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Witney MJ, Tscharke DC. BMX-A and BMX-S: Accessible cell-free methods to estimate peptide-MHC-I affinity and stability. Mol Immunol 2023; 161:1-10. [PMID: 37478775 DOI: 10.1016/j.molimm.2023.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/12/2023] [Accepted: 07/11/2023] [Indexed: 07/23/2023]
Abstract
The affinity and stability of peptide binding to Major Histocompatibility Complex Class I (MHC-I) molecules are fundamental parameters that underpin the specificity and magnitude of CD8+ T cell responses. These parameters can be estimated in some cases by computational tools, but experimental validation remains valuable, especially for stability. Methods to measure peptide binding can be broadly categorised into either cell-based assays using TAP-deficient cell lines such as RMA/S, or cell-free strategies, such as peptide competition-binding assays and surface plasmon resonance. Cell-based assays are subject to confounding biological activity, including peptide trimming by peptidases and dilution of peptide-loaded MHC-I on the surface of cells through cell division. Current cell-free methods require in-house production and purification of MHC-I. In this study, we present the development of new cell-free assays to estimate the relative affinity and dissociation kinetics of peptide binding to MHC-I. These assays, which we have called BMX-A (relative affinity) and BMX-S (kinetic stability), are reliable, scalable and accessible, in that they use off-the-shelf commercial reagents and standard flow cytometry techniques.
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Affiliation(s)
- Matthew J Witney
- John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - David C Tscharke
- John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.
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2
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Mutations of γCOP Gene Disturb Drosophila melanogaster Innate Immune Response to Pseudomonas aeruginosa. Int J Mol Sci 2022; 23:ijms23126499. [PMID: 35742941 PMCID: PMC9223523 DOI: 10.3390/ijms23126499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 05/31/2022] [Accepted: 06/08/2022] [Indexed: 01/27/2023] Open
Abstract
Drosophila melanogaster (the fruit fly) is a valuable experimental platform for modeling host–pathogen interactions. It is also commonly used to define innate immunity pathways and to understand the mechanisms of both host tolerance to commensal microbiota and response to pathogenic agents. Herein, we investigate how the host response to bacterial infection is mirrored in the expression of genes of Imd and Toll pathways when D. melanogaster strains with different γCOP genetic backgrounds are infected with Pseudomonas aeruginosa ATCC 27853. Using microarray technology, we have interrogated the whole-body transcriptome of infected versus uninfected fruit fly males with three specific genotypes, namely wild-type Oregon, γCOPS057302/TM6B and γCOP14a/γCOP14a. While the expression of genes pertaining to Imd and Toll is not significantly modulated by P. aeruginosa infection in Oregon males, many of the components of these cascades are up- or downregulated in both infected and uninfected γCOPS057302/TM6B and γCOP14a/γCOP14a males. Thus, our results suggest that a γCOP genetic background modulates the gene expression profiles of Imd and Toll cascades involved in the innate immune response of D. melanogaster, inducing the occurrence of immunological dysfunctions in γCOP mutants.
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3
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Anderson CK, Brossay L. The role of MHC class Ib-restricted T cells during infection. Immunogenetics 2016; 68:677-91. [PMID: 27368413 DOI: 10.1007/s00251-016-0932-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/22/2016] [Indexed: 01/02/2023]
Abstract
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.
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Affiliation(s)
- Courtney K Anderson
- Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Box G-B618, Providence, RI, 02912, USA
| | - Laurent Brossay
- Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Box G-B618, Providence, RI, 02912, USA.
