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Abstract
Studies of the biology of the IL-2 receptor have played a major part in establishing several of the fundamental principles that govern our current understanding of immunology. Chief among these is the contribution made by lymphokines to regulation of the interactions among vast numbers of lymphocytes, comprising a number of functionally distinct lineages. These soluble mediators likely act locally, within the context of the microanatomic organization of the primary and secondary lymphoid organs, where, in combination with signals generated by direct membrane-membrane interactions, a wide spectrum of cell fate decisions is influenced. The properties of IL-2 as a T-cell growth factor spawned the view that IL-2 worked in vivo to promote clonal T-cell expansion during immune responses. Over time, this singular view has suffered from increasing appreciation that the biologic effects of IL-2R signals are much more complex than simply mediating T-cell growth: depending on the set of conditions, IL-2R signals may also promote cell survival, effector function, and apoptosis. These sometimes contradictory effects underscore the fact that a diversity of intracellular signaling pathways are potentially activated by IL-2R. Furthermore, cell fate decisions are based on the integration of multiple signals received by a lymphocyte from the environment; IL-2R signals can thus be regarded as one input to this integration process. In part because IL-2 was first identified as a T-cell growth factor, the major focus of investigation in IL-R2 signaling has been on the mechanism of mitogenic effects in cultured cell lines. Three critical events have been identified in the generation of the IL-2R signal for cell cycle progression, including heterodimerization of the cytoplasmic domains of the IL-2R beta and gamma(c) chains, activation of the tyrosine kinase Jak3, and phosphorylation of tyrosine residues on the IL-2R beta chain. These proximal events led to the creation of an activated receptor complex, to which various cytoplasmic signaling molecules are recruited and become substrates for regulatory enzymes (especially tyrosine kinases) that are associated with the receptor. One intriguing outcome of the IL-2R signaling studies performed in cell lines is the apparent functional redundancy of the A and H regions of IL-2R beta, and their corresponding downstream pathways, with respect to the proliferative response. Why should the receptor complex induce cell proliferation through more than one mechanism or pathway? One possibility is that this redundancy is an unusual property of cultured cell lines and that primary lymphocytes require signals from both the A and the H regions of IL-2R beta for optimal proliferative responses in vivo. An alternative possibility is that the A and H regions of IL-2R beta are only redundant with respect to proliferation and that each region plays a unique and essential role in regulating other aspects of lymphocyte physiology. As examples, the A or H region could prove to be important for regulating the sensitivity of lymphocytes to AICD or for promoting the development of NK cells. These issues may be resolved by reconstituting IL-2R beta-/-mice with A-and H-deleted forms of the receptor chain and analyzing the effect on lymphocyte development and function in vivo. In addition to the redundant nature of the A and H regions, there remains a large number of biochemical activities mediated by the IL-2R for which no clear physiological role has been identified. Therefore, the circumstances are ripe for discovering new connections between molecular signaling events activated by the IL-2R and the regulation of immune physiology. Translating biochemical studies of Il-2R function into an understanding of how these signals regulate the immune system has been facilitated by the identification of natural mutations in IL-2R components in humans with immunodeficiency and by the generation of mice with targeted mutations in these gen
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Affiliation(s)
- B H Nelson
- Virginia Mason Research Center, Seattle, Washington 98101, USA
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2
