IFN-gamma. Although IFN-gamma is essential for arrest of progressive tuberculosis, it is insufficient for efficacious macrophage killing of the bacteria, which may be due to the ability of M. tuberculosis to inhibit selected macrophage responses to IFN-gamma. In vitro studies have determined that mycobacterial lipoproteins and other components of the M. tuberculosis cell envelope, acting as agonists for TLR2, inhibit IFN-gamma induction of MHC class II. In addition, M. tuberculosis peptidoglycan and IL-6 secreted by infected macrophages inhibit IFN-gamma induction of MHC class II in a TLR2-independent manner. To determine whether TLR2-dependent inhibition of macrophage responses to IFN-gamma is quantitatively dominant over the TLR2-independent mechanisms in vivo, we prepared mixed bone marrow chimeric mice in which the hemopoietic compartment was reconstituted with a mixture of TLR(+/+) and TLR2(-/-) cells. When the chimeric mice were infected with M. tuberculosis, the expression of MHC class II on TLR2(+/+) and TLR2(-/-) macrophages from the lungs of individual infected chimeric mice was indistinguishable. These results indicate that TLR2-dependent and -independent mechanisms of inhibition of responses to IFN-gamma are equivalent in vivo, and that M. tuberculosis uses multiple pathways to abrogate the action of an important effector of adaptive immunity. This work was supported by National Institutes of Health Grants AI 065357-AI 020010.

  3. The major histocompatibility complex in monotremes: an analysis of the evolution of Mhc class I genes across all three mammalian subclasses.

    PubMed

    Miska, Katarzyna B; Harrison, Gavan A; Hellman, Lars; Miller, Robert D

    2002-09-01

    We report the isolation and characterization of cDNA clones of expressed, functional major histocompatibility complex class-I ( Mhc-I) genes from two species of monotremes: the duck-billed platypus and the short-beaked echidna. The cDNA clones were isolated from libraries constructed from spleen RNA, clearly establishing their expression in at least this one peripheral lymphoid organ. From the presence of conserved amino acid residues, it appears the expressed sequences encode molecules that likely function as classical Mhc-I. These clones were isolated using monotreme Mhc-I processed pseudogenes as probes. These processed pseudogenes were isolated from genomic DNA and, based on their structure, are likely independently derived in the platypus and echidna. When all the monotreme sequences were included in phylogenetic analyses, we found no apparent orthologous relationships between the platypus and echidna Mhc-I. Analyses that included a large number of Mhc-I sequences from other taxa support a separate monotreme Mhc-I clade, basal to a therian Mhc-I clade that is comprised of sequences from marsupial and placental mammals. The phylogenies also support the hypothesis that Mhc-I genes of placental mammals, marsupials, and monotremes are derived from three separate lineages of Mhc-I genes, best explained by two rounds of duplications and deletions. The first round would have occurred prior to the divergence of monotremes and therians, and the second prior to the divergence of marsupials and placental mammals. The sequences described here represent the first reported functional monotreme Mhc-I, as well as the first processed pseudogenes of any type from monotremes.

  4. Brucella abortus down-regulates MHC class II by the IL-6-dependent inhibition of CIITA through the downmodulation of IFN regulatory factor-1 (IRF-1).

    PubMed

    Velásquez, Lis N; Milillo, M Ayelén; Delpino, M Victoria; Trotta, Aldana; Fernández, Pablo; Pozner, Roberto G; Lang, Roland; Balboa, Luciana; Giambartolomei, Guillermo H; Barrionuevo, Paula

    2017-03-01

    Brucella abortus is an intracellular pathogen capable of surviving inside of macrophages. The success of B. abortus as a chronic pathogen relies on its ability to orchestrate different strategies to evade the adaptive CD4(+) T cell responses that it elicits. Previously, we demonstrated that B. abortus inhibits the IFN-γ-induced surface expression of MHC class II (MHC-II) molecules on human monocytes, and this phenomenon correlated with a reduction in antigen presentation. However, the molecular mechanisms, whereby B. abortus is able to down-regulate the expression of MHC-II, remained to be elucidated. In this study, we demonstrated that B. abortus infection inhibits the IFN-γ-induced transcription of MHC-II, transactivator (CIITA) and MHC-II genes. Accordingly, we observed that the synthesis of MHC-II proteins was also diminished. B. abortus was not only able to reduce the expression of mature MHC-II, but it also inhibited the expression of invariant chain (Ii)-associated immature MHC-II molecules. Outer membrane protein 19 (Omp19), a prototypical B. abortus lipoprotein, diminished the expression of MHC-II and CIITA transcripts to the same extent as B. abortus infection. IL-6 contributes to these down-regulatory phenomena. In addition, B. abortus and its lipoproteins, through IL-6 secretion, induced the transcription of the negative regulators of IFN-γ signaling, suppressor of cytokine signaling (SOCS)-1 and -3, without interfering with STAT1 activation. Yet, B. abortus lipoproteins via IL-6 inhibit the expression of IFN regulatory factor 1 (IRF-1), a critical regulatory transcription factor for CIITA induction. Overall, these results indicate that B. abortus inhibits the expression of MHC-II molecules at very early points in their synthesis and in this way, may prevent recognition by T cells establishing a chronic infection.

  5. Characterization of the MHC class II region in cattle. The number of DQ genes varies between haplotypes.

    PubMed

    Andersson, L; Rask, L

    1988-01-01

    The organization of the major histocompatibility complex (MHC) class II region in cattle was investigated by Southern blot analysis using human probes corresponding to DO, DP, DQ, and DR genes. Exon-specific probes were also employed to facilitate the assessment of the number of different bovine class II genes. The results indicated the presence of single DO beta and DR alpha genes, at least three DR beta genes, while the number of DQ genes was found to vary between MHC haplotypes. Four DQ haplotypes, DQ alpha 1 beta 1 to DQ alpha 2 beta 4, possessed a single DQ alpha and a single DQ beta gene whereas both these genes were duplicated in eight other haplotypes, DQ alpha 3 beta 5 to DQ alpha 9 beta 12. No firm evidence for the presence of bovine DP genes was obtained. The same human probes were also used to investigate the genetic polymorphism of bovine class II genes. DQ alpha, DQ beta, DR alpha, DR beta, and DO beta restriction fragment length polymorphisms (RFLPs) were resolved and in particular the DQ restriction fragment patterns were highly polymorphic. Comparison of the present result with the current knowledge of the class II region in other mammalian species suggested that the DO, DP, DQ, DR, and DZ subdivision of the class II region was established already in the ancestor of mammals. The DP genes appear to be the least conserved class II genes among mammalian species and may have been lost in cattle. The degree of polymorphism of different class II genes, as revealed by RFLP analyses, shows striking similarities between species.

  6. MHC class I antigens and tumour-infiltrating leucocytes in laryngeal cancer: long-term follow-up.

    PubMed Central

    Esteban, F.; Redondo, M.; Delgado, M.; Garrido, F.; Ruiz-Cabello, F.

    1996-01-01

    Alteration in MHC class I expression may be used by cancer cells to avoid immune destruction. Much experimental evidence supports this idea, although survival studies are very scarce. To investigate whether the presence or absence of HLA-A, -B and -C antigens in laryngeal carcinoma influences survival, a series of 60 primary laryngeal tumours treated surgically and normal tissues were evaluated in frozen sections for the expression of MHC class I antigens and tumour-infiltrating leucocytes (CD3, CD4, CD8, CD11b, CD1, CD20 and CD16), using monoclonal antibodies and the APAAP, technique. Long-term follow-up from the patients is available, ranging from 6 to 10 years. Thirteen tumours presented total HLA-ABC loss, five selective losses of HLA-A antigens and one absence of HLA-B antigens. Total losses were statistically associated with several clinical and pathological parameters, but there were no differences regarding tumour-infiltrating leucocytes. After conducting a prospective study, only T and N staging and scoring according to Glanz's malignancy classification were found to be independently related to patients' outcome. From our data, we conclude that neither complete loss of HLA class I antigens nor tumour-infiltrating leucocytes appear to influence survival in squamous cell carcinoma of the larynx. PMID:8956796

  7. The murine cytomegalovirus immunoevasin gp40 binds MHC class I molecules to retain them in the early secretory pathway.

    PubMed

    Janßen, Linda; Ramnarayan, Venkat Raman; Aboelmagd, Mohamed; Iliopoulou, Maro; Hein, Zeynep; Majoul, Irina; Fritzsche, Susanne; Halenius, Anne; Springer, Sebastian

    2016-01-01

    In the presence of the murine cytomegalovirus (mCMV) gp40 (m152) protein, murine major histocompatibility complex (MHC) class I molecules do not reach the cell surface but are retained in an early compartment of the secretory pathway. We find that gp40 does not impair the folding or high-affinity peptide binding of the class I molecules but binds to them, leading to their retention in the endoplasmic reticulum (ER), the ER-Golgi intermediate compartment (ERGIC) and the cis-Golgi, most likely by retrieval from the cis-Golgi to the ER. We identify a sequence in gp40 that is required for both its own retention in the early secretory pathway and for that of class I molecules.

  8. CD4+CD25- T cells transduced to express MHC class I-restricted epitope-specific TCR synthesize Th1 cytokines and exhibit MHC class I-restricted cytolytic effector function in a human melanoma model.

    PubMed

    Chhabra, Arvind; Yang, Lili; Wang, Pin; Comin-Anduix, Begoña; Das, Raja; Chakraborty, Nitya G; Ray, Swagatam; Mehrotra, Shikhar; Yang, Haiguang; Hardee, Cinnamon L; Hollis, Roger; Dorsky, David I; Koya, Richard; Kohn, Donald B; Ribas, Antoni; Economou, James S; Baltimore, David; Mukherji, Bijay

    2008-07-15

    Cytolytic T cell-centric active specific and adoptive immunotherapeutic approaches might benefit from the simultaneous engagement of CD4(+) T cells. Considering the difficulties in simultaneously engaging CD4(+) and CD8(+) T cells in tumor immunotherapy, especially in an Ag-specific manner, redirecting CD4(+) T cells to MHC class I-restricted epitopes through engineered expression of MHC class I-restricted epitope-specific TCRs in CD4(+) T cells has emerged as a strategic consideration. Such TCR-engineered CD4(+) T cells have been shown to be capable of synthesizing cytokines as well as lysing target cells. We have conducted a critical examination of functional characteristics of CD4(+) T cells engineered to express the alpha- and beta-chains of a high functional avidity TCR specific for the melanoma epitope, MART-1(27-35), as a prototypic human tumor Ag system. We found that unpolarized CD4(+)CD25(-) T cells engineered to express the MART-1(27-35) TCR selectively synthesize Th1 cytokines and exhibit a potent Ag-specific lytic granule exocytosis-mediated cytolytic effector function of comparable efficacy to that of CD8(+) CTL. Such TCR engineered CD4(+) T cells, therefore, might be useful in clinical immunotherapy.

  9. CD4+CD25− T cells transduced to express MHC class I-restricted epitope specific TCR synthesize Th1 cytokines and exhibit MHC class I-restricted cytolytic effector function in a human melanoma model

    PubMed Central

    Chhabra, Arvind; Yang, Lili; Wang, Pin; Comin-Anduix, Begoña; Das, Raja; Chakraborty, Nitya G.; Ray, Swagatam; Mehrotra, Shikhar; Yang, Haiguang; Hardee, Cinnamon L.; Hollis, Roger; Dorsky, David I.; Koya, Richard; Kohn, Donald B.; Ribas, Antoni; Economou, James S.; Baltimore, David; Mukherji, Bijay

    2009-01-01

    Cytolytic T cell-centric active specific and adoptive immunotherapeutic approaches might benefit from the simultaneous engagement of CD4+ T cells. Considering the difficulties in simultaneously engaging CD4+ and CD8+ T cells in tumor immunotherapy -- especially in an antigen specific manner -- “redirecting” CD4+ T cells to MHC class I-restricted epitopes through engineered expression of MHC class I-restricted epitope specific T cell receptors (TCR) in CD4+ T cells has emerged as a strategic consideration. Such TCR engineered CD4+ T cells have been shown to be capable of synthesizing cytokines as well as lysing target cells. We have carried out a critical examination of functional characteristics of CD4+ T cells engineered to express the α and β chains of a high functional avidity TCR specific for the melanoma epitope, MART-127–35 (M1), as a prototypic human tumor antigen system. We found that unpolarized CD4+CD25− T cells engineered to express the M1 TCR selectively synthesize Th1 cytokines and exhibit a potent antigen-specific lytic granule exocytosis-mediated cytolytic effector function of comparable efficacy to that of CD8+ CTL. Such TCR engineered CD4+ T cells, therefore, might be useful in clinical immunotherapy. PMID:18606658

  10. Characterization and evolution of MHC class II B genes in Galápagos marine iguanas (Amblyrhynchus cristatus).

    PubMed

    Glaberman, Scott; Moreno, Maria A; Caccone, Adalgisa

    2009-08-01

    Major histocompatibility complex (MHC) class II molecules play a key role in the adaptive immune system of vertebrates. Class II B genes appear to evolve in a very different manner in mammals and birds. Orthology is commonly observed among mammal loci, while genes tend to cluster phylogenetically within bird species. Here we present class II B data from a representative of another major group of amniotes, the squamates (i.e. lizards, snakes, amphisbaenians), with the ultimate goal of placing mammalian and avian MHC evolution into a broader context. In this study, eight class II B cDNA sequences were obtained from the Galápagos marine iguana (Amblyrhynchus cristatus) which were divided into five locus groups, Amcr-DAB1 through -DAB5, based on similarities along most of the coding and noncoding portions of the transcribed gene. All marine iguana sequences were monophyletic with respect to class II genes from other vertebrates indicating that they originated from a common ancestral locus after squamates split from other reptiles. The beta-1 domain, which is involved in antigen binding, exhibited signatures of positive selection as well as interlocus gene conversion in both long and short tracts-a pattern also observed in birds and fish, but not in mammals. On the other hand, the beta-2 domain was divergent between gene groups, which is characteristic of mammals. Based on these results, we preliminarily show that squamate class II B genes have been shaped by a unique blend of evolutionary forces that have been observed in differing degrees in other vertebrates.

  11. Microglial TNF-α-dependent elevation of MHC class I expression on brain endothelium induced by amyloid-beta promotes T cell transendothelial migration.

    PubMed

    Yang, Yi-Ming; Shang, De-Shu; Zhao, Wei-Dong; Fang, Wen-Gang; Chen, Yu-Hua

    2013-11-01

    The blood-brain barrier (BBB) normally bars peripheral T lymphocytes from entering the cerebrum. Interestingly, activated T cells exist as infiltrates in the brains of Alzheimer's disease (AD) patients, but little is known about the mechanisms involved. In this study, we observed significantly higher MHC class I expression in rat brain endothelial cells compared with controls following the induction of experimental AD models. An in vitro BBB model, which was constructed with human brain microvascular endothelial cells, was established to study the mechanisms underlying the transendothelial migration of T cells. Using in vitro studies, we demonstrated that secretion of TNF-α from Aβ1-42-treated BV2 microglia contributes to the elevated expression of MHC class I on the brain microvessel endothelium. Transmigration assays and adhesion assays confirmed that the upregulation of MHC class I molecules was associated with T cell transendothelial migration. MHC class I knock-down in HBMECs significantly attenuated the migratory and adhesive capability of the T cells. Interestingly, a TNF-α neutralizing antibody effectively blocked the transendothelial migration of T cells triggered by treatment with the supernatant from Aβ1-42-treated BV2 microglia. We propose that microglia-derived TNF-α upregulates MHC class I molecule expression on brain endothelial cells, which represents a mechanism of T cell migration into the brain. This study may provide a new insight into the potential pathomechanism of Alzheimer's disease.

  12. Novel mutations within the RFX-B gene and partial rescue of MHC and related genes through exogenous class II transactivator in RFX-B-deficient cells.

    PubMed

    Nagarajan, U M; Peijnenburg, A; Gobin, S J; Boss, J M; van den elsen, P J

    2000-04-01

    MHC class II deficiency or bare lymphocyte syndrome is a severe combined immunodeficiency caused by defects in MHC-specific regulatory factors. Fibroblasts derived from two recently identified bare lymphocyte syndrome patients, EBA and FZA, were found to contain novel mutations in the RFX-B gene. RFX-B encodes a component of the RFX transcription factor that functions in the assembly of multiple transcription factors on MHC class II promoters. Unlike RFX5- and RFXAP-deficient cells, transfection of exogenous class II transactivator (CIITA) into these RFX-B-deficient fibroblasts resulted in the induction of HLA-DR and HLA-DP and, to a lesser extent, HLA-DQ. Similarly, CIITA-mediated induction of MHC class I, beta2-microglobulin, and invariant chain genes was also found in these RFX-B-deficient fibroblasts. Expression of wild-type RFX-B completely reverted the noted deficiencies in these cells. Transfection of CIITA into Ramia cells, a B cell line that does not produce a stable RFX-B mRNA, resulted in induction of an MHC class II reporter, suggesting that CIITA overexpression may partially override the RFX-B defect.

  13. Direct binding of a myasthenia gravis related epitope to MHC class II molecules on living murine antigen-presenting cells.

    PubMed Central

    Mozes, E; Dayan, M; Zisman, E; Brocke, S; Licht, A; Pecht, I

    1989-01-01

    MHC gene products present antigenic epitopes to the antigen receptor on T cells. Nevertheless, direct binding of such epitopes to MHC class II proteins on normal living antigen-presenting cells (APCs) has not yet been demonstrated. We have previously shown a significant difference in the ability of T cells of myasthenia gravis (MG) patients to proliferate in response to the synthetic peptide p195-212 of the human acetylcholine receptor (AChR) alpha-subunit in comparison to healthy controls. The observed proliferative responses correlated significantly with HLA-DR5. Moreover, lymph node cells of various mouse strains that were primed with the T cell epitope, p195-212, were found to proliferate to different extents. To investigate these observations further, we designed an assay for direct binding of p195-212 to MHC class II proteins on the surface of freshly prepared splenic adherent cells. Binding of a biotinylated p195-212 was monitored using phycoerythrin-avidin by flow cytometry. Fifteen to sixty per cent of the cells were labeled following incubation with the biotinylated peptide. Binding was observed only to splenic adherent cells derived from mouse strains of which T cells were capable of proliferating in response to p195-212. The binding specificity, in terms of epitope structure and its site of interaction on the cells, was shown by its inhibition with an excess of the unlabeled peptide or with the relevant monoclonal anti-I-A antibodies. These results constitute the first direct evidence for the specific binding of a T cell epitope to live APC. PMID:2480232

  14. Combining molecular evolution and environmental genomics to unravel adaptive processes of MHC class IIB diversity in European minnows (Phoxinus phoxinus)

    PubMed Central

    Collin, Helene; Burri, Reto; Comtesse, Fabien; Fumagalli, Luca

    2013-01-01

    Abstract Host–pathogen interactions are a major evolutionary force promoting local adaptation. Genes of the major histocompatibility complex (MHC) represent unique candidates to investigate evolutionary processes driving local adaptation to parasite communities. The present study aimed at identifying the relative roles of neutral and adaptive processes driving the evolution of MHC class IIB (MHCIIB) genes in natural populations of European minnows (Phoxinus phoxinus). To this end, we isolated and genotyped exon 2 of two MHCIIB gene duplicates (DAB1 and DAB3) and 1′665 amplified fragment length polymorphism (AFLP) markers in nine populations, and characterized local bacterial communities by 16S rDNA barcoding using 454 amplicon sequencing. Both MHCIIB loci exhibited signs of historical balancing selection. Whereas genetic differentiation exceeded that of neutral markers at both loci, the populations' genetic diversities were positively correlated with local pathogen diversities only at DAB3. Overall, our results suggest pathogen-mediated local adaptation in European minnows at both MHCIIB loci. While at DAB1 selection appears to favor different alleles among populations, this is only partially the case in DAB3, which appears to be locally adapted to pathogen communities in terms of genetic diversity. These results provide new insights into the importance of host–pathogen interactions in driving local adaptation in the European minnow, and highlight that the importance of adaptive processes driving MHCIIB gene evolution may differ among duplicates within species, presumably as a consequence of alternative selective regimes or different genomic context. Using next-generation sequencing, the present manuscript identifies the relative roles of neutral and adaptive processes driving the evolution of MHC class IIB (MHCIIB) genes in natural populations of a cyprinid fish: the European minnow (Phoxinus phoxinus). We highlight that the relative importance of neutral

  15. MHC class II DRB diversity in raccoons (Procyon lotor) reveals associations with raccoon rabies virus (Lyssavirus).

    PubMed

    Srithayakumar, Vythegi; Castillo, Sarrah; Rosatte, Rick C; Kyle, Christopher J

    2011-02-01

    In North America, the raccoon rabies virus (RRV) is an endemic wildlife disease which causes acute encephalopathies and is a strong selective force on raccoons (Procyon lotor), with estimates of ∼85% of the population succumbing to the disease when epizootic. RRV is regarded as a lethal disease if untreated; therefore, no evolutionary response would be expected of raccoon populations. However, variable immune responses to RRV have been observed in raccoons indicating a potential for evolutionary adaptation. Studies of variation within the immunologically important major histocompatibility complex (MHC) have revealed relationships between MHC alleles and diseases in humans and other wildlife species. This enhances our understanding of how hosts and pathogens adapt and co-evolve. In this study, we used RRV as a model system to study host-pathogen interaction in raccoons from a challenge study and from four wild populations that differ in exposure times and viral lineages. We investigated the potential role of Prlo-DRB polymorphism in relation to susceptibility/resistance to RRV in 113 RRV positive and 143 RRV negative raccoons. Six alleles were found to be associated with RRV negative status and five alleles with RRV positive animals. We found variable patterns of MHC associations given the relative number of selective RRV sweeps in the studied regions and correlations between MHC diversity and RRV lineages. The allelic associations established provide insight into how the genetic variation of raccoons may affect the disease outcome and this can be used to examine similar associations between other rabies variants and their hosts.

  16. Coevolution of MHC genes (LMP/TAP/class Ia, NKT-class Ib, NKp30-B7H6): lessons from cold-blooded vertebrates.

    PubMed

    Ohta, Yuko; Flajnik, Martin F

    2015-09-01

    Comparative immunology provides the long view of what is conserved across all vertebrate taxa versus what is specific to particular organisms or group of organisms. Regarding the major histocompatibility complex (MHC) and coevolution, three striking cases have been revealed in cold-blooded vertebrates: lineages of class Ia antigen-processing and -presenting genes, evolutionary conservation of NKT-class Ib recognition, and the ancient emergence of the natural cytotoxicity receptor NKp30 and its ligand B7H6. While coevolution of transporter associated with antigen processing (TAP) and class Ia has been documented in endothermic birds and two mammals, lineages of LMP7 are restricted to ectotherms. The unambiguous discovery of natural killer T (NKT) cells in Xenopus demonstrated that NKT cells are not restricted to mammals and are likely to have emerged at the same time in evolution as classical α/β and γ/δ T cells. NK cell receptors evolve at a rapid rate, and orthologues are nearly impossible to identify in different vertebrate classes. By contrast, we have detected NKp30 in all gnathostomes, except in species where it was lost. The recently discovered ligand of NKp30, B7H6, shows strong signs of coevolution with NKp30 throughout evolution, i.e. coincident loss or expansion of both genes in some species. NKp30 also offers an attractive IgSF candidate for the invasion of the RAG transposon, which is believed to have initiated T-cell receptor/immunoglobulin adaptive immunity. Besides reviewing these intriguing features of MHC evolution and coevolution, we offer suggestions for future studies and propose a model for the primordial or proto MHC.

  17. Modulation of CD8+ T cell responses to AAV vectors with IgG-derived MHC class II epitopes.

    PubMed

    Hui, Daniel J; Basner-Tschakarjan, Etiena; Chen, Yifeng; Davidson, Robert J; Buchlis, George; Yazicioglu, Mustafa; Pien, Gary C; Finn, Jonathan D; Haurigot, Virginia; Tai, Alex; Scott, David W; Cousens, Leslie P; Zhou, Shangzhen; De Groot, Anne S; Mingozzi, Federico

    2013-09-01

    Immune responses directed against viral capsid proteins constitute a main safety concern in the use of adeno-associated virus (AAV) as gene transfer vectors in humans. Pharmacological immunosuppression has been proposed as a solution to the problem; however, the approach suffers from several potential limitations. Using MHC class II epitopes initially identified within human IgG, named Tregitopes, we showed that it is possible to modulate CD8+ T cell responses to several viral antigens in vitro. We showed that incubation of peripheral blood mononuclear cells with these epitopes triggers proliferation of CD4+CD25+FoxP3+ T cells that suppress killing of target cells loaded with MHC class I antigens in an antigen-specific fashion, through a mechanism that seems to require cell-to-cell contact. Expression of a construct encoding for the AAV capsid structural protein fused to Tregitopes resulted in reduction of CD8+ T cell reactivity against the AAV capsid following immunization with an adenoviral vector expressing capsid. This was accompanied by an increase in frequency of CD4+CD25+FoxP3+ T cells in spleens and lower levels of inflammatory infiltrates in injected tissues. This proof-of-concept study demonstrates modulation of CD8+ T cell reactivity to an antigen using regulatory T cell epitopes is possible.

  18. Induction of tolerance against the arthritogenic antigen with type-II collagen peptide-linked soluble MHC class II molecules.

    PubMed

    Park, Yoon-Kyung; Jung, Sundo; Park, Se-Ho

    2016-06-01

    In murine collagen-induced arthritis (CIA), self-reactive T cells can recognize peptide antigens derived from type-II collagen (CII). Activation of T cells is an important mediator of autoimmune diseases. Thus, T cells have become a focal point of study to treat autoimmune diseases. In this study, we evaluated the efficacy of recombinant MHC class II molecules in the regulation of antigen-specific T cells by using a self peptide derived from CII (CII260-274; IAGFKGEQGPKGEPG) linked to mouse I-A(q) in a murine CIA model. We found that recombinant I-A(q)/CII260-274 molecules could be recognized by CII-specific T cells and inhibit the same T cells in vitro. Furthermore, the development of CIA in mice was successfully prevented by in vivo injection of recombinant I-A(q)/CII260-274 molecules. Thus, treatment with recombinant soluble MHC class II molecules in complex with an immunodominant self-peptide might offer a potential therapeutic for chronic inflammation in autoimmune disease such as rheumatoid arthritis. [BMB Reports 2016; 49(6): 331-336].

  19. Definition of Proteasomal Peptide Splicing Rules for High-Efficiency Spliced Peptide Presentation by MHC Class I Molecules.

    PubMed

    Berkers, Celia R; de Jong, Annemieke; Schuurman, Karianne G; Linnemann, Carsten; Meiring, Hugo D; Janssen, Lennert; Neefjes, Jacques J; Schumacher, Ton N M; Rodenko, Boris; Ovaa, Huib

    2015-11-01

    Peptide splicing, in which two distant parts of a protein are excised and then ligated to form a novel peptide, can generate unique MHC class I-restricted responses. Because these peptides are not genetically encoded and the rules behind proteasomal splicing are unknown, it is difficult to predict these spliced Ags. In the current study, small libraries of short peptides were used to identify amino acid sequences that affect the efficiency of this transpeptidation process. We observed that splicing does not occur at random, neither in terms of the amino acid sequences nor through random splicing of peptides from different sources. In contrast, splicing followed distinct rules that we deduced and validated both in vitro and in cells. Peptide ligation was quantified using a model peptide and demonstrated to occur with up to 30% ligation efficiency in vitro, provided that optimal structural requirements for ligation were met by both ligating partners. In addition, many splicing products could be formed from a single protein. Our splicing rules will facilitate prediction and detection of new spliced Ags to expand the peptidome presented by MHC class I Ags.

  20. The Thermodynamic Mechanism of Peptide–MHC Class II Complex Formation Is a Determinant of Susceptibility to HLA-DM

    PubMed Central

    Templeton, Megan; Hoffman, Megan; Castellini, Margaret J.

