1
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Fu H, Ward EJ, Marelli-Berg FM. Mechanisms of T cell organotropism. Cell Mol Life Sci 2016; 73:3009-33. [PMID: 27038487 PMCID: PMC4951510 DOI: 10.1007/s00018-016-2211-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 02/06/2023]
Abstract
Protective immunity relies upon T cell differentiation and subsequent migration to target tissues. Similarly, immune homeostasis requires the localization of regulatory T cells (Tregs) to the sites where immunity takes place. While naïve T lymphocytes recirculate predominantly in secondary lymphoid tissue, primed T cells and activated Tregs must traffic to the antigen rich non-lymphoid tissue to exert effector and regulatory responses, respectively. Following priming in draining lymph nodes, T cells acquire the 'homing receptors' to facilitate their access to specific tissues and organs. An additional level of topographic specificity is provided by T cells receptor recognition of antigen displayed by the endothelium. Furthermore, co-stimulatory signals (such as those induced by CD28) have been shown not only to regulate T cell activation and differentiation, but also to orchestrate the anatomy of the ensuing T cell response. We here review the molecular mechanisms supporting trafficking of both effector and regulatory T cells to specific antigen-rich tissues.
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Affiliation(s)
- Hongmei Fu
- William Harvey Research Institute, Heart Centre, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Eleanor Jayne Ward
- William Harvey Research Institute, Heart Centre, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Federica M Marelli-Berg
- William Harvey Research Institute, Heart Centre, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.
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2
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Ju JM, Kim MB, Ryu SJ, Kim JY, Chang J, Choi EY. Selection of Thymocytes Expressing Transgenic TCR Specific for a Minor Histocompatibility Antigen, H60. Immune Netw 2015; 15:222-31. [PMID: 26557806 PMCID: PMC4637343 DOI: 10.4110/in.2015.15.5.222] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/03/2015] [Accepted: 09/18/2015] [Indexed: 01/11/2023] Open
Abstract
Minor histocompatibility antigens are MHC-bound peptides and contribute to the generation of allo-responses after allogeneic transplantation. H60 is a dominant minor H antigen that induces a strong CD8 T-cell response in MHC-matched allogeneic transplantation settings. Here, we report establishment of a TCR transgenic mouse line named J15, wherein T cells express TCRs specific for H60 in complex with H-2K(b), and different fates of the thymocytes expressing J15 TCRs in various thymic antigenic environments. Thymocytes expressing the J15 TCRs were positively selected and differentiated into CD8(+) single positive (SP) cells in the thymus of C57BL/6 mice, wherein the cognate antigen H60 is not expressed. However, thymocytes were negatively selected in thymus tissue where H60 was transgenically expressed under the control of the actin promoter, with double-positive stages of cells being deleted. Despite the ability of the H60H peptide (LTFHYRNL) variant to induce cytotoxic activity from H60-specific CTL lines at ~50% of the activity induced by normal H60 peptides (LTFNYRNL), J15-expressing thymocytes were positively selected in the thymus where the variant H60H was transgenically expressed. These results demonstrate that a single amino-acid change in the H60 epitope peptide influences the fate of thymocytes expressing the cognate TCR.
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Affiliation(s)
- Ji-Min Ju
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Min Bum Kim
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Su Jeong Ryu
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Joo Young Kim
- Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Jun Chang
- Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Korea
| | - Eun Young Choi
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
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3
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Hoerter JAH, Brzostek J, Artyomov MN, Abel SM, Casas J, Rybakin V, Ampudia J, Lotz C, Connolly JM, Chakraborty AK, Gould KG, Gascoigne NRJ. Coreceptor affinity for MHC defines peptide specificity requirements for TCR interaction with coagonist peptide-MHC. ACTA ACUST UNITED AC 2013; 210:1807-21. [PMID: 23940257 PMCID: PMC3754861 DOI: 10.1084/jem.20122528] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The requirement for the TCR to interact with coagonists, endogenous MHC–peptide complexes which do not themselves activate the T cell, decreases as the strength of the CD8–class I interaction increases. Recent work has demonstrated that nonstimulatory endogenous peptides can enhance T cell recognition of antigen, but MHCI- and MHCII-restricted systems have generated very different results. MHCII-restricted TCRs need to interact with the nonstimulatory peptide–MHC (pMHC), showing peptide specificity for activation enhancers or coagonists. In contrast, the MHCI-restricted cells studied to date show no such peptide specificity for coagonists, suggesting that CD8 binding to noncognate MHCI is more important. Here we show how this dichotomy can be resolved by varying CD8 and TCR binding to agonist and coagonists coupled with computer simulations, and we identify two distinct mechanisms by which CD8 influences the peptide specificity of coagonism. Mechanism 1 identifies the requirement of CD8 binding to noncognate ligand and suggests a direct relationship between the magnitude of coagonism and CD8 affinity for coagonist pMHCI. Mechanism 2 describes how the affinity of CD8 for agonist pMHCI changes the requirement for specific coagonist peptides. MHCs that bind CD8 strongly were tolerant of all or most peptides as coagonists, but weaker CD8-binding MHCs required stronger TCR binding to coagonist, limiting the potential coagonist peptides. These findings in MHCI systems also explain peptide-specific coagonism in MHCII-restricted cells, as CD4–MHCII interaction is generally weaker than CD8–MHCI.