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Damoiseaux JG, van Breda Vriesman PJ. Pathogenesis of cyclosporin A-induced autoimmunity: absence of T-cell reactivity towards syngeneic antigen presenting cells. Autoimmunity 1998; 27:45-56. [PMID: 9482206 DOI: 10.3109/08916939809008036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cyclosporin A-induced autoimmunity (CsA-AI) is a T-cell mediated inflammatory autoimmune disease of the skin resembling human scleroderma and is often referred to as syngeneic-Graft-versus-Host Disease. Induction of CsA-AI is obtained by total body irradiation in combination with syngeneic bone marrow transplantation (BMT) and subsequent administration of CsA for 4 weeks; about 2 weeks after withdrawal of CsA disease develops. In CsA-AI, irradiation is thought to eliminate peripheral autoregulatory T-cells, whereas CsA interferes with selection in the thymus giving rise to putative autoreactive T-cells. MHC class II-self-peptide complexes have been thought to function as autoantigen(s). Moreover, induction of CsA-AI is used in humans to achieve a Graft-versus-Leukemia effect based on this anti-MHC class II reactivity. In this study we therefore have examined whether T-cells of CsA-AI rats respond to syngeneic dendritic cells (DC). Furthermore we determined the in vitro stimulatory capacity of the presumptive antigen presenting cell (APC) in the target organs, i.e. the keratinocytes. In contrast to keratinocytes of control rats the keratinocytes of CsA-AI rats show in situ a strong reactivity with anti-MHC class II specific monoclonal antibody (mAb) and therefore might induce local T-cell activation. Results reveal that T-cells of CsA-AI rats have no increased response to syngeneic DC. This indicates that MHC class II is not the autoantigen and that the autoantigen(s) are not presented by peripheral APC of control animals. With respect to possible APC in the target organ flow cytometry showed a strong induction of MHC class II and upregulation of MHC class I on keratinocytes of CsA-AI rats. However, these cells were unable to give any stimulatory signal to T-cells of control or diseased animals, indicating that the autoantigen(s) are not presented by keratinocytes of CsA-AI rats and that the MHC induction is probably secondary to the inflammatory reaction in the skin. The nature of the autoantigen(s) therefore remains to be determined.
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Affiliation(s)
- J G Damoiseaux
- Department of Immunology, Maastricht University, The Netherlands
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3
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Genain CP, Gritz L, Joshi N, Panicali D, Davis RL, Whitaker JN, Letvin NL, Hauser SL. Inhibition of allergic encephalomyelitis in marmosets by vaccination with recombinant vaccinia virus encoding for myelin basic protein. J Neuroimmunol 1997; 79:119-28. [PMID: 9394784 DOI: 10.1016/s0165-5728(97)00109-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A primary demyelinating form of experimental allergic encephalomyelitis (EAE) resembling human multiple sclerosis (MS) occurs in Callithrix jacchus marmosets following immunization with human white matter. Participation of a T-cell immune response against myelin basic protein (MBP) in this disease model is supported by observations of increased reactivity against MBP in PBMC and of adoptive transfer of an inflammatory form of EAE by MBP-reactive T-cells. To evaluate the effects of ectopic presentation of MBP on marmoset EAE, animals were vaccinated prior to induction of EAE by subcutaneous injection of attenuated strains of vaccinia virus genetically engineered to contain either the entire coding sequence for human MBP (vT15) or the equine herpes virus glycoprotein gH gene (vAbT249). Vaccination with vT15 was followed by transient cytoplasmic and surface membrane expression of MBP in circulating PBMC (15-45 days). The onset of clinical EAE after immunization (pi) was markedly delayed in vT15-vaccinated animals (37-97 days pi, n = 4) compared to vAbT249-vaccinated controls (14-18 days pi, n = 3). Proliferative responses against MBP but not against vaccinia antigens or phytohemagglutinin were suppressed in protected animals. Thus, development of attenuated live viruses carrying genes for myelin antigens could be useful for induction of immunologic tolerance and for modulation of autoimmune demyelination.
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Affiliation(s)
- C P Genain
- Department of Neurology, University of California, San Francisco 94143-0435, USA.
