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Hofmann OT, Glowatzki H, Bürker C, Rangger GM, Bröker B, Niederhausen J, Hosokai T, Salzmann I, Blum RP, Rieger R, Vollmer A, Rajput P, Gerlach A, Müllen K, Schreiber F, Zojer E, Koch N, Duhm S. Orientation-Dependent Work-Function Modification Using Substituted Pyrene-Based Acceptors. J Phys Chem C Nanomater Interfaces 2017; 121:24657-24668. [PMID: 29152034 PMCID: PMC5682610 DOI: 10.1021/acs.jpcc.7b08451] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/10/2017] [Indexed: 05/17/2023]
Abstract
The adsorption of molecular acceptors is a viable method for tuning the work function of metal electrodes. This, in turn, enables adjusting charge injection barriers between the electrode and organic semiconductors. Here, we demonstrate the potential of pyrene-tetraone (PyT) and its derivatives dibromopyrene-tetraone (Br-PyT) and dinitropyrene-tetraone (NO2-PyT) for modifying the electronic properties of Au(111) and Ag(111) surfaces. The systems are investigated by complementary theoretical and experimental approaches, including photoelectron spectroscopy, the X-ray standing wave technique, and density functional theory simulations. For some of the investigated interfaces the trends expected for Fermi-level pinning are observed, i.e., an increase of the metal work function along with increasing molecular electron affinity and the same work function for Au and Ag with monolayer acceptor coverage. Substantial deviations are, however, found for Br-PyT/Ag(111) and NO2-PyT/Ag(111), where in the latter case an adsorption-induced work function increase of as much as 1.6 eV is observed. This behavior is explained as arising from a face-on to edge-on reorientation of molecules in the monolayer. Our calculations show that for an edge-on orientation much larger work-function changes can be expected despite the prevalence of Fermi-level pinning. This is primarily ascribed to a change of the electron affinity of the adsorbate layer that results from a change of the molecular orientation. This work provides a comprehensive understanding of how changing the molecular electron affinity as well as the adsorbate structure impacts the electronic properties of electrodes.
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Affiliation(s)
- O. T. Hofmann
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
- E-mail:
| | - H. Glowatzki
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - C. Bürker
- Institut
für Angewandte Physik, Universität
Tübingen, Auf
der Morgenstelle 10, Tübingen 72076, Germany
| | - G. M. Rangger
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - B. Bröker
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
| | - J. Niederhausen
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - T. Hosokai
- National
Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - I. Salzmann
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
- The
Institute of Solid State Physics, The University
of Tokyo, Kashiwanoha
5-1-5, Kashiwa, Chiba 277-8581, Japan
| | - R.-P. Blum
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
| | - R. Rieger
- Max Planck
Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - A. Vollmer
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - P. Rajput
- Atomic
& Molecular Physics Division, Bhabha
Atomic Research Centre, Trombay, Mumbai 400085, India
| | - A. Gerlach
- Institut
für Angewandte Physik, Universität
Tübingen, Auf
der Morgenstelle 10, Tübingen 72076, Germany
| | - K. Müllen
- Max Planck
Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
- Institute
of Physical Chemistry, Johannes Gutenberg
University Mainz, Duesbergweg
10-14, Mainz, Germany
| | - F. Schreiber
- Institut
für Angewandte Physik, Universität
Tübingen, Auf
der Morgenstelle 10, Tübingen 72076, Germany
| | - E. Zojer
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - N. Koch
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstraße 15, 12389 Berlin, Germany
- Jiangsu
Key Laboratory for Carbon-Based Functional Materials & Devices
and Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren-Ai Road, Suzhou 215123, P.R. China
| | - S. Duhm
- Jiangsu
Key Laboratory for Carbon-Based Functional Materials & Devices
and Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren-Ai Road, Suzhou 215123, P.R. China
- E-mail:
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Bekeschus S, Kolata J, Winterbourn C, Kramer A, Turner R, Weltmann KD, Bröker B, Masur K. Hydrogen peroxide: A central player in physical plasma-induced oxidative stress in human blood cells. Free Radic Res 2014; 48:542-9. [DOI: 10.3109/10715762.2014.892937] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Bröker B, Hofmann OT, Rangger GM, Frank P, Blum RP, Rieger R, Venema L, Vollmer A, Müllen K, Rabe JP, Winkler A, Rudolf P, Zojer E, Koch N. Density-dependent reorientation and rehybridization of chemisorbed conjugated molecules for controlling interface electronic structure. Phys Rev Lett 2010; 104:246805. [PMID: 20867325 DOI: 10.1103/physrevlett.104.246805] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Indexed: 05/22/2023]
Abstract
The adsorption of the molecular acceptor hexaazatriphenylene-hexacarbonitrile on Ag(111) was investigated as function of layer density. We find that the orientation of the first molecular layer changes from a face-on to an edge-on conformation depending on layer density, facilitated through specific interactions of the peripheral molecular cyano groups with the metal. This is accompanied by a rehybridization of molecular and metal electronic states, which significantly modifies the interface and surface electronic properties, as rationalized by theoretical modeling.