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Affiliation(s)
- John A H Hoerter
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
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4
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Regulation of T cell-dendritic cell interactions by IL-7 governs T-cell activation and homeostasis. Blood 2009; 113:5793-800. [PMID: 19357399 DOI: 10.1182/blood-2008-12-192252] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Interleukin-7 (IL-7) plays a central role in the homeostasis of the T-cell compartment by regulating T-cell survival and proliferation. Whether IL-7 can influence T-cell receptor (TCR) signaling in T cells remains controversial. Here, using IL-7-deficient hosts and TCR-transgenic T cells that conditionally express IL-7R, we examined antigen-specific T-cell responses in vitro and in vivo to viral infection and lymphopenia to determine whether IL-7 signaling influences TCR-triggered cell division events. In vitro, we could find no evidence that IL-7 signaling could costimulate T-cell activation over a broad range of conditions, suggesting that IL-7 does not directly tune TCR signaling. In vivo, however, we found an acute requirement for IL-7 signaling for efficiently triggering T-cell responses to influenza A virus challenge. Furthermore, we found that IL-7 was required for the enhanced homeostatic TCR signaling that drives lymphopenia-induced proliferation by a mechanism involving efficient contacts of T cells with dendritic cells. Consistent with this, saturating antigen-presenting capacity in vivo overcame the triggering defect in response to cognate peptide. Thus, we demonstrate a novel role for IL-7 in regulating T cell-dendritic cell interactions that is essential for both T-cell homeostasis and activation in vivo.
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5
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Carreño LJ, González PA, Kalergis AM. Modulation of T cell function by TCR/pMHC binding kinetics. Immunobiology 2006; 211:47-64. [PMID: 16446170 DOI: 10.1016/j.imbio.2005.09.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 09/05/2005] [Indexed: 01/19/2023]
Abstract
The interaction between the T cell receptor (TCR) and the peptide-MHC complex (pMHC) at the interface between the T cell and the antigen presenting cell (APC) is the main event controlling the specificity of antigen recognition by T cells. It is thought that TCR/pMHC binding kinetics are critical for the selection of the T cell repertoire in the thymus, as well as the activation of mature T cells in the periphery. One of the binding parameters that conditions T cell activation by pMHC ligands is the half-life of the TCR/pMHC interaction. This kinetic parameter is highly significant for the regulation of T cell activation and therefore determines the capacity of T cells to respond against pathogen- and tumor-derived antigens, avoiding self-reactivity. Several studies support the notion that T cells are activated only by TCR/pMHC interactions that are above a threshold of half-life. pMHC complexes that bind TCRs with half-lives below that threshold behave as null or antagonistic ligands. However, since prolonged half-lives can also impair T cell activation, there seems to be a ceiling for the TCR/pMHC half life that leads to efficient activation of T cells. According to these observations, efficient T cell activation would require an optimal half-life of TCR/pMHC interaction. These kinetic restrictions for T cell activation are important to generate a protective adaptive immune response minimizing cross-reactivity against self-constituents. The nature of the TCR/pMHC interaction defines in the thymus whether a thymocyte develops into a mature T cell or is eliminated by apoptosis. In addition, the kinetics of TCR/pMHC binding can determine the type of response shown by mature T cells in the periphery. Although several studies have focused on the modulation of T cell function by the affinity of the TCR/pMHC interaction, the binding kinetics rules governing T cell activation remain poorly understood. Here we review recent data and propose a new model for the regulation of T cell function by TCR/pMHC binding kinetics.
