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Abstract
After selection in the thymus, the post-thymic T cell compartments comprise heterogenous subsets of naive and memory T cells that make continuous T cell receptor (TCR) contact with self-ligands bound to major histocompatibility complex (MHC) molecules. T cell recognition of self-MHC ligands elicits covert TCR signaling and is particularly important for controlling survival of naive T cells. Such tonic TCR signaling is tightly controlled and maintains the cells in a quiescent state to avoid autoimmunity. Here, we review how naive and memory T cells are differentially tuned and wired for TCR sensitivity to self and foreign ligands.
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Affiliation(s)
- Jae-Ho Cho
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang, Korea.,Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Korea
| | - Jonathan Sprent
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Korea.,Immunology Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
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A regulatory role for TGF-β signaling in the establishment and function of the thymic medulla. Nat Immunol 2014; 15:554-61. [DOI: 10.1038/ni.2869] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 03/11/2014] [Indexed: 12/16/2022]
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Bains I, van Santen HM, Seddon B, Yates AJ. Models of self-peptide sampling by developing T cells identify candidate mechanisms of thymic selection. PLoS Comput Biol 2013; 9:e1003102. [PMID: 23935465 PMCID: PMC3723501 DOI: 10.1371/journal.pcbi.1003102] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 05/01/2013] [Indexed: 11/18/2022] Open
Abstract
Conventional and regulatory T cells develop in the thymus where they are exposed to samples of self-peptide MHC (pMHC) ligands. This probabilistic process selects for cells within a range of responsiveness that allows the detection of foreign antigen without excessive responses to self. Regulatory T cells are thought to lie at the higher end of the spectrum of acceptable self-reactivity and play a crucial role in the control of autoimmunity and tolerance to innocuous antigens. While many studies have elucidated key elements influencing lineage commitment, we still lack a full understanding of how thymocytes integrate signals obtained by sampling self-peptides to make fate decisions. To address this problem, we apply stochastic models of signal integration by T cells to data from a study quantifying the development of the two lineages using controllable levels of agonist peptide in the thymus. We find two models are able to explain the observations; one in which T cells continually re-assess fate decisions on the basis of multiple summed proximal signals from TCR-pMHC interactions; and another in which TCR sensitivity is modulated over time, such that contact with the same pMHC ligand may lead to divergent outcomes at different stages of development. Neither model requires that T(conv) and T(reg) are differentially susceptible to deletion or that the two lineages need qualitatively different signals for development, as have been proposed. We find additional support for the variable-sensitivity model, which is able to explain apparently paradoxical observations regarding the effect of partial and strong agonists on T(conv) and T(reg) development.
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Affiliation(s)
- Iren Bains
- Immune Cell Biology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, New York, New York, United States of America
| | - Hisse M. van Santen
- Centro Biologia Molecular Severo Ochoa, CSIC/Universidad Autonoma de Madrid, Madrid, Spain
| | - Benedict Seddon
- Immune Cell Biology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Andrew J. Yates
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, New York, New York, United States of America
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, New York, United States of America
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Self-peptides in TCR repertoire selection and peripheral T cell function. Curr Top Microbiol Immunol 2013; 373:49-67. [PMID: 23612987 DOI: 10.1007/82_2013_319] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The vertebrate antigen receptors are anticipatory in their antigen recognition and display a vast diversity. Antigen receptors are assembled through V(D)J recombination, in which one of each Variable, (Diverse), and Joining gene segment are randomly utilized and recombined. Both gene rearrangement and mutational insertion are generated through randomness; therefore, the process of antigen receptors generation requires a rigorous testing system to select every receptor which is useful to recognize foreign antigens, but which would cause no harm to self cells. In the case of T cell receptors (TCR), such a quality control responsibility rests in thymic positive and negative selection. In this review, we focus on the critical involvement of self-peptides in the generation of a T cell repertoire, discuss the role of T cell thymic development in shaping the specificity of TCR repertoire, and directing function fitness of mature T cells in periphery. Here, we consider thymic positive selection to be not merely a one-time maturing experience for an individual T cell, but a life-long imprinting which influences the function of each individual T cell in periphery.