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Affiliation(s)
- B Bröker
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstrasse 15, D-12489 Berlin, Germany
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Vogelgesang A, Grunwald U, Langner S, Jack R, Bröker B, Kessler C, Dressel A. Das Auftreten von Infektionen bei Schlaganfallpatienten korreliert mit dem Verlust von CD4+ T-Zellen. Akt Neurol 2007. [DOI: 10.1055/s-2007-988081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Bakkeboe M, Vogelgesang A, Jack R, Bröker B, Dressel A. CTLA-4 und ICOS Expression nach Schlaganfall. Akt Neurol 2007. [DOI: 10.1055/s-2007-988083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Busse S, Spanka S, Busse M, Suofu Y, Bröker B, Popa-Wagner A, Dressel A. Expression of CD80 and CD86 in the brain of Lewis rats after induction of stroke. Akt Neurol 2004. [DOI: 10.1055/s-2004-833384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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7
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Bröker B. Accumulation of CTLA-4 expressing T lymphocytes in the germinal centers of human lymphoid tissues. Immunol Lett 1997. [DOI: 10.1016/s0165-2478(97)86845-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Weismann M, Guse AH, Sorokin L, Bröker B, Frieser M, Hallmann R, Mayr GW. Integrin-mediated intracellular Ca2+ signaling in Jurkat T lymphocytes. The Journal of Immunology 1997. [DOI: 10.4049/jimmunol.158.4.1618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
T lymphocytes interact with components of the extracellular matrix after transendothelial migration on their way to sites of inflammation. To characterize the molecular basis of the interaction between T lymphocytes with different extracellular matrix proteins, we investigated the role of intracellular Ca2+ as a signal mediating such interactions and identified the cell surface integrins involved in this process. When Jurkat T lymphocytes loaded with the calcium-sensitive fluorescent dye fura-2 were placed on coverslips coated with human fibronectin, human collagen types I, IV, and VI, human tenascin, human laminin I, or mouse laminin I, an elevation in intracellular Ca2+ concentration was observed. In contrast, contact of the Jurkat T lymphocytes with vitronectin and thrombospondin did not induce Ca2+ signals in more cells as compared with control measurements in which cells were in contact with only BSA or polylysine. Furthermore, the percentage of Jurkat T lymphocytes responding with Ca2+ signals to collagen types I and IV, fibronectin, and laminin I was completely reduced to levels observed on BSA or polylysine when the cells were pretreated with specific anti-integrin Abs, suggesting a role for cell surface integrins as mediators of cell matrix-induced intracellular Ca2+ signaling. Similar results were obtained with peripheral human T lymphocytes activated by phytohemagglutinin.
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Affiliation(s)
- M Weismann
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
| | - A H Guse
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
| | - L Sorokin
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
| | - B Bröker
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
| | - M Frieser
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
| | - R Hallmann
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
| | - G W Mayr
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
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Weismann M, Guse AH, Sorokin L, Bröker B, Frieser M, Hallmann R, Mayr GW. Integrin-mediated intracellular Ca2+ signaling in Jurkat T lymphocytes. J Immunol 1997; 158:1618-27. [PMID: 9029097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
T lymphocytes interact with components of the extracellular matrix after transendothelial migration on their way to sites of inflammation. To characterize the molecular basis of the interaction between T lymphocytes with different extracellular matrix proteins, we investigated the role of intracellular Ca2+ as a signal mediating such interactions and identified the cell surface integrins involved in this process. When Jurkat T lymphocytes loaded with the calcium-sensitive fluorescent dye fura-2 were placed on coverslips coated with human fibronectin, human collagen types I, IV, and VI, human tenascin, human laminin I, or mouse laminin I, an elevation in intracellular Ca2+ concentration was observed. In contrast, contact of the Jurkat T lymphocytes with vitronectin and thrombospondin did not induce Ca2+ signals in more cells as compared with control measurements in which cells were in contact with only BSA or polylysine. Furthermore, the percentage of Jurkat T lymphocytes responding with Ca2+ signals to collagen types I and IV, fibronectin, and laminin I was completely reduced to levels observed on BSA or polylysine when the cells were pretreated with specific anti-integrin Abs, suggesting a role for cell surface integrins as mediators of cell matrix-induced intracellular Ca2+ signaling. Similar results were obtained with peripheral human T lymphocytes activated by phytohemagglutinin.
