601
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Helms T, Boehm BO, Asaad RJ, Trezza RP, Lehmann PV, Tary-Lehmann M. Direct visualization of cytokine-producing recall antigen-specific CD4 memory T cells in healthy individuals and HIV patients. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:3723-32. [PMID: 10725731 DOI: 10.4049/jimmunol.164.7.3723] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have used computer-assisted cytokine ELISA spot analysis to measure the frequencies, the type of cytokine, and the amount of cytokine produced by individual recall Ag-specific CD4 memory cells in freshly isolated blood. We studied the memory cells specific for tetanus toxoid and purified protein derivative in 18 healthy individuals and in 22 HIV-infected patients on highly active antiretroviral therapy (HAART). In healthy individuals, the frequency, cytokine signature, and cytokine production per cell of these memory cells were stable over time. Although it is presently unclear whether the maintenance of the memory T cell pool depends upon Ag persistence, cross-reactive Ag stimulation, or cytokine-driven bystander stimulations and expansions, our data strongly argue for a stable memory cell pool in healthy individuals. In HIV patients, however, the frequency of these memory cells was a function of the viral load. The decreased numbers of functional memory cells in patients with high viral loads might provide one mechanism behind the immunodeficient state. Although the cytokine output per cell was unaffected in most patients (20 of 24), in some patients (4 of 24) it was >100-fold reduced, which might provide an additional mechanism to account for the reduced immunocompetence of these patients. The ability to visualize directly and quantify the cytokine produced by the low frequency memory cells in freshly isolated blood that have been physiologically stimulated by Ag should aid comprehensive studies of the Ag-specific memory cell pool in vivo, in health and disease.
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Affiliation(s)
- T Helms
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
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602
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Malek TR, Porter BO, Codias EK, Scibelli P, Yu A. Normal lymphoid homeostasis and lack of lethal autoimmunity in mice containing mature T cells with severely impaired IL-2 receptors. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:2905-14. [PMID: 10706676 DOI: 10.4049/jimmunol.164.6.2905] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The importance of IL-2Rbeta function for immune regulation is highlighted by the severe impairment in lymphoid cell function in IL-2Rbeta-deficient mice. It has been speculated that failed IL-2/IL-2R signaling in peripheral T cells causes the associated autoimmunity, imbalanced peripheral lymphoid homeostasis, and defective T cell function. This study explored the requirement for IL-2Rbeta function in mature T lymphocytes. We show that transgenic thymic expression of the IL-2R beta-chain in IL-2Rbeta-deficient mice prevents lethal autoimmunity, restores normal production of B lymphocytes, and results in a peripheral T cell compartment that is responsive to triggering through the TCR, but not the IL-2R. The dysfunction of the IL-2R is illustrated by the near complete failure of mature T cells to proliferate to IL-2 in vitro and in vivo, to differentiate into CTL, and to up-regulate IL-2Ralpha expression. These data indicate that lymphoid homeostasis is largely maintained despite a nonfunctional IL-2R in mature T lymphocytes and suggest that IL-2Rbeta provides an essential signal during thymic development to regulate self-reactivity.
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MESH Headings
- Animals
- Autoimmune Diseases/genetics
- Autoimmune Diseases/immunology
- Autoimmune Diseases/mortality
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cells, Cultured
- Cytotoxicity, Immunologic/genetics
- Homeostasis/genetics
- Homeostasis/immunology
- Immune Tolerance/genetics
- Interleukin-2/administration & dosage
- Lymphocyte Activation/genetics
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Interleukin-2/biosynthesis
- Receptors, Interleukin-2/deficiency
- Receptors, Interleukin-2/genetics
- Receptors, Interleukin-2/physiology
- Syndrome
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocytes, Cytotoxic/immunology
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transgenes/immunology
- Up-Regulation/genetics
- Up-Regulation/immunology
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Affiliation(s)
- T R Malek
- Department of Microbiology and Immunology, University of Miami School of Medicine, Miami, FL 33136, USA.
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603
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Affiliation(s)
- Eric S. Huseby
- Department of Immunology, University of Washington, Seattle, Washington 98195
| | - Joan Goverman
- Department of Immunology, University of Washington, Seattle, Washington 98195
- Department of Molecular Biotechnology, University of Washington, Seattle, Washington 98195
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604
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Abstract
Programmed cell death (PCD) can be divided into two distinct but linked sequential processes, killing of the cells and removal of the dead cells, which may be a neighboring cell or a professional phagocyte. Following internalization of the apoptotic cell, the phagocyte typically triggers neither the development of a pro-inflammatory response nor the production of autoantibodies directed against apoptotic self antigens. Since apoptotic cells are characterized by translocation of autoantigens such as nucleosomes to the surface of the cell, we tested the hypothesis that excess or abnormally processed apoptotic cells can generate autoantibodies. We have found that syngeneic apoptotic load can induce transient hypergammaglobulinemia, anti-DNA, anticardiolipin, and glomerular depositions in normal mice. Furthermore, we also found that one of the important mechanisms of uptake of apoptotic cells involves opsonization by the complement system, suggesting that deficient states could lead to aberrant handling of apoptotic cells. Therefore, conditions in which apoptotic cells become immunogenic may explain antigen selection in inflammatory and autoimmune conditions, such as in systemic lupus erythematosus (SLE).
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Affiliation(s)
- D Mevorach
- Laboratory for Cellular and Molecular Immunology, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Israel.
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605
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Helmby H, Jönsson G, Troye-Blomberg M. Cellular changes and apoptosis in the spleens and peripheral blood of mice infected with blood-stage Plasmodium chabaudi chabaudi AS. Infect Immun 2000; 68:1485-90. [PMID: 10678964 PMCID: PMC97305 DOI: 10.1128/iai.68.3.1485-1490.2000] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Infection with blood-stage Plasmodium chabaudi chabaudi AS results in splenomegaly, peripheral leukocytosis, and a major activation of the immune system. The frequencies and absolute numbers of T-cell, B-cell, and macrophage populations in spleen and peripheral blood from P. chabaudi-infected BALB/c mice were compared and found to be significantly altered during acute infection. The kinetics of the redistribution of the different cell types in spleen and peripheral blood were different, with T and B cells appearing in the blood when their frequencies and absolute numbers in the spleen were low. The frequency and absolute number of apoptotic cells in the spleen were increased during acute P. chabaudi infection and involved both T cells, B cells, and macrophages. Both Fas and Fas-ligand expression were increased in the spleen. Taken together, our data provide new information on the complex cellular interactions that take place in the immune system during blood-stage malaria infection in a mouse model.
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Affiliation(s)
- H Helmby
- Department of Immunology, Stockholm University, S-106 91 Stockholm, Sweden
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606
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Maverakis E, Beech JT, Wilson SS, Quinn A, Pedersen B, Sercarz EE. T cell receptor complementarity determining region 3 length analysis reveals the absence of a characteristic public T cell repertoire in neonatal tolerance. The response in the "tolerant" mouse within the residual repertoire is quantitatively similar but qualitatively different. J Exp Med 2000; 191:695-702. [PMID: 10684861 PMCID: PMC2195845 DOI: 10.1084/jem.191.4.695] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
All adult BALB/c mice immunized with hen egg white lysozyme (HEL) or its dominant determinant, peptide (p)106-116, mount a T cell response using a "public" Vbeta8.2Jbeta1.5 T cell clone. Neonatal exposure to tolerance-inducing doses of antigen can drastically diminish responsiveness in the draining lymph nodes but not in the spleens of animals challenged as adults with the cognate antigen. To determine the role of T cell deletion or anergy within the mechanisms of observed neonatal "tolerance," we treated neonatal BALB/c mice with HEL and directly followed the characteristic public clone using complementarity determining region 3 length T cell repertoire analysis. Our results confirm that despite intraperitoneal injection of neonates with a high dose of HEL emulsified in incomplete Freund's adjuvant, a strong splenic proliferative response to HEL was observed upon recall. However, the adult splenic T cell response of these neonatally treated mice lacked the usual Vbeta8.2Jbeta1.5 public clone characteristic of HEL-primed BALB/c mice. After challenge with HEL-complete Freund's adjuvant as adults, immunoglobulin (Ig)G2a isotype antibody was drastically reduced, and IgG1 was found to be the predominant anti-HEL IgG isotype expressed, indicating a deviation of cytokine response toward T helper type 2. 5-wk-old mice, nasally instilled with tolerogenic doses of HEL p106-116, also showed significant inhibition of this public T cell expansion. These results demonstrate that during neonatal and adult nasal tolerance induction, deletion/anergy removes the public clone, exposing a response of similar specificity but that is characterized by the T helper type 2 phenotype and a splenic residence.