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4
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Geiger K, Sarvetnick N. The influence of cytokines on the central nervous system of transgenic mice. Curr Top Microbiol Immunol 1996; 206:101-17. [PMID: 8608713 DOI: 10.1007/978-3-642-85208-4_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- K Geiger
- Department of Neuropharmacology, Scripps Research Institute, La Jolla, CA 92037, USA
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5
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Rebollo A, Gómez J, Martínez-A C. Lessons from immunological, biochemical, and molecular pathways of the activation mediated by IL-2 and IL-4. Adv Immunol 1996; 63:127-96. [PMID: 8787631 DOI: 10.1016/s0065-2776(08)60856-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- A Rebollo
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Universidad Autónoma de Madrid, Spain
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6
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Kroemer G, Hirsch F, González-García A, Martínez C. Differential involvement of Th1 and Th2 cytokines in autoimmune diseases. Autoimmunity 1996; 24:25-33. [PMID: 8937685 DOI: 10.3109/08916939608995354] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
By virtue of their functional antagonism, Th1 cells or cells producing the same cytokines as Th1 cells may behave as "suppressor cells' with respect to Th2 cells and vice versa. An excessive Th1- or Th2-like response may favor the development of different autoimmune diseases. As can be expected from their physiological role, Th-1 cytokines participate in autoimmune diseases with a preferential delayed type hypersensitivity component, i.e. in those diseases in which cytotoxic T cells attack organ-specific target cells. Autoimmune diseases with a predominant Th1 component include experimental autoimmune encephalitis and insulin-dependent diabetes mellitus. In contrast, Th2-type responses participate in systemic autoimmune diseases with a strong humoral component. Such diseases probably include certain drug-induced states of autoaggression, namely mercury-induced autoimmune disease and chlorpromazine-induced autoimmunity. It is tempting to speculate that therapeutic interventions designed to recover a normal Th1/Th2 balance will provide a useful etiological strategy for the re-establishment of self-tolerance.
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Hartman J, Maassen V, Rieber P, Fricke H. T lymphocytes from normal human peritoneum are phenotypically different from their counterparts in peripheral blood and CD3- lymphocyte subsets contain mRNA for the recombination activating gene RAG-1. Eur J Immunol 1995; 25:2626-31. [PMID: 7589136 DOI: 10.1002/eji.1830250933] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The surface antigens of peritoneal lymphocytes of healthy human individuals were studied. B lineage cells comprised 2.3% of the total peritoneal lymphocyte population. Although the majority of peritoneal cavity lymphocyte (PCL) T cells expressed alpha beta T cell receptor (TcR), up to 17% expressed gamma delta TcR. The majority of PCL exhibited markers of the thymus-dependent lineage (CD2+ CD3+ TcR alpha beta + CD4+ or CD8 alpha + beta +) and surface antigens associated with memory and activation (CD45RO+ CD11a+ CD18+ CD49d+ HLA-DR). Up to 92% of both CD4+ and CD8+ T cells bore CDw60, thus characterizing the T cell subset containing helper activity for mitogen-driven B cell differentiation. The majority of PCL T cells were CD8+ and, in addition, up to 60% of this population expressed the homodimeric CD8 alpha + beta -. Messenger RNA for the recombination activating gene RAG-1 was examined in CD3- PCL depleted of CD19+ lineage cells. The PCL population which comprised cells containing RAG-1 mRNA transcripts was CD19-, surface IgM-, cytoplasmic IgM- and CD2- CD3- CD4- CD8- CD56-. However, this population was CD7+ (approx. 75%), and contained both CD7- CD34+ (up to 3%) and CD7- CD34+ (up to 3%) cells. These findings are compatible with the hypothesis that the adult human peritoneum provides a microenvironment capable of supporting a thymus-indenpendent differentiation of T lymphocytes.
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Affiliation(s)
- J Hartman
- Department of Medicine, University of Munich, Germany
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8
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Candore G, Cigna D, Todaro M, De Maria R, Stassi G, Giordano C, Caruso C. T-cell activation in HLA-B8, DR3-positive individuals. Early antigen expression defect in vitro. Hum Immunol 1995; 42:289-94. [PMID: 7558912 DOI: 10.1016/0198-8859(94)00103-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The HLA-B8, DR3 haplotype is overrepresented in several autoimmune diseases, implying that genes predisposing to these disorders are linked to this haplotype. In the patients affected by these diseases, as well as in healthy HLA-B8, DR3 individuals, various dysfunctions reflecting an impairment of T-cell activation have been found. To better characterize T-cell impairment of HLA-B8, DR3-positive healthy individuals, we analyzed the surface expression of early (CD69) and late (CD71) activation phenotypes. MNC cultures were stimulated with PHA and used for T-cell phenotyping by flow cytometry analysis. The results showed that the percentage of CD69+ T cells was