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4
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Yin R, Zheng W, Hao F, Yang XC, Zhong BY, Li QJ. HPV16E7 tumor antigen modified by KDEL sequence induce specific cytotoxic T lymphocytes-dependent antitumor immunity. J Dermatol Sci 2009; 55:116-22. [DOI: 10.1016/j.jdermsci.2009.04.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 04/22/2009] [Accepted: 04/30/2009] [Indexed: 11/29/2022]
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5
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Doi T, Yamada H, Yajima T, Wajjwalku W, Hara T, Yoshikai Y. H2-M3-restricted CD8+ T cells induced by peptide-pulsed dendritic cells confer protection against Mycobacterium tuberculosis. THE JOURNAL OF IMMUNOLOGY 2007; 178:3806-13. [PMID: 17339479 DOI: 10.4049/jimmunol.178.6.3806] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
One of the oligopolymorphic MHC class Ib molecules, H2-M3, presents N-formylated peptides derived from bacteria. In this study, we tested the ability of an H2-M3-binding peptide, TB2, to induce protection in C57BL/6 mice against Mycobacterium tuberculosis. Immunization with bone marrow-derived dendritic cell (BMDC) pulsed with TB2 or a MHC class Ia-binding peptide, MPT64(190-198) elicited an expansion of Ag-specific CD8+ T cells in the spleen and the lung. The number of TB2-specific CD8+ T cells reached a peak on day 6, contracted with kinetics similar to MPT64(190-198)-specific CD8+ T cells and was maintained at an appreciable level for at least 60 days. The TB2-specific CD8+ T cells produced less effector cytokines but have stronger cytotoxic activity than MPT64(190-198)-specific CD8+ T cells. Mice immunized with TB2-pulsed BMDC as well as those with MPT64(190-198)-pulsed BMDC showed significant protection against an intratracheal challenge with M. tuberculosis H37Rv. However, histopathology of the lung in mice immunized with TB2-pulsed BMDC was different from mice immunized with MPT64(190-198)-pulsed BMDC. Our results suggest that immunization with BMDC pulsed with MHC class Ib-restricted peptides would be a useful vaccination strategy against M. tuberculosis.
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Affiliation(s)
- Takehiko Doi
- Division of Host Defense, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
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6
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Abstract
Our understanding of the classical MHC class I molecules (MHC class Ia molecules) has long focused on their extreme polymorphism. These molecules present peptides to T cells and are central to discrimination between self and non-self. By contrast, the functions of the non-polymorphic MHC class I molecules (MHC class Ib molecules) have been elusive, but emerging evidence reveals that, in addition to antigen presentation, MHC class Ib molecules are involved in immunoregulation. As we discuss here, the subset of MHC class Ib molecules that presents peptides to T cells bridges innate and acquired immunity, and this provides insights into the origins of acquired immunity.
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Affiliation(s)
- John R Rodgers
- Department of Immunology, Baylor College of Medicine, Houston, Texas 77030, USA.
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7
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Wang L, Wu YZ, Chen A, Zhang JB, Yang Z, Niu W, Geng M, Ni B, Zhou W, Zou LY, Jiang M. MHC class I-associated presentation of exogenous peptides is not only enhanced but also prolonged by linking with a C-terminal Lys-Asp-Glu-Leu endoplasmic reticulum retrieval signal. Eur J Immunol 2004; 34:3582-94. [PMID: 15495159 DOI: 10.1002/eji.200425215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Vaccination with antigenic peptide-pulsed antigen-presenting cells (APC) represents an attractive approach for therapy for cancer and diseases caused by intracellular infections. It has been suggested that sufficient stable MHC/peptide complexes on the surface of APC might play an important role in the generation of antitumor and antiviral immunity in vivo. In this study, we observed that exogenous peptides that were artificially fused with an endoplasmic reticulum (ER) retrieval signal, a C-terminal Lys-Asp-Glu-Leu sequence, could be efficiently presented by intracellular MHC class I molecules in a TAP- and proteasome-independent, but brefeldin A-sensitive manner. The APC retained the capacity to display surface MHC/peptide complexes for a prolonged period. In addition, our results show that vaccination with DC bearing our fusion peptides induced greatly enhanced specific CTL response, and resulted in significant inhibition of tumor growth. Thus, the ER retrieval signal modification can be regarded as a novel method for targeting exogenous peptides into the intracellular MHC class I presentation pathway, and may improve the clinical utility of vaccines based on synthetic peptide pulsed DC.
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Affiliation(s)
- Li Wang
- Institute of Immunology, PLA, Third Military Medical University, District Shangpingba, Chongqing, People's Republic of China
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8
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D'Orazio SEF, Velasquez M, Roan NR, Naveiras-Torres O, Starnbach MN. The Listeria monocytogenes lemA gene product is not required for intracellular infection or to activate fMIGWII-specific T cells. Infect Immun 2004; 71:6721-7. [PMID: 14638756 PMCID: PMC308916 DOI: 10.1128/iai.71.12.6721-6727.2003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clearance of the intracellular bacterial pathogen Listeria monocytogenes requires antigen-specific CD8(+) T cells. Recently it was shown that activation of class Ib major histocompatibility complex (MHC)-restricted CD8(+) T cells alone is sufficient for immune protection against listeriae. A major component of the class Ib MHC-restricted T-cell response is T cells that recognize formylated peptide antigens presented by M3 molecules. Although three N-formylated peptides derived from L. monocytogenes are known to bind to M3 molecules, fMIGWII is the immunodominant epitope presented by M3 during infection of mice. The source of fMIGWII peptide is the L. monocytogenes lemA gene, which encodes a 30-kDa protein of unknown function. In this report, we describe the generation of two L. monocytogenes lemA deletion mutants. We show that lemA is not required for growth of listeriae in tissue culture cells or for virulence during infection of mice. Surprisingly, we found that fMIGWII-specific T cells were still primed following infection with lemA mutant listeriae, suggesting that L. monocytogenes contains at least one additional antigen that is cross-reactive with the fMIGWII epitope. This cross-reactive antigen appears to be a small protease-resistant molecule that is secreted by L. monocytogenes.