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Affiliation(s)
- Leandro J Carreño
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda #340, Santiago, Chile
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6
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Warmflash A, Weigert M, Dinner AR. Control of Genotypic Allelic Inclusion through TCR Surface Expression. THE JOURNAL OF IMMUNOLOGY 2005; 175:6412-9. [PMID: 16272293 DOI: 10.4049/jimmunol.175.10.6412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To gain insight into the molecular causes and functional consequences of allelic inclusion of TCR alpha-chains, we develop a computational model for thymocyte selection in which the signal that determines cell fate depends on surface expression. Analysis of receptor pairs on selected dual TCR cells reveals that allelic inclusion permits both autoreactive TCR and receptors not in the single TCR cell repertoire to be selected. However, in comparison with earlier theoretical studies, relatively few dual TCR cells display receptors with high avidity for thymic ligands because their alpha-chains compete aggressively for the beta-chain, which hinders rescue from clonal deletion. This feature of the model makes clear that allelic inclusion does not in itself compromise central tolerance. A specific experiment based on modulation of TCR surface expression levels is proposed to test the model.
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7
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Fridkis-Hareli M, Reinherz EL. New approaches to eliciting protective immunity through T cell repertoire manipulation: the concept of thymic vaccination. MEDICAL IMMUNOLOGY (LONDON, ENGLAND) 2004; 3:2. [PMID: 15588284 PMCID: PMC544398 DOI: 10.1186/1476-9433-3-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Accepted: 12/08/2004] [Indexed: 12/24/2022]
Abstract
Conventional vaccines afford protection against infectious diseases by expanding existing pathogen-specific peripheral lymphocytes, both CD8 cytotoxic effector (CTL) and CD4 helper T cells. The latter induce B cell maturation and antibody production. As a consequence, lymphocytes within the memory pool are poised to rapidly proliferate at the time of a subsequent infection. The "thymic vaccination" concept offers a novel way to alter the primary T cell repertoire through exposure of thymocytes to altered peptide ligands (APL) with reduced T cell receptor (TCR) affinity relative to cognate antigens recognized by those same TCRs. Thymocyte maturation (i.e. positive selection) is enhanced by low affinity interaction between a TCR and an MHC-bound peptide in the thymus and subsequent emigration of mature cells into the peripheral T lymphocyte pool follows. In principal, such variants of antigens derived from infectious agents could be utilized for peptide-driven maturation of thymocytes bearing pathogen-specific TCRs. To test this idea, APLs of gp33-41, a Db-restricted peptide derived from the lymphocytic choriomeningitis virus (LCMV) glycoprotein, and of VSV8, a Kb-restricted peptide from the vesicular stomatitis virus (VSV) nucleoprotein, have been designed and their influence on thymic maturation of specific TCR-bearing transgenic thymocytes examined in vivo using irradiation chimeras. Injection of APL resulted in positive selection of CD8 T cells expressing the relevant viral specificity and in the export of those virus-specific CTL to lymph nodes without inducing T cell proliferation. Thus, exogenous APL administration offers the potential of expanding repertoires in vivo in a manner useful to the organism. To efficiently peripheralize antigen-specific T cells, concomitant enhancement of mechanisms promoting thymocyte migration appears to be required. This commentary describes the rationale for thymic vaccination and addresses the potential prophylactic and therapeutic applications of this approach for treatment of infectious diseases and cancer. Thymic vaccination-induced peptide-specific T cells might generate effective immune protection against disease-causing agents, including those for which no effective natural protection exists.
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Affiliation(s)
- Masha Fridkis-Hareli
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, USA
- Department of Medicine, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Ellis L Reinherz
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, USA
- Department of Medicine, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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8
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Fridkis-Hareli M, Reche PA, Reinherz EL. Peptide variants of viral CTL epitopes mediate positive selection and emigration of Ag-specific thymocytes in vivo. THE JOURNAL OF IMMUNOLOGY 2004; 173:1140-50. [PMID: 15240703 DOI: 10.4049/jimmunol.173.2.1140] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
During development, thymocytes carrying TCRs mediating low-affinity interactions with MHC-bound self-peptides are positively selected for export into the mature peripheral T lymphocyte pool. Thus, exogenous administration of certain altered peptide ligands (APL) with reduced TCR affinity relative to cognate Ags may provide a tool to elicit maturation of desired TCR specificities. To test this "thymic vaccination" concept, we designed APL of the viral CTL epitopes gp33-41 and vesicular stomatitis virus nucleoprotein octapeptide N52-59 relevant for the lymphocytic choriomeningitis virus-specific P14- and vesicular stomatitis virus-specific N15-TCRs, respectively, and examined their effects on thymocytes in vivo using irradiation chimeras. Injection of APL into irradiated congenic (Ly-5.1) mice, reconstituted with T cell progenitors from the bone marrow of P14 RAG2(-/-) (Ly-5.2) or N15 RAG2(-/-) (Ly-5.2) transgenic mice, resulted in positive selection of T cells expressing the relevant specificity. Moreover, the variants led to export of virus-specific T cells to lymph nodes, but without inducing T cell proliferation. These findings show that the mature T cell repertoire can be altered by in vivo peptide administration through manipulation of thymic selection.