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Affiliation(s)
- Emanual Maverakis
- La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Jonathan T. Beech
- La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Stephen S. Wilson
- La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Anthony Quinn
- La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Brian Pedersen
- La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Eli E. Sercarz
- La Jolla Institute for Allergy and Immunology, San Diego, California 92121
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607
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Gresham HD, Dale BM, Potter JW, Chang PW, Vines CM, Lowell CA, Lagenaur CF, Willman CL. Negative regulation of phagocytosis in murine macrophages by the Src kinase family member, Fgr. J Exp Med 2000; 191:515-28. [PMID: 10662797 PMCID: PMC2195814 DOI: 10.1084/jem.191.3.515] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Ingestion of opsonized pathogens by professional phagocytes results in the generation and release of microbicidal products that are essential for normal host defense. Because these products can result in significant tissue injury, phagocytosis must be regulated to limit damage to the host while allowing for optimal clearance and destruction of opsonized pathogens. To pursue negative regulation of phagocytosis, we assessed the effect of the Src kinase family member, Fgr, on opsonin-dependent phagocytosis by mouse macrophages. We chose Fgr because it is present in high concentrations in circulating phagocytes but is not essential for Fcgamma receptor-mediated ingestion by mouse macrophages. Although expression of Fgr both in a macrophage cell line and in primary macrophages significantly attenuates ingestion mediated by Fcgamma receptors and CR3, it does not affect macropinocytosis or receptor-mediated endocytosis. This selective effect of Fgr is independent of its tyrosine kinase function. After Fcgamma receptor cross-linking, Fgr becomes associated with the immunoreceptor tyrosine-based inhibition motif (ITIM)-containing receptor, SIRPalpha (a member of the signal-regulatory protein family, also known as Src homology 2 domain-containing protein tyrosine phosphatase [SHP] substrate 1 [SHPS-1], brain immunoglobulin-like molecule with tyrosine-based activation motifs [BIT], and P84) and potentiates the association of the phosphatase SHP-1 with SIRPalpha. This association is responsible, at least in part, for decreasing positive signaling essential for optimal phagocytosis. These data demonstrate an important negative regulatory role for this Src kinase family member and suggest that this homeostatic function must be overcome for optimal uptake and clearance of opsonized pathogens.
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Affiliation(s)
- H D Gresham
- Research Service, Albuquerque Veterans Administration Medical Center, Albuquerque, New Mexico 87108, USA.
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608
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Louis H, Le Moine A, Quertinmont E, Peny MO, Geerts A, Goldman M, Le Moine O, Devière J. Repeated concanavalin A challenge in mice induces an interleukin 10-producing phenotype and liver fibrosis. Hepatology 2000; 31:381-90. [PMID: 10655261 DOI: 10.1002/hep.510310218] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Weekly injections of Concanavalin A (Con A) were performed in BALB/c mice to evaluate the pattern of cytokine production and liver injury. High serum levels of tumor necrosis factor alpha (TNF-alpha), interleukin 2 (IL-2), IL-4, and interferon gamma (IFN-gamma) were found in the serum after the first 2 injections of Con A but rapidly decreased from the third injection. Conversely, IL-10 serum levels after repeated Con A challenge increased by 7 times from week 1 to 20. In vivo depletion studies indicated that CD4(+) T cells are essential in IL-10 production. Hepatocyte necrosis was only observed after the first injections of Con A whereas centrilobular inflammatory infiltrates persisted up to 20 weeks. Perisinusoidal liver fibrosis was also increasingly detected in BALB/c mice, whereas no fibrous change was observed in nude mice after 6 weeks of Con A challenge. The number of stellate cells, detected by immunostaining, increased after 20 weeks of Con A injections. Liver cytokine messenger RNA (mRNA) expression after 20 weeks showed expression of transforming growth factor beta1 (TGF-beta1), IL-10, and IL-4 whereas IL-2 was no more expressed. The present study shows that mice repeatedly injected with Con A develop liver fibrosis. The cytokine-release pattern observed after 1 injection of Con A is rapidly shifted towards an immunomodulatory phenotype characterized by the systemic production of large amounts of IL-10.
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Affiliation(s)
- H Louis
- Laboratories of Experimental Gastroenterology, Faculty of Medicine, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
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609
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Navratil JS, Ahearn JM. Apoptosis and autoimmunity: complement deficiency and systemic lupus erythematosus revisited. Curr Rheumatol Rep 2000; 2:32-8. [PMID: 11123037 DOI: 10.1007/s11926-996-0066-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Apoptosis may have a dual role in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus. First, this process may be integral in the clonal deletion of self-reactive lymphocytes and maintenance of peripheral tolerance. Second, apoptosis generates altered self-antigens with the potential for breaking self-tolerance. This review will discuss these two aspects of apoptosis and autoimmunity, and explore the potential role of the classical complement pathway in this context.
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Affiliation(s)
- J S Navratil
- University of Pittsburgh School of Medicine, University of Pittsburgh Arthritis Institute, E1152 Biomedical Science Tower, 200 South Lothrop Street, Pittsburgh, PA 15261, USA
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610
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Nicholson LB, Anderson AC, Kuchroo VK. Tuning T cell activation threshold and effector function with cross-reactive peptide ligands. Int Immunol 2000; 12:205-13. [PMID: 10653856 DOI: 10.1093/intimm/12.2.205] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We have generated a panel of cross-reactive T cells by immunizing SJL mice (I-A(s)) with Q144 peptide, an analog of an autoantigenic peptide (W144) of myelin proteolipid protein (PLP) 139-151 (HSLGKWLGHPDKF) in which W was replaced by Q at position 144. Following immunization with Q144, T cells were expanded in vitro with W144, which is a cross-reactive, suboptimal ligand, for Q144-specific T cells. The T cell clones responded to both ligands and grew normally on the peptide W144, but were hyperstimulated when activated by Q144 in vitro. This hyperstimulation results in a heteroclitic proliferative response with secretion of additional cytokines not induced by W144. Thus expansion of T cells by a suboptimal cross-reactive ligand effectively lowers the activation threshold so that the immunizing antigen becomes a hyperstimulating ligand for the clones. Surprisingly, when the T cell clones are grown on the hyperstimulating ligand Q144, some adapt by increasing their activation threshold. This desensitization results in a loss of response to a number of cross-reactive ligands and the appearance of a more specific T cell response. Long-term culture with the hyperstimulating ligand is sometimes associated with down-regulation of CD4 expression. These results provide an explanation for the common finding of T cell heteroclicity, and suggest that although the specificity and hierarchy of the response of T cells to peptides is determined by the TCR, activation threshold and effector functions are modified by exposure to cross-reactive ligands. This observation has implications for the development and regulation of autoimmune disease.
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Affiliation(s)
- L B Nicholson
- Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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611
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Affiliation(s)
- S Fidler
- Imperial College School of Science, Technology and Medicine, St Mary's Hospital, London
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612
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Lefrançois L, Altman JD, Williams K, Olson S. Soluble antigen and CD40 triggering are sufficient to induce primary and memory cytotoxic T cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:725-32. [PMID: 10623816 DOI: 10.4049/jimmunol.164.2.725] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The signals directing induction of tolerance rather than immunity are largely unknown. The CD8 T cell response to soluble Ags generally results in deletional tolerance following transient, costimulation-dependent activation. We demonstrated that CD40 signaling reversed the outcome of this response. Adoptive transfer of OVA-specific CD8 T cells followed by soluble OVA immunization resulted in induction of lytic activity and optimal clonal expansion only when CD40 was triggered via an agonistic mAb. Activation of CD8 T cells by CD40 signaling was indirect, because CD40 expression by host cells was required. CD40 signaling along with soluble Ag immunization also induced expansion of secondary lymphoid and intestinal mucosal endogenous OVA-specific CD8 T cells as detected by MHC tetramer reactivity. When CD40 activation was included, long-lived secondary lymphoid and mucosal memory CD8 cells were generated from adoptively transferred and endogenous CD8 T cells. Mucosal and peripheral CD8 memory cells exhibited constitutive Ag-specific lytic activity, with mucosal memory cells being 10-fold more lytic than splenic or lymph node memory cells. These results demonstrated that CD40 signaling during a response to a poorly immunogenic soluble Ag was necessary and sufficient for CTL and memory T cell induction.
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Affiliation(s)
- L Lefrançois
- Division of Rheumatic Diseases, University of Connecticut Health Center, Farmington, CT 06037, USA.