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Affiliation(s)
- Sarah E F D'Orazio
- Department of Microbiology & Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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9
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Sun JY, Senitzer D, Forman SJ, Chatterjee S, Wong KK. Identification of new MHC-restriction elements for presentation of the p210(BCR-ABL) fusion region to human cytotoxic T lymphocytes. Cancer Immunol Immunother 2003; 52:761-70. [PMID: 14564482 PMCID: PMC11032871 DOI: 10.1007/s00262-003-0415-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2003] [Accepted: 05/16/2003] [Indexed: 11/28/2022]
Abstract
Chronic myelogenous leukemia (CML) is characterized by a t(9;22) translocation resulting in expression of BCR-ABL fusion oncoproteins which are unique to the leukemic cells, necessary for oncogenesis, and potentially immunogenic. We have previously shown that human dendritic cells transduced with an adeno-associated virus vector encoding the fusion region of the b3a2 splice variant (p210(b3a2)) of the BCR-ABL oncoprotein elicit specific T-cell responses in vitro. Two cytotoxic T lymphocyte (CTL) clones generated in this fashion displayed restriction with previously unreported HLA alleles. The first, T1/B9, was CD4(+) and restricted by DRB5*0101 (autologous) or DRB1*1101 (allogeneic). The minimum cytotoxic epitope (MCE) binding to DRB5*0101 for this clone was identified as FKQSSKALQ, overlapping the p210(b3a2) fusion point (boldface). The MCE of DRB1*1101 for this clone differed from DRB5*0101, but also included the fusion point. The clonality of CTL T1/B9 was verified by analyses of TCRalpha/beta chain usage and DNA sequence analyses. To our knowledge, this is the first description of a single clone recognizing both DRB5*0101 and DRB1*1101. The other CTL clone, T1/33, was CD8+ and recognized HLA-B*3501 or B*3503 complexed with an MCE, RPVASDFEP, derived from the c-abl sequence in proximity to the p210(b3a2) fusion point. K562 cells transfected with plasmids encoding HLA-DRA + B5*0101, B*3501, or B*3503 but not controls expressing DRA + DRB1*1501 were lysed by cognate CTL clones, confirming that DRB5*0101 and B*3501/3 could present p210(b3a2) joining region epitopes via endogenous processing. The identification of three additional HLA alleles (DRB5*0101, B*3501, and B*3503) presenting the p210(b3a2) fusion-region antigen will broaden the application of vaccine strategies for targeting CML cells. The findings of single CTL clones cross-recognizing autologous (DRB5*0101 or B*3501) and allogeneic (DRB1*1101 or B*3503) HLA alleles presenting BCR-ABL fusion-region epitopes implies the potential separation of graft-versus-leukemia from graft-versus-host effects.