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Affiliation(s)
- M Weismann
- University of Hamburg, Institute of Physiological Chemistry, Department of Enzyme Chemistry, Germany
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Sahly H, Podschun R, Sass R, Bröker B, Kekow J, Gross WL, Ullmann U. Serum antibodies to Klebsiella capsular polysaccharides in ankylosing spondylitis. Arthritis Rheum 1994; 37:754-9. [PMID: 8185704 DOI: 10.1002/art.1780370521] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To measure antibodies to Klebsiella capsular polysaccharides in the sera of HLA-B27 positive patients with ankylosing spondylitis (AS), compared with HLA-B27 positive and HLA-B27 negative healthy control subjects. METHODS Antibodies were detected by means of an enzyme-linked immunosorbent assay specific for each of the 77 known Klebsiella serotypes. RESULTS Significantly elevated frequencies and titers of antibodies to capsular polysaccharides K26, K36, and K50 were detected in sera from AS patients, compared with controls. CONCLUSION These results suggest the predominance of Klebsiella serotypes K26, K36, and K50 in patients with AS.
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Affiliation(s)
- H Sahly
- Department of Medical Microbiology and Virology, University of Kiel, Germany
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11
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Burkhardt H, Yan T, Bröker B, Beck-Sickinger A, Holmdahl R, Von der Mark K, Emmrich F. Antibody binding to a collagen type-II epitope gives rise to an inhibitory peptide for autoreactive T cells. Eur J Immunol 1992; 22:1063-7. [PMID: 1372557 DOI: 10.1002/eji.1830220428] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It is well documented that antigen recognition by T cells requires small peptides which are generated by protein cleavage in antigen-presenting cells. These peptides have to associate with major histocompatibility complex (MHC) molecules in order to be recognized. An inhibitory peptide may bind to the same site of the MHC-encoded protein but is not recognized by the T cell. Here we describe a stimulatory and an inhibitory peptide sequence within human collagen type II (CII) as defined by means of the same autoreactive human T cell clone. Most interestingly, the inhibitory peptide is not generated by regular processing in peripheral blood mononuclear cells but only in the presence of an antibody that binds to the same domain and thereby seems to protect the inhibitory sequence. This finding may indicate that certain autoantibodies have the potential to block autoreactive T cells with specificity for a distinct epitope on the same antigen.
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Affiliation(s)
- H Burkhardt
- Max-Planck-Gesellschaft, Klinische Arbeitsgruppen für Rheumatologie, Medizinischen Klinik III, Universität Erlangen-Nurnberg, FRG
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12
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Yan T, Burkhardt H, Ritter T, Bröker B, Mann KH, Bertling WM, von der Mark K, Emmrich F. Specificity and T cell receptor β chain usage of a human collagen type II-reactive T cell clone derived from a healthy individual. Eur J Immunol 1992; 22:51-6. [PMID: 1370417 DOI: 10.1002/eji.1830220109] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Collagen type II (CII) is a cartilage-specific matrix compound well known as an inducer of an experimental, T cell-dependent autoimmune arthritis, a disease which shows some similarities to human rheumatoid arthritis. Here we report on an HLA-DR7-restricted human CD4 T cell clone (TC9), which was isolated from a healthy donor and recognizes human CII. After screening CNBr fragments of CII and tryptic fragments derived thereof, the T cell epitope could be mapped to amino acid residues 271-285 of the triple helical region of CII that are located within CNBr fragment 11 [alpha 1 (II) CB11]. This epitope was confirmed by a synthetic peptide stimulatory for TC9. The T cell receptor beta chain of TC9 was cloned using the polymerase chain reaction; it comprises V beta 6.7 and contains besides J beta 2.3 and C beta 2 an as yet undescribed sequence for the D segment.
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Affiliation(s)
- T Yan
- Clinical Research Unit for Rheumatology, Friedrich-Alexander-Universität, Erlangen-Nürnberg, FRG
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Smith MD, Bröker B, Moretta L, Ciccone E, Grossi CE, Edwards JC, Yüksel F, Colaco B, Worman C, Mackenzie L. T gamma delta cells and their subsets in blood and synovial tissue from rheumatoid arthritis patients. Scand J Immunol 1990; 32:585-93. [PMID: 2148640 DOI: 10.1111/j.1365-3083.1990.tb03200.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have examined the frequencies of T gamma delta cells in blood, synovial fluids, and synovial membranes of patients with rheumatoid arthritis (RA) and in blood from age-matched controls. Immunocytochemical and immunohistochemical techniques were used with monoclonal antibodies BB3 and A13 to define a major and minor blood subset of T gamma delta cells respectively. Together, these antibodies identify the majority (if not all) of the peripheral blood T gamma delta cells. Significantly lower levels of T gamma delta cells were found in the blood of RA patients compared with controls, whilst higher but not significant numbers were found in the synovial fluids of paired samples. Scattered T gamma delta cells were found only in some synovial membranes with a distribution similar to the T alpha beta cells. Analysis of the two different T gamma delta-cell subsets indicated a ratio of BB3 to A13 of about 5:1 in control and RA blood. However, this ratio was less than 1:1 in the RA synovial fluids and membranes. The migratory nature of the A13+ cells could account for their predominance in these sites. The possible pathological significance of these cells in the rheumatoid synovial fluid and synovial membranes is discussed.
