1
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Nguyen J, Pettmann J, Kruger P, Dushek O. Quantitative contributions of TNF receptor superfamily members to CD8 + T-cell responses. Mol Syst Biol 2021; 17:e10560. [PMID: 34806839 PMCID: PMC8607805 DOI: 10.15252/msb.202110560] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 11/09/2022] Open
Abstract
T-cell responses to infections and cancers are regulated by co-signalling receptors grouped into the binary categories of co-stimulation or co-inhibition. The co-stimulation TNF receptor superfamily (TNFRSF) members 4-1BB, CD27, GITR and OX40 have similar signalling mechanisms raising the question of whether they have similar impacts on T-cell responses. Here, we screened for the quantitative impact of these TNFRSFs on primary human CD8+ T-cell cytokine production. Although both 4-1BB and CD27 increased production, only 4-1BB was able to prolong the duration over which cytokine was produced, and both had only modest effects on antigen sensitivity. An operational model explained these different phenotypes using shared signalling based on the surface expression of 4-1BB being regulated through signalling feedback. The model predicted and experiments confirmed that CD27 co-stimulation increases 4-1BB expression and subsequent 4-1BB co-stimulation. GITR and OX40 displayed only minor effects on their own but, like 4-1BB, CD27 could enhance GITR expression and subsequent GITR co-stimulation. Thus, different co-stimulation receptors can have different quantitative effects allowing for synergy and fine-tuning of T-cell responses.
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Affiliation(s)
- John Nguyen
- SirWilliam Dunn School of PathologyUniversity of OxfordOxfordUK
| | | | - Philipp Kruger
- SirWilliam Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Omer Dushek
- SirWilliam Dunn School of PathologyUniversity of OxfordOxfordUK
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2
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Lindenbergh MFS, Wubbolts R, Borg EGF, van ’T Veld EM, Boes M, Stoorvogel W. Dendritic cells release exosomes together with phagocytosed pathogen; potential implications for the role of exosomes in antigen presentation. J Extracell Vesicles 2020; 9:1798606. [PMID: 32944186 PMCID: PMC7480536 DOI: 10.1080/20013078.2020.1798606] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 06/12/2020] [Accepted: 06/29/2020] [Indexed: 12/11/2022] Open
Abstract
Dendritic cells (DC) have the unique capacity to activate naïve T cells by presenting T cell receptor specific peptides from exogenously acquired antigens bound to Major Histocompatibility Complex (MHC) molecules. MHC molecules are displayed on the DC plasma membrane as well as on extracellular vesicles (EV) that are released by DC, and both have antigen-presenting capacities. However, the physiological role of antigen presentation by EV is still unclear. We here demonstrate that the release of small EV by activated DC is strongly stimulated by phagocytic events. We show that, concomitant with the enhanced release of EV, a significant proportion of phagocytosed bacteria was expulsed back into the medium. High-resolution fluorescence microscopic images revealed that bacteria in phagosomes were surrounded by EV marker-proteins. Moreover, expulsed bacteria were often found associated with clustered HLA II and CD63. Together, these observations suggest that exosomes may be formed by the inward budding into phagosomes, whereupon they are secreted together with the phagosomal content. These findings may have important implications for selective loading of peptides derived from phagocytosed pathogens onto exosome associated HLA molecules, and have important implications for vaccine design.
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Affiliation(s)
- Marthe F. S. Lindenbergh
- Department Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
- Department of Pediatrics and Laboratory of Translational Immunology, University Medical Center Utrecht, University Utrecht, Utrecht, The Netherlands
| | - Richard Wubbolts
- Department Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Ellen G. F. Borg
- Department Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Esther M. van ’T Veld
- Department Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Marianne Boes
- Department of Pediatrics and Laboratory of Translational Immunology, University Medical Center Utrecht, University Utrecht, Utrecht, The Netherlands
| | - W. Stoorvogel
- Department Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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3
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Biernat M, Cydzik M, Stefanowicz P, Kluczyk A, Artym J, Zimecki M, Szewczuk Z. Cyclodimerization of immunosuppressive fragment of HLA-DR molecule. Design, synthesis and ESI-MS/MS analysis. J Pept Sci 2016; 22:525-32. [PMID: 27443978 DOI: 10.1002/psc.2898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/17/2016] [Accepted: 05/17/2016] [Indexed: 11/06/2022]
Abstract
The nonapeptide fragment of the HLA-DR molecule, located in the exposed loop of the alpha-chain (164-172), having the VPRSGEVYT sequence, suppresses the immune response. Based on the three-dimensional structure of the HLA-DR superdimer, we designed a new cyclodimeric analog in which the two parallel peptide chains of VPRSGEVYT sequence are linked through their C-termini by spacer of (Gly5 )2 -Lys-NH2 and the N-termini are also linked by poly(ethylene glycol). The (VPRSGEVYTG5 )2 K-resin analog was synthesized using solid-phase peptide synthesis protocols. The cyclization was achieved by cross-linking the N-terminal positions of the dimeric peptide, attached to a MBHA resin, with alpha, omega-bis (acetic acid) poly(ethylene glycol), activated by esterification with pentafluorophenol. Our results demonstrate that the cyclodimerization of VPRSGEVYT results in enhanced immunosuppressive activity of the peptide. Mass spectrometry fragmentation analysis of the obtained cyclodimeric peptide is also presented. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
- Monika Biernat
- Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland
| | - Marzena Cydzik
- Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland.,Department of Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | | | - Alicja Kluczyk
- Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland
| | - Jolanta Artym
- Institute of Immunology and Experimental Therapy, PAS, Wrocław, Poland
| | - Michał Zimecki
- Institute of Immunology and Experimental Therapy, PAS, Wrocław, Poland
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4
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López CA, Sethi A, Goldstein B, Wilson BS, Gnanakaran S. Membrane-mediated regulation of the intrinsically disordered CD3ϵ cytoplasmic tail of the TCR. Biophys J 2015; 108:2481-2491. [PMID: 25992726 PMCID: PMC4457001 DOI: 10.1016/j.bpj.2015.03.059] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 01/27/2015] [Accepted: 03/02/2015] [Indexed: 10/23/2022] Open
Abstract
The regulation of T-cell-mediated immune responses depends on the phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) on T-cell receptors. Although many details of the signaling cascades are well understood, the initial mechanism and regulation of ITAM phosphorylation remains unknown. We used molecular dynamics simulations to study the influence of different compositions of lipid bilayers on the membrane association of the CD3ϵ cytoplasmic tails of the T-cell receptors. Our results show that binding of CD3ϵ to membranes is modulated by both the presence of negatively charged lipids and the lipid order of the membrane. Free-energy calculations reveal that the protein-membrane interaction is favored by the presence of nearby basic residues and the ITAM tyrosines. Phosphorylation minimizes membrane association, rendering the ITAM motif more accessible to binding partners. In systems mimicking biological membranes, the CD3ϵ chain localization is modulated by different facilitator lipids (e.g., gangliosides or phosphoinositols), revealing a plausible regulatory effect on activation through the regulation of lipid composition in cell membranes.