    2015-01-01

    Peptides bind MHC class II molecules through a thermodynamically nonadditive process consequent to the flexibility of the reactants. Currently, how the specific outcome of this binding process affects the ensuing epitope selection needs resolution. Calorimetric assessment of binding thermodynamics for hemagglutinin 306–319 peptide variants to the human MHC class II HLA-DR1 (DR1) and a mutant DR1 reveals that peptide/DR1 complexes can be formed with different enthalpic and entropic contributions. Complexes formed with a smaller entropic penalty feature circular dichroism spectra consistent with a non–compact form, and molecular dynamics simulation shows a more flexible structure. The opposite binding mode, compact and less flexible, is associated with greater entropic penalty. These structural variations are associated with rearrangements of residues known to be involved in HLA-DR (DM) binding, affinity of DM for the complex, and complex susceptibility to DM-mediated peptide exchange. Thus, the thermodynamic mechanism of peptide binding to DR1 correlates with the structural rigidity of the complex, and DM mediates peptide exchange by “sensing” flexible complexes in which the aforementioned residues are rearranged at a higher frequency than in more rigid ones. PMID:26116504

  1. Structural Basis for the Recognition of Mutant Self by a Tumor-Specific, MHC Class II-Restricted T Cell Receptor

    SciTech Connect

    Deng,L.; Langley, R.; Brown, P.; Xu, G.; Teng, L.; Wang, Q.; Gonzales, M.; Callender, G.; Nishimura, M.; et al.

    2007-01-01

    Structural studies of complexes of T cell receptor (TCR) and peptide-major histocompatibility complex (MHC) have focused on TCRs specific for foreign antigens or native self. An unexplored category of TCRs includes those specific for self determinants bearing alterations resulting from disease, notably cancer. We determined here the structure of a human melanoma-specific TCR (E8) bound to the MHC molecule HLA-DR1 and an epitope from mutant triosephosphate isomerase. The structure had features intermediate between 'anti-foreign' and autoimmune TCR-peptide-MHC class II complexes that may reflect the hybrid nature of altered self. E8 manifested very low affinity for mutant triosephosphate isomerase-HLA-DR1 despite the highly tumor-reactive properties of E8 cells. A second TCR (G4) had even lower affinity but underwent peptide-specific formation of dimers, suggesting this as a mechanism for enhancing low-affinity TCR-peptide-MHC interactions for T cell activation.

  2. 5HT4 agonists inhibit interferon-gamma-induced MHC class II and B7 costimulatory molecules expression on cultured astrocytes.

    PubMed

    Zeinstra, Esther M; Wilczak, Nadine; Wilschut, Jan C; Glazenburg, Lisa; Chesik, Daniel; Kroese, Frans G M; De Keyser, Jacques

    2006-10-01

    A failure of tight control of MHC class II expression on astrocytes may play a role in the development of autoimmune responses in multiple sclerosis. The 5-HT(4) serotonin receptor agonists cisapride and prucalopride, at concentrations between 10(-10) M and 10(-8) M, reduced interferon-gamma-induced MHC class II immunostaining in cultured astrocytes derived from newborn Wistar rats by approximately 50-60%. The magnitude of MHC class II inhibition by 5-HT(4) agonists was comparable to that of interferon-beta. The alpha(1)-adrenergic receptor agonist phenylephrine was without effect. Cisapride (10(-9) M) also prevented interferon-gamma-induced B7-1 and B7-2 immunostaining. Our results suggest that 5-HT(4) agonists may have therapeutic potential in multiple sclerosis by inhibiting the up-regulation of immune responsiveness of astrocytes in the central nervous system.

  3. Intracellular transport of MHC class II and associated invariant chain in antigen presenting cells from AP-3-deficient mocha mice.

    PubMed

    Sevilla, L M; Richter, S S; Miller, J

    2001-06-15

    MHC class II-restricted antigen presentation requires trafficking of newly synthesized class II-invariant chain complexes from the trans-Golgi network to endosomal, peptide-loading compartments. This transport is mediated by dileucine-like motifs within the cytosolic tail of the invariant chain. Although these signals have been well characterized, the cytosolic proteins that interact with these dileucine signals and mediate Golgi sorting and endosomal transport have not been identified. Recently, an adaptor complex, AP-3, has been identified that interacts with dileucine motifs and mediates endosomal/lysosomal transport in yeast, Drosophila, and mammals. In this report, we have assessed class II-invariant chain trafficking in a strain of mice (mocha) which lacks expression of AP-3. Our studies demonstrate that the lack of AP-3 does not affect the kinetics of invariant chain degradation, the route of class II-invariant chain transport, or the rate and extent of class II-peptide binding as assessed by the generation of SDS-stable dimers. The possible role of other known or unknown adaptor complexes in class II-invariant chain transport is discussed.

  4. Immune complexes (IC) down-regulate the basal and interferon-γ-induced expression of MHC Class II on human monocytes

    PubMed Central

    Barrionuevo, P; Beigier-Bompadre, M; De La Barrera, S; Alves-Rosa, M F; Fernandez, G; Palermo, M S; Isturiz, M A

    2001-01-01

    The interaction of Fc receptors for IgG (FcγRs) on monocytes/macrophages with immune complexes (IC) triggers regulatory and effector functions. Previous studies have shown that FcγR–IC interactions inhibit the IFN-γ-induced expression of MHC class II in murine macrophages. However, the mechanism(s) responsible for these effects have not been elucidated. In addition, whether this IC-dependent effect also occurs in human cells is not known. Taking into account the fact that IC and IFN-γ are frequently found in infections and autoimmune disorders, together with the crucial role MHC class II molecules play in the regulation of immune response, we explored the effect and mechanism of IC-induced MHC class II down-regulation in human peripheral blood mononuclear cells (PBMC). This effect was studied either in the presence or absence of IFN-γ. We demonstrate that IC exert a drastic inhibition of basal and IFN-γ-induced expression of MHC class II on human monocytes. This effect was mediated through the interaction of IC with both FcγRI and FcγRII. Moreover, similar results were obtained using supernatants from IC-treated PBMC. The IC-induced down-regulation of MHC class II is abrogated by pepstatin and phosphoramidon, supporting the role of aspartic protease(s) and metalloprotease(s) in this process. In parallel with MHC class II expression, antigen presentation was markedly inhibited in the presence of IC. PMID:11529917

  5. Differential presentation of tumor antigen-derived epitopes by MHC-class I and antigen-positive tumor cells.

    PubMed

    Held, Gerhard; Neumann, Frank; Sturm, Christine; Kaestner, Lars; Dauth, Nina; de Bruijn, Diederik R; Renner, Christoph; Lipp, Peter; Pfreundschuh, Michael

    2008-10-15

    SSX2 is a member of the family of cancer/testis antigens. The SSX2 derived peptide SSX2(103-111) has been shown to be presented to cytotoxic T-lymphocytes (CTL) by Major-Histocompatibility (MHC) Class-I complexes after endogenous processing, more precisely by the allele HLA-A*0201. The HLA-A*0201- and SSX2-positive melanoma cell line SK-Mel-37 but not Me275 had been shown to elicit reactivity in SSX2(103-111) specific cytotoxic T-lymphocytes. To analyze the correlation between SSX2(103-111) presentation and T-cell stimulation, we intended to visualize presentation of SSX2(103-111) in these melanoma cell lines. Fab-antibodies were established from a human phage library with specificity for SSX2(103-111)/HLA-A*0201 complexes (but non-reactive with HLA-A*0201 or SSX2(103-111) alone) and used to visualize the presentation of SSX2(103-111) in the context of HLA-A*0201 by fluorescence microscopy. Presentation of SSX2(103-111) the context of HLA-A*0201 was demonstrated for the majority of SK-Mel-37, but for only a small fraction (<1%) of Me275 as indicated by a clear membrane-staining pattern in fluorescence microscopy. The presentation of SSX2(103-111) on SK-Mel37 and Me275, but not the expression of the SSX2 protein correlated with the capability of these cells to stimulate cells of an SSX2(103-111)-specific T-cell clone. MHC-peptide specific antibodies are a valuable tool for the analysis of antigenic peptides in the context of MHC-I molecules and for the structural definition of immunodominant epitopes.

  6. Methylation status and transcriptional expression of the MHC class I loci in human trophoblast cells from term placenta

    SciTech Connect

    Guillaudeux, T.; Rodriguez, A.M.; Girr, M.

    1995-04-01

    Of the various molecular regulatory mechanisms that may be used by human trophoblast cells to down-regulate expression of HLA class I genes, we chose to investigate the methylation of DNA, generally associated with inhibition of transcription. We analyzed the methylation status of different HLA class I loci in villous and extravillous cytotrophoblast cells and in vitro-differentiated syncytiotrophoblast, purified from human term placenta, as well as in the human trophoblast-derived JAR and JEG-3 cell lines. We then compared methylation status and transcriptional activity. An inverse relationship was established between JAR and JEG-3: HLA-A, -B, and -G are methylated and repressed in JAR, whereas in JEG-3, HLA-A is methylated and repressed but HLA-B and -G are partially methylated and transcribed. HLA-E is unmethylated and transcribed in both cell lines. Apart from HLA-E, which is always unmethylated and transcribed, no such relationship exists for the other class I loci in trophoblast cells. Whereas nonclassical HLA-G and classical HLA-A and -B class I genes are undermethylated in both cytotrophoblast and syncytiotrophoblast, they are clearly transcribed in the former but minimally transcribed in the latter subpopulation. Thus, the down-regulation of class I gene expression in the in vitro-differentiated synctiotrophoblast is unlikely to be caused by DNA methylation. Furthermore, there is no detectable expression of any class I molecule at the cell surface of either trophoblast cell subpopulation, suggesting a negative control on translation and/or on the secretory pathway to the plasma membrane. 50 refs., 11 figs., 1 tab.

  7. Copy number variation and genetic diversity of MHC Class IIb alleles in an alien population of Xenopus laevis.

    PubMed

    Mable, Barbara K; Kilbride, Elizabeth; Viney, Mark E; Tinsley, Richard C

    2015-10-01

    Xenopus laevis (the African clawed frog), which originated through hybridisation and whole genome duplication, has been used as a model for genetics and development for many years, but surprisingly little is known about immune gene variation in natural populations. The purpose of this study was to use an isolated population of X. laevis that was introduced to Wales, UK in the past 50 years to investigate how variation at the MHC compares to that at other loci, following a severe population bottleneck. Among 18 individuals, we found nine alleles based on exon 2 sequences of the Class IIb region (which includes the peptide binding region). Individuals carried from one to three of the loci identified from previous laboratory studies. Genetic variation was an order of magnitude higher at the MHC compared with three single-copy nuclear genes, but all loci showed high levels of heterozygosity and nucleotide diversity and there was not an excess of homozygosity or decrease in diversity over time that would suggest extensive inbreeding in the introduced population. Tajima's D was positive for all loci, which is consistent with a bottleneck. Moreover, comparison with published sequences identified the source of the introduced population as the Western Cape region of South Africa, where most commercial suppliers have obtained their stocks. These factors suggest that despite founding by potentially already inbred individuals, the alien population in Wales has maintained substantial genetic variation at both adaptively important and neutral genes.

  8. Characterization of expressed class II MHC sequences in the banner-tailed kangaroo rat (Dipodomys spectabilis) reveals multiple DRB loci.

    PubMed

    Busch, Joseph D; Waser, Peter M; DeWoody, J Andrew

    2008-11-01

    Genes of the major histocompatibility complex (MHC) are exceptionally polymorphic due to the combined effects of natural and sexual selection. Most research in wild populations has focused on the second exon of a single class II locus (DRB), but complete gene sequences can provide an illuminating backdrop for studies of intragenic selection, recombination, and organization. To this end, we characterized class II loci in the banner-tailed kangaroo rat (Dipodomys spectabilis). Seven DRB-like sequences (provisionally named MhcDisp-DRB*01 through *07) were isolated from spleen cDNA and most likely comprise > or =5 loci; this multiformity is quite unlike the situation in muroid rodents such as Mus, Rattus, and Peromyscus. In silico translation revealed the presence of important structural residues for glycosylation sites, salt bonds, and CD4+ T-cell recognition. Amino-acid distances varied widely among the seven sequences (2-34%). Nuclear DNA sequences from the Disp-DRB*07 locus (approximately 10 kb) revealed a conventional exon/intron structure as well as a number of microsatellites and short interspersed nuclear elements (B4, Alu, and IDL-Geo subfamilies). Rates of nucleotide substitution at Disp-DRB*07 are similar in both exons and introns (pi = 0.015 and 0.012, respectively), which suggests relaxed selection and may indicate that this locus is an expressed pseudogene. Finally, we performed BLASTn searches against Dipodomys ordii genomic sequences (unassembled reads) and find 90-97% nucleotide similarity between the two kangaroo rat species. Collectively, these data suggest that class II diversity in heteromyid rodents is based on polylocism and departs from the muroid architecture.

  9. A Role for cis Interaction between the Inhibitory Ly49A receptor and MHC class I for natural killer cell education.

    PubMed

    Chalifour, Anick; Scarpellino, Léonardo; Back, Jonathan; Brodin, Petter; Devèvre, Estelle; Gros, Frédéric; Lévy, Frédéric; Leclercq, Georges; Höglund, Petter; Beermann, Friedrich; Held, Werner

    2009-03-20

    Natural killer (NK) cells show enhanced functional competence when they express inhibitory receptors specific for inherited major histocompatibility complex class I (MHC-I) molecules. Current models imply that NK cell education requires an interaction of inhibitory receptors with MHC-I expressed on other cells. However, the inhibitory Ly49A receptor can also bind MHC-I ligand on the NK cell itself (in cis). Here we describe a Ly49A variant, which can engage MHC-I expressed on other cells but not in cis. Even though this variant inhibited NK cell effector function, it failed to educate NK cells. The association with MHC-I in cis sequestered wild-type Ly49A, and this was found to relieve NK cells from a suppressive effect of unengaged Ly49A. These data explain how inhibitory MHC-I receptors can facilitate NK cell activation. They dissociate classical inhibitory from educating functions of Ly49A and suggest that cis interaction of Ly49A is necessary for NK cell education.

  10. Definition of an extended MHC class II-peptide binding motif for the autoimmune disease-associated Lewis rat RT1.BL molecule.

    PubMed

    Wauben, M H; van der Kraan, M; Grosfeld-Stulemeyer, M C; Joosten, I

    1997-02-01

    The Lewis rat, an inbred rat strain susceptible to several well-characterized experimental autoimmune diseases, provides a good model to study peptide-mediated immunotherapy. Peptide immunotherapy focussing on the modulation of T cell responses by interfering with TCR-peptide-MHC complex formation requires the elucidation of the molecular basis of TCR-peptide-MHC interactions for an efficient design of modulatory peptides. In the Lewis rat most autoimmune-associated CD4+ T cell responses are MHC class II RT1.BL restricted. In this study, the characteristics of RT1.BL-peptide interactions were explored. A series of substitution analogs of two Lewis rat T cell epitopes was examined in a direct peptide-MHC binding assay on isolated RT1.BL molecules. Furthermore, other autoimmune-related as well as non-disease-related T cell epitopes were tested in the binding assay. This has led to the definition of an extended RT1.BL-peptide binding motif. The RT1.BL-peptide binding motif established in this study is the first described rat MHC-peptide binding motif based on direct MHC-peptide binding experiments. To predict good or intermediate RT1.BL binding peptides, T cell epitope search profiles were deduced from this motif. The motif and search profiles will greatly facilitate the prediction of modulatory peptides based on autoimmune-associated T cell epitopes and the identification of target structures in experimental autoimmune diseases in Lewis rats.

  11. Structure of the Epstein-Barr virus gp42 protein bound to the MHC class II recepter HLA-DR1

    SciTech Connect

    Mullen, M.; Haan, K.M.; Longnecker, R.; Jardetzky, T.

    2010-03-08

    Epstein-Barr virus (EBV) causes infectious mononucleosis, establishes long-term latent infections, and is associated with a variety of human tumors. The EBV gp42 glycoprotein binds MHC class II molecules, playing a critical role in infection of B lymphocytes. EBV gp42 belongs to the C-type lectin superfamily, with homology to NK receptors of the immune system. We report the crystal structure of gp42 bound to the human MHC class II molecule HLA-DR1. The gp42 binds HLA-DR1 using a surface site that is distinct from the canonical lectin and NK receptor ligand binding sites. At the canonical ligand binding site, gp42 forms a large hydrophobic groove, which could interact with other ligands necessary for EBV entry, providing a mechanism for coupling MHC recognition and membrane fusion.

  12. AIDS-protective HLA-B*27/B*57 and chimpanzee MHC class I molecules target analogous conserved areas of HIV-1/SIVcpz.

    PubMed

    de Groot, Natasja G; Heijmans, Corrine M C; Zoet, Yvonne M; de Ru, Arnoud H; Verreck, Frank A; van Veelen, Peter A; Drijfhout, Jan W; Doxiadis, Gaby G M; Remarque, Edmond J; Doxiadis, Ilias I N; van Rood, Jon J; Koning, Frits; Bontrop, Ronald E

    2010-08-24

    In the absence of treatment, most HIV-1-infected humans develop AIDS. However, a minority are long-term nonprogressors, and resistance is associated with the presence of particular HLA-B*27/B*57 molecules. In contrast, most HIV-1-infected chimpanzees do not contract AIDS. In comparison with humans, chimpanzees experienced an ancient selective sweep affecting the MHC class I repertoire. We have determined the peptide-binding properties of frequent chimpanzee MHC class I molecules, and show that, like HLA-B*27/B*57, they target similar conserved areas of HIV-1/SIV(cpz). In addition, many animals appear to possess multiple molecules targeting various conserved areas of the HIV-1/SIV(cpz) Gag protein, a quantitative aspect of the immune response that may further minimize the chance of viral escape. The functional characteristics of the contemporary chimpanzee MHC repertoire suggest that the selective sweep was caused by a lentiviral pandemic.

  13. Lacking prognostic significance of beta 2-microglobulin, MHC class I and class II antigen expression in breast carcinomas.

    PubMed Central

    Wintzer, H. O.; Benzing, M.; von Kleist, S.

    1990-01-01

    To evaluate the impact of MHC antigen expression on the survival of patients with cancer, 77 human breast carcinomas were investigated for the expression of beta 2-microglobulin (beta 2m), HLA-A,B,C and HLA-DR. Thirty-one benign breast tumours were stained for comparison. The results for the carcinomas were related to the survival data of the cancer patients. The expression of beta 2m, HLA-A,B,C and HLA-DR was significantly lower in malignant tumours compared to the benign lesions. Whereas all benign tumours were positive for beta 2m and HLA-A,B,C and 28/31 positive for HLA-DR the following positivity rates were found in carcinomas: 74/77 for beta 2m, 57/77 for HLA-A,B,C and 10/77 for HLA-DR. The follow-up (median 45 months) of 66 cancer patients for overall survival and of 65 patients for disease-free survival revealed no influence of beta 2m, HLA-A,B,C or HLA-DR expression on the prognosis of this cancer. In conclusion, experimental data indicating the importance of MHC antigens in anti-tumour responses are not confirmed by the analysis of cancer patient survival data. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:2201398

  14. The tetraspan protein CD82 is a resident of MHC class II compartments where it associates with HLA-DR, -DM, and -DO molecules.

    PubMed

    Hammond, C; Denzin, L K; Pan, M; Griffith, J M; Geuze, H J; Cresswell, P

    1998-10-01

    In specialized APCs, MHC class II molecules are synthesized in the endoplasmic reticulum and transported through the Golgi apparatus to organelles of the endocytic pathway collectively called MHC class II compartments (MIICs). There, the class II-associated invariant chain is degraded, and peptides derived from internalized Ag bind to empty class II in a reaction that is facilitated by the class II-like molecule HLA-DM. An mAb raised to highly purified, immunoisolated MIICs from human B lymphoblastoid cells recognized CD82, a member of the tetraspan family of integral membrane proteins. Subcellular fractionation, immunofluorescence microscopy, and immunoelectron microscopy showed that CD82 is highly enriched in MIICs, particularly in their internal membranes. Coprecipitation analysis showed that CD82 associates in MIICs with class II, DM, and HLA-DO (an inhibitor of peptide loading that binds DM). Similar experiments showed CD63, another tetraspan protein found in MIICs, also associates with these molecules in the compartment and that CD82 and CD63 associate with each other. Preclearing experiments demonstrated that both CD82 and CD63 form complexes with DM-associated class II and DM-associated DO. The ability of CD82 and CD63 to form complexes with class II, DM, and DO in MIICs suggests that the tetraspan proteins may play an important role in the late stages of MHC class II maturation.

  15. MHC class II complexes sample intermediate states along the peptide exchange pathway

    PubMed Central

    Wieczorek, Marek; Sticht, Jana; Stolzenberg, Sebastian; Günther, Sebastian; Wehmeyer, Christoph; El Habre, Zeina; Álvaro-Benito, Miguel; Noé, Frank; Freund, Christian

    2016-01-01

    The presentation of peptide-MHCII complexes (pMHCIIs) for surveillance by T cells is a well-known immunological concept in vertebrates, yet the conformational dynamics of antigen exchange remain elusive. By combining NMR-detected H/D exchange with Markov modelling analysis of an aggregate of 275 microseconds molecular dynamics simulations, we reveal that a stable pMHCII spontaneously samples intermediate conformations relevant for peptide exchange. More specifically, we observe two major peptide exchange pathways: the kinetic stability of a pMHCII's ground state defines its propensity for intrinsic peptide exchange, while the population of a rare, intermediate conformation correlates with the propensity of the HLA-DM-catalysed pathway. Helix-destabilizing mutants designed based on our model shift the exchange behaviour towards the HLA-DM-catalysed pathway and further allow us to conceptualize how allelic variation can shape an individual's MHC restricted immune response. PMID:27827392

  16. Transcriptional regulation of the MHC class I HLA-A11 promoter by the zinc finger protein ZFX.

    PubMed Central

    L'Haridon, M; Paul, P; Xerri, J G; Dastot, H; Dolliger, C; Schmid, M; de Angelis, N; Grollet, L; Sigaux, F; Degos, L; Gazin, C

    1996-01-01

    Regulation of the human MHC class I HLA-A11 promoter is governed by a complex array of regulatory elements. One of these elements, shown here to be critical for the transcriptional activity of the promoter, was used to screen a lambda gt11 library and allowed the identification of a cDNA which coded for the zinc finger protein ZFX. ZFX was shown to bind the sequences AGGGCCCCA and AGGCCCCGA, located respectively at positions -271 to -263 and -242 to -234 of the HLA-A11 promoter, with similar affinities through its three C-terminal zinc fingers. ZFX575, a short isoform of ZFX, activates transcription from the HLA-All promoter in a Leydig cell line. PMID:8657576

  17. Trans-species polymorphism of the Mhc class II DRB-like gene in banded penguins (genus Spheniscus).

    PubMed

    Kikkawa, Eri F; Tsuda, Tomi T; Sumiyama, Daisuke; Naruse, Taeko K; Fukuda, Michio; Kurita, Masanori; Wilson, Rory P; LeMaho, Yvon; Miller, Gary D; Tsuda, Michio; Murata, Koichi; Kulski, Jerzy K; Inoko, Hidetoshi

    2009-05-01

    The Major Histocompatibility Complex (Mhc) class II DRB locus of vertebrates is highly polymorphic and some alleles may be shared between closely related species as a result of balancing selection in association with resistance to parasites. In this study, we developed a new set of PCR primers to amplify, clone, and sequence overlapping portions of the Mhc class II DRB-like gene from the 5'UTR end to intron 3, including exons 1, 2, and 3 and introns 1 and 2 in four species (20 Humboldt, six African, five Magellanic, and three Galapagos penguins) of penguin from the genus Spheniscus (Sphe). Analysis of gene sequence variation by the neighbor-joining method of 21 Sphe sequences and 20 previously published sequences from four other penguin species revealed overlapping clades within the Sphe species, but species-specific clades for the other penguin species. The overlap of the DRB-like gene sequence variants between the four Sphe species suggests that, despite their allopatric distribution, the Sphe species are closely related and that some shared DRB1 alleles may have undergone a trans-species inheritance because of balancing selection and/or recent rapid speciation. The new primers and PCR assays that we have developed for the identification of the DRB1 DNA and protein sequence variations appear to be useful for the characterization of the molecular evolution of the gene in closely related Penguin species and might be helpful for the assessment of the genetic health and the management of the conservation and captivity of these endangered species.

  18. Predominant Occupation of the Class I MHC Molecule H-2Kwm7 with a Single Self-peptide Suggests a Mechanism for its Diabetes-protective Effect

    SciTech Connect

    Brims, D.; Qian, J; Jarchum, I; Mikesh, L; Palmieri, E; Ramagopal, U; Malashkevich, V; Chaparro, R; Lund, T; et. al.

    2010-01-01

    Type 1 diabetes (T1D) is an autoimmune disease characterized by T cell-mediated destruction of insulin-producing pancreatic {beta} cells. In both humans and the non-obese diabetic (NOD) mouse model of T1D, class II MHC alleles are the primary determinant of disease susceptibility. However, class I MHC genes also influence risk. These findings are consistent with the requirement for both CD{sup 4+} and CD{sup 8+} T cells in the pathogenesis of T1D. Although a large body of work has permitted the identification of multiple mechanisms to explain the diabetes-protective effect of particular class II MHC alleles, studies examining the protective influence of class I alleles are lacking. Here, we explored this question by performing biochemical and structural analyses of the murine class I MHC molecule H-2K{sup wm7}, which exerts a diabetes-protective effect in NOD mice. We have found that H-2K{sup wm7} molecules are predominantly occupied by the single self-peptide VNDIFERI, derived from the ubiquitous protein histone H2B. This unexpected finding suggests that the inability of H-2K{sup wm7} to support T1D development could be due, at least in part, to the failure of peptides from critical {beta}-cell antigens to adequately compete for binding and be presented to T cells. Predominant presentation of a single peptide would also be expected to influence T-cell selection, potentially leading to a reduced ability to select a diabetogenic CD{sup 8+} T-cell repertoire. The report that one of the predominant peptides bound by T1D-protective HLA-A*31 is histone derived suggests the potential translation of our findings to human diabetes-protective class I MHC molecules.

  19. MHC class I and class I-like gene product expression by malignant T cells: relationships between CD1a, HLA-ABC and beta 2-microglobulin.

    PubMed Central

    Jones, R A; Scott, C S; Katz, F E; Child, J A

    1988-01-01

    Beta 2-microglobulin (beta 2m) forms the invariant light chain of the MHC-encoded HLA-ABC and the non-MHC-encoded CD1 molecules. While HLA-ABC (MHC Class I) molecules are virtually ubiquitous in tissue distribution, CD1 determinants by contrast are more restricted. We have assessed, by indirect immunoenzymeassay, the relative membrane densities of these molecules on malignant thymic and post-thymic T cells. It was found that the T cells of mature post-thymic proliferations expressed significantly more beta 2m-associated protein, predominantly HLA-ABC in nature, than thymic-ALL blasts. This parallels the situation found in normal peripheral T cells and thymocytes. In contrast to post-thymic T cells, thymic-ALL blasts showed considerable case to case variation with respect to non-HLA-associated beta 2m and, of particular interest, not all of this excess beta 2m could be accounted for by CD1a. We therefore conclude that other beta 2m-containing molecules may be expressed on thymic-ALL blasts and possibly also on post-thymic leukaemic T cells. In addition, it was found that T cells from CD4+ cases of post-thymic proliferations expressed more beta 2m-associated determinants than other T cells, whether of either normal or malignant origin, and that certain post-thymic malignancies express significantly increased levels of beta 2m-associated protein relative to normal peripheral T-cells. This is in direct contrast to the situation seen in many solid malignancies. PMID:2466592

  20. Songbird genomics: analysis of 45 kb upstream of a polymorphic Mhc class II gene in red-winged blackbirds (Agelaius phoeniceus).

    PubMed

    Gasper, J S; Shiina, T; Inoko, H; Edwards, S V

    2001-07-01

    Here we present the sequence of a 45 kb cosmid containing a previously characterized poly-morphic Mhc class II B gene (Agph-DAB1) from the red-winged blackbird (Agelaius phoeniceus). We compared it with a previously sequenced cosmid from this species, revealing two regions of 7.5 kb and 13.0 kb that averaged greater than 97% similarity to each another, indicating a very recent shared duplication. We found 12 retroelements, including two chicken repeat 1 (CR1) elements, constituting 6.4% of the sequence and indicating a lower frequency of retroelements than that found in mammalian genomic DNA. Agph-DAB3, a new class II B gene discovered in the cosmid, showed a low rate of polymorphism and may be functional. In addition, we found a Mhc class II B gene fragment and three genes likely to be functional (encoding activin receptor type II, a zinc finger, and a putative gamma-filamin). Phylogenetic analysis of exon 2 alleles of all three known blackbird Mhc genes indicated strong clustering of alleles by locus, implying that large amounts of interlocus gene conversion have not occurred since these genes have been diverging. Despite this, interspecific comparisons indicate that all three blackbird Mhc genes diverged from one another less than 35 million years ago and are subject to concerted evolution in the long term. Comparison of blackbird and chicken Mhc promoter regions revealed songbird promoter elements for the first time. The high gene density of this cosmid confirms similar findings for the chicken Mhc, but the segment duplications and diversity of retroelements resembles mammalian sequences.