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Subcellular distribution of Lck during CD4 T-cell maturation in the thymic medulla regulates the T-cell activation threshold. Proc Natl Acad Sci U S A 2012; 109:7415-20. [PMID: 22529380 DOI: 10.1073/pnas.1119272109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Mature peripheral T cells respond to foreign but not to self-antigens. During development in the thymus, deletion of high-affinity self-reactive immature thymocytes contributes to tolerance of mature T cells. However, double-positive thymocytes are positively selected to survive if they respond to self-peptide-MHC complexes; thus, there must be mechanisms to prevent overt reactivity to those same complexes in the periphery. "Developmental tuning" is the active process through which T-cell receptor (TCR)-associated signaling pathways of single-positive (SP) thymocytes are attenuated to respond appropriately to self-peptide-MHC complexes in the periphery. We previously showed that MHC class II expression in the thymic medulla was necessary to tune CD4(+) SP (CD4 SP) thymocytes. CD4 SP thymocytes from mice lacking medullary MHC class II expression had inappropriately enhanced proximal TCR signaling to low-affinity self-ligands that was associated with altered cellular distribution of the tyrosine kinase Lck. Now, we report that activation of both tuned and untuned CD4 SP thymocytes is Lck-dependent. Untuned CD4 SP cells contain a pool of Lck with increased basal phosphorylation that is not associated with the CD4 coreceptor. Phosphorylation of this pool of Lck decreases with tuning. Immunogold transmission electron microscopy of membrane sheets permitted direct visualization of Lck. In the absence of tuning, a significant proportion of Lck and the TCR subunit CD3ζ are expressed on the same protein island; this close association of Lck and the TCR probably explains the enhanced activation of untuned CD4 SP cells. Thus, changes in membrane topography during thymic maturation determine the set point for TCR responsiveness.
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Detanico T, Heiser RA, Aviszus K, Bonorino C, Wysocki LJ. Self-tolerance checkpoints in CD4 T cells specific for a peptide derived from the B cell antigen receptor. THE JOURNAL OF IMMUNOLOGY 2011; 187:82-91. [PMID: 21622865 DOI: 10.4049/jimmunol.1002287] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Linked recognition of Ag by B and T lymphocytes is ensured in part by a state of tolerance acquired by CD4 T cells to germline-encoded sequences within the B cell Ag receptor (BCR). We sought to determine how such tolerance is attained when a peptide from the BCR variable (V) region is expressed by small numbers of B cells as it is in the physiological state. Mixed bone marrow (BM) chimeras were generated using donor BM from mice with B cells that expressed a transgene (Tg)-encoded κ L chain and BM from TCR Tg mice in which the CD4 T cells (CA30) were specific for a Vκ peptide encoded by the κTg. In chimeras where few B cells express the κTg, many CA30 cells were deleted in the thymus. However, a substantial fraction survived to the CD4 single-positive stage. Among single-positive CA30 thymocytes, few reached maturity and migrated to the periphery. Maturation was strongly associated with, and likely promoted by, expression of an endogenous TCR α-chain. CD4(+) CA30 cells that reached peripheral lymphoid tissues were Ag-experienced and anergic, and some developed into regulatory cells. These findings reveal several checkpoints and mechanisms that enforce a state of self-tolerance in developing T cells specific for BCR V region sequences, thus ensuring that T cell help to B cells occurs through linked recognition of foreign Ag.