significantly decreased in MNC from HLA-B8, DR3+ subjects. This defect was detected in cell cultures from all subjects studied, but it attained significance only in females in the early hours after stimulation. The difference in CD69 expression between HLA-B8, DR3-positive individuals and -negative ones was not due to differences in CD4 and CD8 ratios in the HLA-B8, DR3 cells that underwent activation, as following activation the pattern of CD4 and CD8 antigen expression was the same in both groups of subjects. Concerning the late antigen CD71, no significant difference in percentage was observed between T lymphocytes from HLA-B8, DR3+ and HLA-B8, DR3- subjects at all the times studied. The analysis of the requirements for CD69 expression has suggested that sustained PKC activation and an increase of intracellular CA2+ could be responsible for TCR/CD3-mediated CD69 induction. Thus, present data suggest a defect in the signal transduction pathway of the TCR/CD3 complex.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G Candore
- Institute of General Pathology, University of Palermo, Italy
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Kroemer G, Martínez C. Pharmacological inhibition of programmed lymphocyte death. IMMUNOLOGY TODAY 1994; 15:235-42. [PMID: 8024684 DOI: 10.1016/0167-5699(94)90249-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Programmed cell death (PCD) is a necessary process that helps to regulate the lifespan of lymphocytes and maintain the compartmental balance of lymphoid organs. In addition, PCD is required for the generation and maintenance of self-tolerance. Strategies that inhibit PCD cause profound alterations in the (patho)physiology of the immune system. Here, Guido Kroemer and Carlos Martínez-A. discuss the multiplicity of PCD-inducing pathways, which have been revealed through the use of PCD-inhibitory agents, and analyse the levels at which these agents act.
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Tsao BP, Hahn BH. Autoimmunity and tolerance in Ig-transgenic mice: murine SLE as a model to study B cell tolerance. Int Rev Immunol 1994; 11:305-20. [PMID: 7806944 DOI: 10.3109/08830189409051177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- B P Tsao
- Department of Medicine, University of California, Los Angeles 90024-1747
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Baixeras E, Kroemer G, Cuende E, Márquez C, Boscá L, Alés Martínez JE, Martínez C. Signal transduction pathways involved in B-cell induction. Immunol Rev 1993; 132:5-47. [PMID: 8349298 DOI: 10.1111/j.1600-065x.1993.tb00836.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- E Baixeras
- Centro de Biología Molecular (CSIC), Universidad Autónoma, Madrid, Spain
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13
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Abstract
The periphery of the immune system--as opposed to the central lymphoid organs--contains inhomogeneously distributed B and T cells whose phenotype, repertoire, developmental origin, and function are highly divergent. Nonconventional lymphocytes bearing a phenotype that is rare in the blood, spleen, or lymph nodes of undiseased individuals are encountered at high frequency in different localizations, e.g., alpha/beta TCR+CD4-CD8- cells in the bone marrow and gut epithelium, particular invariant gamma/delta TCR+CD4-CD8 alpha+CD8 beta- and gamma/delta TCR+CD4-CD8 alpha-CD8 beta- T cells in various epithelia, or CD5+ B cells in the peritoneum. The antigen receptor repertoire is different in each localization. Thus, different gamma/delta TCR gene products dominant in each site, and the proportion of cells expressing transgenic and endogenous alpha/beta TCR and immunoglobulin gene products follows a gradient, with a maximum of endogenous gene expression in the peritoneum, intermediate values in other peripheral lymphoid organs (spleen, lymph nodes), and minimum values in thymus and bone marrow. Forbidden T cells that bear self-superantigen-reactive V beta gene products are physiologically detected among alpha/beta TCR+CD4-CD8- lymphocytes of the bone marrow, as well as in the gut. Violating previous ideas on self-tolerance preservation, self-peptide-specific gamma/delta T cells are present among intestinal intraepithelial lymphocytes, and CD5+ B cells produce low-affinity crossreactive autoantibodies in a physiological fashion. It appears that, in contrast to the bulk of T and B lymphocytes, certain gamma/delta and alpha/beta T cells found in the periphery, as well as most CD5+ B cells, do not depend on the thymus or bone marrow for their development, respectively, but arise from different, nonconventional lineages. In addition to divergent lineages that are targeted to different organs guided by a spatiotemporal sequence of tissue-specific homing receptors, local induction or selection processes may be important in the diversification of peripheral lymphocyte compartments. Selection may be exerted by local antigens, antigen-presenting cells whose function varies in each anatomical localization, cytokines, and cell-matrix interactions, thus leading to the expansion and maintenance of some clones, whereas others are diluted out or deleted. The spatial compartmentalization of lymphocytes in different microenvironments has major functional consequences and leads to a partial fragmentation of immunoregulatory circuits at the local level. Lymphocytes residing in certain antigen-exposed compartments are likely to combat tissue-specific pathogens or self-proteins.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- G Kroemer