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Affiliation(s)
- Cesar A López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Anurag Sethi
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Byron Goldstein
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Bridget S Wilson
- Department of Pathology and Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico; New Mexico Consortium, Los Alamos, New Mexico.
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5
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Castro M, van Santen HM, Férez M, Alarcón B, Lythe G, Molina-París C. Receptor Pre-Clustering and T cell Responses: Insights into Molecular Mechanisms. Front Immunol 2014; 5:132. [PMID: 24817867 PMCID: PMC4012210 DOI: 10.3389/fimmu.2014.00132] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 03/15/2014] [Indexed: 11/13/2022] Open
Abstract
T cell activation, initiated by T cell receptor (TCR) mediated recognition of pathogen-derived peptides presented by major histocompatibility complex class I or II molecules (pMHC), shows exquisite specificity and sensitivity, even though the TCR-pMHC binding interaction is of low affinity. Recent experimental work suggests that TCR pre-clustering may be a mechanism via which T cells can achieve such high sensitivity. The unresolved stoichiometry of the TCR makes TCR-pMHC binding and TCR triggering, an open question. We formulate a mathematical model to characterize the pre-clustering of T cell receptors (TCRs) on the surface of T cells, motivated by the experimentally observed distribution of TCR clusters on the surface of naive and memory T cells. We extend a recently introduced stochastic criterion to compute the timescales of T cell responses, assuming that ligand-induced cross-linked TCR is the minimum signaling unit. We derive an approximate formula for the mean time to signal initiation. Our results show that pre-clustering reduces the mean activation time. However, additional mechanisms favoring the existence of clusters are required to explain the difference between naive and memory T cell responses. We discuss the biological implications of our results, and both the compatibility and complementarity of our approach with other existing mathematical models.
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Affiliation(s)
- Mario Castro
- Grupo de Dinámica No-Lineal and Grupo Interdisciplinar de Sistemas Complejos (GISC), Escuela Técnica Superior de Ingeniería (ICAI), Universidad Pontificia Comillas , Madrid , Spain
| | - Hisse M van Santen
- Departamento de Biología Celular e Inmunología, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid , Madrid , Spain
| | - María Férez
- Departamento de Biología Celular e Inmunología, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid , Madrid , Spain
| | - Balbino Alarcón
- Departamento de Biología Celular e Inmunología, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid , Madrid , Spain
| | - Grant Lythe
- Department of Applied Mathematics, School of Mathematics, University of Leeds , Leeds , UK
| | - Carmen Molina-París
- Department of Applied Mathematics, School of Mathematics, University of Leeds , Leeds , UK
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6
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Zarnitsyna V, Zhu C. T cell triggering: insights from 2D kinetics analysis of molecular interactions. Phys Biol 2012; 9:045005. [PMID: 22871794 DOI: 10.1088/1478-3975/9/4/045005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Interaction of the T cell receptor (TCR) with pathogen-derived peptide presented by the major histocompatibility complex (pMHC) molecule is central to adaptive immunity as it initiates intracellular signaling to trigger T cell response to infection. Kinetic parameters of this interaction have been under intensive investigation for more than two decades using soluble pMHCs and/or TCRs with at least one of them in the solution (three-dimensional (3D) methods). Recently, several techniques have been developed to enable kinetic analysis on live T cells with pMHCs presented by surrogate antigen presenting cells (APCs) or supported planar lipid bilayers (two-dimensional (2D) methods). Comparison of 2D versus 3D parameters reveals drastic differences with broader ranges of 2D affinities and on-rates and orders of magnitude faster 2D off-rates for functionally distinct pMHCs. Here we review new 2D data and discuss how it may impact previously developed models of T cell discrimination between pMHCs of different potencies.
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Affiliation(s)
- Veronika Zarnitsyna
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.
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7
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Sigalov AB. "Monovalent" ligands that trigger TLR-4 and TCR are not necessarily truly monovalent. Mol Immunol 2012; 51:356-62. [PMID: 22520974 DOI: 10.1016/j.molimm.2012.03.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 03/25/2012] [Indexed: 01/23/2023]
Abstract
Cell surface receptors mediate many cellular responses in health and disease. Recent progress in our understanding of how ligand binding to the extracellular domains of receptors triggers intracellular signaling has underlined the role of ligand-promoted receptor clustering following by oligomerization of the cytoplasmic signaling domains. The clustering suggests the requirement of ligand multivalency and is especially important for triggering receptors involved in innate and adaptive immune responses. However, although numerous studies have established that multivalent, but not monovalent, ligands induce receptor-mediated signal transduction, considerable uncertainty still remains. Here, I hypothesize that "monovalent" ligands that have been reported to trigger immune receptors in vitro are not necessarily truly monovalent. This is illustrated by focusing on studies of signal transduction by toll-like receptor-4 and T cell receptor. By generalizing this concept to a variety of lipid and protein ligands, one would propose an alternative interpretation of apparent ligand monovalency in other receptor activation studies as well.
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8
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Edidin M. Class I MHC molecules as probes of membrane patchiness: from biophysical measurements to modulation of immune responses. Immunol Res 2010; 47:265-72. [PMID: 20077159 DOI: 10.1007/s12026-009-8159-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Here I summarize decades of work using the biophysics of class I MHC molecules to probe the patchiness and heterogeneity of cell surfaces. This program began as a study of membranes generally. MHC molecules were a convenient probe. However, in recent years, it has become clear that the lateral distribution, clustering, of class I MHC molecules in the membrane affects their recognition by effector CTL. This offers the possibility of enhancing or reducing T-cell recognition of targets by altering the clustering of their membrane proteins.