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613
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Affiliation(s)
- A K Abbas
- Department of Pathology, University of California San Francisco School of Medicine, 94123, USA
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614
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Van Ginderachter JA, Liu Y, Geldhof AB, Brijs L, Thielemans K, De Baetselier P, Raes G. B7-1, IFNγ and anti-CTLA-4 co-operate to prevent T-cell tolerization during immunotherapy against a murine T-lymphoma. Int J Cancer 2000. [DOI: 10.1002/1097-0215(20000815)87:4<539::aid-ijc13>3.0.co;2-e] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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615
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Marincola FM, Jaffee EM, Hicklin DJ, Ferrone S. Escape of human solid tumors from T-cell recognition: molecular mechanisms and functional significance. Adv Immunol 1999; 74:181-273. [PMID: 10605607 DOI: 10.1016/s0065-2776(08)60911-6] [Citation(s) in RCA: 805] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- F M Marincola
- Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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616
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Becker JC, Guldberg P, Zeuthen J, Bröcker EB, Straten PT. Accumulation of identical T cells in melanoma and vitiligo-like leukoderma. J Invest Dermatol 1999; 113:1033-8. [PMID: 10594748 DOI: 10.1046/j.1523-1747.1999.00805.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cloning of genes encoding melanoma antigens has opened new possibilities for the treatment of patients with cancer; however, most tumor rejection antigens recognized by tumor infiltrating lymphocytes are the products of genes that are also expressed by normal melanocytes. Hence, a large set of antigenic determinants of the self have not induced self-tolerance and these peptide determinants furnish target structures for immune responses directed against tumors. The notion that the immunotherapeutic targets involved in cancer regression comprise normal differentiation antigens is stressed by the association between vitiligo-like leukoderma, due to destruction of normal melanocytes, and melanoma regression, due to destruction of cancer cells. Nevertheless, this is the first report to demonstrate by means of a new technique based on reverse transcription polymerase chain reaction and denaturing gradient gel electrophoresis, the presence of clonally expanded T cells with identical BV regions in areas of destruction of both normal and neoplastic cells.
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Affiliation(s)
- J C Becker
- Department of Dermatology, Julius-Maximilians-University, Würzburg, Germany.
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617
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Lee KH, Wang E, Nielsen MB, Wunderlich J, Migueles S, Connors M, Steinberg SM, Rosenberg SA, Marincola FM. Increased Vaccine-Specific T Cell Frequency After Peptide-Based Vaccination Correlates with Increased Susceptibility to In Vitro Stimulation But Does Not Lead to Tumor Regression. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.11.6292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Although in vitro sensitization assays have shown increased melanoma Ag (MA)-specific CTL reactivity after vaccination with MA peptides, clinical responses have been uncommon. This paradox questions whether data obtained from the in vitro stimulation and expansion of T cells lead to an overestimation of the immune response to vaccines. Using HLA/peptide tetramer (tHLA), we enumerated MA-specific T cell precursor frequency (TCPF) directly in PBMC from 23 melanoma patients vaccinated with gp100:209–217(210M) (g209–2M) peptide. Vaccine-specific TCPF was higher in postvaccination PBMC from seven of seven patients treated with peptide alone and four of five patients treated with peptide plus IL-12 (range of postvaccination TCPF, 0.2–2.4% and 0.2–2.5%, respectively). The increased TCPF correlated with enhanced susceptibility to in vitro stimulation with the relevant epitope. Paradoxically, no increase in postvaccination TCPF was observed in most patients who had been concomitantly treated with IL-2 (1 of 11 patients; range of postvaccination TCPF, 0.02–1.0%), a combination associated with enhanced rates of tumor regression. The lack of increase in TCPF seen in these patients corresponded to inability to elicit expansion of vaccine-specific T cells in culture. This study shows that a peptide-based vaccine can effectively generate a quantifiable T cell-specific immune response in the PBMC of cancer patients, though such a response does not associate with a clinically evident regression of metastatic melanoma.
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Affiliation(s)
- Kang-Hun Lee
- *Department of Transfusion Medicine, Clinical Center,
| | - Ena Wang
- †Surgery Branch, National Cancer Institute,
| | | | | | - Steven Migueles
- §Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Mark Connors
- §Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Seth M. Steinberg
- ‡Biostatistics and Data Management Section, National Cancer Institute, and
| | | | - Francesco M. Marincola
- *Department of Transfusion Medicine, Clinical Center,
- †Surgery Branch, National Cancer Institute,
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618
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Lepple-Wienhues A, Belka C, Laun T, Jekle A, Walter B, Wieland U, Welz M, Heil L, Kun J, Busch G, Weller M, Bamberg M, Gulbins E, Lang F. Stimulation of CD95 (Fas) blocks T lymphocyte calcium channels through sphingomyelinase and sphingolipids. Proc Natl Acad Sci U S A 1999; 96:13795-800. [PMID: 10570152 PMCID: PMC24144 DOI: 10.1073/pnas.96.24.13795] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Calcium influx through store-operated calcium release-activated calcium channels (CRAC) is required for T cell activation, cytokine synthesis, and proliferation. The CD95 (Apo-1/Fas) receptor plays a role in self-tolerance and tumor immune escape, and it mediates apoptosis in activated T cells. In this paper we show that CD95-stimulation blocks CRAC and Ca(2+) influx in lymphocytes through the activation of acidic sphingomyelinase (ASM) and ceramide release. The block of Ca(2+) entry is lacking in CD95-defective lpr lymphocytes as well as in ASM-defective cells and can be restored by retransfection of ASM. C2 ceramide, C6 ceramide, and sphingosine block CRAC reversibly, whereas the inactive dihydroceramide has no effect. CD95-stimulation or the addition of ceramide prevents store-operated Ca(2+) influx, activation of the transcriptional regulator NFAT, and IL-2 synthesis. The block of CRAC by sphingomyelinase metabolites adds a function to the repertoire of the CD95 receptor inhibiting T cell activation signals.
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Affiliation(s)
- A Lepple-Wienhues
- Department of Physiology I, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
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619
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Wells AD, Li XC, Li Y, Walsh MC, Zheng XX, Wu Z, Nuñez G, Tang A, Sayegh M, Hancock WW, Strom TB, Turka LA. Requirement for T-cell apoptosis in the induction of peripheral transplantation tolerance. Nat Med 1999; 5:1303-7. [PMID: 10545998 DOI: 10.1038/15260] [Citation(s) in RCA: 456] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mechanisms of allograft tolerance have been classified as deletion, anergy, ignorance and suppression/regulation. Deletion has been implicated in central tolerance, whereas peripheral tolerance has generally been ascribed to clonal anergy and/or active immunoregulatory states. Here, we used two distinct systems to assess the requirement for T-cell deletion in peripheral tolerance induction. In mice transgenic for Bcl-xL, T cells were resistant to passive cell death through cytokine withdrawal, whereas T cells from interleukin-2-deficient mice did not undergo activation-induced cell death. Using either agents that block co-stimulatory pathways or the immunosuppressive drug rapamycin, which we have shown here blocks the proliferative component of interleukin-2 signaling but does not inhibit priming for activation-induced cell death, we found that mice with defective passive or active T-cell apoptotic pathways were resistant to induction of transplantation tolerance. Thus, deletion of activated T cells through activation-induced cell death or growth factor withdrawal seems necessary to achieve peripheral tolerance across major histocompatibility complex barriers.
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Affiliation(s)
- A D Wells
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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620
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Lee IH, Li WP, Hisert KB, Ivashkiv LB. Inhibition of interleukin 2 signaling and signal transducer and activator of transcription (STAT)5 activation during T cell receptor-mediated feedback inhibition of T cell expansion. J Exp Med 1999; 190:1263-74. [PMID: 10544198 PMCID: PMC2195684 DOI: 10.1084/jem.190.9.1263] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/1999] [Accepted: 08/20/1999] [Indexed: 01/28/2023] Open
Abstract
Limitation of clonal expansion of activated T cells is necessary for immune homeostasis, and is achieved by growth arrest and apoptosis. Growth arrest and apoptosis can occur passively secondary to cytokine withdrawal, or can be actively induced by religation of the T cell receptor (TCR) in previously activated proliferating T cells. TCR-induced apoptosis appears to require prior growth arrest, and is mediated by death receptors such as Fas. We tested whether TCR religation affects T cell responses to interleukin (IL)-2, a major T cell growth and survival factor. TCR ligation in activated primary human T cells blocked IL-2 induction of signal transducer and activator of transcription (STAT)5 DNA binding, phosphorylation of STAT5, Janus kinase (Jak)1, Jak3, and Akt, and kinase activity of Jak1 and Jak3. Inhibition was mediated by the mitogen-activated protein kinase kinase (MEK)-extracellular stimulus-regulated kinase (ERK) signaling pathway, similar to the mechanism of inhibition of IL-6 signaling we have described previously. TCR ligation blocked IL-2 activation of genes and cell cycle regulatory proteins, and suppressed cell proliferation and expansion. These results identify TCR-induced inhibition of IL-2 signaling as a novel mechanism that underlies antigen-mediated feedback limitation of T cell expansion, and suggest that modulation of cytokine activity by antigen receptor signals plays an important role in the regulation of lymphocyte function.