- Centro de Biología Molecular (CSIC), Universidad Autónoma de Madrid, Spain
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Candore G, Di Lorenzo G, Melluso M, Cigna D, Colucci AT, Modica MA, Caruso C. gamma-Interferon, interleukin-4 and interleukin-6 in vitro production in old subjects. Autoimmunity 1993; 16:275-80. [PMID: 8025206 DOI: 10.3109/08916939309014646] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
It is well known that ageing is associated with various alterations of the lymphoid cell functions. Although both B and T cell are affected, the last appear to be more sensitive to ageing process. During the past years, to gain insight into thé mechanism(s) of this impairment, effort has been centered on the helper T cells specifically engaged in the production of interleukin-2 (IL-2) because of the pivotal role played by this cytokine in the activation of several immune functions. The results have demonstrated that the ability to produce IL-2 declines with age. In this paper we report the results of a study performed to determine the influence of age on the capacity to produce gamma-interferon (gamma-IFN), interleukin-4 (IL-4) and interleukin-6 (IL-6). Mononuclear cells from young and old subjects were assessed for cytokine producing capacity in response to phytohaemagglutinin stimulation. A significant decrease of gamma-IFN production by old subjects has been observed. No significant difference was instead observed between the old subjects and the young ones as regards IL-4 and IL-6 production. We suggest that this imbalanced cytokine production may well account for the pattern of immune response which may be observed in elderly, i.e. a normal or increased humoral response in face of a low T cell immune responsiveness.
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Affiliation(s)
- G Candore
- Istituto di Patologia generale, Università di Palermo, Italy
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Cuende E, Kroemer G, Alonso JM, Nemazee D, Martínez C, Alés-Martínez JE. Inability of IL-2 and IL-10 to counteract B cell clonal deletion. Cell Immunol 1992; 142:94-102. [PMID: 1586962 DOI: 10.1016/0008-8749(92)90271-p] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The B cell antigen receptor (BCR) delivers inhibitory signals in nascent B cells leading to the establishment of tolerance via clonal deletion or clonal anergy depending upon the type of antigen to which the B cells are exposed. In previous work, it has been demonstrated that activated Th2 cells, as well as some recombinant lymphokines, prevent the inhibition of growth and subsequent cell death induced through the BCR in model B cell lymphomas. Herein, we extend this work to another Th2 lymphokine, IL-10, that in contrast to IL-4 does not interfere with the deletion promoted by IgM crosslinking. The effect of individual lymphokines has also begun to be analyzed in a transgenic model of B cell clonal deletion. To this end, we have administered a recombinant vaccinia virus producing human IL-2 to mice expressing an autoreactive H-2Kk,b-specific transgenic IgMk and found that IL-2 does not abrogate B cell deletion in vivo.
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Affiliation(s)
- E Cuende
- Centro de Biología Molecular (CSIC), Universidad Autónoma de Madrid, Spain
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Gonzalo JA, Moreno de Alborán I, Alés-Martínez JE, Martínez C, Kroemer G. Expansion and clonal deletion of peripheral T cells induced by bacterial superantigen is independent of the interleukin-2 pathway. Eur J Immunol 1992; 22:1007-11. [PMID: 1551401 DOI: 10.1002/eji.1830220420] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Injection of the bacterial superantigen Staphylococcus aureus enterotoxin B (SEB) into mice provokes a rapid expansion and subsequent contraction of the pool of SEB-reactive T cells bearing T cell receptor (TcR) V beta 8 gene products. Given that interleukin 2 (IL-2) stimulates proliferation, abolishes anergy, and counteracts apoptotic cell death in T cells in vitro, we tested whether the IL-2 synthesis inhibitor cyclosporin A (CsA) or a vaccinia virus recombinant releasing high amounts of human IL-2 modulate SEB responses in vivo. Surprisingly, neither IL-2 nor CsA were able to change the in vivo kinetics and magnitude of SEB-induced expansion, unresponsiveness to SEB, and peripheral clonal deletion of T cells expressing products of the SEB-reactive TcR V beta 8 gene family. In accord with these in vivo observations, IL-2 is incapable of reversing "anergy" and apoptotic cell death of V beta 8+ SEB-reactive T cells isolated from SEB-primed mice in vitro. Accordingly, upon SEB injection V beta 8+ T cells expand rapidly, without expressing IL-2 receptor (IL-2R)alpha chains in vivo, although SEB induces IL-2R alpha in vitro. Altogether, these results indicate that the IL-2/IL-2R-mediated pathway is not involved in T cell repertoire modulation by bacterial superantigens. Moreover, the data suggest that unresponsiveness of V beta 8+ T cells from SEB-primed mice is not a reversible process, but involves an unreversible commitment to programmed cell death. Absence or presence of IL-2 responsiveness could be a hallmark to distinguish truly reversible anergy and peripheral clonal deletion.