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Affiliation(s)
- Masha Fridkis-Hareli
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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9
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Viret C, He X, Janeway CA. Altered positive selection due to corecognition of floppy peptide/MHC II conformers supports an integrative model of thymic selection. Proc Natl Acad Sci U S A 2003; 100:5354-9. [PMID: 12700352 PMCID: PMC154349 DOI: 10.1073/pnas.0831129100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Thymocytes bearing the E alpha 52-68/I-A(b) complex-specific 1H3.1 alpha beta T cell antigen receptor are positively selected in Ab-Ep [Ab-Ep transgenic, invariant chain (Ii)(-/-), I-A beta(b-/-)] mice, where I-A(b) molecules present only E alpha 52-68. Although Ii reintroduction led to deletion, I-A beta(b) reintroduction disrupted positive selection. T cell antigen receptor transgenic Ab-Ep I-A beta(b+) mice had a large thymus with an increased absolute number of CD4(+)CD8(+) cells and no overt signs of deletion. Unlike Ab-Ep Ii(+) antigen-presenting cells, Ab-Ep I-A beta(b+) antigen-presenting cells did not activate 1H3.1 T cells. However, their capacity to present E alpha 52-68 was intact. Thus, positive selection of 1H3.1 thymocytes on the tight compact E alpha 52-68/I-A(b) complex is neutralized by the corecognition of loose compact self-peptide/I-A(b) conformers that do not interfere with the cognate activation of mature 1H3.1 T cells. The data support the notion that the integration of distinct signals generated by the simultaneous recognition of multiple self-peptide/MHC complexes directs intrathymic selection of T cells.
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Affiliation(s)
- Christophe Viret
- Howard Hughes Medical Institute and Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
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10
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Sanjuán MA, Pradet-Balade B, Jones DR, Martínez-A C, Stone JC, Garcia-Sanz JA, Mérida I. T cell activation in vivo targets diacylglycerol kinase alpha to the membrane: a novel mechanism for Ras attenuation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:2877-83. [PMID: 12626538 DOI: 10.4049/jimmunol.170.6.2877] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol to produce phosphatidic acid, leading to decreased and increased levels, respectively, of these two lipid messengers that play a central role in T cell activation. Nine DGK isoforms, grouped into five subtypes, are found in higher organisms; all contain a conserved C-terminal domain and at least two cysteine-rich motifs of unknown function. In this study, we have researched in vivo the regulation of DGK alpha, using a transgenic mouse model in which injection of an antigenic peptide activates the majority of peripheral T cells. We demonstrate that DGK alpha, highly expressed in resting T lymphocytes, is subject to complex control at the mRNA and protein levels during in vivo T cell activation. Subcellular fractionation of T lymphocytes shortly after in vivo engagement of the TCR shows rapid translocation of cytosolic DGK alpha to the membrane fraction. At early time points, DGK alpha translocation to the membrane correlates with rapid translocation of Ras guanyl nucleotide-releasing protein (RasGRP), a nucleotide exchange activator for Ras that associates to the membrane through a diacylglycerol-binding domain. To demonstrate a causal relationship between DGK alpha activity and RasGRP relocation to the membrane, we determined RasGRP translocation kinetics in a T cell line transiently transfected with constitutive active and dominant-negative DGK alpha mutants. We show that membrane localization of DGK alpha is associated with a negative regulatory signal for Ras activation by reversing RasGRP translocation. This study is the first demonstration of in vivo regulation of DGK alpha, and provides new insight into the functional role of a member of this family of lipid kinases in the regulation of the immune response.