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Affiliation(s)
- Thiago Detanico
- Integrated Department of Immunology, National Jewish Health, University of Colorado School of Medicine, Denver, CO 80206, USA
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Stephen TL, Tikhonova A, Riberdy JM, Laufer TM. The activation threshold of CD4+ T cells is defined by TCR/peptide-MHC class II interactions in the thymic medulla. THE JOURNAL OF IMMUNOLOGY 2009; 183:5554-62. [PMID: 19843939 DOI: 10.4049/jimmunol.0901104] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Immature thymocytes that are positively selected based upon their response to self-peptide-MHC complexes develop into mature T cells that are not overtly reactive to those same complexes. Developmental tuning is the active process through which TCR-associated signaling pathways of single-positive thymocytes are attenuated to respond appropriately to the peptide-MHC molecules that will be encountered in the periphery. In this study, we explore the mechanisms that regulate the tuning of CD4(+) single-positive T cells to MHC class II encountered in the thymic medulla. Experiments with murine BM chimeras demonstrate that tuning can be mediated by MHC class II expressed by either thymic medullary epithelial cells or thymic dendritic cells. Tuning does not require the engagement of CD4 by MHC class II on stromal cells. Rather, it is mediated by interactions between MHC class II and the TCR. To understand the molecular changes that distinguish immature hyperactive T cells from tuned mature CD4(+) T cells, we compared their responses to TCR stimulation. The altered response of mature CD4 single-positive thymocytes is characterized by the inhibition of ERK activation by low-affinity self-ligands and increased expression of the inhibitory tyrosine phosphatase SHP-1. Thus, persistent TCR engagement by peptide-MHC class II on thymic medullary stroma inhibits reactivity to self-Ags and prevents autoreactivity in the mature repertoire.
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Affiliation(s)
- Tom Li Stephen
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Brodeur JF, Li S, Damlaj O, Dave VP. Expression of fully assembled TCR-CD3 complex on double positive thymocytes: synergistic role for the PRS and ER retention motifs in the intra-cytoplasmic tail of CD3epsilon. Int Immunol 2009; 21:1317-27. [PMID: 19819936 DOI: 10.1093/intimm/dxp098] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
TCR expression on double-positive (DP) thymocytes is a prerequisite for thymic selection that results in the generation of mature CD4(+) and CD8(+) single-positive T cells. TCR is expressed at very low level on preselection DP thymocytes and is dramatically up-regulated on positively selected thymocytes. However, mechanism governing TCR expression on developing thymocytes is not understood. In the present report, we demonstrate that the intra-cytoplasmic (IC) domain of CD3epsilon plays a critical role in regulating TCR expression on DP thymocytes. We provide genetic and biochemical evidence to show that the CD3epsilon IC domain mutations result in elevated expression of fully assembled TCR on DP thymocytes. We also demonstrate that TCR up-regulation on DP thymocytes in these transgenic mice occurs in a ligand-independent manner. Further, we show that the proline-rich sequence and endoplasmic reticulum (ER) retention motifs in the IC domain of CD3epsilon play synergistic role in regulating TCR surface expression on DP thymocytes.
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Affiliation(s)
- Jean-Francois Brodeur
- Lymphocyte Development Laboratory, Institut de Recherches Cliniques de Montreal, Montreal, Quebec, Canada H2W 1R7
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Maric M, Barjaktarevic I, Bogunovic B, Stojakovic M, Maric C, Vukmanovic S. Cutting Edge: Developmental Up-Regulation of IFN-γ-Inducible Lysosomal Thiol Reductase Expression Leads to Reduced T Cell Sensitivity and Less Severe Autoimmunity. THE JOURNAL OF IMMUNOLOGY 2009; 182:746-50. [DOI: 10.4049/jimmunol.182.2.746] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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McCaughtry TM, Hogquist KA. Central tolerance: what have we learned from mice? Semin Immunopathol 2008; 30:399-409. [PMID: 19015857 DOI: 10.1007/s00281-008-0137-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 10/01/2008] [Indexed: 10/21/2022]
Abstract
Producing a healthy immune system capable of defending against pathogens, while avoiding autoimmunity, is dependent on thymic selection. Positive selection yields functional T cells that have the potential to recognize both self and foreign antigens. Therefore, negative selection exists to manage potentially self-reactive cells. Negative selection results from the induction of anergy, receptor editing, clonal diversion (agonist selection), and/or clonal deletion (apoptosis) in self-reactive clones. Clonal deletion has been inherently difficult to study because the cells of interest are undergoing apoptosis and being eliminated quickly. Furthermore, analysis of clonal deletion in humans has proved even more difficult due to availability of samples and lack of reagents. Mouse models have thus been instrumental in achieving our current understanding of central tolerance, and the evolution of elegant model systems has led to an explosion of new data to be assimilated. This review will focus on recent advances in the field of clonal deletion with respect to three aspects: the development of physiological model systems, signaling pathways that lead to apoptosis, and antigen presenting cell types involved in the induction of clonal deletion.