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Affiliation(s)
- Ji-Yao Sun
- Division of Hematology and Stem Cell Transplantation, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010 USA
| | - David Senitzer
- Division of Hematology and Stem Cell Transplantation, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010 USA
| | - Stephen J. Forman
- Division of Hematology and Stem Cell Transplantation, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010 USA
| | - Saswati Chatterjee
- Division of Virology, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010 USA
| | - K. K. Wong
- Division of Hematology and Stem Cell Transplantation, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010 USA
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10
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Doyle CK, Davis BK, Cook RG, Rich RR, Rodgers JR. Hyperconservation of the N-formyl peptide binding site of M3: evidence that M3 is an old eutherian molecule with conserved recognition of a pathogen-associated molecular pattern. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:836-44. [PMID: 12847252 DOI: 10.4049/jimmunol.171.2.836] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mouse MHC class I-b molecule H2-M3 has unique specificity for N-formyl peptides, derived from bacteria (and mitochondria), and is thus a pathogen-associated molecular pattern recognition receptor (PRR). To test whether M3 was selected for this PRR function, we studied M3 sequences from diverse murid species of murine genera Mus, Rattus, Apodemus, Diplothrix, Hybomys, Mastomys, and Tokudaia and of sigmodontine genera Sigmodon and PEROMYSCUS: We found that M3 is highly conserved, and the 10 residues coordinating the N-formyl group are almost invariant. The ratio of nonsynonymous and synonymous substitution rates suggests the Ag recognition site of M3, unlike the Ag recognition site of class I-a molecules, is under strong negative (purifying) selection and has been for at least 50-65 million years. Consistent with this, M3 alpha1alpha2 domains from Rattus norvegicus and Sigmodon hispidus and from the "null" allele H2-M3(b) specifically bound N-formyl peptides. The pattern of nucleotide substitution in M3 suggests M3 arose rapidly from murid I-a precursors by an evolutionary leap ("saltation"), perhaps involving intense selective pressure from bacterial pathogens. Alternatively, M3 arose more slowly but prior to the radiation of eutherian (placental) mammals. Older dates for the emergence of M3, and the accepted antiquity of CD1, suggest that primordial class I MHC molecules could have evolved originally as monomorphic PRR, presenting pathogen-associated molecular patterns. Such MHC PRR molecules could have been preadaptations for the evolution of acquired immunity during the early vertebrate radiation.
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Affiliation(s)
- C Kuyler Doyle
- Baylor College of Medicine, Department of Immunology, Houston, TX 77030, USA
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11
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Berwin B, Rosser MFN, Brinker KG, Nicchitta CV. Transfer of GRP94(Gp96)-associated peptides onto endosomal MHC class I molecules. Traffic 2002; 3:358-66. [PMID: 11967129 DOI: 10.1034/j.1600-0854.2002.30505.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
GRP94 (gp96)-associated peptides can elicit cellular immune responses, an activity thought to reflect the presence of a cell surface receptor (CD91) on antigen-presenting cells that mediates GRP94 internalization and trafficking to an amenable site for peptide transfer to major histocompatibility complex class I molecules. We report that GRP94 internalized by receptor-mediated endocytosis is trafficked to a Rab5a, CD1 and transferrin-negative, Fc receptor and major histocompatibility complex class I-positive endocytic compartment. Receptor-internalized GRP94 did not access the endoplasmic reticulum of antigen-presenting cells. To identify the site of re-presentation of GRP94-associated peptides, kinetic analyses were performed utilizing GRP94-OVA (SIINFEKL) peptide complexes, with peptide re-presentation assayed with the Kb-SIINFEKL-specific MAb, 25-D1.16. Analyses of the kinetics of re-presentation of GRP94-associated peptides, under conditions in which de novo synthesis of major histocompatibility complex class I molecules was inhibited, identified a post-endoplasmic reticulum compartment, accessed by mature major histocompatibility complex class I, as the predominant site of GRP94-associated peptide exchange onto major histocompatibility complex class I.
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Affiliation(s)
- B Berwin
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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12
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Stober D, Trobonjaca Z, Reimann J, Schirmbeck R. Dendritic cells pulsed with exogenous hepatitis B surface antigen particles efficiently present epitopes to MHC class I-restricted cytotoxic T cells. Eur J Immunol 2002; 32:1099-108. [PMID: 11920577 DOI: 10.1002/1521-4141(200204)32:4<1099::aid-immu1099>3.0.co;2-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