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MESH Headings
- Animals
- CD28 Antigens/immunology
- CD28 Antigens/metabolism
- CD28 Antigens/physiology
- Cell Membrane/enzymology
- Cell Membrane/immunology
- Cloning, Molecular
- DNA-Binding Proteins/metabolism
- Diacylglycerol Kinase/biosynthesis
- Diacylglycerol Kinase/genetics
- Diacylglycerol Kinase/metabolism
- Gene Expression Regulation, Neoplastic
- Guanine Nucleotide Exchange Factors
- Humans
- Isoenzymes/biosynthesis
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Jurkat Cells
- Lymphocyte Activation
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Protein Transport/immunology
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/physiology
- T-Lymphocytes/enzymology
- T-Lymphocytes/immunology
- Tumor Cells, Cultured
- ras Proteins/metabolism
- ras-GRF1/metabolism
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Affiliation(s)
- Miguel A Sanjuán
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid, Spain
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11
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Smyth LA, Ardouin L, Williams O, Norton T, Tybulewicz V, Kioussis D. Inefficient clustering of tyrosine-phosphorylated proteins at the immunological synapse in response to an antagonist peptide. Eur J Immunol 2002; 32:3386-94. [PMID: 12432569 DOI: 10.1002/1521-4141(200212)32:12<3386::aid-immu3386>3.0.co;2-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Interactions of T cells with MHC plus peptide in the peripheral lymphoid system are important for their survival. In this study we investigated further the molecular consequences of such interactions using F5 TCR transgenic mice and peptides previously shown to induce either negative or positive selection in the thymus. Following TCR ligation with the negatively selecting agonist peptide, mature CD8(+) cells proliferated and up-regulated the activation marker CD69. Interestingly, ligation of this TCR with MHC molecules loaded with high concentrations of the positively selecting peptide also resulted in the aforementioned changes, but with slower kinetics. Analysis of the biochemical changes that occur following stimulation with these peptides showed that phosphorylation of key signaling molecules, such as ZAP-70, CD3zeta, Vav, SLP-76, LAT, and ERK-1 and 2, could be detected after exposure to agonist but not antagonist peptide. Confocal microscopy, however, revealed infrequent phosphorylation 'patches' at the site of contact between T cells and APC presenting the antagonist peptide. Our data suggest that peptides capable of inducing positive selection in the thymus can be recognized by mature T cells and cause proliferation, up-regulation of CD69 and accumulation of phosphorylated proteins at the immunological synapse with low efficiency; however no phosphorylation of signaling molecules can be detected using conventional biochemical assays.
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MESH Headings
- Animals
- Antigen-Presenting Cells/immunology
- Antigen-Presenting Cells/metabolism
- Antigens, CD/metabolism
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Binding Sites
- CD8-Positive T-Lymphocytes/drug effects
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Lectins, C-Type
- Mice
- Mice, Knockout
- Mice, Transgenic
- Peptides/pharmacology
- Phosphorylation
- Proteins/chemistry
- Proteins/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Signal Transduction
- Tyrosine/chemistry
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Affiliation(s)
- Lesley A Smyth
- Division of Molecular Immunology, The National Institute for Medical Research, London, GB
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12
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Hailman E, Burack WR, Shaw AS, Dustin ML, Allen PM. Immature CD4(+)CD8(+) thymocytes form a multifocal immunological synapse with sustained tyrosine phosphorylation. Immunity 2002; 16:839-48. [PMID: 12121665 DOI: 10.1016/s1074-7613(02)00326-6] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The immunological synapse formed during mature T cell activation consists of a central cluster of TCR and MHC molecules surrounded by a ring of LFA-1 and ICAM-1. We examined synapse formation in thymocytes undergoing activation in a lipid bilayer system by following the movement of fluorescent MHC and ICAM-1 molecules. Immature CD4(+)CD8(+) thymocytes formed a decentralized synapse with multiple foci of MHC accumulation corresponding to areas of exclusion of ICAM-1. The MHC clusters and ICAM-1 holes were mobile and transient and correlated with active and sustained signaling, as shown by staining with antibodies against phosphotyrosine and activated Lck. Our findings show that signaling in immature thymocytes can result from a novel, multifocal pattern of receptor accumulation.
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Affiliation(s)
- Eric Hailman
- Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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13
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Abstract
The immune system adjusts its response to the context in which antigens, including self-antigens, are recognized. Recent observations support a conceptual framework for understanding how this may be achieved at the cellular and cell-population levels. At both levels, 'perturbations' elicit competition between excitation and de-excitation, resulting either in adaptation or in various responses. The responsiveness of individual cells is dynamically tuned, reflecting their recent experience. The tuning of T-cell activation thresholds by self-ligands facilitates positive selection and continuously regulates the level of autoreactivity in the periphery. Autoreactivity appears to be involved in regulation of the immune response, homeostasis, maintaining of the functional integrity of naïve and memory cells, and in other physiological functions.