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Affiliation(s)
- Michael Edidin
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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9
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Sigalov AB. The SCHOOL of nature: III. From mechanistic understanding to novel therapies. SELF/NONSELF 2010; 1:192-224. [PMID: 21487477 PMCID: PMC3047783 DOI: 10.4161/self.1.3.12794] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/10/2010] [Accepted: 06/11/2010] [Indexed: 11/19/2022]
Abstract
Protein-protein interactions play a central role in biological processes and thus represent an appealing target for innovative drug design and development. They can be targeted by small molecule inhibitors, modulatory peptides and peptidomimetics, which represent a superior alternative to protein therapeutics that carry many disadvantages. Considering that transmembrane signal transduction is an attractive process to therapeutically control multiple diseases, it is fundamentally and clinically important to mechanistically understand how signal transduction occurs. Uncovering specific protein-protein interactions critical for signal transduction, a general platform for receptor-mediated signaling, the signaling chain homooligomerization (SCHOOL) platform, suggests these interactions as universal therapeutic targets. Within the platform, the general principles of signaling are similar for a variety of functionally unrelated receptors. This suggests that global therapeutic strategies targeting key protein-protein interactions involved in receptor triggering and transmembrane signal transduction may be used to treat a diverse set of diseases. This also assumes that clinical knowledge and therapeutic strategies can be transferred between seemingly disparate disorders, such as T cell-mediated skin diseases and platelet disorders or combined to develop novel pharmacological approaches. Intriguingly, human viruses use the SCHOOL-like strategies to modulate and/or escape the host immune response. These viral mechanisms are highly optimized over the millennia, and the lessons learned from viral pathogenesis can be used practically for rational drug design. Proof of the SCHOOL concept in the development of novel therapies for atopic dermatitis, rheumatoid arthritis, cancer, platelet disorders and other multiple indications with unmet needs opens new horizons in therapeutics.
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10
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Sigalov AB. The SCHOOL of nature: I. Transmembrane signaling. SELF/NONSELF 2010; 1:4-39. [PMID: 21559175 PMCID: PMC3091606 DOI: 10.4161/self.1.1.10832] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 11/30/2009] [Accepted: 12/01/2009] [Indexed: 11/19/2022]
Abstract
Receptor-mediated transmembrane signaling plays an important role in health and disease. Recent significant advances in our understanding of the molecular mechanisms linking ligand binding to receptor activation revealed previously unrecognized striking similarities in the basic structural principles of function of numerous cell surface receptors. In this work, I demonstrate that the Signaling Chain Homooligomerization (SCHOOL)-based mechanism represents a general biological mechanism of transmembrane signal transduction mediated by a variety of functionally unrelated single- and multichain activating receptors. within the SCHOOL platform, ligand binding-induced receptor clustering is translated across the membrane into protein oligomerization in cytoplasmic milieu. This platform resolves a long-standing puzzle in transmembrane signal transduction and reveals the major driving forces coupling recognition and activation functions at the level of protein-protein interactions-biochemical processes that can be influenced and controlled. The basic principles of transmembrane signaling learned from the SCHOOL model can be used in different fields of immunology, virology, molecular and cell biology and others to describe, explain and predict various phenomena and processes mediated by a variety of functionally diverse and unrelated receptors. Beyond providing novel perspectives for fundamental research, the platform opens new avenues for drug discovery and development.
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Affiliation(s)
- Alexander B Sigalov
- Department of Pathology; University of Massachusetts Medical School; Worcester, MA USA
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11
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Signaling Chain Homooligomerization (SCHOOL) Model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 640:121-63. [DOI: 10.1007/978-0-387-09789-3_12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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12
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Risueño RM, Schamel WWA, Alarcón B. T cell receptor engagement triggers its CD3epsilon and CD3zeta subunits to adopt a compact, locked conformation. PLoS One 2008; 3:e1747. [PMID: 18320063 PMCID: PMC2254190 DOI: 10.1371/journal.pone.0001747] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Accepted: 10/08/2007] [Indexed: 11/24/2022] Open
Abstract
How the T cell antigen receptor (TCR) discriminates between molecularly related peptide/Major Histocompatibility Complex (pMHC) ligands and converts this information into different possible signaling outcomes is still not understood. One current model proposes that strong pMHC ligands, but not weak ones, induce a conformational change in the TCR. Evidence supporting this comes from a pull-down assay that detects ligand-induced binding of the TCR to the N-terminal SH3 domain of the adapter protein Nck, and also from studies with a neoepitope-specific antibody. Both methods rely on the exposure of a polyproline sequence in the CD3ε subunit of the TCR, and neither indicates whether the conformational change is transmitted to other CD3 subunits. Using a protease-sensitivity assay, we now show that the cytoplasmic tails of CD3ε and CD3ζ subunits become fully protected from degradation upon TCR triggering. These results suggest that the TCR conformational change is transmitted to the tails of CD3ε and CD3ζ, and perhaps all CD3 subunits. Furthermore, the resistance to protease digestion suggests that CD3 cytoplasmic tails adopt a compact structure in the triggered TCR. These results are consistent with a model in which transduction of the conformational change induced upon TCR triggering promotes condensation and shielding of the CD3 cytoplasmic tails.