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Affiliation(s)
- In-Hong Lee
- Department of Medicine, Hospital for Special Surgery, New York, New York 10021
| | - Wai Ping Li
- Department of Medicine, Hospital for Special Surgery, New York, New York 10021
| | - Katherine B. Hisert
- Cornell/Rockefeller/Sloan-Kettering Tri-Institutional MD-PhD Program, New York, New York 10021
| | - Lionel B. Ivashkiv
- Department of Medicine, Hospital for Special Surgery, New York, New York 10021
- Graduate Program in Immunology, Weill Graduate School of Medical Sciences of Cornell University, New York, New York 10021
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621
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Membrane-Bound Fas (Apo-1/CD95) Ligand on Leukemic Cells: A Mechanism of Tumor Immune Escape in Leukemia Patients. Blood 1999. [DOI: 10.1182/blood.v94.9.3135.421k37_3135_3140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There is evidence from bone marrow transplantation that T cells may be involved in the immunologic control of leukemia. But many patients relapse despite a potent graft-versus-leukemia effect mediated by allogeneic T cells. The expression of the FasL protein has been suggested as a mechanism of tumor immune escape. We, therefore, evaluated the capacity of leukemic cells from patients with acute or chronic myelogenous leukemia to escape the allogeneic or autologous immune response by bearing the FasL molecule. Although almost all leukemic cells express the 37-kD form of FasL, only 54% of acute myeloblastic leukemia and 27% of chronic myeloid leukemia (CML) cells bore a FasL with killing properties, as assessed by the ability of leukemic cells to cause the apoptosis of a Fas-sensitive target cell line or autologous activated T cells in 3 tested leukemic cases. Experiments with a recombinant Fas-Fc molecule confirmed the role of Fas/FasL in leukemic-mediated cell death. Only CML leukemic cells from certain individuals contained the 26-kD truncated form of FasL. Thus, myeloid leukemic cells from some, but not all patients can set up a mechanism of immune escape involving the Fas/FasL pathway. This leukemic escape may have implications for patients eligible for adoptive cellular immunotherapy.
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622
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Affiliation(s)
- S J van Deventer
- Laboratory for Experimental Internal Medicine, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
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623
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Membrane-Bound Fas (Apo-1/CD95) Ligand on Leukemic Cells: A Mechanism of Tumor Immune Escape in Leukemia Patients. Blood 1999. [DOI: 10.1182/blood.v94.9.3135] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
There is evidence from bone marrow transplantation that T cells may be involved in the immunologic control of leukemia. But many patients relapse despite a potent graft-versus-leukemia effect mediated by allogeneic T cells. The expression of the FasL protein has been suggested as a mechanism of tumor immune escape. We, therefore, evaluated the capacity of leukemic cells from patients with acute or chronic myelogenous leukemia to escape the allogeneic or autologous immune response by bearing the FasL molecule. Although almost all leukemic cells express the 37-kD form of FasL, only 54% of acute myeloblastic leukemia and 27% of chronic myeloid leukemia (CML) cells bore a FasL with killing properties, as assessed by the ability of leukemic cells to cause the apoptosis of a Fas-sensitive target cell line or autologous activated T cells in 3 tested leukemic cases. Experiments with a recombinant Fas-Fc molecule confirmed the role of Fas/FasL in leukemic-mediated cell death. Only CML leukemic cells from certain individuals contained the 26-kD truncated form of FasL. Thus, myeloid leukemic cells from some, but not all patients can set up a mechanism of immune escape involving the Fas/FasL pathway. This leukemic escape may have implications for patients eligible for adoptive cellular immunotherapy.
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624
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Raftery MJ, Behrens CK, Müller A, Krammer PH, Walczak H, Schönrich G. Herpes simplex virus type 1 infection of activated cytotoxic T cells: Induction of fratricide as a mechanism of viral immune evasion. J Exp Med 1999; 190:1103-14. [PMID: 10523608 PMCID: PMC2195666 DOI: 10.1084/jem.190.8.1103] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Herpes simplex virus type 1 (HSV1), a large DNA-containing virus, is endemic in all human populations investigated. After infection of mucocutaneous surfaces, HSV1 establishes a latent infection in nerve cells. Recently, it was demonstrated that HSV1 can also infect activated T lymphocytes. However, the consequences of T cell infection for viral pathogenesis and immunity are unknown. We have observed that in contrast to the situation in human fibroblasts, in human T cell lines antigen presentation by major histocompatibility complex class I molecules is not blocked after HSV1 infection. Moreover, HSV1 infection of T cells results in rapid elimination of antiviral T cells by fratricide. To dissect the underlying molecular events, we used a transgenic mouse model of HSV1 infection to demonstrate that CD95 (Apo-1, Fas)-triggered apoptosis is essential for HSV1-induced fratricide, whereas tumor necrosis factor (TNF) also contributes to this phenomenon but to a lesser extent. By contrast, neither TRAIL (TNF-related apoptosis-inducing ligand) nor perforin were involved. Finally, we defined two mechanisms associated with HSV1-associated fratricide of antiviral T cells: (a) T cell receptor-mediated upregulation of CD95 ligand and (b) a viral "competence-to-die" signal that renders activated T lymphocytes susceptible to CD95 signaling. We propose that induction of fratricide is an important immune evasion mechanism of HSV1, helping the virus to persist in the host organism throughout its lifetime.
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Affiliation(s)
- Martin J. Raftery
- Department of Medical Virology, Institute of Hygiene, University of Heidelberg
| | - Christian K. Behrens
- Tumor Immunology Program, Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Anke Müller
- Department of Medical Virology, Institute of Hygiene, University of Heidelberg
| | - Peter H. Krammer
- Tumor Immunology Program, Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Henning Walczak
- Tumor Immunology Program, Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Günther Schönrich
- Department of Medical Virology, Institute of Hygiene, University of Heidelberg
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625
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Dai Z, Lakkis FG. The role of cytokines, CTLA-4 and costimulation in transplant tolerance and rejection. Curr Opin Immunol 1999; 11:504-8. [PMID: 10508707 DOI: 10.1016/s0952-7915(99)00008-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
T cell costimulation and cytokine production play an important role in generating the alloimmune responses that lead to allograft rejection. Recent data, however, provide evidence that costimulatory molecules, such as B7-1 and B7-2, and T cell activating cytokines, such as IFN-gamma and IL-2, also trigger negative feedback mechanisms in T lymphocytes which limit alloimmune responses. These feedback mechanisms are essential for the induction of long-term allograft acceptance and, in certain situations, transplantation tolerance.
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Affiliation(s)
- Z Dai
- Renal Division, Emory University and Veterans Affairs Medical Center, 1670 Clairmont Road - 151N, Atlanta, GA 30033, USA.
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626
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Mellor AL, Munn DH. Tryptophan catabolism and T-cell tolerance: immunosuppression by starvation? IMMUNOLOGY TODAY 1999; 20:469-73. [PMID: 10500295 DOI: 10.1016/s0167-5699(99)01520-0] [Citation(s) in RCA: 459] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Some macrophages inhibit microbial infections by producing indoleamine 2,3 dioxygenase (IDO), which catabolizes tryptophan. Here, Andrew Mellor and David Munn discuss evidence that cells that synthesize IDO protect the mammalian fetus from maternal T-cell attack and argue that this mechanism might have wider implications for the control of T-cell responses.
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Affiliation(s)
- A L Mellor
- Molecular Immunology Program, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912, USA.