  1. Lack of MHC class I surface expression on neoplastic cells and poor activation of the secretory pathway of cytotoxic cells in oral squamous cell carcinomas

    PubMed Central

    Cruz, I; Meijer, C J L M; Walboomers, J M M; Snijders, P J F; Waal, I Van der

    1999-01-01

    Cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells use the secretory pathway of perforin/granzymes to kill their target cells. In contrast to NK cells, CTL responses are MHC class I restricted. In this study we analysed the relative activation of CTL and NK cells in relation with MHC class I expression on oral squamous cell carcinomas (OSCCs). MHC class I expression was investigated in 47 OSCCs by immunohistochemistry using HCA2, HC10 and β2-m antibodies. The presence of CTLs, NK cells, and its activation, was investigated in 21 of these OSCCs using respectively, CD8, CD57 and GrB7 antibodies. The Q-Prodit measuring system was used for quantification of cytotoxic cells. All OSCCs showed weak or absent staining of β2-m on the cell surface. The absence of β2-m was significantly associated with absent expression of MHC class I heavy chain as detected by HC10 antibody (P = 0.004). In tumour infiltrates CTLs always outnumbered NK cells, as reflected by the ratio CD57/CD8 being always inferior to one (mean: 0.19; SD: 0.15). The proportion of activated cytotoxic cells as detected by granzyme B expression was generally low (mean: 8.6%; SD 8.9). A clear correlation between MHC class I expression and the relative proportion of NK cells/CTLs was not found. This study shows that the majority of OSCCs show weak or absent expression of MHC class I molecules on the cell surface, possibly due to alterations in the normal β2-m pathway. The low proportion of granzyme B-positive CTLs/NK cells indicates that the secretory pathway of cytotoxicity is poor in these patients. The lack of correlation between MHC class I expression and CTL/NK cell activation as detected by granzyme B expression suggests that, next to poor antigen presentation, also local factors seem to determine the final outcome of the cytotoxic immune response. © 1999 Cancer Research Campaign PMID:10555762

  2. Lack of MHC class I antigens and tumour aggressiveness of the squamous cell carcinoma of the larynx.

    PubMed Central

    Esteban, F.; Concha, A.; Delgado, M.; Pérez-Ayala, M.; Ruiz-Cabello, F.; Garrido, F.

    1990-01-01

    A series of 60 primary laryngeal and hypopharyngeal tumours, 24 lymph node metastases and normal tissue were evaluated in frozen sections for the expression of MHC class I antigens, using monoclonal antibodies and the APAAP technique. We found 13 tumours presenting total HLA-ABC loss, five with selective loss of HLA-A antigens and one with absence of HLA-B antigens. These losses were statistically associated with clinical and pathological parameters, such as T stage, degree of differentiation, scores according to the Jakobsson and Glanz grading systems and degree of leukocytic infiltration. Our results lead us to the following conclusions: (a) HLA class I losses were found in a group of tumours showing greater aggressiveness and worse prognosis; (b) these alterations in expression were not associated with an increased metastatic potential. Thus, the absence of HLA molecules in laryngeal tumours is related to greater local aggressiveness, and the loss of class I antigens seems to constitute an adaptive tumour mechanism to avoid the different anatomical and immunological barriers within the larynx. Images Figure 1 Figure 2 PMID:2257212

  3. IFNγ producing CD8+ T cells modified to resist major immune checkpoints induce regression of MHC class I-deficient melanomas

    PubMed Central

    Buferne, Michel; Chasson, Lionel; Grange, Magali; Mas, Amandine; Arnoux, Fanny; Bertuzzi, Mélanie; Naquet, Philippe; Leserman, Lee; Schmitt-Verhulst, Anne-Marie; Auphan-Anezin, Nathalie

    2015-01-01

    Tumors with reduced expression of MHC class I (MHC-I) molecules may be unrecognized by tumor antigen-specific CD8+ T cells and thus constitute a challenge for cancer immunotherapy. Here we monitored development of autochthonous melanomas in TiRP mice that develop tumors expressing a known tumor antigen as well as a red fluorescent protein (RFP) reporter knock in gene. The latter permits non-invasive monitoring of tumor growth by biofluorescence. One developing melanoma was deficient in cell surface expression of MHC-I, but MHC-I expression could be rescued by exposure of these cells to IFNγ. We show that CD8+ T cells specific for tumor antigen/MHC-I were efficient at inducing regression of the MHC-I-deficient melanoma, provided that the T cells were endowed with properties permitting their migration into the tumor and their efficient production of IFNγ. This was the case for CD8+ T cells transfected to express an active form of STAT5 (STAT5CA). The amount of IFNγ produced ex vivo from T cells present in tumors after adoptive transfer of the CD8+ T cells was correlated with an increase in surface expression of MHC-I molecules by the tumor cells. We also show that these CD8+ T cells expressed PD-1 and upregulated its ligand PDL-1 on melanoma cells within the tumor. Despite upregulation of this immunosuppressive pathway, efficient IFNγ production in the melanoma microenvironment was found associated with resistance of STAT5CA-expressing CD8+ T cells to inhibition both by PD-1/PDL-1 engagement and by TGFβ1, two main immune regulatory mechanisms hampering the efficiency of immunotherapy in patients. PMID:25949872

  4. IFNγ producing CD8(+) T cells modified to resist major immune checkpoints induce regression of MHC class I-deficient melanomas.

    PubMed

    Buferne, Michel; Chasson, Lionel; Grange, Magali; Mas, Amandine; Arnoux, Fanny; Bertuzzi, Mélanie; Naquet, Philippe; Leserman, Lee; Schmitt-Verhulst, Anne-Marie; Auphan-Anezin, Nathalie

    2015-02-01

    Tumors with reduced expression of MHC class I (MHC-I) molecules may be unrecognized by tumor antigen-specific CD8(+) T cells and thus constitute a challenge for cancer immunotherapy. Here we monitored development of autochthonous melanomas in TiRP mice that develop tumors expressing a known tumor antigen as well as a red fluorescent protein (RFP) reporter knock in gene. The latter permits non-invasive monitoring of tumor growth by biofluorescence. One developing melanoma was deficient in cell surface expression of MHC-I, but MHC-I expression could be rescued by exposure of these cells to IFNγ. We show that CD8(+) T cells specific for tumor antigen/MHC-I were efficient at inducing regression of the MHC-I-deficient melanoma, provided that the T cells were endowed with properties permitting their migration into the tumor and their efficient production of IFNγ. This was the case for CD8(+) T cells transfected to express an active form of STAT5 (STAT5CA). The amount of IFNγ produced ex vivo from T cells present in tumors after adoptive transfer of the CD8(+) T cells was correlated with an increase in surface expression of MHC-I molecules by the tumor cells. We also show that these CD8(+) T cells expressed PD-1 and upregulated its ligand PDL-1 on melanoma cells within the tumor. Despite upregulation of this immunosuppressive pathway, efficient IFNγ production in the melanoma microenvironment was found associated with resistance of STAT5CA-expressing CD8(+) T cells to inhibition both by PD-1/PDL-1 engagement and by TGFβ1, two main immune regulatory mechanisms hampering the efficiency of immunotherapy in patients.

  5. Identification and characterization of the major histocompatibility complex class II DQB (MhcMath-DQB1) alleles in Tibetan macaques (Macaca thibetana).

    PubMed

    Yao, Y-F; Zhao, J-J; Dai, Q-X; Li, J-Y; Zhou, L; Wang, Y-T; Ni, Q-Y; Zhang, M-w; Xu, H-L

    2013-08-01

    Tibetan macaque (Macaca thibetana), an endangered primate species endemic to China, have been used as experimental animal model for various human diseases. Major histocompatibility complex (MHC) genes play a crucial role in the susceptibility and/or resistance to many human diseases, but little is known about Tibetan macaques. To gain an insight into the MHC background and to facilitate the experimental use of Tibetan macaques, the second exon of Mhc-DQB1 gene was sequenced in a cohort of wild Tibetan macaques living in the Sichuan province of China. A total of 23 MhcMath-DQB1 alleles were identified for the first time, illustrating a marked allelic polymorphism at the DQB1 locus for these macaques. Most of the sequences (74%) observed in this study belong to DQB1*06 (9 alleles) and DQB1*18 (8 alleles) lineages, and the rest (26%) belong to DQB1*15 (3 alleles) and DQB1*17 (3 alleles) lineages. The most frequent alleles detected among these macaques were MhcMath-DQB1*15:02:02 (17.9%), followed by Math-DQB1*06:06, 17:03 and 18:01, which were detected in 9 (16.1%) of the monkeys, respectively. Non-synonymous substitutions occurred at a significantly higher frequency than synonymous substitutions in the peptide-binding region, suggesting balancing selection for maintaining polymorphisms at the MHC class II DQB1 locus. Phylogenetic analyses confirms the trans-species model of evolution of the Mhc-DQB1 genes in non-human primates, and in particular, the extensive allele sharing is observed between Tibetan and other macaque species.

  6. Kinetic and thermodynamic studies of the interaction between activating and inhibitory Ly49 natural killer receptors and MHC class I molecules.

    PubMed

    Romasanta, Pablo N; Curto, Lucrecia M; Sarratea, María B; Noli Truant, Sofía; Antonoglou, María B; Fernández Lynch, María J; Delfino, José M; Mariuzza, Roy A; Fernández, Marisa M; Malchiodi, Emilio L

    2017-01-01

    Natural killer (NK) cells are lymphocytes of the innate immune system that eliminate virally infected or malignantly transformed cells. NK cell function is regulated by diverse surface receptors that are both activating and inhibitory. Among them, the homodimeric Ly49 receptors control NK cell cytotoxicity by sensing major histocompatibility complex class I molecules (MHC-I) on target cells. Although crystal structures have been reported for Ly49/MHC-I complexes, the underlying binding mechanism has not been elucidated. Accordingly, we carried out thermodynamic and kinetic experiments on the interaction of four NK Ly49 receptors (Ly49G, Ly49H, Ly49I and Ly49P) with two MHC-I ligands (H-2D(d) and H-2D(k)). These Ly49s embrace the structural and functional diversity of the highly polymorphic Ly49 family. Combining surface plasmon resonance, fluorescence anisotropy and far-UV circular dichroism (CD), we determined that the best model to describe both inhibitory and activating Ly49/MHC-I interactions is one in which the two MHC-I binding sites of the Ly49 homodimer present similar binding constants for the two sites (∼10(6) M(-1)) with a slightly positive co-operativity in some cases, and without far-UV CD observable conformational changes. Furthermore, Ly49/MHC-I interactions are diffusion-controlled and enthalpy-driven. These features stand in marked contrast with the activation-controlled and entropy-driven interaction of Ly49s with the viral immunoevasin m157, which is characterized by strong positive co-operativity and conformational selection. These differences are explained by the distinct structures of Ly49/MHC-I and Ly49/m157 complexes. Moreover, they reflect the opposing roles of NK cells to rapidly scan for virally infected cells and of viruses to escape detection using immunoevasins such as m157.

  7. The central repeat domain 1 of Kaposi's sarcoma-associated herpesvirus (KSHV) latency associated-nuclear antigen 1 (LANA1) prevents cis MHC class I peptide presentation

    SciTech Connect

    Kwun, Hyun Jin; Ramos da Silva, Suzane; Qin Huilian; Ferris, Robert L.; Tan Rusung; Chang Yuan; Moore, Patrick S.

    2011-04-10

    KSHV LANA1, a latent protein expressed during chronic infection to maintain a viral genome, inhibits major histocompatibility complex class I (MHC I) peptide presentation in cis as a means of immune evasion. Through deletional cloning, we localized this function to the LANA1 central repeat 1 (CR1) subregion. Other CR subregions retard LANA1 translation and proteasomal processing but do not markedly inhibit LANA1 peptide processing by MHC I. Inhibition of proteasomal processing ablates LANA1 peptide presentation. Direct expression of LANA1 within the endoplasmic reticulum (ER) overcomes CR1 inhibition suggesting that CR1 acts prior to translocation of cytoplasmic peptides into the ER. By physically separating CR1 from other subdomains, we show that LANA1 evades MHC I peptide processing by a mechanism distinct from other herpesviruses including Epstein-Barr virus (EBV). Although LANA1 and EBV EBNA1 are functionally similar, they appear to use different mechanisms to evade host cytotoxic T lymphocyte surveillance.

  8. A cluster of ten novel MHC class I related genes on human chromosome 6q24.2-q25.3.

    PubMed

    Radosavljevic, Mirjana; Cuillerier, Benoît; Wilson, Michael J; Clément, Oliver; Wicker, Sophie; Gilfillan, Susan; Beck, Stephan; Trowsdale, John; Bahram, Seiamak

    2002-01-01

    We have identified a novel family of human major histocompatibility complex (MHC) class I genes. This MHC class I related gene family is defined by 10 members, among which 6 encode potentially functional glycoproteins. The 180-kb cluster containing them has been generated by serial duplication and minimal diversification of an ancestral prototype. They are not located within the MHC on 6p21.3, but near the tip of its long arm at q24.2-q25.3, close to the human equivalent of the mouse H2-linked t-complex, a subchromosomal region syntenic to a segment of mouse chromosome 10 harboring the orthologous MHC class I related retinoic acid early transcript loci, Raet1a-d. Hence we have named the identified loci RAET1E-N. Human RAET1 products are all devoid of the membrane-proximal immunoglobulin-like alpha3 domain and most, but not all, are predicted to remain membrane-anchored via glycosylphosphatidylinositol linkage and are shown to display an atypical pattern of polymorphism. RAET1 transcripts are absent from hematopoietic tissues, but largely expressed in tumors. The involvement of orthologous mouse RAET1A-D/H60 in natural killer and T-cell activation through NKG2D engagement augurs a similar function for the human RAET1 proteins.

  9. Invariant chain+ N2a neuroblastoma cells stably expressing the class II MHC transactivator CIITA fail to stimulate anti-tumor immunity.

    PubMed

    Rickard, Steve; Ono, Santa Jeremy

    2008-12-01

    A promising cancer treatment strategy involves stimulation of anti-tumor immune responses. CD4(+) T cell responses are particularly desirable, as they enhance CD8(+) T cell activity and provide immune memory. The major histocompatibility complex (MHC) class II transactivator CIITA can be used to stimulate expression of MHC II on tumor cells, thereby promoting CD4(+) T cell activation. In this study, N2a neuroblastoma cells were stably transfected with CIITA. N2aCIITA cells displayed increased expression of MHC I, MHC II and invariant chain; CD80 and CD86 were expressed by neither the parental N2a cells nor by the N2aCIITA cells. All mice injected with N2aCIITA cells developed tumors. Furthermore, no increase in the numbers of T cells, natural killer cells, macrophages, or eosinophils was observed in the spleens or tumors of mice injected with N2aCIITA cells, compared to tissues from mice injected with the parental N2a cells. This absence of an anti-tumor immune response despite MHC II expression is likely due to the presence of invariant chain, in support of the MHCII(+)/Ii(-) paradigm.

  10. MHC-class-II are expressed in a subpopulation of human neural stem cells in vitro in an IFNγ–independent fashion and during development

    PubMed Central

    Vagaska, B.; New, S. E. P.; Alvarez-Gonzalez, C.; D’Acquisto, F.; Gomez, S. G.; Bulstrode, N. W.; Madrigal, A.; Ferretti, P.

    2016-01-01

    Expression of major histocompatibility antigens class-2 (MHC-II) under non-inflammatory conditions is not usually associated with the nervous system. Comparative analysis of immunogenicity of human embryonic/fetal brain-derived neural stem cells (hNSCs) and human mesenchymal stem cells with neurogenic potential from umbilical cord (UC-MSCs) and paediatric adipose tissue (ADSCs), while highlighting differences in their immunogenicity, led us to discover subsets of neural cells co-expressing the neural marker SOX2 and MHC-II antigen in vivo during human CNS development. MHC-II proteins in hNSCs are functional, and differently regulated upon differentiation along different lineages. Mimicking an inflammatory response using the inflammatory cytokine IFNγ induced MHC-II up-regulation in both astrocytes and hNSCs, but not in UC-MSCs and ADSCs, either undifferentiated or differentiated, though IFNγ receptor expression was comparable. Together, hypoimmunogenicity of both UC-MSCs and ADSCs supports their suitability for allogeneic therapy, while significant immunogenicity of hNSCs and their progeny may at least in part underlie negative effects reported in some patients following embryonic neural cell grafts. Crucially, we show for the first time that MHC-II expression in developing human brains is not restricted to microglia as previously suggested, but is present in discrete subsets of neural progenitors and appears to be regulated independently of inflammatory stimuli. PMID:27080443

  11. Synaptic Clusters of MHC Class II Molecules Induced on DCs by Adhesion Molecule–mediated Initial T-Cell ScanningV⃞

    PubMed Central

    de la Fuente, Hortensia; Mittelbrunn, María; Sánchez-Martín, Lorena; Vicente-Manzanares, Miguel; Lamana, Amalia; Pardi, Ruggero; Cabañas, Carlos; Sánchez-Madrid, Francisco

    2005-01-01

    Initial adhesive contacts between T lymphocytes and dendritic cells (DCs) facilitate recognition of peptide-MHC complexes by the TCR. In this report, we studied the dynamic behavior of adhesion and Ag receptors on DCs during initial contacts with T-cells. Adhesion molecules LFA-1- and ICAM-1,3-GFP as well as MHC class II-GFP molecules were very rapidly concentrated at the DC contact area. Binding of ICAM-3, and ICAM-1 to a lesser extent, to LFA-1 expressed by mature but not immature DC, induced MHC-II clustering into the immune synapse. Also, ICAM-3 binding to DC induced the activation of the Vav1-Rac1 axis, a regulatory pathway involved in actin cytoskeleton reorganization, which was essential for MHC-II clustering on DCs. Our results support a model in which ICAM-mediated MHC-II clustering on DC constitutes a priming mechanism to enhance antigen presentation to T-cells. PMID:15872088

  12. Is alopecia areata an autoimmune-response against melanogenesis-related proteins, exposed by abnormal MHC class I expression in the anagen hair bulb?

    PubMed Central

    Paus, R.; Slominski, A.; Czarnetzki, B. M.

    1993-01-01

    The etiology of alopecia areata (AA), a putative autoimmune disease characterized by sudden hair loss, has remained obscure. It is not understood, how the characteristic inflammatory infiltrate that selectively attacks anagen hair follicles in AA is generated. We hypothesize that this reflects an unexplored form of autoimmunity, a cytotoxic T cell attack on rhythmically synthesized autoantigens normally sequestered by a lack or very low level of MHC class I (MHC I)-expression, and suggest the following mechanism of AA pathogenesis: Microtrauma, neurogenic inflammation, or microbial antigens cause a localized breakdown of MHC I-"negativity" in the proximal anagen hair bulb via proinflammatory cytokines. This exposes autoantigens derived from melanogenesis-related proteins (MRP-DP), which are only generated during anagen, and triggers two successive waves of autoimmune responses: CD8+ cytotoxic T cells initiate AA after recognizing MRP-DP abnormally presented by MHC I molecules on hair matrix melanocytes and/or keratinocytes; a secondary attack, carried by CD4+ T cells and antigen presenting cells, is then mounted against MHC class II--presented additional autoantigens exposed by damaged melanocytes and keratinocytes. The latter causes most of the follicular damage, and extrafollicular disease, and depends greatly on the immunogenetic background of affected individuals. This unifying hypothesis explains the clinical heterogeneity and all salient features of AA, and argues that only the unlikely coincidence of multiple predisposing events triggers AA. The suppression of MHC I--expression and synthesis of MRP in the hair bulb, and the "tolerization" of MRP-DP autoreactive CD8+ T cells may be promising strategies for treating AA. PMID:7716973

  13. Matching at the MHC class I K locus is essential for long-term engraftment of purified hematopoietic stem cells: a role for host NK cells in regulating HSC engraftment.

    PubMed

    Huang, Yiming; Rezzoug, Francine; Chilton, Paula M; Grimes, H Leighton; Cramer, Daniel E; Ildstad, Suzanne T

    2004-08-01

    The events that regulate engraftment and long-term repopulating ability of hematopoietic stem cells (HSCs) after transplantation are not well defined. We report for the first time that major histocompatibility complex (MHC) class I K plays a critical role in HSC engraftment via interaction with recipient natural killer (NK) cells. Durable engraftment of purified HSCs requires MHC class I K matching between HSC donor and recipient. In the absence of MHC class I K matching, HSCs exhibit impaired long-term engraftment (P =.01). Dependence on MHC class I K matching is eliminated in B6 beige mice that lack NK cell function, as well as in wild-type mice depleted of NK cells, implicating a possible regulatory role of NK cells for HSC engraftment. The coadministration of CD8+/T-cell receptor-negative (TCR-) graft facilitating cells (FCs) matched at MHC class I K to the HSC donor overcomes the requirement for MHC class I K matching between HSCs and recipient. These data demonstrate that FCs inhibit NK cell effects on the HSCs. Notably, FCs do not suppress the cytotoxic activity of activated NK cells. Enhanced green fluorescent protein-positive (EGFP+) FCs persist for one month following allogeneic transplantation, making cold target inhibition an unlikely mechanism. Therefore, MHC class I may play a critical role in the initiating events that dictate HSC engraftment and/or NK-mediated rejection following allogeneic transplantation.

  14. Drift Rather than Selection Dominates MHC Class II Allelic Diversity Patterns at the Biogeographical Range Scale in Natterjack Toads Bufo calamita

    PubMed Central

    Zeisset, Inga; Beebee, Trevor J. C.

    2014-01-01

    Study of major histocompatibility complex (MHC) loci has gained great popularity in recent years, partly due to their function in protecting vertebrates from infections. This is of particular interest in amphibians on account of major threats many species face from emergent diseases such as chytridiomycosis. In this study we compare levels of diversity in an expressed MHC class II locus with neutral genetic diversity at microsatellite loci in natterjack toad (Bufo (Epidalea) calamita) populations across the whole of the species’ biogeographical range. Variation at both classes of loci was high in the glacial refugium areas (REF) and much lower in postglacial expansion areas (PGE), especially in range edge populations. Although there was clear evidence that the MHC locus was influenced by positive selection in the past, congruence with the neutral markers suggested that historical demographic events were the main force shaping MHC variation in the PGE area. Both neutral and adaptive genetic variation declined with distance from glacial refugia. Nevertheless, there were also some indications from differential isolation by distance and allele abundance patterns that weak effects of selection have been superimposed on the main drift effect in the PGE zone. PMID:24937211

  15. A combination of epitope prediction and molecular docking allows for good identification of MHC class I restricted T-cell epitopes.

    PubMed

    Zhang, Xue Wu

    2013-08-01

    In silico identification of T-cell epitopes is emerging as a new methodology for the study of epitope-based vaccines against viruses and cancer. In order to improve accuracy of prediction, we designed a novel approach, using epitope prediction methods in combination with molecular docking techniques, to identify MHC class I restricted T-cell epitopes. Analysis of the HIV-1 p24 protein and influenza virus matrix protein revealed that the present approach is effective, yielding prediction accuracy of over 80% with respect to experimental data. Subsequently, we applied such a method for prediction of T-cell epitopes in SARS coronavirus (SARS-CoV) S, N and M proteins. Based on available experimental data, the prediction accuracy is up to 90% for S protein. We suggest the use of epitope prediction methods in combination with 3D structural modelling of peptide-MHC-TCR complex to identify MHC class I restricted T-cell epitopes for use in epitope based vaccines like HIV and human cancers, which should provide a valuable step forward for the design of better vaccines and may provide in depth understanding about activation of T-cell epitopes by MHC binding peptides.

  16. Genomics and polymorphism of Agph-DAB1, an Mhc class II B gene in red-winged blackbirds (Agelaius phoeniceus).

    PubMed

    Edwards, S V; Gasper, J; March, M

    1998-03-01

    To further our understanding of the evolution of avian Mhc genes at the genomic level, we screened a cosmid library made from a red-winged blackbird (Agelaius phoeniceus) with a blackbird cDNA probe and subcloned from one of the Mhc-containing cosmids a gene which we designate Agph-DAB1. The structure of the gene is similar to that found for chicken class II B genes, except that the introns are surprisingly large, ranging from 98 to over 600 bp, making this the longest avian class II B gene to date. Using primers targeted toward the introns flanking the peptide-binding region (PBR), we amplified the entirety of the second exon and determined nucleotide sequences of 41 PCR products from eight individual blackbirds. The 10 sequence types found, among which were two probable pseudogene sequences, exhibit the classic hallmarks for evolution of PBRs, namely, an excess of nonsynonymous over synonymous substitutions and evidence of gene conversion events in polymorphic subdomains. Despite these patterns and our use of intron primers, the distribution of sequences among individuals suggests that more than one locus was amplified in most individuals, and the bushlike tree of sequences provides little information as to locus-specific clusters. These results imply a complex history of gene conversion, recent duplication, or possibly, concerted evolution among multiple loci, although Agph-DAB1, the first genomic Mhc sequence from a bird other than chicken, provides important clues in the quest for locus-specific Mhc primers in birds.

  17. The diabetogenic mouse MHC class II molecule I-A[superscript g7] is endowed with a switch that modulates TCR affinity

    SciTech Connect

    Yoshida, Kenji; Corper, Adam L.; Herro, Rana; Jabri, Bana; Wilson, Ian A.; Teyton, Luc

    2010-07-22

    Genetic susceptibility to autoimmunity is frequently associated with specific MHC alleles. Diabetogenic MHC class II molecules, such as human HLA-DQ8 and mouse I-A{sup g7}, typically have a small, uncharged amino acid residue at position 57 of their {beta} chain ({beta}57); this results in the absence of a salt bridge between {beta}57 and Arg{alpha}76, which is adjacent to the P9 pocket of the peptide-binding groove. However, the influence of Arg{alpha}76 on the selection of the TCR repertoire remains unknown, particularly when the MHC molecule binds a peptide with a neutral amino acid residue at position P9. Here, we have shown that diabetogenic MHC class II molecules bound to a peptide with a neutral P9 residue primarily selected and expanded cells expressing TCRs bearing a negatively charged residue in the first segment of their complementarity determining region 3{beta}. The crystal structure of one such TCR in complex with I-Ag7 bound to a peptide containing a neutral P9 residue revealed that a network of favorable long-range (greater than 4 {angstrom}) electrostatic interactions existed among Arg{alpha}76, the neutral P9 residue, and TCR, which supported the substantially increased TCR/peptide-MHC affinity. This network could be modulated or switched to a lower affinity interaction by the introduction of a negative charge at position P9 of the peptide. Our results support the existence of a switch at residue {beta}57 of the I-A{sup g7} and HLA-DQ8 class II molecules and potentially link normal thymic TCR selection with abnormal peripheral behavior.

  18. The diabetogenic mouse MHC class II molecule I-A[subscript g7] is endowed with a switch that modulates TCR affinity

    SciTech Connect

    Yoshida, Kenji; Corper, Adam L.; Herro, Rana; Jabri, Bana; Wilson, Ian A.; Teyton, Luc

    2011-11-16

    Genetic susceptibility to autoimmunity is frequently associated with specific MHC alleles. Diabetogenic MHC class II molecules, such as human HLA-DQ8 and mouse I-A{sub g7}, typically have a small, uncharged amino acid residue at position 57 of their {beta} chain ({beta}57); this results in the absence of a salt bridge between {beta}57 and Arg{alpha}76, which is adjacent to the P9 pocket of the peptide-binding groove. However, the influence of Arg{alpha}76 on the selection of the TCR repertoire remains unknown, particularly when the MHC molecule binds a peptide with a neutral amino acid residue at position P9. Here, we have shown that diabetogenic MHC class II molecules bound to a peptide with a neutral P9 residue primarily selected and expanded cells expressing TCRs bearing a negatively charged residue in the first segment of their complementarity determining region 3{beta}. The crystal structure of one such TCR in complex with I-A{sub g7} bound to a peptide containing a neutral P9 residue revealed that a network of favorable long-range (greater than 4 {angstrom}) electrostatic interactions existed among Arg{alpha}76, the neutral P9 residue, and TCR, which supported the substantially increased TCR/peptide-MHC affinity. This network could be modulated or switched to a lower affinity interaction by the introduction of a negative charge at position P9 of the peptide. Our results support the existence of a switch at residue {beta}57 of the I-Ag7 and HLA-DQ8 class II molecules and potentially link normal thymic TCR selection with abnormal peripheral behavior.