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Affiliation(s)
- Ruth M. Risueño
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Balbino Alarcón
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
- * To whom correspondence should be addressed. E-mail:
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13
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Liou J, Fivaz M, Inoue T, Meyer T. Live-cell imaging reveals sequential oligomerization and local plasma membrane targeting of stromal interaction molecule 1 after Ca2+ store depletion. Proc Natl Acad Sci U S A 2007; 104:9301-6. [PMID: 17517596 PMCID: PMC1890489 DOI: 10.1073/pnas.0702866104] [Citation(s) in RCA: 497] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Stromal interaction molecule 1 (STIM1) has recently been identified by our group and others as an endoplasmic reticulum (ER) Ca(2+) sensor that responds to ER Ca(2+) store depletion and activates Ca(2+) channels in the plasma membrane (PM). The molecular mechanism by which STIM1 transduces signals from the ER lumen to the PM is not yet understood. Here we developed a live-cell FRET approach and show that STIM1 forms oligomers within 5 s after Ca(2+) store depletion. These oligomers rapidly dissociated when ER Ca(2+) stores were refilled. We further show that STIM1 formed oligomers before its translocation within the ER network to ER-PM junctions. A mutant STIM1 lacking the C-terminal polybasic PM-targeting motif oligomerized after Ca(2+) store depletion but failed to form puncta at ER-PM junctions. Using fluorescence recovery after photobleaching measurements to monitor STIM1 mobility, we show that STIM1 oligomers translocate on average only 2 mum to reach ER-PM junctions, arguing that STIM1 ER-to-PM signaling is a local process that is suitable for generating cytosolic Ca(2+) gradients. Together, our live-cell measurements dissect the STIM1 ER-to-PM signaling relay into four sequential steps: (i) dissociation of Ca(2+), (ii) rapid oligomerization, (iii) spatially restricted translocation to nearby ER-PM junctions, and (iv) activation of PM Ca(2+) channels.
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Affiliation(s)
- Jen Liou
- Department of Chemical and Systems Biology, Stanford University Medical School, 318 Campus Drive, Clark Center, Stanford, CA 94305
- *To whom correspondence may be addressed: E-mail: or
| | - Marc Fivaz
- Department of Chemical and Systems Biology, Stanford University Medical School, 318 Campus Drive, Clark Center, Stanford, CA 94305
| | - Takanari Inoue
- Department of Chemical and Systems Biology, Stanford University Medical School, 318 Campus Drive, Clark Center, Stanford, CA 94305
| | - Tobias Meyer
- Department of Chemical and Systems Biology, Stanford University Medical School, 318 Campus Drive, Clark Center, Stanford, CA 94305
- *To whom correspondence may be addressed: E-mail: or
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14
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Franco A, Albani S. Translating the concept of suppressor/regulatory T cells to clinical applications. Int Rev Immunol 2006; 25:27-47. [PMID: 16669133 DOI: 10.1080/08830180500544506] [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: 01/12/2023]
Abstract
The in vivo expansion of suppressor/regulatory T cells (Tregs) is a desirable event in autoimmunity and transplantation. Here we summarize the general rules involved in antigen recognition by T cells and describe Tregs and their requirements, discussing different levels of immune intervention.
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Affiliation(s)
- Alessandra Franco
- Department of Medicine and Pediatrics, University of California, San Diego, La Jolla, California 92093-0731, USA
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15
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Sigalov AB. Multichain immune recognition receptor signaling: different players, same game? Trends Immunol 2005; 25:583-9. [PMID: 15489186 DOI: 10.1016/j.it.2004.08.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Alexander B Sigalov
- Department of Pathology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
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16
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Gil D, Schrum AG, Alarcón B, Palmer E. T cell receptor engagement by peptide-MHC ligands induces a conformational change in the CD3 complex of thymocytes. ACTA ACUST UNITED AC 2005; 201:517-22. [PMID: 15728235 PMCID: PMC1868566 DOI: 10.1084/jem.20042036] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The T cell receptor (TCR) can recognize a variety of cognate peptide/major histocompatibility complex (pMHC) ligands and translate their affinity into distinct cellular responses. To achieve this, the nonsignaling alphabeta heterodimer communicates ligand recognition to the CD3 signaling subunits by an unknown mechanism. In thymocytes, we found that both positive- and negative-selecting pMHC ligands expose a cryptic epitope in the CD3 complex upon TCR engagement. This conformational change is induced in vivo and requires the expression of cognate MHC. We conclude that TCR engagement with a cognate pMHC ligand induces a conformational change in the CD3 complex of thymocytes and propose that this marks an initial event during thymic selection that signals the recognition of self-antigen.
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Affiliation(s)
- Diana Gil
- Department of Research, Laboratory of Transplantation Immunology and Nephrology, University Hospital-Basel, CH-4031 Basel, Switzerland
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17
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Bättig P, Saudan P, Storni T, Gallimore A, Bachmann MF. Limited in vivo reactivity of polyclonal effector cytotoxic T cells towards altered peptide ligands. Microbes Infect 2005; 7:729-37. [PMID: 15857805 DOI: 10.1016/j.micinf.2005.01.014] [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] [Received: 01/06/2005] [Revised: 01/21/2005] [Accepted: 01/25/2005] [Indexed: 10/25/2022]
Abstract
T cell responses are regulated by the affinity/avidity of the T cell receptor for the MHC/peptide complex, available costimulation and duration of antigenic stimulation. Altered peptide ligands (APLs) are usually recognized with a reduced affinity/avidity by the T cell receptor and are often able to only partially activate T cells in vitro or may even function as antagonists. Here we assessed the ability of APLs derived from peptide p33 of lymphocytic choriomeningitis virus (LCMV) to mediate lysis of target cells in vivo, confer anti-viral protection and cause auto-immune disease. In general, in vitro cross-reactivity between APLs was rather limited, and even strongly cross-reactive cytotoxic T lymphocytes were only able to mediate moderate anti-viral protection. Partial protection was observed for infection with LCMV or low doses of recombinant vaccinia virus, while no reduced viral titers could be seen upon infection with high dose of vaccinia virus. In a transgenic mouse model expressing LCMV glycoprotein in the islets of the pancreas, APLs induced a transient insulitis but failed to induce autoimmune diabetes. Thus, effector functions induced by even highly homologous APLs are rather limited in vivo.