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627
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Gao JX, Madrenas J, Zeng W, Cameron MJ, Zhang Z, Wang JJ, Zhong R, Grant D. CD40-deficient dendritic cells producing interleukin-10, but not interleukin-12, induce T-cell hyporesponsiveness in vitro and prevent acute allograft rejection. Immunology 1999; 98:159-70. [PMID: 10540214 PMCID: PMC2326930 DOI: 10.1046/j.1365-2567.1999.00863.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The induction of an immune response or tolerance is mediated by corresponding subsets of dendritic cells (DC). However, the property of tolerogenic DC is not clear. Recently, we have characterized a population of CD11c+ splenic DC derived from long-term mixed leucocyte culture (LT-MLC), which are able to proliferate upon stimulation and have a strong primary mixed leucocyte reaction (MLR)-stimulating activity in conventional MLR. In this study, we show that, in contrast to the irradiated ones, non-irradiated LT-MLC-derived DC induce polyclonal antigen-specific T-cell hyporesponsiveness when cocultured with allogeneic splenocytes for 3-11 days. The degree of the hyporesponsiveness increased with the length of coculture. Although these DC expressed major histocompatibility complex class II and B7 costimulatory molecules, which are down-regulated during coculture, they expressed very low or undetectable CD40 before and after coculture, respectively. The CD40-deficient DC spontaneously produce interleukin-10 (IL-10), but not IL-12. The skewed balance between IL-10 and IL-12 is associated with their capability to induce T-cell hyporesponsiveness, because a neutralizing antibody to IL-10, exogenous recombinant IL-12 or lipopolysaccharide (LPS) significantly blocked the hyporesponsiveness. Accordingly, infusion of a small number of non-irradiated LT-MLC-derived DC (5x105) significantly prolonged the survival of a vascularized heterotopic murine heart transplant, whereas irradiated DC accelerated graft rejection. These data suggest that CD40-deficient DC producing IL-10, but not IL-12 can induce T-cell hyporesponsiveness in vitro and in vivo.
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Affiliation(s)
- J X Gao
- Transplantation and Immunobiology Group, The John P. Robarts Research Institute, London, Ont., Canada
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628
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Abstract
Recently, particular cytokines have been identified to affect progression of a variety of diseases and retrovirus infections. Previously, we demonstrated that interleukin-2 (IL-2), IL-12, and gamma interferon increased in peripheral blood mononuclear cells (PBMCs) from animals with early disease and decreased in PBMCs from animals with late disease stages of bovine leukemia virus (BLV) infection. In contrast, IL-10 increased with disease progression. To examine the effects of these cytokines on BLV expression, BLV tax and pol mRNA and p24 protein were quantified by competitive PCR and immunoblotting, respectively. IL-10 inhibited BLV tax and pol mRNA levels in BLV-infected PBMCs; however, the inhibitory effect of IL-10 was prevented in PBMCs depleted of monocytes and/or macrophages (monocyte/macrophages). To determine whether these factors were secreted or monocyte/macrophage associated, monocyte/macrophage-depleted PBMCs were cultured with isolated monocyte/macrophages in transwells where contact between monocyte/macrophages and nonadherent PBMCs was blocked. BLV tax and pol mRNA levels increased in transwell cultures similar to cultures containing nonseparated cells, and IL-10 addition inhibited the increase of BLV tax and pol mRNA. These results suggest that monocyte/macrophages secrete soluble factor(s) that increases BLV mRNA levels and that secretion of these soluble factor(s) could be inhibited by IL-10. In contrast, IL-2 increased BLV tax and pol mRNA and p24 protein production. Thus, IL-10 production by BLV-infected animals with late stage disease may serve to control BLV mRNA levels, while IL-2 may increase BLV mRNA in the early disease stage. To determine a correlation between cell proliferation and BLV expression, the effect of IL-2 and IL-10 on PBMC proliferation was tested. As anticipated, IL-2 stimulated while IL-10 suppressed antigen-specific PBMC proliferation. The present study, combined with our previous findings, suggests that increased IL-10 production in late disease stages suppresses BLV mRNA levels, while IL-2-activated immune responses stimulate BLV expression by BLV-infected B cells.
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Affiliation(s)
- D Pyeon
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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629
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Sensitivity of CD4+ Peripheral Blood T Cells Toward Spontaneous and CD95 (APO-1/Fas)-Induced Apoptosis in Pediatric Human Immunodeficiency Virus Infection. Blood 1999. [DOI: 10.1182/blood.v94.5.1829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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630
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Pratt JC, van den Brink MRM, Igras VE, Walk SF, Ravichandran KS, Burakoff SJ. Requirement for Shc in TCR-Mediated Activation of a T Cell Hybridoma. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.5.2586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Engagement of the TCR determines the fate of T cells to activate their functional programs, proliferate, or undergo apoptosis. The intracellular signal transduction pathways that dictate the specific outcome of receptor engagement have only been partially elucidated. The adapter protein, Shc, is involved in cytokine production, mitogenesis, transformation, and apoptosis in different cell systems. We found that Shc becomes phosphorylated on tyrosine residues upon stimulation of the TCR in DO11.10 hybridoma T cells; therefore, we investigated the role of Shc in activation-induced cell death in these cells by creating a series of stably transfected cell lines. Expression of Shc-SH2 (the SH2 domain of Shc) or Shc-Y239/240F (full-length Shc in which tyrosines 239 and 240 have been mutated to phenylalanine) resulted in the inhibition of activation-induced cell death and Fas ligand up-regulation after TCR cross-linking. Expression of wild-type Shc or Shc-Y317F had no significant effect. In addition, we found that Shc-SH2 and Shc-Y239/240F, but not Shc-Y317F, inhibited phosphorylation of extracellular signal-regulated protein kinase and production of IL-2 after TCR cross-linking. These results indicate an important role for Shc in the early signaling events that lead to activation-induced cell death and IL-2 production after TCR activation.
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Affiliation(s)
- Joanne C. Pratt
- *Division of Pediatric Oncology, Dana-Farber Cancer Institute, and
- †Department of Pediatrics, Harvard Medical School, Boston, MA 02115
| | - Marcel R. M. van den Brink
- *Division of Pediatric Oncology, Dana-Farber Cancer Institute, and
- ‡Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215; and
| | - Vivien E. Igras
- *Division of Pediatric Oncology, Dana-Farber Cancer Institute, and
| | - Scott F. Walk
- §Beirne Carter Center for Immunology, University of Virginia, Charlottesville, VA 22908
| | | | - Steven J. Burakoff
- *Division of Pediatric Oncology, Dana-Farber Cancer Institute, and
- †Department of Pediatrics, Harvard Medical School, Boston, MA 02115
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631
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Galli F, Canestrari F, Buoncristiani U. Biological effects of oxidant stress in haemodialysis: the possible roles of vitamin E. Blood Purif 1999; 17:79-94. [PMID: 10449865 DOI: 10.1159/000014379] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Oxidative stress has been proposed to play a role in many disease states, including cardiovascular and infectious diseases, cancer, diabetes and neurodegenerative pathologies. The fact that these diseases have an increased incidence in uremia, and particularly in dialysis patients, suggests an increased exposure to oxidative stress in this condition. In haemodialysis (HD), the absence of a complete correction of the uremic toxicity together with the untoward effects of the dialysis, malnutrition and the progressive worsening of the clinical condition, can lead to a high susceptibility to oxidative stress by an abnormal production of oxidants - including reactive oxygen species (ROS) and uremic toxins with prooxidant function - and defective antioxidant protection. One of the most investigated biological effects of the oxidative stress in the HD patients is lipid peroxidation in plasma and blood cell membranes. Moreover, we have recently described how abnormal apoptosis in peripheral blood leukocytes is associated with cell oxidative stress (intracellular thiol depletion). Vitamin E, in both in vitro and in vivo conditions, has been proposed to partially correct these effects. In this review we evaluated some features of two new dialysis strategies using an antioxidant approach to the protection against the oxidant stress in HD. Their rationale is based on the emerging role of vitamin E in counteracting some biological effects associated with oxidant stress namely lipid peroxidation and apoptosis. These techniques use: 1) the recirculation of the dialysate through a suspension of vitamin E-enriched liposomes combined with the supplementation by the dialysate with ascorbic acid, this method has been called hemolipodialysis; 2) the coating of the dialysis membrane with vitamin E (vitamin E- modified dialysis membranes). These unconventional approaches to the antioxidant therapy in HD open a widely unexplored and promising field in the evolution of the biomaterials and dialysis quality.
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Affiliation(s)
- F Galli
- 'G. Fornaini' Institute of Biological Chemistry, University of Urbino, Italy.
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632
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Berzins SP, Godfrey DI, Miller JF, Boyd RL. A central role for thymic emigrants in peripheral T cell homeostasis. Proc Natl Acad Sci U S A 1999; 96:9787-91. [PMID: 10449772 PMCID: PMC22288 DOI: 10.1073/pnas.96.17.9787] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
After initial seeding by thymic emigrants, homeostatic regulation of the T cell pool has been thought to occur entirely within the periphery. Here we report that the degree of thymic emigration directly affects the number and the CD4/CD8 ratio of peripheral T cells. We demonstrate that the increase in T cell pool size caused by the engraftment of 2, 6, or 9 thymic lobes correlates almost exactly with the number of emigrants exported from those grafts in the previous 3 weeks, regardless of how long the graft has been in place. The extent of the increase supports the concept of a 3-week period after thymic export in which emigrant T cells are exempt from peripheral T cell homeostasis. This apparent exclusion of recent thymic emigrants from the niche-based regulation of peripheral T cell numbers ensures repertoire turnover throughout adult life and provides the basis of a direct and previously unrecognized role for the thymus in the regulation of peripheral T cell homeostasis.