L(d)- and K(b)-binding epitopes processed by murine dendritic cells (DC) pulsed with exogenous, particulate hepatitis B surface antigen (HBsAg) are presented to cytotoxic T lymphocytes (CTL). The specific and dose-dependent induction of IFN-gamma release and cytotoxicity in CTL by metabolically active DC did not depend on antigenic peptides contaminating the particles, was cytochalasin D resistant, independent of the maturation state of DC, and blocked by primaquine, amiloride and NH(4)Cl (indicating involvement of acid proteolysis). The specific immunostimulatory phenotype of pulsed DC was maintained for about 3 h after the end of the pulse but rapidly decayed thereafter. Processing of L(d)- and K(b)-binding epitopes from exogenous HBsAg particles by pulsed DC for presentation was TAP independent. Surface-associated 'empty' (presentation-deficient) 64(+) L(d) molecules (defined by the mAb 64-3-7), but not trimeric (presentation-competent) 30(+) L(d) molecules (defined by the mAb 30-5-7) had to be available during the pulse of DC with exogenous HBsAg particles to generate 30(+) L(d)molecules that present the antigenic S(28-39) peptide. Exogenous beta2-microglobulin present during the pulse of DC with HBsAg particles facilitated presentation of L(d)- and K(b)-restricted epitopes. DC generated from bone marrow progenitors in vitro, as well as splenic and liver DC (generated in vivo) presented epitopes to specific CTL. HBsAg particles thus efficiently enter an alternative processing pathway in DC that leads to presentation of epitopes to MHC class I-restricted CTL.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 2
- ATP-Binding Cassette Transporters/physiology
- Animals
- Antigen Presentation/immunology
- Bone Marrow Cells/drug effects
- Bone Marrow Cells/immunology
- Cell Differentiation/drug effects
- Cells, Cultured/drug effects
- Cells, Cultured/immunology
- Coculture Techniques
- Culture Media, Serum-Free
- Dendritic Cells/immunology
- Dose-Response Relationship, Immunologic
- Epitopes/immunology
- Female
- H-2 Antigens/immunology
- Hepatitis B Surface Antigens/immunology
- Interferon-gamma/metabolism
- Liver/cytology
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Peptide Fragments/immunology
- Recombinant Fusion Proteins/immunology
- Spleen/cytology
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- beta 2-Microglobulin/immunology
- beta 2-Microglobulin/pharmacology
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Affiliation(s)
- Detlef Stober
- Institute of Medical Microbiology and Immunology, University of Ulm, Ulm, Germany
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13
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Lybarger L, Yu YY, Chun T, Wang CR, Grandea AG, Van Kaer L, Hansen TH. Tapasin enhances peptide-induced expression of H2-M3 molecules, but is not required for the retention of open conformers. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:2097-105. [PMID: 11489993 DOI: 10.4049/jimmunol.167.4.2097] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
H2-M3 is a class Ib MHC molecule that binds a highly restricted pool of peptides, resulting in its intracellular retention under normal conditions. However, addition of exogenous M3 ligands induces its escape from the endoplasmic reticulum (ER) and, ultimately, its expression at the cell surface. These features of M3 make it a powerful and novel model system to study the potentially interrelated functions of the ER-resident class I chaperone tapasin. The functions ascribed to tapasin include: 1) ER retention of peptide-empty class I molecules, 2) TAP stabilization resulting in increased peptide transport, 3) direct facilitation of peptide binding by class I, and 4) peptide editing. We report in this study that M3 is associated with the peptide-loading complex and that incubation of live cells with M3 ligands dramatically decreased this association. Furthermore, high levels of open conformers of M3 were efficiently retained intracellularly in tapasin-deficient cells, and addition of exogenous M3 ligands resulted in substantial surface induction that was enhanced by coexpression of either membrane-bound or soluble tapasin. Thus, in the case of M3, tapasin directly facilitates intracellular peptide binding, but is not required for intracellular retention of open conformers. As an alternative approach to define unique aspects of M3 biosynthesis, M3 was expressed in human cell lines that lack an M3 ortholog, but support expression of murine class Ia molecules. Unexpectedly, peptide-induced surface expression of M3 was observed in only one of two cell lines. These results demonstrate that M3 expression is dependent on a unique factor compared with class Ia molecules.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 2
- ATP Binding Cassette Transporter, Subfamily B, Member 3
- ATP-Binding Cassette Transporters/metabolism
- Adjuvants, Immunologic/deficiency
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/metabolism
- Adjuvants, Immunologic/physiology
- Animals
- Antiporters/deficiency
- Antiporters/genetics
- Antiporters/metabolism
- Antiporters/physiology
- Cell Line, Transformed
- Epitopes/chemistry
- Epitopes/genetics
- Epitopes/metabolism
- H-2 Antigens/metabolism
- HeLa Cells
- Histocompatibility Antigen H-2D
- Histocompatibility Antigens Class I/biosynthesis
- Histocompatibility Antigens Class I/chemistry
- Histocompatibility Antigens Class I/genetics
- Histocompatibility Antigens Class I/metabolism
- Humans
- Immunoglobulins/deficiency
- Immunoglobulins/genetics
- Immunoglobulins/metabolism
- Immunoglobulins/physiology
- L Cells
- Membrane Transport Proteins
- Mice
- Mutagenesis, Site-Directed
- Peptides/metabolism
- Peptides/pharmacology
- Protein Binding/genetics
- Protein Binding/immunology
- Protein Conformation
- Transfection
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Affiliation(s)
- L Lybarger
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
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