  19. Characterization of the Canine MHC Class I DLA-88*50101 Peptide Binding Motif as a Prerequisite for Canine T Cell Immunotherapy

    PubMed Central

    Barth, Sharon M.; Schreitmüller, Christian M.; Proehl, Franziska; Oehl, Kathrin; Lumpp, Leonie M.; Kowalewski, Daniel J.; Di Marco, Moreno; Sturm, Theo; Backert, Linus; Schuster, Heiko; Stevanović, Stefan; Rammensee, Hans-Georg; Planz, Oliver

    2016-01-01

    There are limitations in pre-clinical settings using mice as a basis for clinical development in humans. In cancer, similarities exist between humans and dogs; thus, the dog patient can be a link in the transition from laboratory research on mouse models to clinical trials in humans. Knowledge of the peptides presented on MHC molecules is fundamental for the development of highly specific T cell-based immunotherapies. This information is available for human MHC molecules but is absent for the canine MHC. In the present study, we characterized the binding motif of dog leukocyte antigen (DLA) class I allele DLA-88*50101, using human C1R and K562 transfected cells expressing the DLA-88*50101 heavy chain. MHC class I immunoaffinity-purification revealed 3720 DLA-88*50101 derived peptides, which enabled the determination of major anchor positions. The characterized binding motif of DLA-88*50101 was similar to HLA-A*02:01. Peptide binding analyses on HLA-A*02:01 and DLA-88*50101 via flow cytometry showed weak binding of DLA-88*50101 derived peptides to HLA-A*02:01, and vice versa. Our results present for the first time a detailed peptide binding motif of the canine MHC class I allelic product DLA-88*50101. These data support the goal of establishing dogs as a suitable animal model for the evaluation and development of T cell-based cancer immunotherapies, benefiting both dog and human patients. PMID:27893789

  20. DMA and DMB are the only genes in the class II region of the human MHC needed for class II-associated antigen processing

    SciTech Connect

    Ceman, S.; Rudersdorf, R.A.; Petersen, J.M.

    1995-03-15

    Previous studies have shown that homozygous mutations between the LMP2 and DNA loci in the human MHC cause class II molecules to be abnormally conformed and unstable in the presence of SDS at low temperature, and impede class II-associated Ag processing and presentation. These abnormalities result from impaired ability to form intracellular class II/peptide complexes that predominate in normal cells. We show in this work that this defect results from deficient expression of either the DMA or the DMB gene. Human B-LCL.174 (DR3) cells, which have a deletion of all known expressible genes in the class II region, express transgene-encoded HLA-DR3, but have the abnormalities. Transfer of cosmid HA14, which contains the DMA and DMB genes, into .174 (DR3) cells restored normal DR3 conformation, stability in 0.4% SDS at 0{degrees}, and ability to process and present tetanus toxoid, but only when both DMA and DMB mRNAs were present. The requirement for both genetic expressions in engendering normal phenotypes was confirmed by transferring the cloned genes into .174 (DR3) cells separately or together. Because normal phenotypes were fully restored in transferent cells expressing DMA plus DMB, other genes in the {approximately} 1-mb homozygous class II region deletion in .174 (DR3) cells either do not participate in or are dispensable for apparently normal production of intracellular class II/peptide complexes. The properties of DM-deficient EBV-transformed B lymphoblastoid cell lines (LCLs) suggest ways of identifying humans in whom DM deficiency contributes to congenital immunodeficiency and malignancy. 67 refs., 5 figs., 1 tab.

  1. Characterization of polymorphism within the H2-M MHC class II loci.

    PubMed

    Hermel, E; Yuan, J; Monaco, J J

    1995-01-01

    The products of the class II-like H2-M genes of the major histocompatibility complex are required for class II antigen processing. We sequenced H2-Ma and Mb from several mouse strains to determine whether these genes are polymorphic like the classical H2-A and E genes, or are oligomorphic, like H2-O. Both Mb loci appear to be transcribed and are distinct from each other. Mb1 and Mb2 differ by about 11% at the nucleotide level and are most dissimilar in their second exons (corresponding to the beta 1 domain). Relative to the published Mb1d haplotype sequence, the products of the b, g7, f, and k2 alleles of Mb1 from Mus musculus domesticus and the separate mouse species Mus spretus differ by only one to four amino acids. The majority of the changes occurred in the second exon of Mb1, in contrast to HLA-DMB, the human orthologue. Little polymorphism was seen for Mb2, and Ma was invariant in all strains tested. The similarity of the g7 allele to those from other haplotypes makes it unlikely that the M class II genes play a role in the autoimmune diabetes of NOD strain mice. The M genes are regulated in a manner similar to classical class II genes, in that they are upregulated by IFN-gamma in macrophages, and to a lesser extent by IL4 in B cells. When modeled on the crystal structure of the HLA-DR1 class II molecule, nearly all of the differences between M beta 1 and M beta 2 affect residues facing away from the putative peptide binding groove.

  2. Prevalent expression of the immunostimulatory MHC class I chain–related molecule is counteracted by shedding in prostate cancer

    PubMed Central

    Wu, Jennifer D.; Higgins, Lily M.; Steinle, Alexander; Cosman, David; Haugk, Kathy; Plymate, Stephen R.

    2004-01-01

    The MHC class I chain–related molecules (MICs) have previously been shown to be induced on most epithelial tumor cells. Engagement of MIC by the activating immune receptor NKG2D triggers NK cells and augments antigen-specific CTL anti-tumor immunity. The MIC-NKG2D system was proposed to participate in epithelial tumor immune surveillance. Paradoxically, studies suggest that tumors may evade MIC-NKG2D–mediated immunity by MIC shedding–induced impairment of effector cell function. Here we demonstrate the first evidence to our knowledge of a significant correlation of MIC shedding and deficiency in NK cell function with the grade of disease in prostate cancer. MIC is widely expressed in prostate carcinoma. The presence of surface target MIC, however, is counteracted by shedding. A significant increase in serum levels of soluble MIC (sMIC) and deficiency in NK cell function was shown in patients with advanced cancer. Finally, the deficiency in NK cell function can be overcome by treatment with IL-2 or IL-15 in vitro. Our results suggest that (a) deficiency in MIC-NKG2D immune surveillance may contribute to prostate cancer progression, (b) sMIC may be a novel biomarker for prostate cancer, and (c) using cytokines to restore MIC-NKG2D–mediated immunity may have clinical significance for prostate cancer in cell-based adaptive immunotherapy. PMID:15314693

  3. Characterization of 40 full-length MHC class IIA functional alleles in miiuy croaker: Polymorphism and positive selection.

    PubMed

    Xu, Tianjun; Liu, Jiang; Sun, Yueyan; Zhu, Zhihuang; Liu, Tianxing

    2016-02-01

    The major histocompatibility complex is a highly polymorphic gene superfamily in vertebrates that plays an important role in adaptive immune response. In the present study, we identified 40 full-length miiuy croaker MHC class IIA (Mimi-DAA) functional alleles from 26 miiuy croaker individuals and found that the alleles encode 30 amino acid sequences. A high level of polymorphism in Mimi-DAA was detected in miiuy croaker. The rate of non-synonymous substitutions (d(N)) occurred at a significantly higher frequency than that of synonymous substitutions (d(S)) in the peptide-binding region (PBR) and non-PBR. This result suggests that balancing selection maintains polymorphisms at the Mimi-DAA locus. Phylogenetic analysis based on the full-length sequences showed that the Mimi-DAA alleles clustered into three groups. However, the phylogenetic tree constructed using the exon 2 sequences indicated that the Mimi-DAA alleles clustered into two groups. A total of 22 positively selected sites were identified on the Mimi-DAA alleles after testing for positive selection, and five sites were predicted to be associated with the binding of peptide antigen, suggesting that a few selected residues may play a significant role in immune function.

  4. Inhibition of HLA-DM Mediated MHC Class II Peptide Loading by HLA-DO Promotes Self Tolerance.

    PubMed

    Denzin, Lisa K

    2013-12-17

    Major histocompatibility class II (MHCII) molecules are loaded with peptides derived from foreign and self-proteins within the endosomes and lysosomes of antigen presenting cells (APCs). This process is mediated by interaction of MHCII with the conserved, non-polymorphic MHCII like molecule HLA-DM (DM). DM activity is directly opposed by HLA-DO (DO), another conserved, non-polymorphic MHCII like molecule. DO is an MHCII substrate mimic. Binding of DO to DM prevents MHCII from binding to DM, thereby inhibiting peptide loading. Inhibition of DM function enables low stability MHC complexes to survive and populate the surface of APCs. As a consequence, DO promotes the display of a broader pool of low abundance self-peptides. Broadening the peptide repertoire theoretically reduces the likelihood of inadvertently acquiring a density of self-ligands that is sufficient to activate self-reactive T cells. One function of DO, therefore, is to promote T cell tolerance by shaping the visible image of self. Recent data also shows that DO influences the adaptive immune response by controlling B cell entry into the germinal center reaction. This review explores the data supporting these concepts.

  5. Inhibition of HLA-DM Mediated MHC Class II Peptide Loading by HLA-DO Promotes Self Tolerance

    PubMed Central

    Denzin, Lisa K.

    2013-01-01

    Major histocompatibility class II (MHCII) molecules are loaded with peptides derived from foreign and self-proteins within the endosomes and lysosomes of antigen presenting cells (APCs). This process is mediated by interaction of MHCII with the conserved, non-polymorphic MHCII like molecule HLA-DM (DM). DM activity is directly opposed by HLA-DO (DO), another conserved, non-polymorphic MHCII like molecule. DO is an MHCII substrate mimic. Binding of DO to DM prevents MHCII from binding to DM, thereby inhibiting peptide loading. Inhibition of DM function enables low stability MHC complexes to survive and populate the surface of APCs. As a consequence, DO promotes the display of a broader pool of low abundance self-peptides. Broadening the peptide repertoire theoretically reduces the likelihood of inadvertently acquiring a density of self-ligands that is sufficient to activate self-reactive T cells. One function of DO, therefore, is to promote T cell tolerance by shaping the visible image of self. Recent data also shows that DO influences the adaptive immune response by controlling B cell entry into the germinal center reaction. This review explores the data supporting these concepts. PMID:24381574

  6. A role for the MHC class I-like Mill molecules in nutrient metabolism and wound healing.

    PubMed

    Rabinovich, Brian A; Ketchem, Randal R; Wolfson, Martin; Goldstein, Lynn; Skelly, Marylin; Cosman, David

    2008-01-01

    MHC class I family members serve multiple functions beyond antigen presentation. We provide insight into the structure, expression and function of the Mill subfamily. This family includes two surface glycoproteins, Mill1 and Mill2. Protein sequences for Mill1 and Mill2 are most highly related to the NKG2D ligands, MICA and MICB, but neither of them bound to NKG2D. Computer-based protein modelling indicated that hereditary haemochromatosis protein (HFE), a molecule involved in iron uptake, was most similar. Mill1 and Mill2 were observed on cycling thymocytes, proliferating smooth muscle cells and fibroblasts. Using soluble Mill proteins, we found evidence for a soluble ligand in serum. Like HFE, the Mill family may be involved in nutrient metabolism. Skin was one of the only three organs found to express transcripts for both Mill1 and Mill2. Addition of antibodies specific for Mill2 to wounded skin enhanced healing. Our results suggest a role for the Mill proteins in cellular metabolism, with possible therapeutic significance.

  7. Crystal structure of a Gammadelta T-cell Receptor Specific for the Human MHC class I Homolog MICA

    SciTech Connect

    B Xu; J Pizarro; M Holmes; C McBeth; V Groh; T Spies; R Strong

    2011-12-31

    {gamma}{delta} T cells play important roles in bridging innate and adaptive immunity, but their recognition mechanisms remain poorly understood. Human {gamma}{delta} T cells of the V{sub {delta}}1 subset predominate in intestinal epithelia and respond to MICA and MICB (MHC class I chain-related, A and B; MIC) self-antigens, mediating responses to tumorigenesis or viral infection. The crystal structure of an MIC-reactive V{sub {delta}}1 {gamma}{delta} T-cell receptor (TCR) showed expected overall structural homology to antibodies, {alpha}{beta}, and other {gamma}{delta} TCRs, but complementary determining region conformations and conservation of V{sub {delta}}1 use revealed an uncharacteristically flat potential binding surface. MIC, likewise, serves as a ligand for the activating immunoreceptor natural killer group 2, D (NKG2D), also expressed on {gamma}{delta} T cells. Although MIC recognition drives both the TCR-dependent stimulatory and NKG2D-dependent costimulatory signals necessary for activation, interaction analyses showed that MIC binding by the two receptors was mutually exclusive. Analysis of relative binding kinetics suggested sequential recognition, defining constraints for the temporal organization of {gamma}{delta} T-cell/target cell interfaces.

  8. Negative relationships between cellular immune response, Mhc class II heterozygosity and secondary sexual trait in the montane water vole

    PubMed Central

    Charbonnel, Nathalie; Bryja, Josef; Galan, Maxime; Deter, Julie; Tollenaere, Charlotte; Chaval, Yannick; Morand, Serge; Cosson, Jean-François

    2010-01-01

    Heterogeneities in immune responsiveness may affect key epidemiological parameters and the dynamics of pathogens. The roles of immunogenetics in these variations remain poorly explored. We analysed the influence of Major histocompatibility complex (Mhc) genes and epigamic traits on the response to phytohaemagglutinin in males from cyclic populations of the montane water vole (Arvicola scherman). Besides, we tested the relevance of lateral scent glands as honest signals of male quality. Our results did not corroborate neither the hypotheses of genome-wide heterozygosity-fitness correlation nor the Mhc heterozygote advantage. We found a negative relationship between Mhc hetetozygosity and response to phytohaemagglutinin, mediated by a specific Mhc homozygous genotype. Our results therefore support the hypothesis of the Arte-Dqa-05 homozygous genotype being a ‘good’ Mhc variant in terms of immunogenetic quality. The development of the scent glands seems to be an honest signal for mate choice as it is negatively correlated with helminth load. The ‘good gene’ hypothesis was not validated as Arte-Dqa-05 homozygous males did not exhibit larger glands. Besides, the negative relationship observed between the size of these glands and the response to phytohaemagglutinin, mainly for Mhc homozygotes, corroborates the immunocompetence handicap hypothesis. The Mhc variants associated with larger glands remain yet to be determined. PMID:25567924

  9. Negative relationships between cellular immune response, Mhc class II heterozygosity and secondary sexual trait in the montane water vole.

    PubMed

    Charbonnel, Nathalie; Bryja, Josef; Galan, Maxime; Deter, Julie; Tollenaere, Charlotte; Chaval, Yannick; Morand, Serge; Cosson, Jean-François

    2010-05-01

    Heterogeneities in immune responsiveness may affect key epidemiological parameters and the dynamics of pathogens. The roles of immunogenetics in these variations remain poorly explored. We analysed the influence of Major histocompatibility complex (Mhc) genes and epigamic traits on the response to phytohaemagglutinin in males from cyclic populations of the montane water vole (Arvicola scherman). Besides, we tested the relevance of lateral scent glands as honest signals of male quality. Our results did not corroborate neither the hypotheses of genome-wide heterozygosity-fitness correlation nor the Mhc heterozygote advantage. We found a negative relationship between Mhc hetetozygosity and response to phytohaemagglutinin, mediated by a specific Mhc homozygous genotype. Our results therefore support the hypothesis of the Arte-Dqa-05 homozygous genotype being a 'good' Mhc variant in terms of immunogenetic quality. The development of the scent glands seems to be an honest signal for mate choice as it is negatively correlated with helminth load. The 'good gene' hypothesis was not validated as Arte-Dqa-05 homozygous males did not exhibit larger glands. Besides, the negative relationship observed between the size of these glands and the response to phytohaemagglutinin, mainly for Mhc homozygotes, corroborates the immunocompetence handicap hypothesis. The Mhc variants associated with larger glands remain yet to be determined.

  10. Multiple parasites mediate balancing selection at two MHC class II genes in the fossorial water vole: insights from multivariate analyses and population genetics.

    PubMed

    Tollenaere, C; Bryja, J; Galan, M; Cadet, P; Deter, J; Chaval, Y; Berthier, K; Ribas Salvador, A; Voutilainen, L; Laakkonen, J; Henttonen, H; Cosson, J-F; Charbonnel, N

    2008-09-01

    We investigated the factors mediating selection acting on two MHC class II genes (DQA and DRB) in water vole (Arvicola scherman) natural populations in the French Jura Mountains. Population genetics showed significant homogeneity in allelic frequencies at the DQA1 locus as opposed to neutral markers (nine microsatellites), indicating balancing selection acting on this gene. Moreover, almost exhaustive screening for parasites, including gastrointestinal helminths, brain coccidia and antibodies against viruses responsible for zoonoses, was carried out. We applied a co-inertia approach to the genetic and parasitological data sets to avoid statistical problems related to multiple testing. Two alleles, Arte-DRB-11 and Arte-DRB-15, displayed antagonistic associations with the nematode Trichuris arvicolae, revealing the potential parasite-mediated selection acting on DRB locus. Selection mechanisms acting on the two MHC class II genes thus appeared different. Moreover, overdominance as balancing selection mechanism was showed highly unlikely in this system.

  11. Genetic Variation at Exon 2 of the MHC Class II DQB Locus in Blue Whale (Balaenoptera musculus) from the Gulf of California.

    PubMed

    Moreno-Santillán, Diana D; Lacey, Eileen A; Gendron, Diane; Ortega, Jorge

    2016-01-01

    The genes of the Major Histocompatibility Complex (MHC) play an important role in the vertebrate immune response and are among the most polymorphic genes known in vertebrates. In some marine mammals, MHC genes have been shown to be characterized by low levels of polymorphism compared to terrestrial taxa; this reduction in variation is often explained as a result of lower pathogen pressures in marine habitats. To determine if this same reduction in variation applies to the migratory population of blue whales (Balaenoptera musculus) that occurs in the Gulf of California, we genotyped a 172 bp fragment of exon 2 of the MHC Class II DQB locus for 80 members of this population. Twenty-two putatively functional DQB allotypes were identified, all of which were homologous with DQB sequences from other cetacean species. Up to 5 putative alleles per individual were identified, suggesting that gene duplication has occurred at this locus. Rates of non-synonymous to synonymous substitutions (ω) and maximum likelihood analyses of models of nucleotide variation provided potential evidence of ongoing positive selection at this exon. Phylogenetic analyses of DQB alleles from B. musculus and 16 other species of cetaceans revealed trans-specific conservation of MHC variants, suggesting that selection has acted on this locus over prolonged periods of time. Collectively our findings reveal that immunogenic variation in blue whales is comparable to that in terrestrial mammals, thereby providing no evidence that marine taxa are subject to reduced pathogen-induced selective pressures.

  12. Genetic Variation at Exon 2 of the MHC Class II DQB Locus in Blue Whale (Balaenoptera musculus) from the Gulf of California

    PubMed Central

    Moreno-Santillán, Diana D.; Lacey, Eileen A.; Gendron, Diane; Ortega, Jorge

    2016-01-01

    The genes of the Major Histocompatibility Complex (MHC) play an important role in the vertebrate immune response and are among the most polymorphic genes known in vertebrates. In some marine mammals, MHC genes have been shown to be characterized by low levels of polymorphism compared to terrestrial taxa; this reduction in variation is often explained as a result of lower pathogen pressures in marine habitats. To determine if this same reduction in variation applies to the migratory population of blue whales (Balaenoptera musculus) that occurs in the Gulf of California, we genotyped a 172 bp fragment of exon 2 of the MHC Class II DQB locus for 80 members of this population. Twenty-two putatively functional DQB allotypes were identified, all of which were homologous with DQB sequences from other cetacean species. Up to 5 putative alleles per individual were identified, suggesting that gene duplication has occurred at this locus. Rates of non-synonymous to synonymous substitutions (ω) and maximum likelihood analyses of models of nucleotide variation provided potential evidence of ongoing positive selection at this exon. Phylogenetic analyses of DQB alleles from B. musculus and 16 other species of cetaceans revealed trans-specific conservation of MHC variants, suggesting that selection has acted on this locus over prolonged periods of time. Collectively our findings reveal that immunogenic variation in blue whales is comparable to that in terrestrial mammals, thereby providing no evidence that marine taxa are subject to reduced pathogen-induced selective pressures. PMID:26761201

  13. Genetic variation of the MHC class II DRB genes in the Japanese weasel, Mustela itatsi, endemic to Japan, compared with the Siberian weasel, Mustela sibirica.

    PubMed

    Nishita, Y; Abramov, A V; Kosintsev, P A; Lin, L-K; Watanabe, S; Yamazaki, K; Kaneko, Y; Masuda, R

    2015-12-01

    Major histocompatibility complex (MHC) genes encode proteins that play a critical role in vertebrate immune system and are highly polymorphic. To further understand the molecular evolution of the MHC genes, we compared MHC class II DRB genes between the Japanese weasel (Mustela itatsi), a species endemic to Japan, and the Siberian weasel (Mustela sibirica), a closely related species on the continent. We sequenced a 242-bp region of DRB exon 2, which encodes antigen-binding sites (ABS), and found 24 alleles from 31 M. itatsi individuals and 17 alleles from 21 M. sibirica individuals, including broadly distributed, species-specific and/or geographically restricted alleles. Our results suggest that pathogen-driven balancing selection have acted to maintain the diversity in the DRB genes. For predicted ABS, nonsynonymous substitutions exceeded synonymous substitutions, also indicating positive selection, which was not seen at non-ABS. In a Bayesian phylogenetic tree, two M. sibirica DRB alleles were basal to the rest of the sequences from mustelid species and may represent ancestral alleles. Trans-species polymorphism was evident between many mustelid DRB alleles, especially between M. itatsi and M. sibirica. These two Mustela species divided about 1.7 million years ago, but still share many MHC alleles, indicative of their close phylogenetic relationship.

  14. CD4 and MHC class I down-modulation activities of nef alleles from brain- and lymphoid tissue-derived primary HIV-1 isolates

    PubMed Central

    Gray, Lachlan R.; Gabuzda, Dana; Cowley, Daniel; Ellett, Anne; Chiavaroli, Lisa; Wesselingh, Steven L.; Churchill, Melissa J.; Gorry, Paul R.

    2015-01-01

    HIV-1 nef undergoes adaptive evolution in the CNS, reflecting altered requirements for HIV-1 replication in macrophages/microglia and brain-specific immune selection pressures. The role of Nef in HIV-1 neurotropism and the pathogenesis of HIV-associated dementia (HAD) is unclear. In this study, we characterized 82 nef alleles cloned from brain, CSF, spinal cord and blood/lymphoid tissue-derived HIV-1 isolates from 7 subjects with HAD. CNS isolate-derived nef alleles were genetically compartmentalized and had reduced sequence diversity compared to those from lymphoid tissue isolates. Defective nef alleles predominated in a brain-derived isolate from one of the 7 subjects (MACS2-br). The ability of Nef to down-modulate CD4 and MHC class 1 (MHC-1) was generally conserved among nef alleles from both CNS and lymphoid tissues. However, the potency of CD4 and MHC-1 down-modulation was variable, which was associated with sequence alterations known to influence these Nef functions. These results suggest that CD4 and MHC-1 down-modulation are highly conserved functions among nef alleles from CNS- and lymphoid tissue-derived HIV-1 isolates that may contribute to viral replication and escape from immune surveillance in the CNS. PMID:21165790

  15. MHC class II transactivator is an in vivo regulator of osteoclast differentiation and bone homeostasis co-opted from adaptive immunity.

    PubMed

    Benasciutti, Elisa; Mariani, Elisabetta; Oliva, Laura; Scolari, Maria; Perilli, Egon; Barras, Emmanuele; Milan, Enrico; Orfanelli, Ugo; Fazzalari, Nicola L; Campana, Lara; Capobianco, Annalisa; Otten, Luc; Particelli, Francesca; Acha-Orbea, Hans; Baruffaldi, Fabio; Faccio, Roberta; Sitia, Roberto; Reith, Walter; Cenci, Simone

    2014-02-01

    The molecular networks controlling bone homeostasis are not fully understood. The common evolution of bone and adaptive immunity encourages the investigation of shared regulatory circuits. MHC Class II Transactivator (CIITA) is a master transcriptional co-activator believed to be exclusively dedicated for antigen presentation. CIITA is expressed in osteoclast precursors, and its expression is accentuated in osteoporotic mice. We thus asked whether CIITA plays a role in bone biology. To this aim, we fully characterized the bone phenotype of two mouse models of CIITA overexpression, respectively systemic and restricted to the monocyte-osteoclast lineage. Both CIITA-overexpressing mouse models revealed severe spontaneous osteoporosis, as assessed by micro-computed tomography and histomorphometry, associated with increased osteoclast numbers and enhanced in vivo bone resorption, whereas osteoblast numbers and in vivo bone-forming activity were unaffected. To understand the underlying cellular and molecular bases, we investigated ex vivo the differentiation of mutant bone marrow monocytes into osteoclasts and immune effectors, as well as osteoclastogenic signaling pathways. CIITA-overexpressing monocytes differentiated normally into effector macrophages or dendritic cells but showed enhanced osteoclastogenesis, whereas CIITA ablation suppressed osteoclast differentiation. Increased c-fms and receptor activator of NF-κB (RANK) signaling underlay enhanced osteoclast differentiation from CIITA-overexpressing precursors. Moreover, by extending selected phenotypic and cellular analyses to additional genetic mouse models, namely MHC Class II deficient mice and a transgenic mouse line lacking a specific CIITA promoter and re-expressing CIITA in the thymus, we excluded MHC Class II expression and T cells from contributing to the observed skeletal phenotype. Altogether, our study provides compelling genetic evidence that CIITA, the molecular switch of antigen presentation

  16. Up-regulated MHC-class II expression and gamma-IFN and soluble IL-2R in lupus nephritis.

    PubMed

    Yokoyama, H; Takabatake, T; Takaeda, M; Wada, T; Naito, T; Ikeda, K; Goshima, S; Takasawa, K; Tomosugi, N; Kobayashi, K

    1992-09-01

    Expression of MHC-class II molecules (HLA-DR and -DQ), serum gamma-interferon (gamma-IFN) and soluble interleukin-2 receptor (sIL-2R) levels were studied in 35 Japanese patients with lupus nephritis (LN) to clarify intraglomerular cellular activation and cytokine involvement in human LN. In 11 normal kidney specimens, HLA-DR(Ia1) was noted in glomerular tufts, but HLA-DQ was either not or was faintly detected in glomeruli by the indirect immunofluorescence technique. HLA-DR and -DQ were observed mainly on the surface of glomerular endothelial cells in 100% and 50% of 28 lupus kidney specimens except for necrotic or sclerotic lesions. HLA-DQ was expressed in a high incidence of 67%, 86% in patients with proliferative LN (WHO Class III-IV) and active lesions, respectively. Serum gamma-IFN and sIL-2R levels were 1.2 +/- 0.2 U/ml and 190 +/- 24 U/ml (mean +/- SEM; N = 30) in normal controls, and elevated in patients with proliferative LN (4.1 +/- 1.0 U/ml, 383 +/- 81 U/ml, N = 25), especially with active lesions (6.2 +/- 1.5 U/ml, 500 +/- 110 U/ml, N = 14). Overall, glomerular lesions such as HLA-DQ expression, the activity index and leukocyte infiltration correlated positively with serum gamma-IFN levels (r = 0.55; P less than 0.01 for HLA-DQ, r = 0.68; P less than 0.001 for activity index, r = 0.38; P less than 0.05 for leukocyte infiltration), but not with serum sIL-2R levels, anti-DNA antibody titers and CH50 titers.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Btn2a2, a T cell immunomodulatory molecule coregulated with MHC class II genes

    PubMed Central

    Sarter, Kerstin; Leimgruber, Elisa; Gobet, Florian; Agrawal, Vishal; Dunand-Sauthier, Isabelle; Barras, Emmanuèle; Mastelic-Gavillet, Béatris; Kamath, Arun; Fontannaz, Paola; Guéry, Leslie; Duraes, Fernanda do Valle; Lippens, Carla; Ravn, Ulla; Santiago-Raber, Marie-Laure; Magistrelli, Giovanni; Fischer, Nicolas; Siegrist, Claire-Anne; Hugues, Stéphanie

    2016-01-01

    Evidence has recently emerged that butyrophilins, which are members of the extended B7 family of co-stimulatory molecules, have diverse functions in the immune system. We found that the human and mouse genes encoding butyrophilin-2A2 (BTN2A2) are regulated by the class II trans-activator and regulatory factor X, two transcription factors dedicated to major histocompatibility complex class II expression, suggesting a role in T cell immunity. To address this, we generated Btn2a2-deficient mice. Btn2a2−/− mice exhibited enhanced effector CD4+ and CD8+ T cell responses, impaired CD4+ regulatory T cell induction, potentiated antitumor responses, and exacerbated experimental autoimmune encephalomyelitis. Altered immune responses were attributed to Btn2a2 deficiency in antigen-presenting cells rather than T cells or nonhematopoietic cells. These results provide the first genetic evidence that BTN2A2 is a co-inhibitory molecule that modulates T cell–mediated immunity. PMID:26809444

  18. Genome-wide association study identifies SNPs in the MHC class II loci that are associated with self-reported history of whooping cough.