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MESH Headings
- Animals
- Antigens, Viral/chemistry
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Antigens, Viral/pharmacology
- Autoimmune Diseases/etiology
- Autoimmune Diseases/immunology
- Autoimmune Diseases/prevention & control
- Cross Reactions
- Diabetes Mellitus, Type 1/etiology
- Diabetes Mellitus, Type 1/immunology
- Diabetes Mellitus, Type 1/prevention & control
- Disease Models, Animal
- Glycoproteins/chemistry
- Glycoproteins/genetics
- Glycoproteins/immunology
- Glycoproteins/pharmacology
- Ligands
- Lymphocyte Activation/drug effects
- Lymphocytic Choriomeningitis/complications
- Lymphocytic Choriomeningitis/immunology
- Lymphocytic choriomeningitis virus/immunology
- Lymphocytic choriomeningitis virus/pathogenicity
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Peptide Fragments/chemistry
- Peptide Fragments/genetics
- Peptide Fragments/immunology
- Peptide Fragments/pharmacology
- Peptides/chemistry
- Peptides/genetics
- Peptides/immunology
- Peptides/pharmacology
- T-Lymphocytes, Cytotoxic/immunology
- Vaccinia virus/genetics
- Viral Proteins/chemistry
- Viral Proteins/genetics
- Viral Proteins/immunology
- Viral Proteins/pharmacology
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Affiliation(s)
- Patrick Bättig
- Cytos Biotechnology, AG Wagistrasse 25, 8952 Zürich-Schlieren, Switzerland
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18
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Shi Y, Agematsu K, Ochs HD, Sugane K. Functional analysis of human memory B-cell subpopulations: IgD+CD27+ B cells are crucial in secondary immune response by producing high affinity IgM. Clin Immunol 2003; 108:128-37. [PMID: 12921759 DOI: 10.1016/s1521-6616(03)00092-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The number of memory B cells in peripheral blood has been assayed in various diseases by using CD27 as a memory B-cell marker. However, the defining differences of characteristic and function between the two memory B-cell subpopulations separated by immunoglobulin (Ig)D expression remain to be clearly elucidated. We analyzed here IgD(+)CD27(+) B cells (circulating B cells 2, cB2) and IgD(-)CD27(+) memory B cells (cB3) in comparison with IgD(+)CD27(-) naive B cells (cB1). cB2 were found to be morphologically similar to cB3 with abundant cytoplasm, whereas cB3 expressed CD80, CD86, and CD95 on their surface more predominantly than cB2. A majority of cB2 expressed both IgD and IgM, and cB3 expressed IgA or IgG. Mature gamma1 and gamma2 transcripts were found in cB3, but at very low levels in cB2, and activation-induced cytidine deaminase (AID) mRNA expression was recognized only in cB3. The frequencies of somatic hypermutation in cB2 and cB3 were comparable levels studied by VH5. cB2 did not shift to cB3 in vitro by the stimuli such as via B-cell receptor or CD40. cB2 produced large amounts of IgM predominantly and promptly, which is in accordance with the known characteristics of memory B cells. Taken together, although cB2 are unclass-switched, cB2 have the functions of memory B cells and are not in the process of transition from naive to switched memory B cells, playing a crucial role in secondary immune response by producing high-affinity IgM in the early phase of infections.
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Affiliation(s)
- Yuhui Shi
- Department of Infectious Immunology, Shinshu University, Graduate School of Medicine, Asahi 3-1-1, 390-8621, Matsumoto, Japan
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19
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Storni T, Ruedl C, Renner WA, Bachmann MF. Innate immunity together with duration of antigen persistence regulate effector T cell induction. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:795-801. [PMID: 12847247 DOI: 10.4049/jimmunol.171.2.795] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Proliferation of T cells is important for the expansion of specific T cell clones during immune responses. In addition, for the establishment of protective immunity against viruses, bacteria, and tumors, the expanded T cells must differentiate into effector T cells. Here we show that effector T cell generation is driven by activation of APCs and duration of antigenic stimulation. Adoptively transferred TCR-transgenic T cells extensively proliferated upon immunization. However, these T cells failed to differentiate into effector cells and died within 1 wk after immunization unless antigenic peptides persisted for >1 day or were presented by activated APCs. The induction of protective immunity in a nontransgenic system was more stringent, since activation of APCs or prolonged Ag persistence alone was not sufficient to drive immunity. In contrast, Ag had to be presented for several days by activated APCs to trigger protective T cell responses. Thus, activation of APCs and duration of Ag presentation together regulate the induction of protective T cell responses.
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MESH Headings
- Animals
- Antigen Presentation/genetics
- Antigen Presentation/immunology
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Antigens, Viral/administration & dosage
- Antigens, Viral/immunology
- Antigens, Viral/metabolism
- Biomarkers/analysis
- Cell Division/genetics
- Cell Division/immunology
- Female
- Glycoproteins/administration & dosage
- Glycoproteins/immunology
- Glycoproteins/metabolism
- Hyaluronan Receptors/biosynthesis
- Immunity, Innate/genetics
- Lectins, C-Type
- Lymphocyte Activation/genetics
- Lymphocytic choriomeningitis virus/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Peptide Fragments/administration & dosage
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- Receptors, Interleukin-2/biosynthesis
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/virology
- Time Factors
- Up-Regulation/genetics
- Up-Regulation/immunology
- Viral Proteins/administration & dosage
- Viral Proteins/immunology
- Viral Proteins/metabolism
- Viral Vaccines/administration & dosage
- Viral Vaccines/immunology
- Viral Vaccines/metabolism
- Virion/immunology
- Virion/metabolism
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Affiliation(s)
- Tazio Storni
- Cytos Biotechnology, Schlieren-Zurich, Switzerland
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20
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Swietnicki W, Barnie AM, Dyas BK, Ulrich RG. Zinc binding and dimerization of Streptococcus pyogenes pyrogenic exotoxin C are not essential for T-cell stimulation. J Biol Chem 2003; 278:9885-95. [PMID: 12473669 DOI: 10.1074/jbc.m206957200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Streptococcal pyrogenic enterotoxin C (Spe-C) is a superantigen virulence factor produced by Streptococcus pyogenes that activates T-cells polyclonally. The biologically active form of Spe-C is thought to be a homodimer containing an essential zinc coordination site on each subunit, consisting of the residues His(167), His(201), and Asp(203). Crystallographic data suggested that receptor specificity is dependent on contacts between the zinc coordination site of Spe-C and the beta-chain of the major histocompatibility complex type II (MHCII) molecule. Our results indicate that only a minor fraction of dimer is present at T-cell stimulatory concentrations of Spe-C following mutation of the unpaired side chain of cysteine at residue 27 to serine. Mutations of amino acid residues His(167), His(201), or Asp(203) had only minor effects on protein stability but resulted in greatly diminished MHCII binding, as measured by surface plasmon resonance with isolated receptor/ligand pairs and flow cytometry with MHCII-expressing cells. However, with the exception of the mutants D203A and D203N, mutation of the zinc-binding site of Spe-C did not significantly impact T-cell activation. The mutation Y76A, located in a polar pocket conserved among most superantigens, resulted in significant loss of T-cell stimulation, although no effect was observed on the overall binding to human MHCII molecules, perhaps because of the masking of this lower affinity interaction by the dominant zinc-dependent binding. To a lesser extent, mutations of side chains found in a second conserved MHCII alpha-chain-binding site consisting of a hydrophobic surface loop decreased T-cell stimulation. Our results demonstrate that dimerization and zinc coordination are not essential for biological activity of Spe-C and suggest the contribution of an alternative MHCII binding mode to T-cell activation.