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Affiliation(s)
- Tom M McCaughtry
- Center for Immunology, Laboratory Medicine & Pathology, University of Minnesota, Mayo Mail Code 334, 420 Delaware Street SE, Minneapolis, MN, 55454, USA
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McCaughtry TM, Baldwin TA, Wilken MS, Hogquist KA. Clonal deletion of thymocytes can occur in the cortex with no involvement of the medulla. ACTA ACUST UNITED AC 2008; 205:2575-84. [PMID: 18936237 PMCID: PMC2571932 DOI: 10.1084/jem.20080866] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The thymic medulla is generally held to be a specialized environment for negative selection. However, many self-reactive thymocytes first encounter ubiquitous self-antigens in the cortex. Cortical epithelial cells are vital for positive selection, but whether such cells can also promote negative selection is controversial. We used the HYcd4 model, where T cell receptor for antigen (TCR) expression is appropriately timed and a ubiquitous self-antigen drives clonal deletion in male mice. We demonstrated unambiguously that this deletion event occurs in the thymic cortex. However, the kinetics in vivo indicated that apoptosis was activated asynchronously relative to TCR activation. We found that radioresistant antigen-presenting cells and, specifically, cortical epithelial cells do not efficiently induce apoptosis, although they do cause TCR activation. Rather, thymocytes undergoing clonal deletion were preferentially associated with rare CD11c+ cortical dendritic cells, and elimination of such cells impaired deletion.
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Affiliation(s)
- Tom M McCaughtry
- Center for Immunology, Laboratory Medicine, and Pathology, University of Minnesota, Minneapolis, MN 55454, USA
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Gil D, Schrum AG, Daniels MA, Palmer E. A role for CD8 in the developmental tuning of antigen recognition and CD3 conformational change. THE JOURNAL OF IMMUNOLOGY 2008; 180:3900-9. [PMID: 18322198 DOI: 10.4049/jimmunol.180.6.3900] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TCR engagement by peptide-MHC class I (pMHC) ligands induces a conformational change (Deltac) in CD3 (CD3Deltac) that contributes to T cell signaling. We found that when this interaction took place between primary T lineage cells and APCs, the CD8 coreceptor was required to generate CD3Deltac. Interestingly, neither enhancement of Ag binding strength nor Src kinase signaling explained this coreceptor activity. Furthermore, Ag-induced CD3Deltac was developmentally attenuated by the increase in sialylation that accompanies T cell maturation and limits CD8 activity. Thus, both weak and strong ligands induced CD3Deltac in preselection thymocytes, but only strong ligands were effective in mature T cells. We propose that CD8 participation in the TCR/pMHC interaction can physically regulate CD3Deltac induction by "translating" productive Ag encounter from the TCR to the CD3 complex. This suggests one mechanism by which the developmentally regulated variation in CD8 sialylation may contribute to the developmental tuning of T cell sensitivity.