    PubMed

    McMahon, George; Ring, Susan M; Davey-Smith, George; Timpson, Nicholas J

    2015-10-15

    Whooping cough is currently seeing resurgence in countries despite high vaccine coverage. There is considerable variation in subject-specific response to infection and vaccine efficacy, but little is known about the role of human genetics. We carried out a case-control genome-wide association study of adult or parent-reported history of whooping cough in two cohorts from the UK: the ALSPAC cohort and the 1958 British Birth Cohort (815/758 cases and 6341/4308 controls, respectively). We also imputed HLA alleles using dense SNP data in the MHC region and carried out gene-based and gene-set tests of association and estimated the amount of additive genetic variation explained by common SNPs. We observed a novel association at SNPs in the MHC class II region in both cohorts [lead SNP rs9271768 after meta-analysis, odds ratio [95% confidence intervals (CIs)] 1.47 (1.35, 1.6), P-value 1.21E - 18]. Multiple strong associations were also observed at alleles at the HLA class II loci. The majority of these associations were explained by the lead SNP rs9271768. Gene-based and gene-set tests and estimates of explainable common genetic variation could not establish the presence of additional associations in our sample. Genetic variation at the MHC class II region plays a role in susceptibility to whooping cough. These findings provide additional perspective on mechanisms of whooping cough infection and vaccine efficacy.

  19. Vanilloid Receptor 1 Agonists, Capsaicin and Resiniferatoxin, Enhance MHC Class I-restricted Viral Antigen Presentation in Virus-infected Dendritic Cells

    PubMed Central

    Lee, Young-Hee; Im, Sun-A; Kim, Ji-Wan

    2016-01-01

    DCs, like the sensory neurons, express vanilloid receptor 1 (VR1). Here we demonstrate that the VR1 agonists, capsaicin (CP) and resiniferatoxin (RTX), enhance antiviral CTL responses by increasing MHC class I-restricted viral antigen presentation in dendritic cells (DCs). Bone marrow-derived DCs (BM-DCs) were infected with a recombinant vaccinia virus (VV) expressing OVA (VV-OVA), and then treated with CP or RTX. Both CP and RTX increased MHC class I-restricted presentation of virus-encoded endogenous OVA in BM-DCs. Oral administration of CP or RTX significantly increased MHC class I-restricted OVA presentation by splenic and lymph node DCs in VV-OVA-infected mice, as assessed by directly measuring OVA peptide SIINFEKL-Kb complexes on the cell surface and by performing functional assays using OVA-specific CD8 T cells. Accordingly, oral administration of CP or RTX elicited potent OVA-specific CTL activity in VV-OVA-infected mice. The results from this study demonstrate that VR1 agonists enhance anti-viral CTL responses, as well as a neuro-immune connection in anti-viral immune responses. PMID:27574502

  20. Toward a Network Model of MHC Class II-Restricted Antigen Processing

    PubMed Central

    Miller, Michael A.; Ganesan, Asha Purnima V.; Eisenlohr, Laurence C.

    2013-01-01

    The standard model of Major Histocompatibility Complex class II (MHCII)-restricted antigen processing depicts a straightforward, linear pathway: internalized antigens are converted into peptides that load in a chaperone dependent manner onto nascent MHCII in the late endosome, the complexes subsequently trafficking to the cell surface for recognition by CD4+ T cells (TCD4+). Several variations on this theme, both moderate and radical, have come to light but these alternatives have remained peripheral, the conventional pathway generally presumed to be the primary driver of TCD4+ responses. Here we continue to press for the conceptual repositioning of these alternatives toward the center while proposing that MHCII processing be thought of less in terms of discrete pathways and more in terms of a network whose major and minor conduits are variable depending upon many factors, including the epitope, the nature of the antigen, the source of the antigen, and the identity of the antigen-presenting cell. PMID:24379819

  1. A novel regulatory pathway for autoimmune disease: binding of partial MHC class II constructs to monocytes reduces CD74 expression and induces both specific and bystander T-cell tolerance.

    PubMed

    Vandenbark, Arthur A; Meza-Romero, Roberto; Benedek, Gil; Andrew, Shayne; Huan, Jianya; Chou, Yuan K; Buenafe, Abigail C; Dahan, Rony; Reiter, Yoram; Mooney, Jeffery L; Offner, Halina; Burrows, Gregory G

    2013-02-01

    Treatment with partial (p)MHC class II-β1α1 constructs (also referred to as recombinant T-cell receptor ligands - RTL) linked to antigenic peptides can induce T-cell tolerance, inhibit recruitment of inflammatory cells and reverse autoimmune diseases. Here we demonstrate a novel regulatory pathway that involves RTL binding to CD11b(+) mononuclear cells through a receptor comprised of MHC class II invariant chain (CD74), cell-surface histones and MHC class II itself for treatment of experimental autoimmune encephalomyelitis (EAE). Binding of RTL constructs with CD74 involved a previously unrecognized MHC class II-α1/CD74 interaction that inhibited CD74 expression, blocked activity of its ligand, macrophage migration inhibitory factor, and reduced EAE severity. These findings implicate binding of RTL constructs to CD74 as a key step in both antigen-driven and bystander T-cell tolerance important in treatment of inflammatory diseases.

  2. Linkage relationships and haplotype polymorphism among cichlid Mhc class II B loci.

    PubMed Central

    Málaga-Trillo, E; Zaleska-Rutczynska, Z; McAndrew, B; Vincek, V; Figueroa, F; Sültmann, H; Klein, J

    1998-01-01

    The species flocks of cichlid fishes in the Great East African Lakes are paradigms of adaptive radiation and hence, of great interest to evolutionary biologists. Phylogenetic studies of these fishes have, however, been hampered by the lack of suitable polymorphic markers. The genes of the major histocompatibility complex hold the promise to provide, through their extensive polymorphism, a large number of such markers, but their use has been hampered by the complexity of the genetic system and the lack of definition of the individual loci. In this study we take the first substantial step to alleviate this problem. Using a combination of methods, including the typing of single sperm cells, gyno- or androgenetic individuals, and haploid embryos, as well as sequencing of class II B restriction fragments isolated from gels for Southern blots, we identify the previously characterized homology groups as distinct loci. At least 17 polymorphic class II B loci, all of which are presumably transcribed, have been found among the different species studied. Most of these loci are shared across the various cichlid species and genera. The number of loci per haplotype varies from individual to individual, ranging from 1 to 13. A total of 21 distinct haplotypes differing in the number of loci they carry has thus far been identified. All the polymorphic loci are part of the same cluster in which, however, distances between at least some of the loci (as indicated by recombination frequencies) are relatively large. Both the individual loci and the haplotypes can now be used to study phylogenetic relationships among the members of the species flocks and the mode in which speciation occurs during adaptive radiation. PMID:9649539

  3. Docosahexaenoic acid modifies the clustering and size of lipid rafts and the lateral organization and surface expression of MHC class I of EL4 cells.

    PubMed

    Shaikh, Saame Raza; Rockett, Benjamin Drew; Salameh, Muhammad; Carraway, Kristen

    2009-09-01

    An emerging molecular mechanism by which docosahexaenoic acid (DHA) exerts its effects is modification of lipid raft organization. The biophysical model, based on studies with liposomes, shows that DHA avoids lipid rafts because of steric incompatibility between DHA and cholesterol. The model predicts that DHA does not directly modify rafts; rather, it incorporates into nonrafts to modify the lateral organization and/or conformation of membrane proteins, such as the major histocompatibility complex (MHC) class I. Here, we tested predictions of the model at a cellular level by incorporating oleic acid, eicosapentaenoic acid (EPA), and DHA, compared with a bovine serum albumin (BSA) control, into the membranes of EL4 cells. Quantitative microscopy showed that DHA, but not EPA, treatment, relative to the BSA control diminished lipid raft clustering and increased their size. Approximately 30% of DHA was incorporated directly into rafts without changing the distribution of cholesterol between rafts and nonrafts. Quantification of fluorescence colocalization images showed that DHA selectively altered MHC class I lateral organization by increasing the fraction of the nonraft protein into rafts compared with BSA. Both DHA and EPA treatments increased antibody binding to MHC class I compared with BSA. Antibody titration showed that DHA and EPA did not change MHC I conformation but increased total surface levels relative to BSA. Taken together, our findings are not in agreement with the biophysical model. Therefore, we propose a model that reconciles contradictory viewpoints from biophysical and cellular studies to explain how DHA modifies lipid rafts on several length scales. Our study supports the notion that rafts are an important target of DHA's mode of action.

  4. MHC class II diversity of koala (Phascolarctos cinereus) populations across their range.

    PubMed

    Lau, Q; Jaratlerdsiri, W; Griffith, J E; Gongora, J; Higgins, D P

    2014-10-01

    Major histocompatibility complex class II (MHCII) genes code for proteins that bind and present antigenic peptides and trigger the adaptive immune response. We present a broad geographical study of MHCII DA β1 (DAB) and DB β1 (DBB) variants of the koala (Phascolarctos cinereus; n=191) from 12 populations across eastern Australia, with a total of 13 DAB and 7 DBB variants found. We identified greater MHCII variation and, possibly, additional gene copies in koala populations in the north (Queensland and New South Wales) relative to the south (Victoria), confirmed by STRUCTURE analyses and genetic differentiation using analysis of molecular variance. The higher MHCII diversity in the north relative to south could potentially be attributed to (i) significant founder effect in Victorian populations linked to historical translocation of bottlenecked koala populations and (ii) increased pathogen-driven balancing selection and/or local genetic drift in the north. Low MHCII genetic diversity in koalas from the south could reduce their potential response to disease, although the three DAB variants found in the south had substantial sequence divergence between variants. This study assessing MHCII diversity in the koala with historical translocations in some populations contributes to understanding the effects of population translocations on functional genetic diversity.

  5. MHC class I protects motor neurons from astrocyte-induced toxicity in amyotrophic lateral sclerosis (ALS)

    PubMed Central

    Braun, Lyndsey; Meyer, Kathrin; Frakes, Ashley E.; Ferraiuolo, Laura; Likhite, Shibi; Bevan, Adam K.; Foust, Kevin D.; McConnell, Michael J.; Walker, Christopher M.; Kaspar, Brian K.

    2016-01-01

    Astrocytes isolated from individuals with amyotrophic lateral sclerosis (ALS) are toxic towards motor neurons (MNs) and play a non-cell autonomous role in disease pathogenesis. The mechanisms underlying the susceptibility of motor neurons to cell death remains unclear. Here, we report that astrocytes derived from mice bearing ALS mutations and from individuals with ALS reduce expression of major histocompatibility complex class I (MHCI) on MNs. Reduced MHCI expression makes these MNs susceptible to astrocyte-induced cell death. Increasing MHCI expression on MNs increases survival and motor performance in a mouse model of ALS and protects MN against astrocyte toxicity. A single MHCI molecule, HLA-F, protects MNs from ALS astrocyte-mediated toxicity, while knockdown of its receptor, the killer cell immunoglobulin-like receptor KIR3DL2, an inhibitory receptor that recognizes MHCI, on astrocytes results in enhanced MN death. These data indicate that in ALS upon loss of MHCI expression MNs become vulnerable to astrocyte-mediated toxicity. PMID:26928464

  6. Isolation over 35 years in a heated biotest basin causes selection on MHC class IIß genes in the European perch (Perca fluviatilis L.)

    PubMed Central

    Björklund, Mats; Aho, Teija; Behrmann-Godel, Jasminca

    2015-01-01

    Genes that play key roles in host immunity such as the major histocompatibility complex (MHC) in vertebrates are expected to be major targets of selection. It is well known that environmental conditions can have an effect on host–parasite interactions and may thus influence the selection on MHC. We analyzed MHC class IIß variability over 35 years in a population of perch (Perca fluviatilis) from the Baltic Sea that was split into two populations separated from each other. One population was subjected to heating from cooling water of a nuclear power plant and was isolated from the surrounding environment in an artificial lake, while the other population was not subjected to any change in water temperature (control). The isolated population experienced a change of the allelic composition and a decrease in allelic richness of MHC genes compared to the control population. The two most common MHC alleles showed cyclic patterns indicating ongoing parasite–host coevolution in both populations, but the alleles that showed a cyclic behavior differed between the two populations. No such patterns were observed at alleles from nine microsatellite loci, and no genetic differentiation was found between populations. We found no indications for a genetic bottleneck in the isolated population during the 35 years. Additionally, differences in parasitism of the current perch populations suggest that a change of the parasite communities has occurred over the isolation period, although the evidence in form of in-depth knowledge of the change of the parasite community over time is lacking. Our results are consistent with the hypothesis of a selective sweep imposed by a change in the parasite community. PMID:25897384

  7. Differential tapasin dependence of MHC class I molecules correlates with conformational changes upon peptide dissociation: A molecular dynamics simulation study

    SciTech Connect

    Sieker, Florian; Straatsma, TP; Springer, Sebastian; Zacharias, Martin W

    2008-08-01

    Efficiency of peptide loading to MHC class I molecules in the endoplasmatic reticulum depends on the class I allele and can involve interaction with tapasin and other proteins of the loading complex. Allele HLA-B*4402 (Asp at position 116) depends on tapasin for efficient peptide loading whereas HLA-B*4405 (identical to B*4402 except for Tyr116) can efficiently load peptides in the absence of tapasin. Both alleles adopt very similar structures in the presence of the same peptide. Molecular dynamics (MD) simulations on induced peptide termini dissociation from the α1/α2 peptide binding domains have been performed to characterize free energy changes and associated structural changes in the two alleles. A smooth free energy change along the distance dissociation coordinate was obtained for N terminus dissociation. A different shape and magnitude of the calculated free energy change and was obtained for induced peptide C terminus dissociation in case of the tapasin independent allele B*4405 compared to B*4402. Structural changes during C terminus dissociation occurred mainly in the first segment of the α2-1 helix that flanks the peptide C-terminus binding region (F-pocket) and contacts residue 116. This segment is also close to the proposed tapasin contact region. For B*4402, a stable shift towards an altered open F-pocket structure deviating significantly from the bound form was observed. In contrast, B*4405 showed only a transient opening of the F-pocket followed by relaxation towards a structure close to the bound form upon C terminus dissociation. The greater tendency for peptide-receptive conformation in the absence of peptide combined with a more long-range character of the interactions with the peptide C terminus facilitates peptide binding to B*4405 and could be responsible for the tapasin independence of this allele. A possible role of tapasin in case of HLA-B*4402 and other tapasin-dependent alleles could be the stabilization of a peptide receptive class I

  8. MHC class I-related chain A and B ligands are differentially expressed in human cervical cancer cell lines

    PubMed Central

    2011-01-01

    Background Natural killer (NK) cells are an important resource of the innate immune system directly involved in the spontaneous recognition and lysis of virus-infected and tumor cells. An exquisite balance of inhibitory and activating receptors tightly controls the NK cell activity. At present, one of the best-characterized activating receptors is NKG2D, which promotes the NK-mediated lysis of target cells by binding to a family of cell surface ligands encoded by the MHC class I chain-related (MIC) genes, among others. The goal of this study was to describe the expression pattern of MICA and MICB at the molecular and cellular levels in human cervical cancer cell lines infected or not with human papillomavirus, as well as in a non-tumorigenic keratinocyte cell line. Results Here we show that MICA and MICB exhibit differential expression patterns among HPV-infected (SiHa and HeLa) and non-infected cell lines (C33-A, a tumor cell line, and HaCaT, an immortalized keratinocyte cell line). Cell surface expression of MICA was higher than cell surface expression of MICB in the HPV-positive cell lines; in contrast, HPV-negative cells expressed lower levels of MICA. Interestingly, the MICA levels observed in C33-A cells were overcome by significantly higher MICB expression. Also, all cell lines released higher amounts of soluble MICB than of soluble MICA into the cell culture supernatant, although this was most pronounced in C33-A cells. Additionally, Real-Time PCR analysis demonstrated that MICA was strongly upregulated after genotoxic stress. Conclusions This study provides evidence that even when MICA and MICB share a high degree of homology at both genomic and protein levels, differential regulation of their expression and cell surface appearance might be occurring in cervical cancer-derived cells. PMID:21631944

  9. The Human Cytomegalovirus MHC Class I Homolog UL18 Inhibits LIR-1+ but Activates LIR-1− NK Cells1

    PubMed Central

    Prod’homme, Virginie; Griffin, Cora; Aicheler, Rebecca J.; Wang, Eddie C. Y.; McSharry, Brian P.; Rickards, Carole R.; Stanton, Richard J.; Borysiewicz, Leszek K.; López-Botet, Miguel; Wilkinson, Gavin W. G.; Tomasec, Peter

    2010-01-01

    The inhibitory leukocyte Ig-like receptor 1 (LIR-1, also known as ILT2, CD85j, or LILRB1) was identified by its high affinity for the human CMV (HCMV) MHC class I homolog gpUL18. The role of this LIR-1-gpUL18 interaction in modulating NK recognition during HCMV infection has previously not been clearly defined. In this study, LIR-1+ NKL cell-mediated cytotoxicity was shown to be inhibited by transduction of targets with a replication-deficient adenovirus vector encoding UL18 (RAd-UL18). Fibroblasts infected with an HCMV UL18 mutant (ΔUL18) also exhibited enhanced susceptibility to NKL killing relative to cells infected with the parental virus. In additional cytolysis assays, UL18-mediated protection was also evident in the context of adenovirus vector transduction and HCMV infection of autologous fibroblast targets using IFN-α-activated NK bulk cultures derived from a donor with a high frequency of LIR-1+ NK cells. A single LIR-1high NK clone derived from this donor was inhibited by UL18, while 3 of 24 clones were activated. CD107 mobilization assays revealed that LIR-1+ NK cells were consistently inhibited by UL18 in all tested donors, but this effect was often masked in the global response by UL18-mediated activation of a subset of LIR-1− NK cells. Although Ab-blocking experiments support UL18 inhibition being induced by a direct interaction with LIR-1, the UL18-mediated activation is LIR-1 independent. PMID:17372005

  10. Allergen-specific MHC class II tetramer+ cells are detectable in allergic, but not in nonallergic, individuals.

    PubMed

    Macaubas, Claudia; Wahlstrom, Jan; Galvão da Silva, Ana Paula; Forsthuber, Thomas G; Sønderstrup, Grete; Kwok, William W; DeKruyff, Rosemarie H; Umetsu, Dale T

    2006-04-15

    Allergen-specific cells are present in very low frequency in peripheral blood of humans, and differ in function in allergic and nonallergic individuals. We report in this study that soluble class II MHC tetramers can be used to directly identify and study such allergen epitope-specific CD4+ T cells in humans. We identified the major antigenic epitope of rye grass allergen Lol p 1 in HLA-DRB1*0401 individuals using HLA-DR*0401 transgenic mice and peripheral blood cells from HLA-DR*0401 individuals. Using DRB1*0401 tetramers loaded with this major epitope of Lol p 1, we detected allergen-specific CD4+ T cells in the peripheral blood of DRB1*0401 rye grass allergic individuals after ex vivo expansion with allergen. These tetramer-positive cells produced IL-4, but little IFN-gamma. In contrast, we were unable to detect rye grass tetramer-positive cells in cultures from HLA-DR*0401 nonallergic individuals, even after expansion with IL-2. Thus, our results suggest that rye grass allergen-specific T cells in DR*0401 nonallergic subjects are present at very low levels (e.g., because of deletion or suppression), differ in a fundamental way in their requirement for ex vivo expansion (e.g., they may be anergic), or use TCRs distinct from those of allergic individuals. Thus, analysis using DRB1*0401 tetramers loaded with a major epitope of Lol p 1 indicates that allergen-specific CD4+ T cells in nonallergic individuals are distinct from those in allergic subjects.

  11. LAMP-2C Inhibits MHC Class II Presentation of Cytoplasmic Antigens by Disrupting Chaperone-Mediated Autophagy.

    PubMed

    Pérez, Liliana; McLetchie, Shawna; Gardiner, Gail J; Deffit, Sarah N; Zhou, Delu; Blum, Janice S

    2016-03-15

    Cells use multiple autophagy pathways to sequester macromolecules, senescent organelles, and pathogens. Several conserved isoforms of the lysosome-associated membrane protein-2 (LAMP-2) regulate these pathways influencing immune recognition and responses. LAMP-2A is required for chaperone-mediated autophagy (CMA), which promotes Ag capture and MHC class II (MHCII) presentation in B cells and signaling in T cells. LAMP-2B regulates lysosome maturation to impact macroautophagy and phagocytosis. Yet, far less is known about LAMP-2C function. Whereas LAMP2A and LAMP2B mRNA were broadly detected in human tissues, LAMP2C expression was more limited. Transcripts for the three LAMP2 isoforms increased with B cell activation, although specific gene induction varied depending on TLR versus BCR engagement. To examine LAMP-2C function in human B cells and specifically its role in Ag presentation, we used ectopic gene expression. Increased LAMP-2C expression in B cells did not alter MHCII expression or invariant chain processing, but did perturb cytoplasmic Ag presentation via CMA. MHCII presentation of epitopes from exogenous and membrane Ags was not affected by LAMP-2C expression in B cells. Similarly, changes in B cell LAMP-2C expression did not impact macroautophagy. The gene expression of other LAMP2 isoforms and proteasome and lysosomal proteases activities were unperturbed by LAMP-2C ectopic expression. LAMP-2C levels modulated the steady-state expression of several cytoplasmic proteins that are targeted for degradation by CMA and diminished peptide translocation via this pathway. Thus, LAMP-2C serves as a natural inhibitor of CMA that can selectively skew MHCII presentation of cytoplasmic Ags.

  12. Mamu-A*01/K{sup b} transgenic and MHC Class I knockout mice as a tool for HIV vaccine development

    SciTech Connect

    Li Jinliang; Srivastava, Tumul; Rawal, Ravindra; Manuel, Edwin; Isbell, Donna; Tsark, Walter; La Rosa, Corinna; Wang Zhongde; Li Zhongqi; Barry, Peter A.; Hagen, Katharine D.; Longmate, Jeffrey; Diamond, Don J.

    2009-04-25

    We have developed a murine model expressing the rhesus macaque (RM) Mamu-A*01 MHC allele to characterize immune responses and vaccines based on antigens of importance to human disease processes. Towards that goal, transgenic (Tg) mice expressing chimeric RM (alpha1 and alpha2 Mamu-A*01 domains) and murine (alpha3, transmembrane, and cytoplasmic H-2K{sup b} domains) MHC Class I molecules were derived by transgenesis of the H-2K{sup b}D{sup b} double MHC Class I knockout strain. After immunization of Mamu-A*01/K{sup b} Tg mice with rVV-SIVGag-Pol, the mice generated CD8{sup +} T-cell IFN-gamma responses to several known Mamu-A*01 restricted epitopes from the SIV Gag and Pol antigen sequence. Fusion peptides of highly recognized CTL epitopes from SIV Pol and Gag and a strong T-help epitope were shown to be immunogenic and capable of limiting an rVV-SIVGag-Pol challenge. Mamu-A*01/K{sup b} Tg mice provide a model system to study the Mamu-A*01 restricted T-cell response for various infectious diseases which are applicable to a study in RM.

  13. Crystal structure of the human CD4 N-terminal two-domain fragment complexed to a class II MHC molecule.

    SciTech Connect

    Wang, J.-H.; Meijers, R.; Xiong, Y.; Liu, J.-H.; Sakihama, T.; Zhang, R.-G.; Joachimiak, A.; Reinherz, E. L.; Biosciences Division; Dana-Farber Cancer Inst.; Harvard Medical School

    2001-09-11

    The structural basis of the interaction between the CD4 coreceptor and a class II major histocompatibility complex (MHC) is described. The crystal structure of a complex containing the human CD4 N-terminal two-domain fragment and the murine I-A{sup k }class II MHC molecule with associated peptide (pMHCII) shows that only the 'top corner' of the CD4 molecule directly contacts pMHCII. The CD4 Phe-43 side chain extends into a hydrophobic concavity formed by MHC residues from both {alpha}2 and {beta}2 domains. A ternary model of the CD4-pMHCII-T-cell receptor (TCR) reveals that the complex appears V-shaped with the membrane-proximal pMHCII at the apex. This configuration excludes a direct TCR-CD4 interaction and suggests how TCR and CD4 signaling is coordinated around the antigenic pMHCII complex. Human CD4 binds to HIV gp120 in a manner strikingly similar to the way in which CD4 interacts with pMHCII. Additional contacts between gp120 and CD4 give the CD4-gp120 complex a greater affinity. Thus, ligation of the viral envelope glycoprotein to CD4 occludes the pMHCII-binding site on CD4, contributing to immunodeficiency.

  14. FOXP1 suppresses immune response signatures and MHC class II expression in activated B-cell-like diffuse large B-cell lymphomas

    PubMed Central

    Brown, P J; Wong, K K; Felce, S L; Lyne, L; Spearman, H; Soilleux, E J; Pedersen, L M; Møller, M B; Green, T M; Gascoyne, D M; Banham, A H

    2016-01-01

    The FOXP1 (forkhead box P1) transcription factor is a marker of poor prognosis in diffuse large B-cell lymphoma (DLBCL). Here microarray analysis of FOXP1-silenced DLBCL cell lines identified differential regulation of immune response signatures and major histocompatibility complex class II (MHC II) genes as some of the most significant differences between germinal center B-cell (GCB)-like DLBCL with full-length FOXP1 protein expression versus activated B-cell (ABC)-like DLBCL expressing predominantly short FOXP1 isoforms. In an independent primary DLBCL microarray data set, multiple MHC II genes, including human leukocyte antigen DR alpha chain (HLA-DRA), were inversely correlated with FOXP1 transcript expression (P<0.05). FOXP1 knockdown in ABC-DLBCL cells led to increased cell-surface expression of HLA-DRA and CD74. In R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone)-treated DLBCL patients (n=150), reduced HLA-DRA (<90% frequency) expression correlated with inferior overall survival (P=0.0003) and progression-free survival (P=0.0012) and with non-GCB subtype stratified by the Hans, Choi or Visco–Young algorithms (all P<0.01). In non-GCB DLBCL cases with <90% HLA-DRA, there was an inverse correlation with the frequency (P=0.0456) and intensity (P=0.0349) of FOXP1 expression. We propose that FOXP1 represents a novel regulator of genes targeted by the class II MHC transactivator CIITA (MHC II and CD74) and therapeutically targeting the FOXP1 pathway may improve antigen presentation and immune surveillance in high-risk DLBCL patients. PMID:26500140

  15. Properties of the Principal Eigenvalues of a General Class of Non-classical Mixed Boundary Value Problems

    NASA Astrophysics Data System (ADS)

    Cano-Casanova, Santiago; López-Gómez, Julián

    2002-01-01

    In this paper we characterize the existence of principal eigenvalues for a general class of linear weighted second order elliptic boundary value problems subject to a very general class of mixed boundary conditions. Our theory is a substantial extension of the classical theory by P. Hess and T. Kato (1980, Comm. Partial Differential Equations5, 999-1030). In obtaining our main results we must give a number of new results on the continuous dependence of the principal eigenvalue of a second order linear elliptic boundary value problem with respect to the underlying domain and the boundary condition itself. These auxiliary results complement and in some sense complete the theory of D. Daners and E. N. Dancer (1997, J. Differential Equations138, 86-132). The main technical tool used throughout this paper is a very recent characterization of the strong maximum principle in terms of the existence of a positive strict supersolution due to H. Amann and J. López-Gómez (1998, J. Differential Equations146, 336-374).