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MESH Headings
- Amino Acid Sequence
- Antigens/chemistry
- Aspartic Acid/chemistry
- Bacterial Toxins/chemistry
- Binding Sites
- Binding, Competitive
- Cations
- Chromatography, Gel
- Chromatography, Liquid
- Circular Dichroism
- Cloning, Molecular
- DNA, Complementary/metabolism
- Dimerization
- Dose-Response Relationship, Drug
- Histidine/chemistry
- Humans
- Hydrogen-Ion Concentration
- Kinetics
- Mass Spectrometry
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Protein Binding
- Protein Structure, Secondary
- Receptors, Antigen, T-Cell/metabolism
- Recombinant Proteins/chemistry
- Sequence Homology, Amino Acid
- Serine/chemistry
- Streptococcus pyogenes/metabolism
- Surface Plasmon Resonance
- T-Lymphocytes/metabolism
- Thermodynamics
- Ultraviolet Rays
- Zinc/chemistry
- Zinc/metabolism
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Affiliation(s)
- Wieslaw Swietnicki
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702, USA.
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21
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Fahmy TM, Bieler JG, Schneck JP. Probing T cell membrane organization using dimeric MHC-Ig complexes. J Immunol Methods 2002; 268:93-106. [PMID: 12213346 DOI: 10.1016/s0022-1759(02)00203-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In this report, we review a novel method for probing the membrane organization of T cells using dimeric major histocompatibility complexes (MHC), MHC-Ig. MHC-Ig complexes are useful reagents for quantitative analysis of binding data since their valency is controlled. These complexes can be easily labeled and loaded with a variety of peptides. A binding assay using these dimers and quantitative analysis of the MHC-Ig dimer-T cell binding curves is described in detail. Using this approach, we show that the organization of TCR on activated T cells is different from TCR organization on nai;ve T cells. The implications of these findings are discussed with regards to current models of T cell recognition. This analysis offers insight into how T cell controls their biological range of responsiveness. Specifically, these findings reveal the biophysical basis of the ability of activated T cells to recognize low amounts of antigen independent of costimulation.
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Affiliation(s)
- Tarek M Fahmy
- Department of Pathology, Division of Immunopathology, Johns Hopkins School of Medicine, 664G Ross Bldg., 720 Rutland Avenue, Baltimore, MD 21205, USA
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22
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Dreier T, Lorenczewski G, Brandl C, Hoffmann P, Syring U, Hanakam F, Kufer P, Riethmuller G, Bargou R, Baeuerle PA. Extremely potent, rapid and costimulation-independent cytotoxic T-cell response against lymphoma cells catalyzed by a single-chain bispecific antibody. Int J Cancer 2002; 100:690-7. [PMID: 12209608 DOI: 10.1002/ijc.10557] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A recent study reported on an anti-CD19/anti-CD3 single-chain bispecific antibody (bscCD19xCD3) exhibiting high activity against human B lymphoma cell lines (Löffler et al., Blood 2000;95:2098-103). In the present study, we have explored in detail the in vitro efficacy, T-cell donor variability, binding characteristics, specificity, kinetics and interleukin-2 (IL-2) dependence of bscCD19xCD3. We found that a majority of human donor T cells tested (n = 86) gave half-maximal B-lymphoma cell lysis (ED(50)) within a range of 10-50 pg/ml bscCD19xCD3, corresponding to sub-picomolar concentrations of the bispecific antibody. Under identical experimental conditions, the anti-CD20 monoclonal antibody rituximab had an at least 100,000-fold lower in vitro efficacy. The extreme potency of bscCD19xCD3 was in sharp contrast to the relatively low affinity of the anti-CD3 and anti-CD19 single-chain Fv portions in K(D) ranges of 10(-7) and 10(-9) M, respectively. Cell lysis by bscCD19xCD3 was predominantly mediated by the population of CD8/CD45RO-positive T cells. Both immortalized CD4- and CD8-positive human T-cell clones were highly active effector cells as well. Cell lysis by bscCD19xCD3 was rapid and specific. The respective parental monoclonal antibodies inhibited cell lysis and CD19-negative cells were not harmed by T cells in the presence of high amounts of bscCD19xCD3. The potent T-cell stimulus IL-2 could not markedly augment the activity of bscCD19xCD3-stimulated T cells. In conclusion, bscCD19xCD3 could redirect unstimulated cytotoxic T cells against CD19-positive cells in an unexpectedly potent, rapid and specific fashion.