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Affiliation(s)
- S P Berzins
- Department of Pathology and Immunology, Monash Medical School, Commercial Road, Prahran, Victoria 3181, Australia.
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633
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Abstract
Recent advances have enabled researchers to induce tolerance in animal transplant models. Although it has been relatively easy to do so in rodents, it has been much more difficult to translate such strategies into primates. Understanding the cellular and molecular mechanisms of the alloimmune response has prompted the development of novel strategies that may obviate the need for immunosuppression in humans. Mechanisms of tolerance and promising new therapies, as well as the inherent difficulties in bringing them into clinical practice, are reviewed.
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Affiliation(s)
- V M Dong
- Laboratory of Immunogenetics and Transplantation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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634
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Scheel-Toellner D, Pilling D, Akbar AN, Hardie D, Lombardi G, Salmon M, Lord JM. Inhibition of T cell apoptosis by IFN-beta rapidly reverses nuclear translocation of protein kinase C-delta. Eur J Immunol 1999; 29:2603-12. [PMID: 10458775 DOI: 10.1002/(sici)1521-4141(199908)29:08<2603::aid-immu2603>3.0.co;2-l] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Type I interferons rescue activated human T cells from cytokine deprivation-induced apoptosis. Our data now show that IFN-beta also rapidly inhibits apoptotic signals induced through the Fas receptor (CD95) in human T cells. To identify upstream signaling elements that could be targets of IFN-beta, we have studied protein kinase C (PKC). PKC-delta is actively involved in the regulation of apoptosis and immunofluorescence staining revealed that early in apoptosis PKC-delta accumulated in the nucleus. Addition of IFN-beta to T cells already deprived of survival factors or treated with anti-Fas antibody caused a rapid retranslocation of PKC-delta away from the nucleus. Furthermore, the generation of a constitutively active catalytic fragment by cleavage of PKC-delta by caspase 3 occurred only after translocation of full-length PKC-delta to the nucleus. IFN-beta also inhibited caspase 3 and the proteolytic activation of PKC-delta. We conclude from these studies that nuclear translocation of PKC-delta is an early event in T cell apoptosis and that IFN-beta rapidly reverses this process.
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Affiliation(s)
- D Scheel-Toellner
- MRC Centre for Immune Regulation, Division of Immunity and Infection, University of Birmingham, Birmingham, GB
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635
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Litherland SA, Xie XT, Hutson AD, Wasserfall C, Whittaker DS, She JX, Hofig A, Dennis MA, Fuller K, Cook R, Schatz D, Moldawer LL, Clare-Salzler MJ. Aberrant prostaglandin synthase 2 expression defines an antigen-presenting cell defect for insulin-dependent diabetes mellitus. J Clin Invest 1999; 104:515-23. [PMID: 10449443 PMCID: PMC408519 DOI: 10.1172/jci4852] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/1998] [Accepted: 07/13/1999] [Indexed: 12/21/2022] Open
Abstract
Prostaglandins (PGs) are lipid molecules that profoundly affect cellular processes including inflammation and immune response. Pathways contributing to PG output are highly regulated in antigen-presenting cells such as macrophages and monocytes, which produce large quantities of these molecules upon activation. In this report, we demonstrate aberrant constitutive expression of the normally inducible cyclooxygenase PG synthase 2 (PGS(2)/ COX-2) in nonactivated monocytes of humans with insulin-dependent diabetes mellitus (IDDM) and those with islet autoantibodies at increased risk of developing this disease. Constitutive PGS(2) appears to characterize a high risk for diabetes as it correlates with and predicts a low first-phase insulin response in autoantibody-positive subjects. Abnormal PGS(2) expression in at-risk subjects affected immune response in vitro, as the presence of a specific PGS(2) inhibitor, NS398, significantly increased IL-2 receptor alpha-chain (CD25) expression on phytohemagglutinin-stimulated T cells. The effect of PGS(2) on CD25 expression was most profound in subjects expressing both DR04 and DQbeta0302 high-risk alleles, suggesting that this cyclooxygenase interacts with diabetes-associated MHC class II antigens to limit T-cell activation. These results indicate that constitutive PGS(2) expression in monocytes defines an antigen-presenting cell defect affecting immune response, and that this expression is a novel cell-associated risk marker for IDDM.
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Affiliation(s)
- S A Litherland
- Department of Immunology, Pathology, and Laboratory Medicine, College of Medicine, College of Medicine, University of Florida, Gainesville 32610, USA
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636
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Affiliation(s)
- N Novak
- Department of Dermatology, University of Bonn, Germany
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637
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Martins GA, Vieira LQ, Cunha FQ, Silva JS. Gamma interferon modulates CD95 (Fas) and CD95 ligand (Fas-L) expression and nitric oxide-induced apoptosis during the acute phase of Trypanosoma cruzi infection: a possible role in immune response control. Infect Immun 1999; 67:3864-71. [PMID: 10417150 PMCID: PMC96666 DOI: 10.1128/iai.67.8.3864-3871.1999] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously shown that splenocytes from mice acutely infected with Trypanosoma cruzi exhibit high levels of nitric oxide (NO)-mediated apoptosis. In the present study, we used the gamma interferon (IFN-gamma)-knockout (IFN-gamma(-/-)) mice to investigate the role of IFN-gamma in modulating apoptosis induction and host protection during T. cruzi infection in mice. IFN-gamma(-/-) mice were highly susceptible to infection and exhibited significant reduction of NO production and apoptosis levels in splenocytes but normal lymphoproliferative response compared to the infected wild-type (WT) mice. Furthermore, IFN-gamma modulates an enhancement of Fas and Fas-L expression after infection, since the infected IFN-gamma(-/-) mice showed significantly lower levels of Fas and Fas-L expression. The addition of recombinant murine IFN-gamma to spleen cells cultures from infected IFN-gamma(-/-) mice increased apoptosis levels, Fas expression, and NO production. In the presence of IFN-gamma and absence of NO, although Fas expression was maintained, apoptosis levels were significantly reduced but still higher than those found in splenocytes from uninfected mice, suggesting that Fas-Fas-L interaction could also play a role in apoptosis induction in T. cruzi-infected mice. Moreover, in vivo, the treatment of infected WT mice with the inducible nitric oxide synthase inhibitor aminoguanidine also led to decreased NO and apoptosis levels but not Fas expression, suggesting that IFN-gamma modulates apoptosis induction by two independent and distinct mechanisms: induction of NO production and of Fas and Fas-L expression. We suggest that besides being of crucial importance in mediating resistance to experimental T. cruzi infection, IFN-gamma could participate in the immune response control through apoptosis modulation.
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Affiliation(s)
- G A Martins
- Departments of Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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638
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Rodman TC, Sullivan JJ, Bai X, Winston R. The human uniqueness of HIV: innate immunity and the viral Tat protein. Hum Immunol 1999; 60:631-9. [PMID: 10439309 DOI: 10.1016/s0198-8859(99)00052-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have previously reported, and confirm here, that the human innate system of natural antibodies includes two, each of which is reactive, presumably by happenstance, with a specific sequence of HIV Tat protein. Comparison of cohorts of HIV+ and normal (HIV-) sera indicate that, following a period of post-infection latency, the titers of those natural antibodies decline and other Tat reactive antibodies, as evidence of induced immune response, do not arise. That human-typical pattern of innate/adaptive reactivity with HIV Tat protein is shared by chimpanzees, but not by other mammals tested in this study, in which those natural antibodies are not present, and apparently induced Tat-reactive antibodies do arise. Evidence of a temporal relationship between the decline of the Tat reactive natural antibodies and progression of HIV pathogenesis, including demise of CD4+T cells, suggests a role for those antibodies in retardation of that pathoprogression. However, that providential arrest of Tat-related pathogenicity may be limited by the immune system recognition of the natural antibody-reactive sequences of Tat as "self" with consequent induction of tolerance and restriction of production of those antibodies. The limited occurrence of progression to AIDS in chimpanzees may reflect an additional innate characteristic, one of resistance to tolerance-based diminishment of the protective natural antibodies. Although not yet defined, that characteristic may be shared by the occasionally observed HIV+ humans known as LTNP (longterm-non-progressors).