  16. Serologic cross-reactivity between Class I MHC molecules and an H-2- linked differentiation antigen as detected by monoclonal antibodies

    PubMed Central

    1984-01-01

    Analysis of anti-Class I major histocompatibility complex (MHC) monoclonal antibodies by immunofluorescence and flow microfluorometry demonstrated an unexpected cross-reactivity. Two of fifteen antibodies examined (20-8-4, anti-Kb,Kd,r,s and 34-1-2, antiKd,Dd,Kb,r,s,q,p) were observed to detect an antigen determined by gene(s) mapping to the right of H-2D. Two-color immunofluorescence analysis demonstrated that this antigen, unlike classical H-2K and D antigens, was expressed in high amounts on peripheral T cells, but only weakly on Ia-positive cells and on small subpopulations of thymus and bone marrow cells. Mapping, absorption, blocking, and tissue distribution studies suggested that the cross-reactive antigen is Qa-like, but distinct from previously described Qa antigens. Thus, these data demonstrate serological cross-reactivity between a Class I MHC antigen and a differentiation antigen determined by genes linked to H-2. It seems likely that the gene responsible for this new antigen is one of the numerous Class I-like sequences detected by DNA hybridization analyses, but previously undefined in terms of tissue expression. These data suggest that many of these DNA sequences may be expressed in specific tissues and that cross-reactions of anti-Class I MAbs may provide useful probes for studying the products of such homologous genes. PMID:6363595

  17. Duplication, balancing selection and trans-species evolution explain the high levels of polymorphism of the DQA MHC class II gene in voles (Arvicolinae).

    PubMed

    Bryja, J; Galan, M; Charbonnel, N; Cosson, J F

    2006-04-01

    Major histocompatibility complex (MHC) genes play important role in host-parasite interactions and parasites are crucial factors influencing the population dynamics of hosts. We described the structure and diversity of exon 2 of the MHC class II DQA gene in three species of voles (Arvicolinae) exhibiting regular multi-annual fluctuations of population density and analysed the processes leading to the observed MHC polymorphism. By using cloning-sequencing methodology and capillary electrophoresis-single strand conformation polymorphism, we described seven sequences in the water, eight in the common, and seven in the bank voles coming from an area of 70 km(2) around the Nozeroy canton in the Jura Mountains (Franche Comté, France). All exon 2 sequences translate to give unique amino acid sequences and positive selection was found to act very intensively on antigen binding sites. We documented the presence of recombination at vole DQA region but its importance in generating allelic polymorphism seems to be relatively limited. For the first time within rodents, we documented the duplication of the DQA gene in all three species with both copies being transcriptionally active. Phylogenetic analysis of allelic sequences revealed extensive trans-species polymorphism within the subfamily although no alleles were shared between species in our data set. We discuss possible role of parasites in forming the recent polymorphism pattern of the DQA locus in voles.

  18. Genome-Wide Analysis Identifies a Quantitative Trait Locus in the MHC Class II Region Associated with Generalized Vitiligo Age of Onset

    PubMed Central

    Jin, Ying; Birlea, Stanca A.; Fain, Pamela R.; Gowan, Katherine; Riccardi, Sheri L.; Holland, Paulene J.; Bennett, Dorothy C.; Herbstman, Deborah M.; Wallace, Margaret R.; McCormack, Wayne T.; Kemp, E. Helen; Gawkrodger, David J.; Weetman, Anthony P.; Picardo, Mauro; Leone, Giovanni; Taïeb, Alain; Jouary, Thomas; Ezzedine, Khaled; van Geel, Nanny; Lambert, Jo; Overbeck, Andreas; Spritz, Richard A.

    2011-01-01

    Generalized vitiligo is a common autoimmune disease in which acquired patchy depigmentation of skin, hair, and mucous membranes results from loss of melanocytes from involved areas. Previous genetic analyses have focused on vitiligo susceptibility, and have identified a number of genes involved in disease risk. Age of onset of generalized vitiligo also involves a substantial genetic component, but has not previously been studied systematically. In this study, we report a genome-wide association study of vitiligo age of onset in 1,339 generalized vitiligo patients, with replication in an independent cohort of 677 cases. We identified a quantitative trait locus for vitiligo age of onset in the major histocompatibility complex (MHC) class II region, located near c6orf10-BTNL2 (rs7758128; P = 8.14×10−11), a region that is also associated with generalized vitiligo susceptibility. In contrast, there was no association of vitiligo age of onset with any other MHC or non-MHC loci that are associated with vitiligo susceptibility. These findings highlight the differing roles played by genes involved in vitiligo susceptibility versus vitiligo age of onset, and illustrate that genome-wide analyses can be used to identify genes involved in quantitative aspects of disease natural history, as well as disease susceptibility per se. PMID:21326295

  19. Patterns of MHC-G-Like and MHC-B Diversification in New World Monkeys

    PubMed Central

    Lugo, Juan S.; Cadavid, Luis F.

    2015-01-01

    The MHC class I (MHC-I) region in New World monkeys (Platyrrhini) has remained relatively understudied. To evaluate the diversification patterns and transcription behavior of MHC-I in Platyrrhini, we first analyzed public genomic sequences from the MHC-G-like subregion in Saimiri boliviensis, Ateles geoffroyi and Callicebus moloch, and from the MHC-B subregion in Saimiri boliviensis. While S. boliviensis showed multiple copies of both MHC-G-like (10) and –B (15) loci, A. geoffroyi and C. moloch had only three and four MHC-G-like genes, respectively, indicating that not all Platyrrhini species have expanded their MHC-I loci. We then sequenced MHC-G-like and -B cDNAs from nine Platyrrhini species, recovering two to five unique cDNAs per individual for both loci classes. In two Saguinus species, however, no MHC-B cDNAs were found. In phylogenetic trees, MHC-G-like cDNAs formed genus-specific clusters whereas the MHC-B cDNAs grouped by Platyrrhini families, suggesting a more rapid diversification of the former. Furthermore, cDNA sequencing in 12 capuchin monkeys showed that they transcribe at least four MHC-G-like and five MHC-B polymorphic genes, showing haplotypic diversity for gene copy number and signatures of positive natural selection at the peptide binding region. Finally, a quantitative index for MHC:KIR affinity was proposed and tested to predict putative interacting pairs. Altogether, our data indicate that i) MHC-I genes has expanded differentially among Platyrrhini species, ii) Callitrichinae (tamarins and marmosets) MHC-B loci have limited or tissue-specific expression, iii) MHC-G-like genes have diversified more rapidly than MHC-B genes, and iv) the MHC-I diversity is generated mainly by genetic polymorphism and gene copy number variation, likely promoted by natural selection for ligand binding. PMID:26121030

  20. Changes in variation at the MHC class II DQA locus during the final demise of the woolly mammoth

    NASA Astrophysics Data System (ADS)

    Pečnerová, Patrícia; Díez-Del-Molino, David; Vartanyan, Sergey; Dalén, Love

    2016-05-01

    According to the nearly-neutral theory of evolution, the relative strengths of selection and drift shift in favour of drift at small population sizes. Numerous studies have analysed the effect of bottlenecks and small population sizes on genetic diversity in the MHC, which plays a central role in pathogen recognition and immune defense and is thus considered a model example for the study of adaptive evolution. However, to understand changes in genetic diversity at loci under selection, it is necessary to compare the genetic diversity of a population before and after the bottleneck. In this study, we analyse three fragments of the MHC DQA gene in woolly mammoth samples radiocarbon dated to before and after a well-documented bottleneck that took place about ten thousand years ago. Our results indicate a decrease in observed heterozygosity and number of alleles, suggesting that genetic drift had an impact on the variation on MHC. Based on coalescent simulations, we found no evidence of balancing selection maintaining MHC diversity during the Holocene. However, strong trans-species polymorphism among mammoths and elephants points to historical effects of balancing selection on the woolly mammoth lineage.

  1. Changes in variation at the MHC class II DQA locus during the final demise of the woolly mammoth.

    PubMed

    Pečnerová, Patrícia; Díez-Del-Molino, David; Vartanyan, Sergey; Dalén, Love

    2016-05-04

    According to the nearly-neutral theory of evolution, the relative strengths of selection and drift shift in favour of drift at small population sizes. Numerous studies have analysed the effect of bottlenecks and small population sizes on genetic diversity in the MHC, which plays a central role in pathogen recognition and immune defense and is thus considered a model example for the study of adaptive evolution. However, to understand changes in genetic diversity at loci under selection, it is necessary to compare the genetic diversity of a population before and after the bottleneck. In this study, we analyse three fragments of the MHC DQA gene in woolly mammoth samples radiocarbon dated to before and after a well-documented bottleneck that took place about ten thousand years ago. Our results indicate a decrease in observed heterozygosity and number of alleles, suggesting that genetic drift had an impact on the variation on MHC. Based on coalescent simulations, we found no evidence of balancing selection maintaining MHC diversity during the Holocene. However, strong trans-species polymorphism among mammoths and elephants points to historical effects of balancing selection on the woolly mammoth lineage.

  2. Changes in variation at the MHC class II DQA locus during the final demise of the woolly mammoth

    PubMed Central

    Pečnerová, Patrícia; Díez-del-Molino, David; Vartanyan, Sergey; Dalén, Love

    2016-01-01

    According to the nearly-neutral theory of evolution, the relative strengths of selection and drift shift in favour of drift at small population sizes. Numerous studies have analysed the effect of bottlenecks and small population sizes on genetic diversity in the MHC, which plays a central role in pathogen recognition and immune defense and is thus considered a model example for the study of adaptive evolution. However, to understand changes in genetic diversity at loci under selection, it is necessary to compare the genetic diversity of a population before and after the bottleneck. In this study, we analyse three fragments of the MHC DQA gene in woolly mammoth samples radiocarbon dated to before and after a well-documented bottleneck that took place about ten thousand years ago. Our results indicate a decrease in observed heterozygosity and number of alleles, suggesting that genetic drift had an impact on the variation on MHC. Based on coalescent simulations, we found no evidence of balancing selection maintaining MHC diversity during the Holocene. However, strong trans-species polymorphism among mammoths and elephants points to historical effects of balancing selection on the woolly mammoth lineage. PMID:27143688

  3. A four-step model for the IL-6 amplifier, a regulator of chronic inflammations in tissue-specific MHC class II-associated autoimmune diseases.

    PubMed

    Murakami, Masaaki; Hirano, Toshio

    2011-01-01

    It is commonly thought that autoimmune diseases are caused by the breakdown of self-tolerance, which suggests the recognition of specific antigens by autoreactive CD4+ T cells contribute to the specificity of autoimmune diseases (Marrack et al., 2001; Mathis and Benoist, 2004). In several cases, however, even for diseases associated with class II major histocompatibility complex (MHC) alleles, the causative tissue-specific antigens recognized by memory/activated CD4+ T cells have not been established (Mocci et al., 2000; Skapenko et al., 2005). Rheumatoid arthritis (RA) and arthritis in F759 knock-in mice (F759 mice) are such examples (Atsumi et al., 2002; Brennan et al., 2002; Falgarone et al., 2009). These include associations with class II MHC and CD4 molecules; increased numbers of memory/activated CD4+ T cells; and improved outcomes in response to suppressions and/or deficiencies in class II MHC molecules, CD4+ T cells, and the T cell survival cytokine IL-7. Regarding the development of arthritis in F759 mice, it is not only the immune system, but also non-immune tissue that are involved, indicating that the importance of their interactions (Sawa et al., 2006, 2009; Ogura et al., 2008; Hirano, 2010; Murakami et al., 2011). Furthermore, we have shown that local events such as microbleeding together with an accumulation of activated CD4+ T cells in a manner independent of tissue antigen-recognitions induces arthritis in the joints of F759 mice (Murakami et al., 2011). For example, local microbleeding-mediated CCL20 expression induce such an accumulation, causing arthritis development via chronic activation of an IL-17A-dependent IL-6 signaling amplification loop in type 1 collagen+ cells that is triggered by CD4+ T cell-derived cytokine(s) such as IL-17A, which leads to the synergistic activation of STAT3 and NFκB in non-hematopoietic cells in the joint (Murakami et al., 2011). We named this loop the IL-6-mediated inflammation amplifier, or IL-6 amplifier for

  4. MHC class II super-enhancer increases surface expression of HLA-DR and HLA-DQ and affects cytokine production in autoimmune vitiligo

    PubMed Central

    Cavalli, Giulio; Hayashi, Masahiro; Jin, Ying; Yorgov, Daniel; Santorico, Stephanie A.; Holcomb, Cherie; Rastrou, Melinda; Erlich, Henry; Tengesdal, Isak W.; Dagna, Lorenzo; Neff, C. Preston; Palmer, Brent E.; Spritz, Richard A.; Dinarello, Charles A.

    2016-01-01

    Genetic risk for autoimmunity in HLA genes is most often attributed to structural specificity resulting in presentation of self-antigens. Autoimmune vitiligo is strongly associated with the MHC class II region. Here, we fine-map vitiligo MHC class II genetic risk to three SNPs only 47 bp apart, located within a predicted super-enhancer in an intergenic region between HLA-DRB1 and HLA-DQA1, localized by a genome-wide association study of 2,853 Caucasian vitiligo patients. The super-enhancer corresponds to an expression quantitative trait locus for expression of HLA-DR and HLA-DQ RNA; we observed elevated surface expression of HLA-DR (P = 0.008) and HLA-DQ (P = 0.02) on monocytes from healthy subjects homozygous for the high-risk SNP haplotype. Unexpectedly, pathogen-stimulated peripheral blood mononuclear cells from subjects homozygous for the high-risk super-enhancer haplotype exhibited greater increase in production of IFN-γ and IL-1β than cells from subjects homozygous for the low-risk haplotype. Specifically, production of IFN-γ on stimulation of dectin-1, mannose, and Toll-like receptors with Candida albicans and Staphylococcus epidermidis was 2.5- and 2.9-fold higher in high-risk subjects than in low-risk subjects, respectively (P = 0.007 and P = 0.01). Similarly, production of IL-1β was fivefold higher in high-risk subjects than in low-risk subjects (P = 0.02). Increased production of immunostimulatory cytokines in subjects carrying the high-risk haplotype may act as an “adjuvant” during the presentation of autoantigens, tying together genetic variation in the MHC with the development of autoimmunity. This study demonstrates that for risk of autoimmune vitiligo, expression level of HLA class II molecules is as or more important than antigen specificity. PMID:26787888

  5. Proteomic screening identifies calreticulin as a miR-27a direct target repressing MHC class I cell surface exposure in colorectal cancer

    PubMed Central

    Colangelo, T; Polcaro, G; Ziccardi, P; Pucci, B; Muccillo, L; Galgani, M; Fucci, A; Milone, M R; Budillon, A; Santopaolo, M; Votino, C; Pancione, M; Piepoli, A; Mazzoccoli, G; Binaschi, M; Bigioni, M; Maggi, C A; Fassan, M; Laudanna, C; Matarese, G; Sabatino, L; Colantuoni, V

    2016-01-01

    Impairment of the immune response and aberrant expression of microRNAs are emerging hallmarks of tumour initiation/progression, in addition to driver gene mutations and epigenetic modifications. We performed a preliminary survey of independent adenoma and colorectal cancer (CRC) miRnoma data sets and, among the most dysregulated miRNAs, we selected miR-27a and disclosed that it is already upregulated in adenoma and further increases during the evolution to adenocarcinoma. To identify novel genes and pathways regulated by this miRNA, we employed a differential 2DE-DIGE proteome analysis. We showed that miR-27a modulates a group of proteins involved in MHC class I cell surface exposure and, mechanistically, demonstrated that calreticulin is a miR-27a direct target responsible for most downstream effects in epistasis experiments. In vitro miR-27a affected cell proliferation and angiogenesis; mouse xenografts of human CRC cell lines expressing different miR-27a levels confirmed the protein variations and recapitulated the cell growth and apoptosis effects. In vivo miR-27a inversely correlated with MHC class I molecules and calreticulin expression, CD8+ T cells infiltration and cytotoxic activity (LAMP-1 exposure and perforin release). Tumours with high miR-27a, low calreticulin and CD8+ T cells' infiltration were associated with distant metastasis and poor prognosis. Our data demonstrate that miR-27a acts as an oncomiRNA, represses MHC class I expression through calreticulin downregulation and affects tumour progression. These results may pave the way for better diagnosis, patient stratification and novel therapeutic approaches. PMID:26913609

  6. Long-term Persistence of CD4+ but Rapid Disappearance of CD8+ T Cells Expressing an MHC Class I-restricted TCR of Nanomolar Affinity

    PubMed Central

    Engels, Boris; Chervin, Adam S; Sant, Andrea J; Kranz, David M; Schreiber, Hans

    2012-01-01

    Most T cells have T cell receptors (TCR) of micromolar affinity for peptide-major histocompatibility complex (MHC) ligands, but genetic engineering can generate TCRs of nanomolar affinity. The affinity of the TCR used, m33, for its cognate non-self peptide–MHC-I complex (SIYRYYGL-Kb) is 1,000-fold higher than of the wild-type TCR 2C. The affinity of m33 for the self-peptide dEV-8 on Kb is only twofold higher. Mouse CD8+ T cells transduced with an m33-encoding retrovirus showed binding of SIY-Kb and potent function in vitro, but in vivo these T cells disappeared within hours after transfer into syngeneic hosts without causing graft-versus-host disease (GVHD). Accordingly, in cases where such CD8-dependent self-reactivity might occur in human adoptive T cell therapies, our results show that a peripheral T-cell deletion mechanism could operate to avoid reactions with the host. In contrast to CD8+ T cells, we show that CD4+ T cells expressing m33 survived for months in vivo. Furthermore, the m33-transduced CD4+ T cells were able to mediate antigen-specific rejection of 6-day-old tumors. Together, we show that CD8+ T cell expressing a MHC class I-restricted high-affinity TCR were rapidly deleted whereas CD4+ T cells expressing the same TCR survived and provided function while being directed against a class I-restricted antigen. PMID:22233579

  7. Quantum chemical calculations predict biological function: The case of T cell receptor interaction with a peptide/MHC class I

    NASA Astrophysics Data System (ADS)

    Antipas, Georgios S. E.; Germenis, Anastasios

    2015-02-01

    A combination of atomic correlation statistics and quantum chemical calculations are shown to predict biological function. In the present study, various antigenic peptide-Major Histocompatibility Complex (pMHC) ligands with near-identical stereochemistries, in complexation with the same T cell receptor (TCR), were found to consistently induce distinctly different quantum chemical behavior, directly dependent on the peptide’s electron spin density and intrinsically expressed by the protonation state of the peptide’s N-terminus. Furthermore, the cumulative coordination difference of any variant in respect to the native peptide was found to accurately reflect peptide biological function and immerges as the physical observable which is directly related to the immunological end-effect of pMHC-TCR interaction.

  8. Comparison of MHC Class I Risk Haplotypes in Thai and Caucasian Psoriatics Reveals Locus Heterogeneity at PSORS1

    PubMed Central

    Stuart, Philip E.; Nair, Rajan P.; Hiremagalore, Ravi; Kullavanijaya, Preya; Kullavanijaya, Prisana; Tejasvi, Trilokraj; Lim, Henry W.; Voorhees, John J.; Elder, James T.

    2010-01-01

    Earlier studies have shown that psoriasis in Japan and Thailand is associated with two different MHC haplotypes—those bearing HLA-Cw6 and those bearing HLA-Cw1 and HLA-B46. In an independent case-control sample from Thailand, we confirmed association of psoriasis with both haplotypes. No association was seen in Thai HLA-Cw1 haplotypes lacking HLA-B46, nor was HLA-Cw1 associated with psoriasis in a large Caucasian sample. To assess whether these risk haplotypes share a common origin, we sequenced genomic DNA from a Thai HLA-Cw1-B46 homozygote across the ~300 kb MHC risk interval, and compared it to sequence of a HLA-Cw6-B57 risk haplotype. Three small regions of homology were found, but these regions share equivalent sequence similarity with one or more clearly non-risk haplotypes, and they contain no polymorphism alleles unique to all risk haplotypes. Differences in psoriasis phenotype were also observed, including lower risk of disease, greater nail involvement, and later age at onset in HLA-Cw1-B46 carriers compared to HLA-Cw6 carriers. These findings suggest locus heterogeneity at PSORS1, the major psoriasis susceptibility locus in the MHC, with HLA-Cw6 imparting risk in both Caucasians and Asians, and an allele other than HLA-Cw1 on the HLA-Cw1-B46 haplotype acting as an additional risk variant in East Asians. PMID:20604894

  9. Crystallographic and Computational Studies of a Class II MHC Complex with a Nonconforming Peptide: HLA-DRA/DRB3*0101

    NASA Astrophysics Data System (ADS)

    Parry, Christian S.; Gorski, Jack; Stern, Lawrence J.

    2003-03-01

    The stable binding of processed foreign peptide to a class II major histocompatibility (MHC) molecule and subsequent presentation to a T cell receptor is a central event in immune recognition and regulation. Polymorphic residues on the floor of the peptide binding site form pockets that anchor peptide side chains. These and other residues in the helical wall of the groove determine the specificity of each allele and define a motif. Allele specific motifs allow the prediction of epitopes from the sequence of pathogens. There are, however, known epitopes that do not satisfy these motifs: anchor motifs are not adequate for predicting epitopes as there are apparently major and minor motifs. We present crystallographic studies into the nature of the interactions that govern the binding of these so called nonconforming peptides. We would like to understand the role of the P10 pocket and find out whether the peptides that do not obey the consensus anchor motif bind in the canonical conformation observed in in prior structures of class II MHC-peptide complexes. HLA-DRB3*0101 complexed with peptide crystallized in unit cell 92.10 x 92.10 x 248.30 (90, 90, 90), P41212, and the diffraction data is reliable to 2.2ÅWe are complementing our studies with dynamical long time simulations to answer these questions, particularly the interplay of the anchor motifs in peptide binding, the range of protein and ligand conformations, and water hydration structures.

  10. Pseudomonas aeruginosa Cif protein enhances the ubiquitination and proteasomal degradation of the transporter associated with antigen processing (TAP) and reduces major histocompatibility complex (MHC) class I antigen presentation.

    PubMed

    Bomberger, Jennifer M; Ely, Kenneth H; Bangia, Naveen; Ye, Siying; Green, Kathy A; Green, William R; Enelow, Richard I; Stanton, Bruce A

    2014-01-03

    Cif (PA2934), a bacterial virulence factor secreted in outer membrane vesicles by Pseudomonas aeruginosa, increases the ubiquitination and lysosomal degradation of some, but not all, plasma membrane ATP-binding cassette transporters (ABC), including the cystic fibrosis transmembrane conductance regulator and P-glycoprotein. The goal of this study was to determine whether Cif enhances the ubiquitination and degradation of the transporter associated with antigen processing (TAP1 and TAP2), members of the ABC transporter family that play an essential role in antigen presentation and intracellular pathogen clearance. Cif selectively increased the amount of ubiquitinated TAP1 and increased its degradation in the proteasome of human airway epithelial cells. This effect of Cif was mediated by reducing USP10 deubiquitinating activity, resulting in increased polyubiquitination and proteasomal degradation of TAP1. The reduction in TAP1 abundance decreased peptide antigen translocation into the endoplasmic reticulum, an effect that resulted in reduced antigen available to MHC class I molecules for presentation at the plasma membrane of airway epithelial cells and recognition by CD8(+) T cells. Cif is the first bacterial factor identified that inhibits TAP function and MHC class I antigen presentation.

  11. Nonclassicality of local bipartite correlations

    NASA Astrophysics Data System (ADS)

    Jebaratnam, C.; Aravinda, S.; Srikanth, R.

    2017-03-01

    Simulating quantum nonlocality and steering requires augmenting preshared randomness with nonvanishing communication cost. This prompts the question of how one may provide such an operational characterization for the quantumness of correlations due to even unentangled states. Here we show that for a certain class of states, such quantumness can be pointed out by superlocality, the requirement for a larger dimension of the preshared randomness to simulate the correlations than that of the quantum state that generates them. This provides an approach to define the nonclassicality of local multipartite correlations in convex operational theories.

  12. Differential regulation of expression of the MHC class II molecules RT1.B and RT1.D on rat B lymphocytes: effects of interleukin-4, interleukin-13 and interferon-gamma.

    PubMed Central

    Roos, A; Schilder-Tol, E J; Chand, M A; Claessen, N; Lakkis, F G; Pascual, D W; Weening, J J; Aten, J

    1998-01-01

    Susceptibility to induction of both T helper 1- (Th1) and Th2-mediated autoimmunity is multifactorial and involves genetic linkage to the major histocompatibility complex (MHC) class II haplotype. Brown Norway (BN) rats exposed to mercuric chloride develop a Th2-dependent systemic autoimmunity, whereas Lewis rats, which are highly susceptible to Th1-mediated autoimmunity, develop immune suppression after mercuric chloride exposure. Exposure to mercuric chloride is known to enhance B-lymphocyte expression of the MHC class II molecule RT1.B, predominantly in BN rats. We demonstrate that, in contrast, expression of RT1.D was unmodified on these B cells, whereas both RT1.B and RT1.D were up-regulated on epithelial cells. Regulation of B-cell MHC class II isotype expression was further studied in vitro, using BN rat lymph node (LN) cells. Interleukin-4 (IL-4) strongly enhanced B-cell expression of RT1.B (2.8-fold), whereas RT1.D expression was only slightly, although significantly, modified (1.2-fold). B cells from Lewis rats showed a similar IL-4-induced enhancement of RT1.B expression (2.5-fold), whereas, in contrast, RT1.D expression was unmodified. Exposure of LN cells from BN rats to interferon-gamma induced a moderate increase of B-cell MHC class II expression, predominantly of RT1.B. Strong and rapid enhancement of B-cell RT1.D expression was observed after stimulation by phorbol 12-myristate 13-acetate and ionomycin. Rat IL-13 did not modify B-cell MHC class II expression; however, it induced typical morphological changes in peritoneal macrophages. These experiments demonstrate isotype-specific and strain-dependent regulation of MHC class II expression on rat B lymphocytes, which may be of pathophysiological relevance for the strain-dependent susceptibility for Th1- or Th2-mediated autoimmunity. Images Figure 1 Figure 5 PMID:9536116

  13. Spatial separation of the processing and MHC class I loading compartments for cross-presentation of the tumor-associated antigen HER2/neu by human dendritic cells.

    PubMed

    Baleeiro, Renato B; Rietscher, René; Diedrich, Andrea; Czaplewska, Justyna A; Lehr, Claus-Michael; Scherließ, Regina; Hanefeld, Andrea; Gottschaldt, Michael; Walden, Peter

    2015-11-01

    Cross-presentation is the process by which professional antigen presenting cells (APCs) (B cells, dendritic cells (DCs) and macrophages) present endocytosed antigens (Ags) via MHC-I to CD8(+) T cells. This process is crucial for induction of adaptive immune responses against tumors and infected cells. The pathways and cellular compartments involved in cross-presentation are unresolved and controversial. Among the cells with cross-presenting capacity, DCs are the most efficient, which was proposed to depend on prevention of endosomal acidification to block degradation of the epitopes. Contrary to this view, we show in this report that some cargoes induce strong endosomal acidification following uptake by human DCs, while others not. Moreover, processing of the tumor-associated antigen HER2/neu delivered in nanoparticles (NP) for cross-presentation of the epitope HER2/neu369-377 on HLA-A2 depended on endosomal acidification and cathepsin activity as well as proteasomes, and newly synthesized HLA class I. However, the HLA-A*0201/HER2/neu369-377 complexes were not found in the endoplasmic reticulum (ER) nor in endolysosomes but in hitherto not described vesicles. The data thus indicate spatial separation of antigen processing and loading of MHC-I for cross-presentation: antigen processing occurs in the uptake compartment and the cytosol whereas MHC-I loading with peptide takes place in a distinct subcellular compartment. The findings further elucidate the cellular pathways involved in the cross-presentation of a full-length, clinically relevant tumor-associated antigen by human DCs, and the impact of the vaccine formulation on antigen processing and CD8(+) T cell induction.

  14. Identification of the expressed MHC class II DQB gene of the Asiatic black bear, Ursus thibetanus, in Japan.

    PubMed

    Yasukochi, Yoshiki; Kurosaki, Toshifumi; Yoneda, Masaaki; Koike, Hiroko

    2010-04-01

    Genetic diversity estimation of the major histocompatibility complex (MHC) gene may be an important tool in the assessment of immune response ability against infectious disease. We were able to identify a near full-length expressed DQB sequence by RACE-PCR method from the Asiatic black bear, Ursus thibetanus in Japan. This is the first such full length expression in the Ursidae. The bear had at least one functional DQB locus. In phylogenetic tree analysis its DQB amino acid sequence formed a monophyletic group with DQB sequences from members of the order Carnivora and had a 90% nucleotide sequence similarity with the DQB allele of the California sea lion, Zalophus californianus. We compared the DQB amino acid composition of U. thibetanus with those of several other mammalian species including Homo sapiens. Amino acid residues known to be functionally important for human MHC genes, tended to be also conserved among other mammalian species while PBRs in the beta1 domain were heterogeneous among mammalian species. The DQB sequence obtained from the bear had not only no putative frameshifts or deletions but also no abnormal amino acid mutations such as had been observed in human DQB molecules. This suggests that the bear DQB sequence was an apparently functional DQB allele. As a preliminary study, we sequenced the exon 2 region of DQB alleles from genomic DNA, and succeeded to amplify the exon 2 of DQB loci. Our study will provide useful information for conservation genetics of the U. thibetanus as well as more generally regarding the mammalian MHC region.