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Affiliation(s)
- Torsten Dreier
- Micromet AG, Am Klopferspitz 19, 82152 Martinsried, Germany
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23
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Nguyen LT, Bachmann MF, Ohashi PS. Contribution of LCMV transgenic models to understanding T lymphocyte development, activation, tolerance, and autoimmunity. Curr Top Microbiol Immunol 2002; 263:119-43. [PMID: 11987812 DOI: 10.1007/978-3-642-56055-2_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- L T Nguyen
- Department of Immunology, Ontario Cancer Institute, 610 University Avenue, Toronto, Ontario, Canada, M5G 2M9
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24
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Holler PD, Lim AR, Cho BK, Rund LA, Kranz DM. CD8(-) T cell transfectants that express a high affinity T cell receptor exhibit enhanced peptide-dependent activation. J Exp Med 2001; 194:1043-52. [PMID: 11602635 PMCID: PMC2193521 DOI: 10.1084/jem.194.8.1043] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
T cells are activated by binding of the T cell receptor (TCR) to a peptide-major histocompatibility complex (MHC) complex (pMHC) expressed on the surface of antigen presenting cells. Various models have predicted that activation is limited to a narrow window of affinities (or dissociation rates) for the TCR-pMHC interaction and that above or below this window, T cells will fail to undergo activation. However, to date there have not been TCRs with sufficiently high affinities in order to test this hypothesis. In this report we examined the activity of a CD8-negative T cell line transfected with a high affinity mutant TCR (K(D) = 10 nM) derived from cytotoxic T lymphocyte clone 2C by in vitro engineering. The results show that despite a 300-fold higher affinity and a 45-fold longer off-rate compared with the wild-type TCR, T cells that expressed the mutant TCRs were activated by peptide. In fact, activation could be detected at significantly lower peptide concentrations than with T cells that expressed the wild-type TCR. Furthermore, binding and functional analyses of a panel of peptide variants suggested that pMHC stability could account for apparent discrepancies between TCR affinity and T cell activity observed in several prior studies.
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Affiliation(s)
- Phillip D. Holler
- Department of Biochemistry, University of Illinois, Urbana, IL 61801
| | - Alice R. Lim
- Department of Biochemistry, University of Illinois, Urbana, IL 61801
| | - Bryan K. Cho
- Department of Biochemistry, University of Illinois, Urbana, IL 61801
| | - Laurie A. Rund
- Department of Biochemistry, University of Illinois, Urbana, IL 61801
| | - David M. Kranz
- Department of Biochemistry, University of Illinois, Urbana, IL 61801
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25
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Hesse MD, Karulin AY, Boehm BO, Lehmann PV, Tary-Lehmann M. A T cell clone's avidity is a function of its activation state. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:1353-61. [PMID: 11466353 DOI: 10.4049/jimmunol.167.3.1353] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
At present it is unclear how Ag dose-dependent T cell functions, such as cytokine production, reflect TCR affinity and how the signal strength afforded by the Ag dose affects the kinetics of cytokine production by the individual T cell. We used a computer-assisted ELISPOT approach to address these issues. IFN-gamma release by a clonal population of CD4 T cells was monitored on a clonal population of APC while titrating the nominal peptide. The frequency of cytokine-producing cells, the net per-cell output of cytokine, and the onset of cytokine production were each found to be functions of the signal strength. Sigmoidal dose-response curves were seen at the clonal population level, but the activation thresholds for the individual T cells followed a Gaussian distribution. Moreover, the overall dose-response curve of the T cell clone revealed cyclic changes, becoming increasingly shifted toward lower Ag concentrations with the duration of time that elapsed since the last restimulation with Ag. Therefore, responsiveness to Ag ("functional avidity") is not a constant parameter of a T cell clone but a function of the T cell's history of last Ag encounter. The implications of such shifting activation thresholds are discussed for autoimmune disease.
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Affiliation(s)
- M D Hesse
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
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26
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Cochran JR, Cameron TO, Stone JD, Lubetsky JB, Stern LJ. Receptor proximity, not intermolecular orientation, is critical for triggering T-cell activation. J Biol Chem 2001; 276:28068-74. [PMID: 11384988 DOI: 10.1074/jbc.m103280200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Engagement of antigen receptors on the surface of T-cells with peptides bound to major histocompatibility complex (MHC) proteins triggers T-cell activation in a mechanism involving receptor oligomerization. Receptor dimerization by soluble MHC oligomers is sufficient to induce several characteristic activation processes in T-cells including internalization of engaged receptors and up-regulation of cell surface proteins. In this work, the influence of intermolecular orientation within the activating receptor dimer was studied. Dimers of class II MHC proteins coupled in a variety of orientations and topologies each were able to activate CD4+ T-cells, indicating that triggering was not dependent on a particular receptor orientation. In contrast to the minimal influence of receptor orientation, T-cell triggering was affected by the inter-molecular distance between MHC molecules, and MHC dimers coupled through shorter cross-linkers were consistently more potent than those coupled through longer cross-linkers. These results are consistent with a mechanism in which intermolecular receptor proximity, but not intermolecular orientation, is the key determinant for antigen-induced CD4+ T-cell activation.
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Affiliation(s)
- J R Cochran
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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27
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Rosette C, Werlen G, Daniels MA, Holman PO, Alam SM, Travers PJ, Gascoigne NR, Palmer E, Jameson SC. The impact of duration versus extent of TCR occupancy on T cell activation: a revision of the kinetic proofreading model. Immunity 2001; 15:59-70. [PMID: 11485738 DOI: 10.1016/s1074-7613(01)00173-x] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The widely accepted kinetic proofreading theory proposes that rapid TCR dissociation from a peptide/MHC ligand allows for stimulation of early but not late T cell activation events, explaining why low-affinity TCR ligands are poor agonists. We identified a low-affinity TCR ligand which stimulated late T cell responses but, contrary to predictions from kinetic proofreading, inefficiently induced early activation events. Furthermore, responses induced by this ligand were kinetically delayed compared to its high-affinity counterpart. Using peptide/MHC tetramers, we showed that activation characteristics could be dissociated from TCR occupancy by the peptide/MHC ligands. Our data argue that T cell responses are triggered by a cumulative signal which is reached at different time points for different TCR ligands.