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Affiliation(s)
- J A Gonzalo
- Centro de Biología Molecular, CSIC, Universidad Autónoma, Madrid, Spain
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Kroemer G, Martínez C. Clonal deletion, anergy and immunosuppression are connected in series to guarantee self-tolerance. RESEARCH IN IMMUNOLOGY 1992; 143:335-40. [PMID: 1631417 DOI: 10.1016/s0923-2494(92)80133-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- G Kroemer
- Centro de Biología Molecular del CSIC, Universidad Autónoma de Madrid
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Kroemer G, Francese C, Martínez C. The role of interleukin 2 in the development of autoimmune thyroiditis. Int Rev Immunol 1992; 9:107-23. [PMID: 1487652 DOI: 10.3109/08830189209061786] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Interleukin 2 (IL-2) is a lymphokine that may disrupt immunological self-tolerance. While being incapable of interfering with intrathymic or peripheral clonal deletion, IL-2 may overcome functional antigen unresponsiveness in anergic T lymphocytes. Anergy of T helper cells of the inflammatory phenotype implies selective silencing of the transcription of the IL-2 gene and thus precludes autocrine IL-2/IL-2 receptor (IL-2R) mediated growth, as well as delivery of help to other T cells or B lymphocytes. Thus, IL-2 serves as a servomodulator regulating post-deletional self-tolerance. IL-2-producing and IL-2-receptive cells are present in a variety of autoimmune lesions, including spontaneous autoimmune thyroiditis developing in the Obese strain (OS) of chickens, in Hashimoto's struma lymphomatosa, and in Graves' disease. Whereas the OS is characterized by a hyperinducibility of the IL-2/IL-2R system that predisposes to the development of severe thyroid infiltration, the state of the IL-2/IL-R system in circulating lymphocytes of patients developing thyroid autoimmunity, or at risk of doing so, remains to be defined. The most frequent autoimmune side-effect of IL-2 treatment concerns the thyroid gland. IL-2 induces a lymphoid thyroiditis leading to primary hypothyroidism, especially in those patients that have pre-treatment antithyroid autoantibodies. The hypothesis is extrapolated that IL-2 induces autoimmune disease in those patients that bear undeleted thyroid-specific T cells, and in which the lack of manifest thyroiditis relies upon peripheral, post-deletional tolerance.
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Affiliation(s)
- G Kroemer
- Centro de Biología Molecular, CSIC, Madrid, Spain
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Abstract
Immunological self-tolerance is guaranteed by several complementary mechanisms arranged in a fail-safe hierarchy--namely, clonal deletion, inactivation, and suppression. Only failure of all these self-tolerance-preserving systems allows autoimmune disease to develop. The notion of such a fail-safe organisation of the immune system is compatible with several features of autoimmune disease: its multicausal nature, its slowly progressive and relapsing course, and the diverse range of interventions available to restore autotolerance. This hypothesis has practical implications for the understanding of both the pathogenesis of iatrogenic autoimmune disease and the design of strategies to re-establish self-tolerance.
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Affiliation(s)
- G Kroemer
- Centro de Biología Molecular del CSIC, Universidad Autómoma de Madrid, Spain
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