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Affiliation(s)
- M D Smith
- Department of Immunology, University College, London, UK
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Lydyard PM, Tsoulfa G, Sharif M, Bröker B, Smith M, Rook GA. Immunity to heat shock proteins in rheumatoid arthritis. Clin Exp Rheumatol 1990; 8 Suppl 5:69-74. [PMID: 2245530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Heat shock proteins (hsp) or "stress proteins" are a group of highly conserved proteins which are important in the day to day function of all cells. Early studies by others have indicated that immunity to the 65 kDa hsp of mycobacteria is important in the development of arthritis in the adjuvant arthritis model in rats. In this paper, we review the evidence suggesting that, as for the rat model, immune reactivity to hsp is of importance in the human disease. Elevated levels of IgG antibodies to the 65 kDa hsp of mycobacteria are characteristic of rheumatoid arthritis (RA) patients. Much of this antibody cross-reacts with human 65 kDa hsp and is therefore autoreactive. The 65 kDa hsp is found in synovial fluid and is therefore a potential target for antibody. Antibodies to the 70 kDa hsp (both of mycobacterial and human origin) are elevated, but not specifically, in RA. Increased T cell responses to the 65 kDa hsp are also found in synovial fluid of RA patients. Although gamma delta T cells are present in the synovial joint of RA patients, they do not appear to be particularly increased in frequency although the subset distribution of these cells is clearly different from that seen in the circulation. In fact, the synovium looks like the "gut" with regard to these subsets!
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Affiliation(s)
- P M Lydyard
- Department of Immunology, University College and Middlesex School of Medicine, London, U.K
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Abstract
A small population of T cells does not express the conventional T cell receptor characterized by the alpha and beta polypeptide chains (TCR alpha beta) but instead, two polypeptides termed gamma and delta (TCR gamma delta). This alternative receptor is able to recognize antigen. It appears early in T cell ontogeny, but its role in the thymus prior to the availability of TCR alpha beta remains unclear. In selected sites such as skin or gut TCR gamma delta predominates in mice which might suggest a role of gamma delta T cells in the first line of defense against infection. gamma delta T cells secrete lymphokines and display cytotoxic activity. However, their activation requirements may differ from what is known for alpha beta T cells since MHC-nonrestricted and also CD4 and CD8 negative gamma delta T cells have been described. Preferential activation by mycobacterial antigens possibly indicates a special repertoire of the gamma delta T cells. In various diseases slightly increased numbers of gamma delta T cells were found, but these preliminary studies have not yet provided evidence for a major pathogenetic role of gamma delta T cells.
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Affiliation(s)
- B Bröker
- Max-Planck-Gesellschaft, MPG Gruppe Rheumatologie/Immunologie, Erlangen
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Lydyard PM, Quartey-Papafio R, Bröker B, Mackenzie L, Jouquan J, Blaschek MA, Steele J, Petrou M, Collins P, Isenberg D. The antibody repertoire of early human B cells. I. High frequency of autoreactivity and polyreactivity. Scand J Immunol 1990; 31:33-43. [PMID: 2154032 DOI: 10.1111/j.1365-3083.1990.tb02740.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cord blood and fetal liver B cells were immortalized using Epstein-Barr virus, and IgM antibodies from the resulting lines and clones were examined for their binding to a variety of auto-antigens and micro-organisms by ELISA and fluorescence assays. Auto-antigens tested included Fc of IgG, ssDNA and dsDNA, cardiolipin, histones 1-4, collagens type I and II, thyroglobulin, cytoskeletal components, and a tissue section screen. Of 71 cell lines tested, all but 19 showed some autoreactivity. All 32 fetal liver lines reacted to some self-antigens. In cord blood clones, 16 out of 26 bound to auto-antigens. Many of the clones reacted with more than one auto-antigen and were 'polyreactive'. Some of the cord blood clones bound to extracts of micro-organisms, showing specificity for both endogenous and exogenous antigens. The high frequency of CD5+ B cells in the cord blood (greater than 50%) and fetal liver (greater than 70%) argues for many of these clones being derived from this subset. Therefore, our data support the concept that many 'early' B cells produce polyreactive IgM which can bind to a variety of different auto-antigens and micro-organisms. These IgM antibodies are similar to those described by others as 'natural antibodies'.
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Affiliation(s)
- P M Lydyard
- Department of Immunology, University College and Middlesex School of Medicine, London, UK
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