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Affiliation(s)
- C Rosette
- Department of Laboratory Medicine and Pathology, Center for Immunology, University of Minnesota, Minneapolis, MN 55455, USA
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28
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Hudrisier D, Riond J, Burlet-Schiltz O, von Herrath MG, Lewicki H, Monsarrat B, Oldstone MB, Gairin JE. Structural and functional identification of major histocompatibility complex class I-restricted self-peptides as naturally occurring molecular mimics of viral antigens. Possible role in CD8+ T cell-mediated, virus-induced autoimmune disease. J Biol Chem 2001; 276:19396-403. [PMID: 11278441 DOI: 10.1074/jbc.m008864200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Structural similarity (molecular mimicry) between viral epitopes and self-peptides can lead to the induction of autoaggressive CD4(+) as well as CD8(+) T cell responses. Based on the flexibility of T cell receptor/antigen/major histocompatibility complex recognition, it has been proposed that a self-peptide could replace a viral epitope for T cell recognition and therefore participate in pathophysiological processes in which T cells are involved. To address this issue, we used, as a molecular model of viral antigen, the H-2D(b)-restricted immunodominant epitope nucleoprotein (NP)-(396-404) (FQPQNGQFI) of lymphocytic choriomeningitis virus (LCMV). We identified peptide sequences from murine self-proteins that share structural and functional homology with LCMV NP-(396-404) and that bound to H-2D(b) with high affinity. One of these self-peptides, derived from tumor necrosis factor receptor I (FGPSNWHFM, amino acids 302-310), maintained LCMV-specific CD8(+) T cells in an active state as observed both in vitro in cytotoxic assays and in vivo in a model of virus-induced autoimmune diabetes, the rat insulin promoter-LCMV NP transgenic mouse. The natural occurrence and molecular concentration at the surface of H-2(b) spleen cells of tumor necrosis factor receptor I-(302-310) were determined by on-line micro-high pressure liquid chromatography/mass spectrometry and supported its biological relevance.
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Affiliation(s)
- D Hudrisier
- Institut de Pharmacologie et de Biologie Structurale, CNRS, 205 route de Narbonne, 31400 Toulouse, France
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29
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Abstract
The mechanism of T cell receptor signaling is unclear. Included among models for TCR signaling is ligand-induced oligomerization in a fashion analogous to other cell surface receptors. Published kinetic, saturation binding, and light scattering experiments have been interpreted to suggest a propensity for soluble alpha beta TCR/peptide/MHC ectodomain complexes to oligomerize. Upon performing these experiments with soluble ectodomains of human class I and class II restricted alpha beta TCRs, we find no evidence for dimerization or oligomerization of complexes. Apparently, oligomerization in solution to a detectable extent is not a general property of soluble alpha beta TCRs or their complexes with ligand. Our results suggest that membrane-anchored, fully assembled TCRs should be studied to determine the role oligomerization plays in T cell signaling.
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Affiliation(s)
- B M Baker
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA
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30
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Cochran JR, Aivazian D, Cameron TO, Stern LJ. Receptor clustering and transmembrane signaling in T cells. Trends Biochem Sci 2001; 26:304-10. [PMID: 11343923 DOI: 10.1016/s0968-0004(01)01815-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
T cells are activated via engagement of their cell-surface receptors with molecules of the major histocompatibility complex (MHC) displayed on another cell surface. This process, which is a key step in the recognition of foreign antigens by the immune system, involves oligomerization of receptor components. Recent characterization of the T-cell response to soluble arrays of MHC-peptide complexes has provided insights into the triggering mechanism for T-cell activation.
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Affiliation(s)
- J R Cochran
- Dept of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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31
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Abstract
The serial engagement model provides an attractive and plausible explanation for how a typical antigen presenting cell, exhibiting a low density of peptides recognized by a T cell, can initiate T cell responses. If a single peptide displayed by a major histocompatibility complex (MHC) can bind, sequentially, to different T cell receptors (TCR), then a few peptides can activate many receptors. To date, arguments supporting and questioning the prevalence of serial engagement have centered on the down-regulation of TCR after contact of T cells with antigen presenting cells. Recently, the existence of serial engagement has been challenged by the demonstration that engagement of TCR can down-regulate nonengaged bystander TCR. Here we show that for binding and dissociation rates that characterize interactions between T cell receptors and peptide-MHC, substantial serial engagement occurs. The result is independent of mechanisms and measurements of receptor down-regulation. The conclusion that single peptide-MHC engage many TCR, before diffusing out of the contact region between the antigen-presenting cell and the T cell, is based on a general first passage time calculation for a particle alternating between states in which different diffusion coefficients govern its transport.
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Affiliation(s)
- C Wofsy
- Department of Mathematics and Statistics, University of New Mexico, Albuquerque, New Mexico 87131, USA
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32
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33
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Qadri A, Radu CG, Thatte J, Cianga P, Ober BT, Ober RJ, Ward ES. A role for the region encompassing the c" strand of a TCR V alpha domain in T cell activation events. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:820-9. [PMID: 10878356 DOI: 10.4049/jimmunol.165.2.820] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The distinct strand topology of TCR V alpha domains results in a flatter surface in the region encompassing the c" strand than the corresponding region in Ig V domains. In the current study a possible role for this region in T cell activation has been investigated by inserting a potential glycosylation site at V alpha residue 82. This residue is in proximity to the c" strand and distal to the putative interaction site for cognate peptide:MHC ligand. An additional N-linked carbohydrate at this position would create a protrusion on the V alpha domain surface, and this may interfere with TCR aggregation and/or recruitment of signaling molecules. The modified TCR has been expressed in transfected T cells, and the phenotype following stimulation has been compared with that of cells expressing the wild-type TCR. The mutation has significant effects on activation-induced cell death and TCR internalization, but, unexpectedly, does not affect IL-2 secretion. Furthermore, analyses with tetrameric, peptide:MHC class II complexes suggest that the mutation decreases the ability of the TCR to aggregate into a configuration compatible with avid binding by these multivalent ligands.
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MESH Headings
- Animals
- Antibodies, Monoclonal/analysis
- Apoptosis/genetics
- Apoptosis/immunology
- Cell Line
- Down-Regulation/genetics
- Down-Regulation/immunology
- Immunoblotting
- Interleukin-2/metabolism
- Lymphocyte Activation/genetics
- Mice
- Myelin Basic Protein/genetics
- Myelin Basic Protein/immunology
- Myelin Basic Protein/pharmacology
- Peptide Fragments/genetics
- Peptide Fragments/immunology
- Peptide Fragments/pharmacology
- Phosphotyrosine/immunology
- Protein Structure, Tertiary
- Receptors, Antigen, T-Cell, alpha-beta/antagonists & inhibitors
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Recombinant Proteins/immunology
- Recombinant Proteins/pharmacology
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Transfection/immunology
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Affiliation(s)
- A Qadri
- Center for Immunology and Cancer Immunobiology Center, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
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