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Affiliation(s)
- T C Rodman
- Laboratory of Bacterial Pathogenesis, Rockefeller University, New York, NY 10021, USA
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639
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Ernst B, Lee DS, Chang JM, Sprent J, Surh CD. The peptide ligands mediating positive selection in the thymus control T cell survival and homeostatic proliferation in the periphery. Immunity 1999; 11:173-81. [PMID: 10485652 DOI: 10.1016/s1074-7613(00)80092-8] [Citation(s) in RCA: 604] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Positive selection to self-MHC/peptide complexes has long been viewed as a device for skewing the T cell repertoire toward recognition of foreign peptides presented by self-MHC molecules. Here, we provide evidence for an alternative possibility, namely, that the self-peptides controlling positive selection in the thymus serve to maintain the longevity of mature T cells in the periphery. Surprisingly, when total T cell numbers are reduced, these self-ligands become overtly stimulatory and cause naive T cells to proliferate and undergo homeostatic expansion.
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Affiliation(s)
- B Ernst
- Department of Immunology, IMM26, The Scripps Research Institute, La Jolla, California 92037, USA
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640
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Hassan AT, Dai Z, Konieczny BT, Ring GH, Baddoura FK, Abou-Dahab LH, El-Sayed AA, Lakkis FG. Regulation of alloantigen-mediated T-cell proliferation by endogenous interferon-gamma: implications for long-term allograft acceptance. Transplantation 1999; 68:124-9. [PMID: 10428279 DOI: 10.1097/00007890-199907150-00023] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recent data suggest that interferon (IFN)-gamma is not an essential mediator of acute rejection but, instead, is critical for the induction of long-term allograft acceptance. The in vivo mechanisms by which endogenous IFN-gamma regulates the alloimmune response and thus facilitates the induction of long-term allograft survival are not known. METHODS We examined long-term cardiac and skin allograft survival, alloantigen-induced T-cell proliferation, and alloantigen-induced T-cell apoptosis in wild-type (IFN-gamma+/+) and IFN-gamma gene-knockout (IFN-gamma-/-) mice treated with either B7-CD28 T-cell costimulation blockade alone or B7-CD28 T-cell costimulation blockade combined with donor splenocyte transfusion. RESULTS We found that IFN-gamma is essential for long-term allograft survival induced by treating mice with either B7-CD28 T-cell costimulation blockade alone or B7-CD28 T-cell costimulation blockade combined with donor splenocyte transfusion. Alloantigen-induced T-cell proliferation in vivo was significantly greater in IFN-gamma-/- mice than in IFN-gamma+/+ mice, and T-cell costimulation blockade abrogated alloantigen-induced T-cell proliferation in wild-type mice but failed to do so in mice that lack IFN-gamma. In contrast, alloantigen-induced T lymphocyte apoptosis in vivo did not differ between IFN-gamma+/+ and IFN-gamma-/- mice, and T-cell costimulation blockade enhanced alloantigen-induced T-cell apoptosis in both mouse strains. CONCLUSIONS These data suggest that endogenous IFN-gamma facilitates the induction of long-term allograft survival by limiting the proliferation of alloactivated T lymphocytes. The data also suggest that B7-CD28 T-cell costimulation blockade exerts immunosuppressive actions by inhibiting the proliferation of activated T lymphocytes and by promoting their apoptosis.
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Affiliation(s)
- A T Hassan
- The Carlos and Marguerite Mason Transplantation Research Center, Department of Medicine and Veterans Affairs Medical Center, Atlanta, Georgia 30033, USA
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641
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Massive Activation-Induced Cell Death of Alloreactive T Cells With Apoptosis of Bystander Postthymic T Cells Prevents Immune Reconstitution in Mice With Graft-Versus-Host Disease. Blood 1999. [DOI: 10.1182/blood.v94.2.390] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
After hematopoietic stem cell transplantation, the persistence and expansion of grafted mature postthymic T cells allow both transfer of donor immunologic memory and generation of a diverse T repertoire. This thymic-independent process, which is particularly important in humans, because most transplant recipients present severe thymus atrophy, is impaired by graft-versus-host disease (GVHD). The goal of this study was to decipher how GVHD influences the fate of grafted postthymic T cells. Two major findings emerged. First, we found that, after a brisk proliferation phase, alloreactive antihost T cells underwent a massive activation-induced cell death (AICD). For both CD4+ and CD8+ T cells, the Fas pathway was found to play a major role in this AICD: alloreactive T cells upregulated Fas and FasL, and AICD of antihost T cells was much decreased in the case of lpr (Fas-deficient) donors. Second, whereas non–host-reactive donor T cells neither upregulated Fas nor suffered apoptosis when transplanted alone, they showed increased membrane Fas expression and apoptosis when coinjected with host-reactive T cells. We conclude that GVHD-associated AICD of antihost T cells coupled with bystander lysis of grafted non–host-reactive T cells abrogate immune reconstitution by donor-derived postthymic T lymphocytes. Furthermore, we speculate that massive lymphoid apoptosis observed in the acute phase of GVHD might be responsible for the occurrence of autoimmunity in the chronic phase of GVHD.
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642
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Massive Activation-Induced Cell Death of Alloreactive T Cells With Apoptosis of Bystander Postthymic T Cells Prevents Immune Reconstitution in Mice With Graft-Versus-Host Disease. Blood 1999. [DOI: 10.1182/blood.v94.2.390.414k27_390_400] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
After hematopoietic stem cell transplantation, the persistence and expansion of grafted mature postthymic T cells allow both transfer of donor immunologic memory and generation of a diverse T repertoire. This thymic-independent process, which is particularly important in humans, because most transplant recipients present severe thymus atrophy, is impaired by graft-versus-host disease (GVHD). The goal of this study was to decipher how GVHD influences the fate of grafted postthymic T cells. Two major findings emerged. First, we found that, after a brisk proliferation phase, alloreactive antihost T cells underwent a massive activation-induced cell death (AICD). For both CD4+ and CD8+ T cells, the Fas pathway was found to play a major role in this AICD: alloreactive T cells upregulated Fas and FasL, and AICD of antihost T cells was much decreased in the case of lpr (Fas-deficient) donors. Second, whereas non–host-reactive donor T cells neither upregulated Fas nor suffered apoptosis when transplanted alone, they showed increased membrane Fas expression and apoptosis when coinjected with host-reactive T cells. We conclude that GVHD-associated AICD of antihost T cells coupled with bystander lysis of grafted non–host-reactive T cells abrogate immune reconstitution by donor-derived postthymic T lymphocytes. Furthermore, we speculate that massive lymphoid apoptosis observed in the acute phase of GVHD might be responsible for the occurrence of autoimmunity in the chronic phase of GVHD.
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643
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Ina K, Itoh J, Fukushima K, Kusugami K, Yamaguchi T, Kyokane K, Imada A, Binion DG, Musso A, West GA, Dobrea GM, McCormick TS, Lapetina EG, Levine AD, Ottaway CA, Fiocchi C. Resistance of Crohn’s Disease T Cells to Multiple Apoptotic Signals Is Associated with a Bcl-2/Bax Mucosal Imbalance. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.2.1081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Crohn’s disease (CD) is a condition characterized by excessive numbers of activated T cells in the mucosa. We investigated whether a defect in apoptosis could prolong T cell survival and contribute to their accumulation in the mucosa. Apoptotic, Bcl-2+, and Bax+ cells in tissue sections were detected by the TUNEL method and immunohistochemistry. T cell apoptosis was induced by IL-2 deprivation, Fas Ag ligation, and exposure to TNF-α and nitric oxide. TUNEL+ leukocytes were few in control, CD, and ulcerative colitis (UC) mucosa, with occasional CD68+ and myeloperoxidase+, but no CD45RO+, apoptotic cells. Compared with control and UC, CD T cells grew remarkably more in response to IL-2 and were significantly more resistant to IL-2 deprivation-induced apoptosis. CD T cells were also more resistant to Fas- and nitric oxide-mediated apoptosis, whereas TNF-α failed to induce cell death in all groups. Compared with control, CD mucosa contained similar numbers of Bcl-2+, but fewer Bax+, cells, while UC mucosa contained fewer Bcl-2+, but more Bax+, cells. Hence, the Bcl-2/Bax ratio was significantly higher in CD and lower in UC. These results indicate that CD may represent a disorder where the rate of T cell proliferation exceeds that of cell death. Insufficient T cell apoptosis may interfere with clonal deletion and maintenance of tolerance, and result in inappropriate T cell accumulation contributing to chronic inflammation.