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Affiliation(s)
- Z Grossman
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.
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14
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Kraj P, Pacholczyk R, Ignatowicz H, Kisielow P, Jensen P, Ignatowicz L. Positive selection of CD4(+) T cells is induced in vivo by agonist and inhibited by antagonist peptides. J Exp Med 2001; 194:407-16. [PMID: 11514598 PMCID: PMC2193504 DOI: 10.1084/jem.194.4.407] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2001] [Accepted: 06/19/2001] [Indexed: 11/04/2022] Open
Abstract
The nature of peptides that positively select T cells in the thymus remains poorly defined. Here we report an in vivo model to study the mechanisms of positive selection of CD4(+) T cells. We have restored positive selection of TCR transgenic CD4(+) thymocytes, arrested at the CD4(+)CD8(+) stage, due to the lack of the endogenously selecting peptide(s), in mice deficient for H2-M and invariant chain. A single injection of soluble agonist peptide(s) initiated positive selection of CD4(+) transgenic T cells that lasted for up to 14 days. Positively selected CD4(+) T cells repopulated peripheral lymphoid organs and could respond to the antigenic peptide. Furthermore, coinjection of the antagonist peptide significantly inhibited agonist-driven positive selection. Hence, contrary to the prevailing view, positive selection of CD4(+) thymocytes can be induced in vivo by agonist peptides and may be a result of accumulation of signals from TCR engaged by different peptides bound to major histocompatibility complex class II molecules. We have also identified a candidate natural agonist peptide that induces positive selection of CD4(+) TCR transgenic thymocytes.
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Affiliation(s)
- Piotr Kraj
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912
| | - Rafal Pacholczyk
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912
| | - Hanna Ignatowicz
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912
| | - Pawel Kisielow
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, 53-114 Wroclaw, Poland
| | - Peter Jensen
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322
| | - Leszek Ignatowicz
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912
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15
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Graziano M, St-Pierre Y, Potworowski EF. UEA-I-binding to thymic medullary epithelial cells selectively reduces numbers of cortical TCRalphabeta+ thymocytes in FTOCs. Immunol Lett 2001; 77:143-50. [PMID: 11410246 DOI: 10.1016/s0165-2478(01)00218-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Thymic medullary epithelial cells (TMECs) constitute a major stromal cell type, the function of which is incompletely understood. Some TMECs express L-fucose-glycosylated proteins on their plasma membrane; these have been shown to specifically bind the lectin UEA-I. We exploited this observation to investigate the consequences of in situ blockage of TMECs in FTOCs by UEA-I. In UEA-I-treated FTOCs, we noted a decreased cellularity among TCRalphabeta+ but not TCRgammadelta+ cells. In fact, CD3- and CD3lo cortical cells were markedly depleted, while CD3hi cells were unaffected. Since the affected cell subsets are in a different compartment from that where UEA-I binding occurs, it is likely that the effect is mediated through a soluble factor. Two possible mechanisms are proposed: a reduced activation of either TMECs or of medullary thymocytes which normally bind to them, results in lowered production of soluble factors responsible for cortical thymocyte proliferation. Alternately, the binding of UEA-I to TMECs could activate the latter to produce signals inhibitory to cortical thymocytes.
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Affiliation(s)
- M Graziano
- Human Health Research Center, INRS-Institut Armand Frappier, 531 boul. des Prairies, Québec, H7N 4Z3, Laval, Canada
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16
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Wong P, Barton GM, Forbush KA, Rudensky AY. Dynamic tuning of T cell reactivity by self-peptide-major histocompatibility complex ligands. J Exp Med 2001; 193:1179-87. [PMID: 11369789 PMCID: PMC2193333 DOI: 10.1084/jem.193.10.1179] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Intrathymic self-peptide–major histocompatibility complex class II (MHC) molecules shape the T cell repertoire through positive and negative selection of immature CD4+CD8+ thymocytes. By analyzing the development of MHC class II–restricted T cell receptor (TCR) transgenic T cells under conditions in which the endogenous peptide repertoire is altered, we show that self-peptide–MHC complexes are also involved in setting T cell activation thresholds. This occurs through changes in the expression level of molecules on thymocytes that influence the sensitivity of TCR signaling. Our results suggest that the endogenous peptide repertoire modulates T cell responsiveness in the thymus in order to enforce tolerance to self-antigens.