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Affiliation(s)
- Diana Gil
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Specificity of amyloid precursor-like protein 2 interactions with MHC class I molecules. Immunogenetics 2008; 60:303-13. [PMID: 18452037 DOI: 10.1007/s00251-008-0296-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 04/02/2008] [Indexed: 10/22/2022]
Abstract
The ubiquitously expressed amyloid precursor-like protein 2 (APLP2) has been previously found to regulate cell surface expression of the major histocompatibility complex (MHC) class I molecule K(d) and bind strongly to K(d). In the study reported here, we demonstrated that APLP2 binds, in varied degrees, to several other mouse MHC class I allotypes and that the ability of APLP2 to affect cell surface expression of an MHC class I molecule is not limited to K(d). L(d), like K(d), was found associated with APLP2 in the Golgi, but K(d) was also associated with APLP2 within intracellular vesicular structures. We also investigated the effect of beta(2)m on APLP2/MHC interaction and found that human beta(2)m transfection increased the association of APLP2 with mouse MHC class I molecules, likely by affecting H2 class I heavy chain conformation. APLP2 was demonstrated to bind specifically to the conformation of L(d) having folded outer domains, consistent with our previous results with K(d) and indicating APLP2 interacts with the alpha1alpha2 region on each of these H2 class I molecules. Furthermore, we observed that binding to APLP2 involved the MHC alpha3/transmembrane/cytoplasmic region, suggesting that conserved as well as polymorphic regions of the H2 class I molecule may participate in interaction with APLP2. In summary, we demonstrated that APLP2's binding, co-localization pattern, and functional impact vary among H2 class I molecules and that APLP2/MHC association is influenced by multiple domains of the MHC class I heavy chain and by beta(2)m's effects on the conformation of the heavy chain.
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Mingueneau M, Sansoni A, Grégoire C, Roncagalli R, Aguado E, Weiss A, Malissen M, Malissen B. The proline-rich sequence of CD3epsilon controls T cell antigen receptor expression on and signaling potency in preselection CD4+CD8+ thymocytes. Nat Immunol 2008; 9:522-32. [PMID: 18408722 DOI: 10.1038/ni.1608] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 03/13/2008] [Indexed: 12/11/2022]
Abstract
Antigen recognition by T cell antigen receptors (TCRs) is thought to 'unmask' a proline-rich sequence (PRS) present in the CD3epsilon cytosolic segment, which allows it to trigger T cell activation. Using 'knock-in' mice with deletion of the PRS, we demonstrate here that elimination of the CD3epsilon PRS had no effect on mature T cell responsiveness. In contrast, in preselection CD4+CD8+ thymocytes, the CD3epsilon PRS acted together with the adaptor protein SLAP to promote CD3zeta degradation, thereby contributing to downregulation of TCR expression on the cell surface. In addition, analysis of CD4+CD8+ thymocytes of TCR-transgenic mice showed that the CD3epsilon PRS enhanced TCR sensitivity to weak ligands. Our results identify previously unknown functions for the evolutionarily conserved CD3epsilon PRS at the CD4+CD8+ developmental stage and suggest a rather limited function in mature T cells.
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Affiliation(s)
- Michaël Mingueneau
- Centre d'Immunologie de Marseille-Luminy, Université de la Méditerrannée, Case 906, Institut National de la Santé et de la Recherche Médicale U631, and Centre National de la Recherche Scientifique UMR6102, 13288 Marseille Cedex 9, France
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Haraldsson MK, Louis-Dit-Sully CA, Lawson BR, Sternik G, Santiago-Raber ML, Gascoigne NRJ, Theofilopoulos AN, Kono DH. The lupus-related Lmb3 locus contains a disease-suppressing Coronin-1A gene mutation. Immunity 2008; 28:40-51. [PMID: 18199416 PMCID: PMC2274909 DOI: 10.1016/j.immuni.2007.11.023] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 11/12/2007] [Accepted: 11/28/2007] [Indexed: 10/22/2022]
Abstract
Here, we show that a lupus-suppressing locus is caused by a nonsense mutation of the filamentous actin-inhibiting Coronin-1A gene. This mutation was associated with developmental and functional alterations in T cells including reduced migration, survival, activation, and Ca2+ flux. T-dependent humoral responses were impaired, but no intrinsic B cell defects were detected. By transfer of T cells, it was shown that suppression of autoimmunity could be accounted for by the presence of the Coro1a(Lmb3) mutation in T cells. Our results demonstrate that Coronin-1A is required for the development of systemic lupus and identify actin-cytoskeleton regulatory proteins as potential targets for modulating autoimmune diseases.