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Affiliation(s)
- Kenji Ina
- *Division of Gastroenterology and
- ‡First Department of Internal Medicine, Nagoya University School of Medicine, Nagoya, Japan
| | | | - Kouhei Fukushima
- §First Department of Surgery, Tohoku University School of Medicine, Sendai, Japan; and
| | - Kazuo Kusugami
- ‡First Department of Internal Medicine, Nagoya University School of Medicine, Nagoya, Japan
| | - Takeo Yamaguchi
- ‡First Department of Internal Medicine, Nagoya University School of Medicine, Nagoya, Japan
| | - Kazuhiro Kyokane
- ‡First Department of Internal Medicine, Nagoya University School of Medicine, Nagoya, Japan
| | - Akira Imada
- ‡First Department of Internal Medicine, Nagoya University School of Medicine, Nagoya, Japan
| | | | | | | | | | - Thomas S. McCormick
- †Molecular Cardiovascular Research Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Eduardo G. Lapetina
- †Molecular Cardiovascular Research Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106
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644
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Affiliation(s)
- J C Reed
- Burnham Institute, La Jolla, California 92037, USA
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645
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Mallet V, Fournel S, Schmitt C, Campan A, Lenfant F, Le Bouteiller P. Primary cultured human thymic epithelial cells express both membrane-bound and soluble HLA-G translated products. J Reprod Immunol 1999; 43:225-34. [PMID: 10479058 DOI: 10.1016/s0165-0378(99)00036-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This report demonstrates that both membrane-bound and soluble HLA-G isoforms are present in primary cultured human thymic epithelial cells (TEC). HLA-G transcriptional isoforms have been detected by RT-PCR, using different sets of HLA-G specific primers. A flow cytometry analysis, using two anti-HLA-G mAbs, namely 87G and BFL.1, revealed the presence of HLA-G translated products at the cell surface of a subpopulation of TEC. Finally, it was shown that HLA-G soluble forms were secreted in TEC culture supernatant, using a sandwich ELISA with BFL.1 and W6/32 mAbs. These results confirm and extent those previously described showing that HLA-G expressing cells were detectable by immunohistochemistry in thymic medullary epithelial cells.
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Affiliation(s)
- V Mallet
- INSERM U395, CHU Purpan, Toulouse, France
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646
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Abstract
Apoptosis or programmed cell death regulates many aspects in immunological homeostasis and, thus, controls the initiation, magnitude, duration, and termination of immune responses. Recent studies on dendritic cells (DC), including Langerhans cells (LC), have reinforced this concept by documenting that these antigen presenting cells express surface receptors and ligands that are known to mediate apoptotic cell death and that they are highly susceptible to apoptotic signals. In this review article, four major topics concerning apoptosis in the biology of DC will be overviewed: (a) molecular mechanisms of apoptosis; (b) DC apoptosis induced by various stimuli; (c) regulation of DC apoptosis; and (d) cross-priming and cross-tolerance induced by DC ingesting apoptotic bodies.
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Affiliation(s)
- H Matsue
- Department of Dermatology, University of Texas Southwestern Medical Center, Dallas 75325-9069, USA.
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647
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Mannie MD. Immunological self/nonself discrimination: integration of self vs nonself during cognate T cell interactions with antigen-presenting cells. Immunol Res 1999; 19:65-87. [PMID: 10374696 DOI: 10.1007/bf02786477] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The hypothesis is presented that immunological integration of nonefficacious vs efficacious T cell antigen receptor (TCR) signals are foundational for self/nonself discrimination and that multiple integrative mechanisms are intrinsic to the molecular to molar organization of an adaptive immune response. These integrative mechanisms are proposed to adaptively regulate expression of costimulatory signals, such that foreign proteins are associated with the expression of costimulatory signals, whereas self-proteins are associated with the lack of costimulatory signaling. Overall, this model offers several unique contributions to the study of immunology. First, this model postulates that cognate TCR/major histocompatibility complex (MHC) interactions are sufficient to adaptively mediate immunological self/nonself discrimination. This model thereby offers a unique alternative to models that largely rely on innate immunity to prime immune discrimination. Second, the integrative model argues that the immune system can simultaneously reinforce self-tolerance and promote immunity to foreign organisms at the same time and in the same location. Many alternative models presume that pathogenic self-reactive T cells do not exist at the outset of an immune response against foreign agents. Third, the integrative model uniquely predicts relationships between immunodeficiency and autoimmune pathogenesis. Fourth, this model illustrates the regulatory advantages of cognate antigen presenting cell (APC) systems (i.e., T cell or B cell APC) compared to nonspecific APC. Cognate APC systems together with the respective clonotypic responders may comprise a fundamental "network" of lymphoid cells. Such networks would have clone-specific regulatory capabilities and may be central for immunological self/nonself discrimination. Fifth, this model provides an explanation for "infectious" tolerance without creating specialized subsets of "suppressor" or "regulatory" T cells. Each mature T cell retains the potential to reinforce tolerance or mediate immunity, depending on the specific antigenic cues present in the immediate environment.
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Affiliation(s)
- M D Mannie
- Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, NC 27858-4354, USA.
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648
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Abstract
Major histocompatibility complex class I-specific inhibitory receptors on natural killer cells prevent the lysis of healthy autologous cells. The outcome of this negative signal is not anergy or apoptosis of natural killer cells but a transient abortion of activation signals. The natural killer inhibitory receptors fulfill this function by recruiting the tyrosine phosphatase SHP-1 through a cytoplasmic immunoreceptor tyrosine-based inhibition motif. This immunoreceptor tyrosine-based inhibition motif has become the hallmark of a growing family of receptors with inhibitory potential, which are expressed in various cell types such as monocytes, macrophages, dendritic cells, leukocytes, and mast cells. Most of the natural killer inhibitory receptors and two members of a monocyte inhibitory-receptor family bind major histocompatibility complex class I molecules. Ligands for many of the other receptors have yet to be identified. The inhibitory-receptor superfamily appears to regulate many types of immune responses by blocking cellular activation signals.
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Affiliation(s)
- E O Long
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA.
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649
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Abstract
Apoptosis is a critical mechanism for regulating cell numbers during development, normal responses to hormones and other stimuli, and immune and inflammatory reactions. Recent advances in defining the biochemical mechanisms of cell death, and the development of animal models with isolated defects in cell death pathways, have led to an increasing appreciation of the pathophysiologic importance of lymphocyte apoptosis. In this article, we review our current understanding of the pathways and roles of apoptosis in lymphocytes, with an emphasis on transgenic and knockout models. We also summarize the relevance of these animal models to human diseases.
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Affiliation(s)
- Y Refaeli
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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650
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Mohan C, Yu Y, Morel L, Yang P, Wakeland EK. Genetic Dissection of Sle Pathogenesis: Sle3 on Murine Chromosome 7 Impacts T Cell Activation, Differentiation, and Cell Death. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.11.6492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Polyclonal, generalized T cell defects, as well as Ag-specific Th clones, are likely to contribute to pathology in murine lupus, but the genetic bases for these mechanisms remain unknown. Mapping studies indicate that loci on chromosomes 1 (Sle1), 4 (Sle2), 7 (Sle3), and 17 (Sle4) confer disease susceptibility in the NZM2410 lupus strain. B6.NZMc7 mice are C57BL/6 (B6) mice congenic for the NZM2410-derived chromosome 7 susceptibility interval, bearing Sle3. Compared with B6 controls, B6.NZMc7 mice exhibit elevated CD4:CD8 ratios (2.0 vs 1.34 in 1- to 3-mo-old spleens); an age-dependent accumulation of activated CD4+ T cells (33.4% vs 21.9% in 9- to 12-mo-old spleens); a more diffuse splenic architecture; and a stronger immune response to T-dependent, but not T-independent, Ags. In vitro, Sle3-bearing T cells show stronger proliferation, increased expansion of CD4+ T cells, and reduced apoptosis (with or without anti-Fas) following stimulation with anti-CD3. With age, the B cells in this strain acquire an activated phenotype. Thus, the NZM2410 allele of Sle3 appears to impact generalized T cell activation, and this may be causally related to the low grade, polyclonal serum autoantibodies seen in this strain. Epistatic interactions with other loci may be required to transform this relatively benign phenotype into overt autoimmunity, as seen in the NZM2410 strain.
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Affiliation(s)
- Chandra Mohan
- *Simmons Arthritis Research Center and Center for Immunology, University of Texas Southwestern Medical Center, Dallas, TX 75235; and
| | - Ying Yu
- †Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Laurence Morel
- †Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Ping Yang
- †Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Edward K. Wakeland
- *Simmons Arthritis Research Center and Center for Immunology, University of Texas Southwestern Medical Center, Dallas, TX 75235; and
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