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Affiliation(s)
- Phillip Wong
- Department of Immunology and Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle,Washington 98195
| | - Gregory M. Barton
- Department of Immunology and Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle,Washington 98195
| | - Katherine A. Forbush
- Department of Immunology and Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle,Washington 98195
| | - Alexander Y. Rudensky
- Department of Immunology and Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle,Washington 98195
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17
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Simon AK, Williams O, Mongkolsapaya J, Jin B, Xu XN, Walczak H, Screaton GR. Tumor necrosis factor-related apoptosis-inducing ligand in T cell development: sensitivity of human thymocytes. Proc Natl Acad Sci U S A 2001; 98:5158-63. [PMID: 11309507 PMCID: PMC33180 DOI: 10.1073/pnas.091100398] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2000] [Accepted: 02/28/2001] [Indexed: 01/25/2023] Open
Abstract
TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is a recently identified member of the tumor necrosis factor cytokine superfamily. TRAIL has been shown to induce apoptosis in various tumor cell lines, whereas most primary cells seem to be resistant. These observations have raised considerable interest in the use of TRAIL in tumor therapy. Yet little is known about the physiological function of TRAIL. This is particularly the case in the immune system, where TRAIL has been suggested by some to be involved in target cell killing and lymphocyte death. We have developed a panel of mAbs and soluble proteins to address the role of TRAIL in lymphocyte development. These studies demonstrate activation-induced sensitization of thymocytes to TRAIL-mediated apoptosis and expression of the apoptosis-inducing TRAIL receptors. However, with the use of several model systems, our subsequent experiments rule out the possibility that TRAIL plays a major role in antigen-induced deletion of thymocytes. In contrast to thymocytes, there is no up-regulation of TRAIL receptors in peripheral T cells on activation, which remain resistant to TRAIL. Thus, susceptibility to TRAIL-induced apoptosis is controlled differently by central and peripheral T cells.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 2
- ATP-Binding Cassette Transporters/genetics
- Animals
- Antibodies, Monoclonal
- Apoptosis/drug effects
- Apoptosis Regulatory Proteins
- CD4 Antigens/analysis
- CD8 Antigens/analysis
- Cells, Cultured
- Child, Preschool
- Clonal Deletion/drug effects
- Cytotoxicity, Immunologic
- Flow Cytometry
- Genes, RAG-1/genetics
- Humans
- Infant
- Jurkat Cells
- Lymphocyte Activation
- Membrane Glycoproteins/metabolism
- Membrane Glycoproteins/pharmacology
- Mice
- Mice, Knockout
- Organ Culture Techniques
- Receptors, TNF-Related Apoptosis-Inducing Ligand
- Receptors, Tumor Necrosis Factor/metabolism
- T-Lymphocytes/cytology
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- TNF-Related Apoptosis-Inducing Ligand
- Thymus Gland/cytology
- Thymus Gland/drug effects
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Tumor Necrosis Factor-alpha/metabolism
- Tumor Necrosis Factor-alpha/pharmacology
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Affiliation(s)
- A K Simon
- Medical Research Council Human Immunology Unit, Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, United Kingdom.
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18
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Bommhardt U, Scheuring Y, Bickel C, Zamoyska R, Hünig T. MEK activity regulates negative selection of immature CD4+CD8+ thymocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:2326-37. [PMID: 10679067 DOI: 10.4049/jimmunol.164.5.2326] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
CD4+CD8+ thymocytes are either positively selected and subsequently mature to CD4 single positive (SP) or CD8 SP T cells, or they die by apoptosis due to neglect or negative selection. This clonal selection is essential for establishing a functional self-restricted T cell repertoire. Intracellular signals through the three known mitogen-activated protein (MAP) kinase pathways have been shown to selectively guide positive or negative selection. Whereas the c-Jun N-terminal kinase and p38 MAP kinase regulate negative selection of thymocytes, the extracellular signal-regulated kinase (ERK) pathway is required for positive selection and T cell lineage commitment. In this paper, we show that the MAP/ERK kinase (MEK)-ERK pathway is also involved in negative selection. Thymocytes from newborn TCR transgenic mice were cultured with TCR/CD3epsilon-specific Abs or TCR-specific agonist peptides to induce negative selection. In the presence of the MEK-specific pharmacological inhibitors PD98059 or UO126, cell recovery was enhanced and deletion of DP thymocytes was drastically reduced. Furthermore, development of CD4 SP T cells was blocked, but differentiation of mature CD8 SP T cells proceeded in the presence of agonist peptides when MEK activity was blocked. Thus, our data indicate that the outcome between positively and negatively selecting signals is critically dependent on MEK activity.