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Affiliation(s)
| | | | - Brian R. Lawson
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037
| | - Gabriel Sternik
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037
| | | | | | | | - Dwight H. Kono
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037
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Abstract
Conventional αβ T cell precursors undergo positive selection in the thymic cortex. When this is successful, they migrate to the medulla and are exposed to tissue-specific antigens (TSA) for purposes of central tolerance, and they undergo maturation to become functionally responsive T cells. It is commonly understood that thymocytes spend up to 2 wk in the medulla undergoing these final maturation steps before emigrating to peripheral lymphoid tissues. In addition, emigration is thought to occur via a stochastic mechanism whereby some progenitors leave early and others leave late—a so-called “lucky dip” process. However, recent research has revealed that medullary thymocytes are a heterogeneous mix of naive αβ T cell precursors, memory T cells, natural killer T cells, and regulatory T cells. Given this, we revisited the question of how long it takes naive αβ T cell precursors to emigrate. We combined the following three approaches to study this question: BrdU labeling, intrathymic injection of a cellular tag, and RAG2p-GFP reporter mice. We established that, on average, naive αβ T cell precursors emigrate only 4–5 d after becoming single-positive (SP) thymocytes. Furthermore, emigration occurs via a strict “conveyor belt” mechanism, where the oldest thymocytes leave first.
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Affiliation(s)
- Tom M McCaughtry
- Center for Immunology, Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455
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Kuwano Y, Prazma CM, Yazawa N, Watanabe R, Ishiura N, Kumanogoh A, Okochi H, Tamaki K, Fujimoto M, Tedder TF. CD83 influences cell-surface MHC class II expression on B cells and other antigen-presenting cells. Int Immunol 2007; 19:977-92. [PMID: 17804692 DOI: 10.1093/intimm/dxm067] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
CD83 is a member of the Ig superfamily expressed primarily by mature dendritic cells (DCs). In mice, CD83 expression by thymic stromal cells regulates CD4(+) T cell development, with CD83(-/-) mice demonstrating dramatic reductions in both thymus and peripheral CD4(+) T cells. In this study, CD83 expression was also found to affect MHC class II antigen expression within the thymus and periphery. CD83 deficiency reduced cell-surface class II antigen expression by 25-50% on splenic B cells and DCs, thymic epithelial cells and peritoneal macrophages. Reduced class II expression was a stable and intrinsic property that resulted from increased internalization of class II from the surface of CD83(-/-) B cells. Otherwise, class II antigen transcription, intracellular expression, heterodimer structure, antigen processing and antigen presentation were normal. Reduced class II antigen expression was not the primary cause of the CD83(-/-) phenotype since thymocyte and peripheral T cell development was normal in class II(+/-) mice. Comparable blocks in CD4(+) thymocyte development were also observed in CD83(-/-) and CD83(-/-)class II(+/-) littermates. TCR and CD69 expression patterns in CD83(-/-) mice further suggested that double-positive thymocytes proceed through the class II-dependent stages of positive selection in the absence of CD83. These studies further emphasize a role for CD83 in lymphocyte development and immune regulation and reveal an unexpected role for CD83 expression in influencing cell-surface MHC class II turnover.
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Affiliation(s)
- Yoshihiro Kuwano
- Department of Dermatology, Faculty of Medicine, University of Tokyo, Tokyo, Japan
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