  15. miR-9 modulates the expression of interferon-regulated genes and MHC class I molecules in human nasopharyngeal carcinoma cells

    SciTech Connect

    Gao, Fei; Zhao, Zun-Lan; Zhao, Wen-Tao; Fan, Quan-Rong; Wang, Sheng-Chun; Li, Jing; Zhang, Yu-Qing; Shi, Jun-Wen; Lin, Xiao-Lin; Yang, Sheng; Xie, Rao-Ying; Liu, Wei; Zhang, Ting-Ting; Sun, Yong-Liang; Xu, Kang; Yao, Kai-Tai; Xiao, Dong

    2013-02-15

    Highlights: ► miR-9 can negatively or positively modulate interferon-induced gene expression. ► miR-9 can up-regulate major histocompatibility complex class I molecule expression. ► miR-9 can down-regulate the expression of interleukin-related genes. -- Abstract: The functions of miR-9 in some cancers are recently implicated in regulating proliferation, epithelial–mesenchymal transition (EMT), invasion and metastasis, apoptosis, and tumor angiogenesis, etc. miR-9 is commonly down-regulated in nasopharyngeal carcinoma (NPC), but the exact roles of miR-9 dysregulation in the pathogenesis of NPC remains unclear. Therefore, we firstly used miR-9-expressing CNE2 cells to determine the effects of miR-9 overexpression on global gene expression profile by microarray analysis. Microarray-based gene expression data unexpectedly demonstrated a significant number of up- or down-regulated immune- and inflammation-related genes, including many well-known interferon (IFN)-induced genes (e.g., IFI44L, PSMB8, IRF5, PSMB10, IFI27, PSB9{sub H}UMAN, IFIT2, TRAIL, IFIT1, PSB8{sub H}UMAN, IRF1, B2M and GBP1), major histocompatibility complex (MHC) class I molecules (e.g., HLA-B, HLA-C, HLA-F and HLA-H) and interleukin (IL)-related genes (e.g., IL20RB, GALT, IL7, IL1B, IL11, IL1F8, IL1A, IL6 and IL7R), which was confirmed by qRT-PCR. Moreover, the overexpression of miR-9 with the miRNA mimics significantly up- or down-regulated the expression of above-mentioned IFN-inducible genes, MHC class I molecules and IL-related genes; on the contrary, miR-9 inhibition by anti-miR-9 inhibitor in CNE2 and 5–8F cells correspondingly decreased or increased the aforementioned immune- and inflammation-related genes. Taken together, these findings demonstrate, for the first time, that miR-9 can modulate the expression of IFN-induced genes and MHC class I molecules in human cancer cells, suggesting a novel role of miR-9 in linking inflammation and cancer, which remains to be fully characterized.

  16. A second lineage of mammalian major histocompatibility complex class I genes.

    PubMed Central

    Bahram, S; Bresnahan, M; Geraghty, D E; Spies, T

    1994-01-01

    Major histocompatibility complex (MHC) class I genes typically encode polymorphic peptide-binding chains which are ubiquitously expressed and mediate the recognition of intracellular antigens by cytotoxic T cells. They constitute diverse gene families in different species and include the numerous so-called nonclassical genes in the mouse H-2 complex, of which some have been adapted to variously modified functions. We have identified a distinct family of five related sequences in the human MHC which are distantly homologous to class I chains. These MIC genes (MHC class I chain-related genes) evolved in parallel with the human class I genes and with those of most if not all mammalian orders. The MICA gene in this family is located near HLA-B and is by far the most divergent mammalian MHC class I gene known. It is further distinguished by its unusual exon-intron organization and preferential expression in fibroblasts and epithelial cells. However, the presence of diagnostic residues in the MICA amino acid sequence translated from cDNA suggests that the putative MICA chain folds similarly to typical class I chains and may have the capacity to bind peptide or other short ligands. These results define a second lineage of evolutionarily conserved MHC class I genes. This implies that MICA and possibly other members in this family have been selected for specialized functions that are either ancient or derived from those of typical MHC class I genes, in analogy to some of the nonclassical mouse H-2 genes. Images PMID:8022771

  17. Lysis of pig endothelium by IL-2 activated human natural killer cells is inhibited by swine and human major histocompatibility complex (MHC) class I gene products.

    PubMed

    Itescu, S; Artrip, J H; Kwiatkowski, P A; Wang, S F; Minanov, O P; Morgenthau, A S; Michler, R E

    1997-01-01

    We have previously described a form of xenograft rejection, mediated by natural killer (NK) cells, occurring in pig-to-primate organ transplants beyond the period of antibody-mediated hyperacute rejection. In this study, two distinct NK activation pathways were identified as mechanisms of pig aortic endotheliual cell (PAEC) lysis by human NK cells. Using an antibody-dependent cellular cytotoxicity (ADCC) assay, a progressive increase in human NK lysis of PAEC was observed following incubation with human IgG at increasing serum titer. In the absence of IgG, a second mechanism of PAEC lysis by human NK cells was observed following activation with IL-2. IL-2 activation of human NK cells increased lysis of PAEC by over 3-fold compared with ADCC. These results indicate that IL-2 activation of human NK cells induces significantly higher levels of lytic activity than does conventional ADCC involving IgG and FcRIII. We next investigated the role of MHC class I molecules in the regulation of NK lysis following IL-2 activation. PAEC expression of SLA class I molecules was increased by up to 75% by treatment with human TNFa. Following treatment with TNFa at 1 u/ml, IL-2 activated human NK lysis of PAEC was inhibited at every effector:target (E:T) ratio tested. Maximal effect occurred at an E:T ratio of 10:1, with TNFa inhibiting specific lysis by 59% (p < 0.01). Incubation with an anti-SLA class I Mab, but not IgG isotype control, abrogated the protective effects of TNFa on NK lysis of PAEC, suggesting direct inhibitory effects of SLA class I molecules on human NK function. To investigate whether human MHC class I molecules might have similar effects on human NK lysis of PAEC, further experiments were performed using a soluble peptide derived from the alpha-helical region of HLA-B7. Incubation with the HLA-B7 derived peptide significantly reduced the IL-2 activated NK lytic activity against PAEC in a dose-dependent fashion. Maximal effect occurred at a concentration of 10 mg

  18. Apparent lack of MHC restriction in binding of class I HLA molecules to solid-phase peptides

    PubMed Central

    1990-01-01

    The specificity of binding of solubilized, purified HLA-A,B molecules to solid-phase peptides has been examined using the assay described by Bouillet et al. [1989. Nature (Lond.). 339:473.] 64 peptides derived from the sequences of viral antigens, HLA-A,B,C heavy chains, and clathrin light chains were tested for binding to HLA-A2.1, Aw68.1, Aw69, B44, and B5, molecules that differ by 5-17 residues of the peptide binding groove. 15 of the peptides, including those known to be T cell epitopes, gave significant binding. The pattern of peptide binding for each of the five HLA-A,B molecules was not significantly different. Binding was demonstrated to be a property of native beta 2m- associated HLA-A,B molecules that preserved conformational antigenic determinants after binding to peptide. In comparison to our previous results from solution-based assays the proportion of HLA-A,B molecules that can bind solid-phase peptides is very high. This accessibility of solid-phase peptides to the binding site of MHC molecules may be directly related to the observed absence of MHC specificity in the binding. PMID:1696957

  19. MHC class II restricted innate-like double negative T cells contribute to optimal primary and secondary immunity to Leishmania major.

    PubMed

    Mou, Zhirong; Liu, Dong; Okwor, Ifeoma; Jia, Ping; Orihara, Kanami; Uzonna, Jude Ezeh

    2014-09-01

    Although it is generally believed that CD4(+) T cells play important roles in anti-Leishmania immunity, some studies suggest that they may be dispensable, and that MHC II-restricted CD3(+)CD4(-)CD8(-) (double negative, DN) T cells may be more important in regulating primary anti-Leishmania immunity. In addition, while there are reports of increased numbers of DN T cells in Leishmania-infected patients, dogs and mice, concrete evidence implicating these cells in secondary anti-Leishmania immunity has not yet been documented. Here, we report that DN T cells extensively proliferate and produce effector cytokines (IFN-γ, TNF and IL-17) and granzyme B (GrzB) in the draining lymph nodes and spleens of mice following primary and secondary L. major infections. DN T cells from healed mice display functional characteristics of protective anti-Leishmania memory-like cells: rapid and extensive proliferation and effector cytokines production following L. major challenge in vitro and in vivo. DN T cells express predominantly (> 95%) alpha-beta T cell receptor (αβ TCR), are Leishmania-specific, restricted mostly by MHC class II molecules and display transcriptional profile of innate-like genes. Using in vivo depletion and adoptive transfer studies, we show that DN T cells contribute to optimal primary and secondary anti-Leishmania immunity in mice. These results directly identify DN T cells as important players in effective and protective primary and secondary anti-L. major immunity in experimental cutaneous leishmaniasis.

  20. Rapid discrimination of MHC class I and killer cell lectin-like receptor allele variants by high-resolution melt analysis.

    PubMed

    Lundgren, Alyssa; Kim, Sharon; Stadnisky, Michael D; Brown, Michael G

    2012-08-01

    Ly49G and H-2 class I D(k) molecules are critical to natural killer cell-mediated viral control. To examine their contributions in greater depth, we established NK gene complex (NKC)/Ly49 congenic strains and a novel genetic model defined by MHC class I D(k) disparity in congenic and transgenic mouse strains. Generation and maintenance of Ly49 and H-2 class I select strains require efficient and reproducible genotyping assays for highly polygenic and polymorphic sequences. Thus, we coupled gene- and allele-specific PCR with high-resolution melt (HRM) analysis to discriminate Ly49g and H-2 class I D and K alleles in select strains and in the F(2) and backcross hybrid offspring of different genetic crosses. We show that HRM typing for these critical immune response genes is fast, accurate, and dependable. We further demonstrate that H-2 class I D HRM typing is competent to detect and quantify transgene copy numbers in different mice with distinct genetic backgrounds. Our findings substantiate the utility and practicality of HRM genotyping for highly related genes and alleles, even those belonging to clustered multigene families. Based on these findings, we envision that HRM is capable to interrogate and quantify gene- and allele-specific variations due to differential regulation of gene expression.

  1. Negative selection and peptide chemistry determine the size of naive foreign peptide-MHC class II-specific CD4+ T cell populations.

    PubMed

    Chu, H Hamlet; Moon, James J; Kruse, Andrew C; Pepper, Marion; Jenkins, Marc K

    2010-10-15

    Naive CD4(+) T cell populations that express TCRs specific for different foreign peptide-MHC class II complex (pMHCII) ligands can vary in size over several orders of magnitude. This variation may explain why immune responses to some peptides are stronger than others. In this study, we used a sensitive pMHCII-tetramer-based cell enrichment method to study the derivation of two naive foreign pMHCII-specific naive CD4(+) T cell populations that differed in size by 8-fold in normal mice. Analysis of mice in which thymic negative selection was impaired revealed that the smaller population underwent more clonal deletion than the larger population. In addition, large naive cell populations tended to recognize peptides with tryptophan residues as TCR contacts. Thus, the foreign pMHCII that tend to be recognized by large naive populations induce minimal clonal deletion and contain certain amino acids with the capacity to interact favorably with TCRs.

  2. A novel mutation in TAP1 gene leading to MHC class I deficiency: Report of two cases and review of the literature.

    PubMed

    Hanalioglu, Damla; Ayvaz, Deniz Cagdas; Ozgur, Tuba Turul; van der Burg, Mirjam; Sanal, Ozden; Tezcan, Ilhan

    2017-02-02

    Major histocompatibility complex (MHC) class I deficiency syndrome is a rare primary immunodeficiency caused by mutations in the peptide transporter complex associated with antigen presentation (TAP) gene which plays a crucial role in intracellular peptide antigen presentation. A few cases have been reported to date. Recurrent sinopulmonary infections and skin ulcers are the main characteristics of the syndrome. Here we report two siblings diagnosed with TAP1 deficiency syndrome associated only with recurrent sinopulmonary infections with the description of a novel mutation leading to a premature stop codon in TAP1 gene and review of the relevant literature. Both of the siblings had recurrent sinopulmonary infections since childhood, responded to antibiotherapy well, neither of them had hospitalization history because of infections. One had chronic hepatitis B infection which may possibly be related to TAP1 gene defect.

  3. Reversal of epigenetic silencing of MHC class I chain-related protein A and B improves immune recognition of Merkel cell carcinoma

    PubMed Central

    Ritter, Cathrin; Fan, Kaiji; Paulson, Kelly G.; Nghiem, Paul; Schrama, David; Becker, Jürgen C.

    2016-01-01

    Merkel cell carcinoma (MCC) is a virally associated cancer characterized by its aggressive behavior and strong immunogenicity. Both viral infection and malignant transformation induce expression of MHC class I chain-related protein (MIC) A and B, which signal stress to cells of the immune system via Natural Killer group 2D (NKG2D) resulting in elimination of target cells. However, despite transformation and the continued presence of virally-encoded proteins, MICs are only expressed in a minority of MCC tumors in situ and are completely absent on MCC cell lines in vitro. This lack of MIC expression was due to epigenetic silencing via MIC promoter hypo-acetylation; indeed, MIC expression was re-induced by pharmacological inhibition of histone deacetylases (HDACs) both in vitro and in vivo. This re-induction of MICs rendered MCC cells more sensitive to immune-mediated lysis. Thus, epigenetic silencing of MICs is an important immune escape mechanism of MCCs. PMID:26902929

  4. HLA-DRB1*11 and variants of the MHC class II locus are strong risk factors for systemic juvenile idiopathic arthritis.

    PubMed

    Ombrello, Michael J; Remmers, Elaine F; Tachmazidou, Ioanna; Grom, Alexei; Foell, Dirk; Haas, Johannes-Peter; Martini, Alberto; Gattorno, Marco; Özen, Seza; Prahalad, Sampath; Zeft, Andrew S; Bohnsack, John F; Mellins, Elizabeth D; Ilowite, Norman T; Russo, Ricardo; Len, Claudio; Hilario, Maria Odete E; Oliveira, Sheila; Yeung, Rae S M; Rosenberg, Alan; Wedderburn, Lucy R; Anton, Jordi; Schwarz, Tobias; Hinks, Anne; Bilginer, Yelda; Park, Jane; Cobb, Joanna; Satorius, Colleen L; Han, Buhm; Baskin, Elizabeth; Signa, Sara; Duerr, Richard H; Achkar, J P; Kamboh, M Ilyas; Kaufman, Kenneth M; Kottyan, Leah C; Pinto, Dalila; Scherer, Stephen W; Alarcón-Riquelme, Marta E; Docampo, Elisa; Estivill, Xavier; Gül, Ahmet; de Bakker, Paul I W; Raychaudhuri, Soumya; Langefeld, Carl D; Thompson, Susan; Zeggini, Eleftheria; Thomson, Wendy; Kastner, Daniel L; Woo, Patricia

    2015-12-29

    Systemic juvenile idiopathic arthritis (sJIA) is an often severe, potentially life-threatening childhood inflammatory disease, the pathophysiology of which is poorly understood. To determine whether genetic variation within the MHC locus on chromosome 6 influences sJIA susceptibility, we performed an association study of 982 children with sJIA and 8,010 healthy control subjects from nine countries. Using meta-analysis of directly observed and imputed SNP genotypes and imputed classic HLA types, we identified the MHC locus as a bona fide susceptibility locus with effects on sJIA risk that transcended geographically defined strata. The strongest sJIA-associated SNP, rs151043342 [P = 2.8 × 10(-17), odds ratio (OR) 2.6 (2.1, 3.3)], was part of a cluster of 482 sJIA-associated SNPs that spanned a 400-kb region and included the class II HLA region. Conditional analysis controlling for the effect of rs151043342 found that rs12722051 independently influenced sJIA risk [P = 1.0 × 10(-5), OR 0.7 (0.6, 0.8)]. Meta-analysis of imputed classic HLA-type associations in six study populations of Western European ancestry revealed that HLA-DRB1*11 and its defining amino acid residue, glutamate 58, were strongly associated with sJIA [P = 2.7 × 10(-16), OR 2.3 (1.9, 2.8)], as was the HLA-DRB1*11-HLA-DQA1*05-HLA-DQB1*03 haplotype [6.4 × 10(-17), OR 2.3 (1.9, 2.9)]. By examining the MHC locus in the largest collection of sJIA patients assembled to date, this study solidifies the relationship between the class II HLA region and sJIA, implicating adaptive immune molecules in the pathogenesis of sJIA.

  5. Experimental Validation of Multi-Epitope Peptides Including Promising MHC Class I- and II-Restricted Epitopes of Four Known Leishmania infantum Proteins.

    PubMed

    Agallou, Maria; Athanasiou, Evita; Koutsoni, Olga; Dotsika, Eleni; Karagouni, Evdokia

    2014-01-01

    Leishmaniasis is a significant worldwide health problem for which no vaccine exists. Activation of CD4(+) and CD8(+) T cells is crucial for the generation of protective immunity against parasite. Recent trend in vaccine design has been shifted to epitope-based vaccines that are more specific, safe, and easy to produce. In the present study, four known antigenic Leishmania infantum proteins, cysteine peptidase A (CPA), histone H1, KMP-11, and Leishmania eukaryotic initiation factor (LeIF) were analyzed for the prediction of binding epitopes to H2(d) MHC class I and II molecules, using online available algorithms. Based on in silico analysis, eight peptides including highly scored MHC class I- and II-restricted epitopes were synthesized. Peptide immunogenicity was validated in MHC compatible BALB/c mice immunized with each synthetic peptide emulsified in complete Freund's adjuvant/incomplete Freund's adjuvant. CPA_p2, CPA_p3, H1_p1, and LeIF_p6 induced strong spleen cell proliferation upon in vitro peptide re-stimulation. In addition, the majority of the peptides, except of LeIF_p1 and KMP-11_p1, induced IFN-γ secretion, while KMP-11_p1 indicated a suppressive effect on IL-10 production. CPA_p2, CPA_p3, LeIF_p3, and LeIF_p6 induced IFN-γ-producing CD4(+) T cells indicating a TH1-type response. In addition, CPA_p2, CPA_p3, and H1_p1 induced also the induction of CD8(+) T cells. The induction of peptide-specific IgG in immunized mice designated also the existence of B cell epitopes in peptide sequences. Combining immunoinformatic tools and experimental validation, we demonstrated that CPA_p2, CPA_p3, H1_p1, H1_p3, CPA_p2, LeIF_p3, and LeIF_p6 are likely to include potential epitopes for the induction of protective cytotoxic and/or TH1-type immune responses supporting the feasibility of peptide-based vaccine development for leishmaniasis.

  6. Gene transfer of costimulatory molecules into a human colorectal cancer cell line: requirement of CD54, CD80 and class II MHC expression for enhanced immunogenicity.

    PubMed

    Lindauer, M; Rudy, W; Gückel, B; Doeberitz, M V; Meuer, S C; Moebius, U

    1998-03-01

    Colorectal cancer is considered a non-immunogenic malignany. One strategy to augment the immunogenicity of such tumours is represented by the expression of costimulatory molecules by gene transfer. Using transfected variants of the human colorectal cancer cell line SW480 we tested various costimulatory molecules (CD80, CD86, CD54) and a class II major histocompatibility complex (MHC) allele (HLA-DR3) alone or in combination on their ability to support primary T-lymphocyte activation in vitro. Expression of CD80 or CD86 similarly as the combination of both was not sufficient to induce proliferation of human allogeneic T cells. Expression of CD54 together with CD80 strongly augmented the costimulatory function of CD80, as observed in the presence of a CD3 monoclonal antibody (mAb), but did not lead directly to a T-cell response against modified tumour cells. Importantly, SW480 cells coexpressing CD54, CD80 and the HLA-DR3 allele effectively promoted T-lymphocyte proliferation. Moreover, the use of such CD54+/CD80+/HLA-DR3+ SW480 variants for repetitive stimulations resulted in the generation of T-cell lines predominantly composed of CD8+ T cells exhibiting class I MHC restricted cytolytic activity towards untransfected SW480 tumour cells. This demonstrates that the generation of immunogenic tumour cell variants, i.e. for the use as cellular vaccines, requires multiple genetic alterations in the case of non-immunogenic human tumours cells, such as colorectal cancer cells.

  7. Understanding MHC class I presentation of viral antigens by human dendritic cells as a basis for rational design of therapeutic vaccines.

    PubMed

    van Montfoort, Nadine; van der Aa, Evelyn; Woltman, Andrea M

    2014-01-01

    Effective viral clearance requires the induction of virus-specific CD8(+) cytotoxic T lymphocytes (CTL). Since dendritic cells (DC) have a central role in initiating and shaping virus-specific CTL responses, it is important to understand how DC initiate virus-specific CTL responses. Some viruses can directly infect DC, which theoretically allow direct presentation of viral antigens to CTL, but many viruses target other cells than DC and thus the host depends on the cross-presentation of viral antigens by DC to activate virus-specific CTL. Research in mouse models has highly enhanced our understanding of the mechanisms underlying cross-presentation and the dendritic cells (DC) subsets involved, however, these results cannot be readily translated toward the role of human DC in MHC class I-antigen presentation of human viruses. Here, we summarize the insights gained in the past 20 years on MHC class I presentation of viral antigen by human DC and add to the current debate on the capacities of different human DC subsets herein. Furthermore, possible sources of viral antigens and essential DC characteristics for effective induction of virus-specific CTL are evaluated. We conclude that cross-presentation is not only an efficient mechanism exploited by DC to initiate immunity to viruses that do not infect DC but also to viruses that do infect DC, because cross-presentation has many conceptual advantages and bypasses direct immune modulatory effects of the virus on its infected target cells. Since knowledge on the mechanism of viral antigen presentation and the preferred DC subsets is crucial for rational vaccine design, the obtained insights are very instrumental for the development of effective anti-viral immunotherapy.

  8. De novo transcriptome assembly facilitates characterisation of fast-evolving gene families, MHC class I in the bank vole (Myodes glareolus).

    PubMed

    Migalska, M; Sebastian, A; Konczal, M; Kotlík, P; Radwan, J

    2017-04-01

    The major histocompatibility complex (MHC) plays a central role in the adaptive immune response and is the most polymorphic gene family in vertebrates. Although high-throughput sequencing has increasingly been used for genotyping families of co-amplifying MHC genes, its potential to facilitate early steps in the characterisation of MHC variation in nonmodel organism has not been fully explored. In this study we evaluated the usefulness of de novo transcriptome assembly in characterisation of MHC sequence diversity. We found that although de novo transcriptome assembly of MHC I genes does not reconstruct sequences of individual alleles, it does allow the identification of conserved regions for PCR primer design. Using the newly designed primers, we characterised MHC I sequences in the bank vole. Phylogenetic analysis of the partial MHC I coding sequence (2-4 exons) of the bank vole revealed a lack of orthology to MHC I of other Cricetidae, consistent with the high gene turnover of this region. The diversity of expressed alleles was characterised using ultra-deep sequencing of the third exon that codes for the peptide-binding region of the MHC molecule. High allelic diversity was demonstrated, with 72 alleles found in 29 individuals. Interindividual variation in the number of expressed loci was found, with the number of alleles per individual ranging from 5 to 14. Strong signatures of positive selection were found for 8 amino acid sites, most of which are inferred to bind antigens in human MHC, indicating conservation of structure despite rapid sequence evolution.

  9. Polymorphism in the major histocompatibility complex (MHC class II B) genes of the Rufous-backed Bunting (Emberiza jankowskii)

    PubMed Central

    Li, Dan; Zhao, Yunjiao; Lin, Aiqing; Li, Shi; Feng, Jiang

    2017-01-01

    Genetic diversity is one of the pillars of conservation biology research. High genetic diversity and abundant genetic variation in an organism may be suggestive of capacity to adapt to various environmental changes. The major histocompatibility complex (MHC) is known to be highly polymorphic and plays an important role in immune function. It is also considered an ideal model system to investigate genetic diversity in wildlife populations. The Rufous-backed Bunting (Emberiza jankowskii) is an endangered species that has experienced a sharp decline in both population and habitat size. Many historically significant populations are no longer present in previously populated regions, with only three breeding populations present in Inner Mongolia (i.e., the Aolunhua, Gahaitu and Lubei557 populations). Efforts focused on facilitating the conservation of the Rufous-backed Bunting (Emberiza jankowskii) are becoming increasingly important. However, the genetic diversity of E. jankowskii has not been investigated. In the present study, polymorphism in exon 2 of the MHCIIB of E. jankowskii was investigated. This polymorphism was subsequently compared with a related species, the Meadow Bunting (Emberiza cioides). A total of 1.59 alleles/individual were detected in E. jankowskii and 1.73 alleles/individual were identified in E. cioides. The maximum number of alleles per individual from the three E. jankowskii populations suggest the existence of at least three functional loci, while the maximum number of alleles per individual from the three E. cioides populations suggest the presence of at least four functional loci. Two of the alleles were shared between the E. jankowskii and E. cioides. Among the 12 unique alleles identified in E. jankowskii, 10.17 segregating sites per allele were detected, and the nucleotide diversity was 0.1865. Among the 17 unique alleles identified in E. cioides, eight segregating sites per allele were detected, and the nucleotide diversity was 0

  10. Characterization of class II β chain major histocompatibility complex genes in a family of Hawaiian honeycreepers: 'amakihi (Hemignathus virens).

    PubMed

    Jarvi, Susan I; Bianchi, Kiara R; Farias, Margaret Em; Txakeeyang, Ann; McFarland, Thomas; Belcaid, Mahdi; Asano, Ashley

    2016-07-01

    Hawaiian honeycreepers (Drepanidinae) have evolved in the absence of mosquitoes for over five million years. Through human activity, mosquitoes were introduced to the Hawaiian archipelago less than 200 years ago. Mosquito-vectored diseases such as avian malaria caused by Plasmodium relictum and Avipoxviruses have greatly impacted these vulnerable species. Susceptibility to these diseases is variable among and within species. Due to their function in adaptive immunity, the role of major histocompatibility complex genes (Mhc) in disease susceptibility is under investigation. In this study, we evaluate gene organization and levels of diversity of Mhc class II β chain genes (exon 2) in a captive-reared family of Hawaii 'amakihi (Hemignathus virens). A total of 233 sequences (173 bp) were obtained by PCR+1 amplification and cloning, and 5720 sequences were generated by Roche 454 pyrosequencing. We report a total of 17 alleles originating from a minimum of 14 distinct loci. We detected three linkage groups that appear to represent three distinct haplotypes. Phylogenetic analysis revealed one variable cluster resembling classical Mhc sequences (DAB) and one highly conserved, low variability cluster resembling non-classical Mhc sequences (DBB). High net evolutionary divergence values between DAB and DBB resemble that seen between chicken BLB system and YLB system genes. High amino acid identity among non-classical alleles from 12 species of passerines (DBB) and four species of Galliformes (YLB) was found, suggesting that these non-classical passerine sequences may be related to the Galliforme YLB sequences.

  11. Characterization of major histocompatibility complex class I and class II genes from the Tasmanian devil (Sarcophilus harrisii).

    PubMed

    Siddle, Hannah V; Sanderson, Claire; Belov, Katherine

    2007-09-01

    The Tasmanian devil (Sarcophilus harrisii) is currently threatened by an emerging wildlife disease, devil facial tumour disease. The disease is decreasing devil numbers dramatically and may lead to the extinction of the species. At present, nothing is known about the immune genes or basic immunology of the devil. In this study, we report the construction of the first genetic library for the Tasmanian devil, a spleen cDNA library, and the isolation of full-length MHC Class I and Class II genes. We describe six unique Class II beta chain sequences from at least three loci, which belong to the marsupial Class II DA gene family. We have isolated 13 unique devil Class I sequences, representing at least seven Class I loci, two of which are most likely non-classical genes. The MHC Class I sequences from the devil have little heterogeneity, indicating recent divergence. The MHC genes described here are most likely involved in antigen presentation and are an important first step for studying MHC diversity and immune response in the devil.

  12. The diversity of bovine MHC class II DRB3 genes in Japanese Black, Japanese Shorthorn, Jersey and Holstein cattle in Japan.