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Affiliation(s)
- U Bommhardt
- Institute of Virology and Immunobiology, Würzburg, Germany.
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19
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Sebzda E, Mariathasan S, Ohteki T, Jones R, Bachmann MF, Ohashi PS. Selection of the T cell repertoire. Annu Rev Immunol 1999; 17:829-74. [PMID: 10358775 DOI: 10.1146/annurev.immunol.17.1.829] [Citation(s) in RCA: 358] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Advances in gene technology have allowed the manipulation of molecular interactions that shape the T cell repertoire. Although recognized as fundamental aspects of T lymphocyte development, only recently have the mechanisms governing positive and negative selection been examined at a molecular level. Positive selection refers to the active process of rescuing MHC-restricted thymocytes from programmed cell death. Negative selection refers to the deletion or inactivation of potentially autoreactive thymocytes. This review focuses on interactions during thymocyte maturation that define the T cell repertoire, with an emphasis placed on current literature within this field.
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Affiliation(s)
- E Sebzda
- Ontario Cancer Institute, Toronto, Canada
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20
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Germain RN, Stefanová I. The dynamics of T cell receptor signaling: complex orchestration and the key roles of tempo and cooperation. Annu Rev Immunol 1999; 17:467-522. [PMID: 10358766 DOI: 10.1146/annurev.immunol.17.1.467] [Citation(s) in RCA: 317] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
T cells constantly sample their environment using receptors (TCR) that possess both a germline-encoded low affinity for major histocompatibility complex (MHC) molecules and a highly diverse set of CDR3 regions contributing to a range of affinities for specific peptides bound to these MHC molecules. The decision of a T cell "to sense and to respond" with proliferation and effector activity rather than "to sense, live on, but not respond" is dependent on TCR interaction with a low number of specific foreign peptide:MHC molecule complexes recognized simultaneously with abundant self peptide-containing complexes. Interaction with self-complexes alone, on the other hand, generates a signal for survival without a full activation response. Current models for how this distinction is achieved are largely based on translating differences in receptor affinity for foreign versus self ligands into intracellular signals that differ in quality, intensity, and/or duration. A variety of rate-dependent mechanisms involving assembly of molecular oligomers and enzymatic modification of proteins underlie this differential signaling. Recent advances have been made in measuring TCR:ligand interactions, in understanding the biochemical origin of distinct proximal and distal signaling events resulting from TCR binding to various ligands, and in appreciating the role of feedback pathways. This new information can be synthesized into a model of how self and foreign ligand recognition each evoke the proper responses from T cells, how these two classes of signaling events interact, and how pathologic responses may arise as a result of the underlying properties of the system. The principles of signal spreading and stochastic resonance incorporated into this model reveal a striking similarity in mechanisms of decision-making among T cells, neurons, and bacteria.
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Affiliation(s)
- R N Germain
- Lymphocyte Biology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. ,
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21
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Mariathasan S, Bachmann MF, Bouchard D, Ohteki T, Ohashi PS. Degree of TCR Internalization and Ca2+ Flux Correlates with Thymocyte Selection. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.11.6030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Recent evidence suggests that TCR down-regulation directly reflects the number of TCRs that have engaged MHC/peptide ligand complexes. Here, we examined the influence of defined peptides on thymic selection based on their ability to induce differential TCR internalization. Our results demonstrate that there is a direct correlation: peptides that induce strong TCR down-regulation are most efficient at mediating negative selection, whereas peptides that induce suboptimal TCR internalization are more efficient at triggering positive selection. As a consequence of suboptimal TCR internalization, a proportion of TCR complexes that remain on the cell surface may be able to relay continual signals required for survival and differentiation. In addition, we show that the magnitude of Ca2+ influx set by these peptides reflects the hierarchy of TCR down-regulation and correlates with positive vs negative selection of transgenic thymocytes. Together, our data suggest that T cell selection is mediated by differing intensities of the same TCR-mediated signal, rather than by distinct signals.
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Affiliation(s)
- Sanjeev Mariathasan
- *Departments of Medical Biophysics and Immunology, Ontario Cancer Institute, and
| | - Martin F. Bachmann
- *Departments of Medical Biophysics and Immunology, Ontario Cancer Institute, and
| | | | - Toshiaki Ohteki
- *Departments of Medical Biophysics and Immunology, Ontario Cancer Institute, and
| | - Pamela S. Ohashi
- *Departments of Medical Biophysics and Immunology, Ontario Cancer Institute, and
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