    PubMed

    Takeshima, S; Saitou, N; Morita, M; Inoko, H; Aida, Y

    2003-10-16

    We sequenced exon 2 of the major histocompatibility complex (MHC) class II DRB3 gene from 471 individuals in four different Japanese populations of cattle (201 Japanese Black, 101 Holstein, 100 Japanese Shorthorn, and 69 Jersey cattle) using a new method for sequence-based typing (SBT). We identified the 34 previously reported alleles and four novel alleles. These alleles were 80.0-100.0% identical at the nucleotide level and 77.9-100.0% identical at the amino acid level to the bovine MHC (BoLA)-DRB3 cDNA clone NR1. Among the 38 alleles, eight alleles were found in only one breed in this study. However, these alleles did not form specific clusters on a phylogenetic tree of 236-base pairs (bp) nucleotide sequences. Furthermore, these breeds exhibited similar variations with respect to average frequencies of nucleotides and amino acids, as well as synonymous and non-synonymous substitutions, in all pairwise comparisons of the alleles found in this study. By contrast, analysis of the frequencies of the various BoLA-DRB3 alleles in each breed indicated that DRB3*1101 was the most frequent allele in Holstein cattle (16.8%), DRB3*4501 was the most frequent allele in Jersey cattle (18.1%), DRB3*1201 was the most frequent allele in Japanese Shorthorn cattle (16.0%) and DRB3*1001 was the most frequent allele in Japanese Black cattle (17.4%), indicating that the frequencies of alleles were differed in each breed. In addition, a population tree based on the frequency of BoLA-DRB3 alleles in each breed suggested that Holstein and Japanese Black cattle were the most closely related, and that Jersey cattle were more different from both these breeds than Japanese Shorthorns.

  13. Rejection versus escape: the tumor MHC dilemma.

    PubMed

    Garrido, Federico; Ruiz-Cabello, Francisco; Aptsiauri, Natalia

    2017-02-01

    Most tumor cells derive from MHC-I-positive normal counterparts and remain positive at early stages of tumor development. T lymphocytes can infiltrate tumor tissue, recognize and destroy MHC class I (MHC-I)-positive cancer cells ("permissive" phase I). Later, MHC-I-negative tumor cell variants resistant to T-cell killing emerge. During this process, tumors first acquire a heterogeneous MHC-I expression pattern and finally become uniformly MHC-I-negative. This stage (phase II) represents a "non-permissive" encapsulated structure with tumor nodes surrounded by fibrous tissue containing different elements including leukocytes, macrophages, fibroblasts, etc. Molecular mechanisms responsible for total or partial MHC-I downregulation play a crucial role in determining and predicting the antigen-presenting capacity of cancer cells. MHC-I downregulation caused by reversible ("soft") lesions can be upregulated by TH1-type cytokines released into the tumor microenvironment in response to different types of immunotherapy. In contrast, when the molecular mechanism of the tumor MHC-I loss is irreversible ("hard") due to a genetic defect in the gene/s coding for MHC-I heavy chains (chromosome 6) or beta-2-microglobulin (B2M) (chromosome 15), malignant cells are unable to upregulate MHC-I, remain undetectable by cytotoxic T-cells, and continue to grow and metastasize. Based on the tumor MHC-I molecular analysis, it might be possible to define MHC-I phenotypes present in cancer patients in order to distinguish between non-responders, partial/short-term responders, and likely durable responders. This highlights the need for designing strategies to enhance tumor MHC-I expression that would allow CTL-mediated tumor rejection.

  14. Cryptic MHC class I-binding peptides are revealed by aminoglycoside-induced stop codon read-through into the 3' UTR.

    PubMed

    Goodenough, Elliot; Robinson, Tara M; Zook, Matthew B; Flanigan, Kevin M; Atkins, John F; Howard, Michael T; Eisenlohr, Laurence C

    2014-04-15

    Aminoglycosides have been proposed as therapies for genetic disorders caused by nonsense mutations, because of their capacity to enhance translational read-through of premature termination codons (PTCs), thereby permitting expression of functional full-length protein. However, a potential consequence of this strategy is the development of an autoimmune response to HLA-presented epitopes encoded downstream of the PTC or other stop codons. Using a recombinant virus-expression system in tissue culture and in mice, we demonstrate that gentamicin can induce expression and MHC class I presentation of a model epitope encoded downstream of a PTC at levels sufficient to activate CD8(+) T cells. The degree of read-through-derived peptide presentation varies with the sequence of the stop codon and +1 nucleotide. Additionally, we applied a mass spectrometry exploration of the HLA class I peptide repertoire of gentamicin-treated cells and identified multiple peptides derived from read-through of conventional stop codons. These results substantiate the possibility of self-reactivity to cryptic epitopes revealed by stop codon read-through therapies and potentially other therapeutic approaches involving compounds that alter translational fidelity.

  15. Characterization of two avian MHC-like genes reveals an ancient origin of the CD1 family

    PubMed Central

    Miller, Marcia M.; Wang, Carren; Parisini, Emilio; Coletta, Ricardo D.; Goto, Ronald M.; Lee, Stella Y.; Barral, Duarte C.; Townes, Maria; Roura-Mir, Carme; Ford, Heide L.; Brenner, Michael B.; Dascher, Christopher C.

    2005-01-01

    Many of the genes that comprise the vertebrate adaptive immune system are conserved across wide evolutionary time scales. Most notably, homologs of the mammalian MHC gene family have been found in virtually all jawed vertebrates, including sharks, bony fishes, reptiles, and birds. The CD1 family of antigen-presenting molecules are related to the MHC class I family but have evolved to bind and present lipid antigens to T cells. Here, we describe two highly divergent nonclassical MHC class I genes found in the chicken (Gallus gallus) that have sequence homology to the mammalian CD1 family of proteins. One of the chicken CD1 genes expresses a full-length transcript, whereas the other has multiple splice variants. Both Southern blot and single nucleotide polymorphism analysis indicates that chicken CD1 is relatively nonpolymorphic. Moreover, cross-hybridizing bands are present in other bird species, suggesting broad conservation in the avian class. Northern analysis of chicken tissue shows a high level of CD1 expression in the bursa and spleen. In addition, molecular modeling predicts that the potential antigen-binding pocket is probably hydrophobic, a universal characteristic of CD1 molecules. Genomic analysis indicates that the CD1 genes are located on chicken chromosome 16 and maps to within 200 kb of the chicken MHC B locus, suggesting that CD1 genes diverged from classical MHC genes while still linked to the major histocompatibility complex locus. The existence of CD1 genes in an avian species suggests that the origin of CD1 extends deep into the evolutionary history of terrestrial vertebrates. PMID:15939884

  16. Humans differ from other hominids in lacking an activating NK cell receptor that recognizes the C1 epitope of MHC class I.

    PubMed

    Moesta, Achim K; Graef, Thorsten; Abi-Rached, Laurent; Older Aguilar, Anastazia M; Guethlein, Lisbeth A; Parham, Peter

    2010-10-01

    Modulation of human NK cell function by killer cell Ig-like receptors (KIR) and MHC class I is dominated by the bipartite interactions of inhibitory lineage III KIR with the C1 and C2 epitopes of HLA-C. In comparison, the ligand specificities and functional contributions of the activating lineage III KIR remain poorly understood. Using a robust, sensitive assay of KIR binding and a representative panel of 95 HLA class I targets, we show that KIR2DS1 binds C2 with ~50% the avidity of KIR2DL1, whereas KIR2DS2, KIR2DS3, and KIR2DS5 have no detectable avidity for C1, C2, or any other HLA class I epitope. In contrast, the chimpanzee has activating C1- and C2-specific lineage III KIR with strong avidity, comparable to those of their paired inhibitory receptors. One variant of chimpanzee Pt-KIR3DS2, the activating C2-specific receptor, has the same avidity for C2 as does inhibitory Pt-KIR3DL4, and a second variant has ~73% the avidity. Chimpanzee Pt-KIR3DS6, the activating C1-specific receptor, has avidity for C1 that is ~70% that of inhibitory Pt-KIR2DL6. In both humans and chimpanzees we observe an evolutionary trend toward reducing the avidity of the activating C1- and C2-specific receptors through selective acquisition of attenuating substitutions. However, the extent of attenuation has been extreme in humans, as exemplified by KIR2DS2, an activating C1-specific receptor that has lost all detectable avidity for HLA class I. Supporting such elimination of activating C1-specific receptors as a uniquely human phenomenon is the presence of a high-avidity activating C1-specific receptor (Gg-KIR2DSa) in gorilla.

  17. MHC class II/ESO tetramer-based generation of in vitro primed anti-tumor T-helper lines for adoptive cell therapy of cancer.

    PubMed

    Poli, Caroline; Raffin, Caroline; Dojcinovic, Danijel; Luescher, Immanuel; Ayyoub, Maha; Valmori, Danila

    2013-02-01

    Generation of tumor-antigen specific CD4(+) T-helper (T(H)) lines through in vitro priming is of interest for adoptive cell therapy of cancer, but the development of this approach has been limited by the lack of appropriate tools to identify and isolate low frequency tumor antigen-specific CD4(+) T cells. Here, we have used recently developed MHC class II/peptide tetramers incorporating an immunodominant peptide from NY-ESO-1 (ESO), a tumor antigen frequently expressed in different human solid and hematologic cancers, to implement an in vitro priming platform allowing the generation of ESO-specific T(H) lines. We isolated phenotypically defined CD4(+) T-cell subpopulations from circulating lymphocytes of DR52b(+) healthy donors by flow cytometry cell sorting and stimulated them in vitro with peptide ESO(119-143), autologous APC and IL-2. We assessed the frequency of ESO-specific cells in the cultures by staining with DR52b/ESO(119-143) tetramers (ESO-tetramers) and TCR repertoire of ESO-tetramer(+) cells by co-staining with TCR variable β chain (BV) specific antibodies. We isolated ESO-tetramer(+) cells by flow cytometry cell sorting and expanded them with PHA, APC and IL-2 to generate ESO-specific T(H) lines. We characterized the lines for antigen recognition, by stimulation with ESO peptide or recombinant protein, cytokine production, by intracellular staining using specific antibodies, and alloreactivity, by stimulation with allo-APC. Using this approach, we could consistently generate ESO-tetramer(+) T(H) lines from conventional CD4(+)CD25(-) naïve and central memory populations, but not from effector memory populations or CD4(+)CD25(+) Treg. In vitro primed T(H) lines recognized ESO with affinities comparable to ESO-tetramer(+) cells from patients immunized with an ESO vaccine and used a similar TCR repertoire. In this study, using MHC class II/ESO tetramers, we have implemented an in vitro priming platform allowing the generation of ESO

  18. [Histocompatibility HLA system of man. Considerations in the light of current concepts. VII. Nonclassical HLA- E, F, and H loci].

    PubMed

    Kedzierska, A; Turowski, G

    2001-01-01

    Current opinions connected with HLA-E and HLA-F genes determining "nonclassical" (HLA-Ib) class I antigens of the Main Histocompatibility Complex MHC, and formed in the consequence of mutation or partial deletion of HLA-H pseudogene loci were presented. The expression of protein products of HLA-E and -F genes on some cells and tissues, their polymorphism, and also their biological functions in organisms were qualified by the use of molecular technics. The kind and frequency of occurrence of mutations 845 A (C282Y) and 187 G (H63D) in gene HLA-H were analysed, and in this context some genetic aspects of hereditary hemochromatozy (HH) were discussed.

  19. Sorting signals in the MHC class II invariant chain cytoplasmic tail and transmembrane region determine trafficking to an endocytic processing compartment

    PubMed Central

    1994-01-01

    Targeting of MHC class II molecules to the endocytic compartment where they encounter processed antigen is determined by the invariant chain (Ii). By analysis of Ii-transferrin receptor (TR) chimera trafficking, we have identified sorting signals in the Ii cytoplasmic tail and transmembrane region that mediate this process. Two non-tyrosine-based sorting signals in the Ii cytoplasmic tail were identified that mediate localization to plasma membrane clathrin-coated pits and promote rapid endocytosis. Leu7 and Ile8 were required for the activity of the signal most distal to the cell membrane whereas Pro15 Met16 Leu17 were important for the membrane-proximal signal. The same or overlapping non- tyrosine-based sorting signals are essential for delivery of Ii-TR chimeras, either by an intracellular route or via the plasma membrane, to an endocytic compartment where they are rapidly degraded. The Ii transmembrane region is also required for efficient delivery to this endocytic processing compartment and contains a signal distinct from the Ii cytoplasmic tail. More than 80% of the Ii-TR chimera containing the Ii cytoplasmic tail and transmembrane region is delivered directly to the endocytic pathway by an intracellular route, implying that the Ii sorting signals are efficiently recognized by sorting machinery located in the trans-Golgi. PMID:8034737

  20. H2-O, a MHC class II-like protein, sets a threshold for B-cell entry into germinal centers.

    PubMed

    Draghi, Nicole A; Denzin, Lisa K

    2010-09-21

    Upon antigen (Ag) encounter, B cells require T-cell help to enter the germinal center (GC). They obtain this help by presenting Ag-derived peptides on MHC class II (MHCII) for recognition by the T-cell receptor (TCR) of CD4(+) T cells. Peptides are loaded onto MHCII in endosomal compartments in a process catalyzed by the MHCII-like protein H2-M (HLA-DM in humans). This process is modulated by another MHCII-like protein, H2-O (HLA-DO in humans). H2-O is a biochemical inhibitor of peptide loading onto MHCII; however, on the cellular level, it has been shown to have varying effects on Ag presentation. Thus, the function of H2-O in the adaptive immune response remains unclear. Here, we examine the effect of H2-O expression on the ability of Ag-specific B cells to enter the GC. We show that when Ag specific WT and H2-O(-/-) B cells are placed in direct competition, H2-O(-/-) B cells preferentially populate the GC. This advantage is confined to Ag-specific B cells and is due to their superior ability to obtain Ag-specific T-cell help when T-cell help is limiting. Overall, our work shows that H2-O expression reduces the ability of B cells to gain T-cell help and participate in the GC reaction.

  1. Hydroxyethylene isosteres introduced in type II collagen fragments substantially alter the structure and dynamics of class II MHC A(q)/glycopeptide complexes.

    PubMed

    Lindgren, Cecilia; Andersson, Ida E; Berg, Lotta; Dobritzsch, Doreen; Ge, Changrong; Haag, Sabrina; Uciechowska, Urszula; Holmdahl, Rikard; Kihlberg, Jan; Linusson, Anna

    2015-06-14

    Class II major histocompatibility complex (MHC) proteins are involved in initiation of immune responses to foreign antigens via presentation of peptides to receptors of CD4(+) T-cells. An analogous presentation of self-peptides may lead to autoimmune diseases, such as rheumatoid arthritis (RA). The glycopeptide fragment CII259-273, derived from type II collagen, is presented by A(q) MHCII molecules in the mouse and has a key role in development of collagen induced arthritis (CIA), a validated model for RA. We have introduced hydroxyethylene amide bond isosteres at the Ala(261)-Gly(262) position of CII259-273. Biological evaluation showed that A(q) binding and T cell recognition were dramatically reduced for the modified glycopeptides, although static models predicted similar binding modes as the native type II collagen fragment. Molecular dynamics (MD) simulations demonstrated that introduction of the hydroxyethylene isosteres disturbed the entire hydrogen bond network between the glycopeptides and A(q). As a consequence the hydroxyethylene isosteric glycopeptides were prone to dissociation from A(q) and unfolding of the β1-helix. Thus, the isostere induced adjustment of the hydrogen bond network altered the structure and dynamics of A(q)/glycopeptide complexes leading to the loss of A(q) affinity and subsequent T cell response.

  2. Cell surface expression of MR1B, a splice variant of the MHC class I-related molecule MR1, revealed with antibodies.

    PubMed

    Yamaguchi, Hisateru; Tsukamoto, Kentaro; Hashimoto, Keiichiro

    2014-01-10

    The major histocompatibility complex (MHC) class I-related molecule, MR1, is highly conserved in mammals and can present bacteria-derived vitamin B metabolites to mucosal-associated invariant T (MAIT) cells, possibly having important defense function in the microbial infection. MR1B is a splice variant of MR1 and possesses an intriguing domain structure with only two extracellular domains resembling some NKG2D ligand molecules. Thus far, cell surface expression of MR1B could not be analyzed with flow cytometry due to a lack of appropriate antibodies reactive with MR1B. Here we clarified the expression of MR1B recombinant protein on the cell surface of the transfected cells by flow cytometry analyses using the antiserum against MR1. Consistently, MR1B tagged with FLAG peptide at the N-terminus also could be detected with anti-FLAG monoclonal antibodies. Our result showed that MR1B can be recognized on the cell surface by macromolecules such as antibodies, indicating its potential of interaction with certain receptor(s). We discuss possibility of interaction of MR1B and/or the full-length MR1 with some receptor(s) other than αβ T cell receptor (TCR) of MAIT cells based on the highly conserved characteristic residues of the ligand-binding domains of MR1 and its MAIT cells αβTCR footprints.

  3. Exosome-driven transfer of tumor-associated Pioneer Translation Products (TA-PTPs) for the MHC class I cross-presentation pathway

    PubMed Central

    Duvallet, Emilie; Boulpicante, Mathilde; Yamazaki, Takahiro; Daskalogianni, Chrysoula; Prado Martins, Rodrigo; Baconnais, Sonia; Manoury, Bénédicte; Fahraeus, Robin; Apcher, Sébastien

    2016-01-01

    ABSTRACT Cellular immune reactions against non-self-epitopes require activation of cytotoxic CD8+ T-cells via cross-presentation of MHC class I-restricted peptides by professional antigen presenting cells (pAPCs), with the consequent detection and elimination of cells expressing the same antigens via the endogenous (direct) pathway. The source of peptides for the endogenous pathway is constituted of alternative mRNA translation products; however, it is still unclear which source of peptides is used for cross-presentation. Furthermore, the presentation of non-canonical translation products, produced during a non-conventional translation event, on class I molecules of tumor cells has been reported but how these peptides are generated, presented to pAPCs, and their capacity to stimulate CD8+ T cells is still not known. Here, we report that pioneer translation peptides (PTPs) derived from intron or exon pre-mRNAs can serve as tumor-associated antigens (TA-PTPs) and are delivered from the producing tumor cells to pAPCs via exosomes where they are processed by the cytosolic pathway. Injection of TA-PTPs and tumor-derived exosomes efficiently induce CD8+ T-cell proliferation and prevent tumor growth in mice. Our results show that TA-PTPs represent an efficient source of antigenic peptides for CD8+ T cell activation and that full-length proteins are not required for cross-presentation. These findings can have interesting implications for generating tolerance and for designing vectors to generate vaccines. PMID:27757298

  4. Deficient Peptide Loading and MHC Class II Endosomal Sorting in a Human Genetic Immunodeficiency Disease: the Chediak-Higashi Syndrome

    PubMed Central

    Faigle, Wolfgang; Raposo, Graça; Tenza, Daniele; Pinet, Valérie; Vogt, Anne B.; Kropshofer, Harald; Fischer, Alain; de Saint-Basile, Geneviève; Amigorena, Sebastian

    1998-01-01

    The Chediak-Higashi syndrome (CHS) is a human recessive autosomal disease caused by mutations in a single gene encoding a protein of unknown function, called lysosomal-trafficking regulator. All cells in CHS patients bear enlarged lysosomes. In addition, T- and natural killer cell cytotoxicity is defective in these patients, causing severe immunodeficiencies. We have analyzed major histocompatibility complex class II functions and intracellular transport in Epstein Barr Virus–transformed B cells from CHS patients. Peptide loading onto major histocompatibility complex class II molecules and antigen presentation are strongly delayed these cells. A detailed electron microscopy analysis of endocytic compartments revealed that only lysosomal multilaminar compartments are enlarged (reaching 1–2 μm), whereas late multivesicular endosomes have normal size and morphology. In contrast to giant multilaminar compartments that bear most of the usual lysosomal markers in these cells (HLA-DR, HLA-DM, Lamp-1, CD63, etc.), multivesicular late endosomes displayed reduced levels of all these molecules, suggesting a defect in transport from the trans-Golgi network and/or early endosomes into late multivesicular endosomes. Further insight into a possible mechanism of this transport defect came from immunolocalizing the lysosomal trafficking regulator protein, as antibodies directed to a peptide from its COOH terminal domain decorated punctated structures partially aligned along microtubules. These results suggest that the product of the Lyst gene is required for sorting endosomal resident proteins into late multivesicular endosomes by a mechanism involving microtubules. PMID:9606205

  5. Deficient peptide loading and MHC class II endosomal sorting in a human genetic immunodeficiency disease: the Chediak-Higashi syndrome.

    PubMed

    Faigle, W; Raposo, G; Tenza, D; Pinet, V; Vogt, A B; Kropshofer, H; Fischer, A; de Saint-Basile, G; Amigorena, S

    1998-06-01

    The Chediak-Higashi syndrome (CHS) is a human recessive autosomal disease caused by mutations in a single gene encoding a protein of unknown function, called lysosomal-trafficking regulator. All cells in CHS patients bear enlarged lysosomes. In addition, T- and natural killer cell cytotoxicity is defective in these patients, causing severe immunodeficiencies. We have analyzed major histocompatibility complex class II functions and intracellular transport in Epstein Barr Virus-transformed B cells from CHS patients. Peptide loading onto major histocompatibility complex class II molecules and antigen presentation are strongly delayed these cells. A detailed electron microscopy analysis of endocytic compartments revealed that only lysosomal multilaminar compartments are enlarged (reaching 1-2 micron), whereas late multivesicular endosomes have normal size and morphology. In contrast to giant multilaminar compartments that bear most of the usual lysosomal markers in these cells (HLA-DR, HLA-DM, Lamp-1, CD63, etc.), multivesicular late endosomes displayed reduced levels of all these molecules, suggesting a defect in transport from the trans-Golgi network and/or early endosomes into late multivesicular endosomes. Further insight into a possible mechanism of this transport defect came from immunolocalizing the lysosomal trafficking regulator protein, as antibodies directed to a peptide from its COOH terminal domain decorated punctated structures partially aligned along microtubules. These results suggest that the product of the Lyst gene is required for sorting endosomal resident proteins into late multivesicular endosomes by a mechanism involving microtubules.

  6. An immunocytochemical study of pulpal responses to cavity preparation by laser ablation in rat molars by using antibodies to heat shock protein (Hsp) 25 and class II MHC antigen.

    PubMed

    Suzuki, Takeshi; Nomura, Shuichi; Maeda, Takeyasu; Ohshima, Hayato

    2004-03-01

    Initial responses of odontoblasts and immunocompetent cells to cavity preparation by laser ablation were investigated in rat molars. In untreated control teeth, intense heat shock protein (Hsp) 25 immunoreactivity was found in the cell bodies of odontoblasts, whereas cells immunopositive for the class II major histocompatibility complex (MHC) antigen were predominantly located beneath the odontoblast layer in the dental pulp. Cavity preparation caused the destruction of the odontoblast layer and the shift of most class-II-MHC-positive cells from the pulp-dentin border toward the pulp core at the affected site. Twelve hours after cavity preparation, numerous class-II-MHC-positive cells appeared along the pulp-dentin border and extended their processes deep into the exposed dentinal tubules, but subsequently disappeared from the pulp-dentin border together with Hsp-25-immunopositive cells by 24 h after the operation. By 3-5 days postoperation, distinct abscess formation consisting of polymorphonuclear leukocytes was found in the dental pulp. The penetration of masses of oral bacteria was recognizable in the dentinal tubules beneath the prepared cavity. These findings indicate that cavity preparation by laser ablation induces remarkable inflammation by continuous bacterial infections via dentinal tubules in this experimental model, thereby delaying pulpal regeneration.

  7. Antigen Presentation by MHC-Dressed Cells

    PubMed Central

    Nakayama, Masafumi

    2015-01-01

    Professional antigen-presenting cells (APCs) such as conventional dendritic cells (DCs) process protein antigens to MHC-bound peptides and then present the peptide–MHC complexes to T cells. In addition to this canonical antigen presentation pathway, recent studies have revealed that DCs and non-APCs can acquire MHC class I (MHCI) and/or MHC class II (MHCII) from neighboring cells through a process of cell–cell contact-dependent membrane transfer called trogocytosis. These MHC-dressed cells subsequently activate or regulate T cells via the preformed antigen peptide–MHC complexes without requiring any further processing. In addition to trogocytosis, intercellular transfer of MHCI and MHCII can be mediated by secretion of membrane vesicles such as exosomes from APCs, generating MHC-dressed cells. This review focuses on the physiological role of antigen presentation by MHCI- or MHCII-dressed cells, and also discusses differences and similarities between trogocytosis and exosome-mediated transfer of MHC. PMID:25601867

  8. Differential expression of MHC class I antigens on the placenta of the rat. A mechanism for the survival of the fetal allograft

    PubMed Central

    1987-01-01

    In some mating combinations in rats, there is a maternal antibody response to the maternal antigenic components of the placenta without any previous immunization of the mother. The highest response occurs in the WF (u) female mated to the DA (a) male, and it is against a unique MHC-encoded class I antigen, the Pa antigen, and not against the major allele-specific transplantation antigen of the DA strain, RT1.Aa. The development of mAbs to the Pa and Aa antigens allowed us to localize these antigens on the placenta and to explore the reason for the differential antibody response to them using immunohistochemical and biochemical techniques. Both antibodies reacted with the WF X DA placenta and stained the endovascular and interstitial trophoblast of the decidua, the basal trophoblast, Reichert's membrane, and the yolk sac epithelium, but they did not stain the labyrinthine trophoblast. Blocking studies showed that each antibody reacted with a separate molecule in the placenta. Anti-class II mAbs reactive with the a or u haplotype did not stain the WF X DA, DA X DA, or WF X WF placenta; hence, there are no class II antigens in the placenta. Electron microscopic studies of the semiallogeneic WF X DA placenta using the immunogold technique with both single- and double-labeling showed that only the Pa antigen was expressed on the surface of the basal trophoblast, but that both the Pa and Aa antigens were in the cytoplasm of these cells; neither antigen was found in the labyrinthine trophoblast. By contrast, the placenta from the syngeneic DA X DA mating expressed both the Pa and Aa antigens on the surface of the basal trophoblast as well as in the cytoplasm; neither antigen was found in the labyrinthine trophoblast. These observations were quantified morphometrically using electron photomicrographs of single- labeled tissues. Both the Pa and Aa antigens isolated from the plasma membrane of lymphocytes have heavy chains of 46 kD, but those antigens isolated from the

  9. Non-Classical Inhibition of Carbonic Anhydrase

    PubMed Central

    Lomelino, Carrie L.; Supuran, Claudiu T.; McKenna, Robert

    2016-01-01

    Specific isoforms from the carbonic anhydrase (CA) family of zinc metalloenzymes have been associated with a variety of diseases. Isoform-specific carbonic anhydrase inhibitors (CAIs) are therefore a major focus of attention for specific disease treatments. Classical CAIs, primarily sulfonamide-based compounds and their bioisosteres, are examined as antiglaucoma, antiepileptic, antiobesity, antineuropathic pain and anticancer compounds. However, many sulfonamide compounds inhibit all CA isoforms nonspecifically, diluting drug effectiveness and causing undesired side effects due to off-target inhibition. In addition, a small but significant percentage of the general population cannot be treated with sulfonamide-based compounds due to a sulfa allergy. Therefore, CAIs must be developed that are not only isoform specific, but also non-classical, i.e. not based on sulfonamides, sulfamates, or sulfamides. This review covers the classes of non-classical CAIs and the recent advances in the development of isoform-specific inhibitors based on phenols, polyamines, coumarins and their derivatives. PMID:27438828

  10. Characterization of the major histocompatibility complex class II DQB (MhcMamu-DQB1) alleles in a cohort of Chinese rhesus macaques (Macaca mulatta).

    PubMed

    Qiu, Chen-Li; Yang, Gui-Bo; Yu, Kai; Li, Yue; Li, Xiao-Li; Liu, Qiang; Zhao, Hui; Xing, Hui; Shao, Yiming

    2008-08-01

    Rhesus macaques have long been used in animal models for various human diseases, the susceptibility and/or resistance to some of which have been associated with the major histocompatibilty complex (MHC). To gain insight into the MHC background and to facilitate the experimental use of Chinese rhesus macaques, the second exon of MhcMamu-DQB1 genes in 105 rhesus macaques were characterized by cloning and sequencing. A total of 37 MhcMamu-DQB1 alleles were identified, illustrating a marked allelic polymorphism at DQB1 in these monkeys. In addition to 10 alleles were novel sequences that had not been documented in earlier reports, at least 14 alleles reported in earlier studies were not detected in this study. Most of the sequences (73%) observed in this study belong to