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CD137 agonist antibody prevents cancer recurrence: contribution of CD137 on both hematopoietic and nonhematopoietic cells. Blood 2010; 115:1941-8. [PMID: 20068221 DOI: 10.1182/blood-2008-12-192591] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Antigen-specific memory T cells (Tms) are essential in the immune surveillance of residual and metastatic tumors. Activation of Tms requires designing vaccines based on tumor rejection antigens, which are often not available to cancer patients. Therefore, it is desirable to have a general applicable approach to activate Tms without extensive knowledge of tumor antigens. Here, we report that activation of antigen-specific Tms could be achieved by the administration of agonistic anti-CD137 monoclonal antibody without additional tumor vaccination, leading to the prevention of recurrence and metastases after surgical resection of primary tumors in mouse models. By reconstitution with CD137-deficient Tms, we demonstrate that expression of CD137 on antigen-specific Tms is only partially required for the effect of anti-CD137 antibody. Other host cells, including those from hematopoietic and nonhematopoietic origins, are also important because ablation of CD137 from these cells partially but significantly eliminates antitumor effect of anti-CD137 antibody. Our findings implicate a potential new approach to prevent recurrence and metastases in cancer patients.
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52
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Wang S, Chen L. Immunobiology of cancer therapies targeting CD137 and B7-H1/PD-1 cosignal pathways. Curr Top Microbiol Immunol 2010; 344:245-67. [PMID: 20582531 DOI: 10.1007/82_2010_81] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cancer immunotherapy is finally entering a new era with manipulation of cosignaling pathways as a therapeutic approach, for which the principle was proved nearly two decades ago. In addition to CTLA-4, CD137 and B7-H1/PD-1 pathways are two new targets in the stage. CD137 pathway is costimulatory and its agonistic antibody delivers potent signal to drive T cell growth and activation. On the other hand, blockade of B7-H1/PD-1 pathway with antagonistic antibody has shown to protect ongoing T cell responses from impairment by immune evasion mechanism in cancer microenvironment. With these tools in hand, a mechanism-based design of combined immunotherapy with high efficacy is becoming a reality.
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Affiliation(s)
- Shengdian Wang
- Center for Infection and Immunity, Institute for Biophysics, Chinese Academy of Sciences, Beijing, China
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53
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Wang Q, Zhang P, Zhang Q, Wang X, Li J, Ma C, Sun W, Zhang L. Analysis of CD137 and CD137L expression in human primary tumor tissues. Croat Med J 2008; 49:192-200. [PMID: 18461674 DOI: 10.3325/cmj.2008.2.192] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AIM To assess the expression of CD137 and CD137L in human primary tumor tissues and their potential role in tumor immunity. METHODS Expression of CD137 and CD137L was assessed by immunohistochemistry in frozen sections of 12 human normal tissues, 15 benign tumors of epithelial or mesenchymal origin (adenoma and leiomyoma), and 36 malignant tumors of epithelial origin (squamous cell carcinoma and adenocarcinoma). The expression of CD137L on 9 human tumor cell lines (3 hepatocarcinoma, 2 lung carcinoma, 2 colon carcinoma, 1 lymphoma, and 1 leukemia) was detected by reverse transcription polymerase chain reaction. To analyze the role of CD137L expressed on tumor cells, we co-cultured tumor cells expressing CD137L with activated T lymphocytes expressing CD137 or with Chinese hamster ovary cells expressing CD137 and then detected by ELISA the levels of cytokines (IL-8, IFN-gamma) secreted by tumor cells or activated T cells. RESULTS The expression of CD137 and CD137L was observed only in human benign (2/15, 3/15) or malignant tumors (15/36, 21/36), but not in normal tissues (0/12, 0/12). CD137 was expressed on the vessel walls within tumor tissues, whereas CD137L was expressed on tumor cells. The expression of CD137 and CD137L was more common in malignant tumors, especially in moderate or low-differentiated tumors. Furthermore, CD137L expression found on tumor cell lines was functional because the ligation of CD137L on lung squamous carcinoma cells L78 with CD137 on T cells induced IFN-gamma production by T cells, and ligation of CD137L on hepatocarcinoma cells HepG2.2.15 with CD137 triggered tumor cells to produce IL-8. CONCLUSION CD137 and CD137L are expressed in different human primary tumor tissues, suggesting that they may influence the progression of tumors.
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Affiliation(s)
- Qun Wang
- Department of Immunology, Shandong University School of Medicine, Jinan, People's Republic of China
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54
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Saiki H, Suzuki JI, Kosuge H, Haraguchi G, Ishihara T, Haga T, Maejima Y, Isobe M, Uede T. Blockade of the 4-1BB pathway attenuates graft arterial disease in cardiac allografts. Int Heart J 2008; 49:105-18. [PMID: 18360069 DOI: 10.1536/ihj.49.105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
4-1BB, a member of the tumor necrosis factor (TNF) receptor superfamily, binds the 4-1BB ligand (4-1BBL) and works as a costimulatory molecule and regulates T cell-mediated immune responses. Because T cell-mediated immunity is associated with graft arterial disease (GAD), we investigated the role of the 4-1BB pathway in the progression of GAD. Hearts from C57BL/6 mice were transplanted into Bm12 mice (class II mismatch). 4-1BB expression was induced on CD4(+) and CD8(+) splenocytes in allografts after cardiac transplantation. 4-1BBL was detected in the vessel wall of the rejecting cardiac allograft and in cultured smooth muscle cells (SMCs) stimulated with fetal calf serum. Recipients were injected intraperitoneally with 4-1BBIg every 7 days for 8 weeks. GAD was significantly attenuated by 4-1BBIg treatment (luminal occlusion, 15.4 +/- 3.1% versus control IgG treatment, 75.6 +/- 4.6%, P < 0.001). T-cell infiltration of cardiac allografts and expression of interferon-g , interleukin-6, and interleukin-15 in cardiac allografts were suppressed by 4-1BBIg treatment. Coculture of SMCs with sensitized splenocytes after transplantation induced SMC proliferation, and this was inhibited by addition of 4-1BBIg. The 4-1BB pathway regulates not only T-cell activation but also SMC proliferation. Blockade of the 4-1BB pathway is a promising strategy to prevent progression of GAD.
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Affiliation(s)
- Hitoshi Saiki
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Tokyo, Japan
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55
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Niu L, Strahotin S, Hewes B, Zhang B, Zhang Y, Archer D, Spencer T, Dillehay D, Kwon B, Chen L, Vella AT, Mittler RS. Cytokine-mediated disruption of lymphocyte trafficking, hemopoiesis, and induction of lymphopenia, anemia, and thrombocytopenia in anti-CD137-treated mice. THE JOURNAL OF IMMUNOLOGY 2007; 178:4194-213. [PMID: 17371976 PMCID: PMC2770095 DOI: 10.4049/jimmunol.178.7.4194] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
CD137-mediated signals costimulate T cells and protect them from activation-induced apoptosis; they induce curative antitumor immunity and enhance antiviral immune responses in mice. In contrast, anti-CD137 agonistic mAbs can suppress T-dependent humoral immunity and reverse the course of established autoimmune disease. These results have provided a rationale for assessing the therapeutic potential of CD137 ligands in human clinical trials. In this study, we report that a single 200-mug injection of anti-CD137 given to otherwise naive BALB/c or C57BL/6 mice led to the development of a series of immunological anomalies. These included splenomegaly, lymphadenopathy, hepatomegaly, multifocal hepatitis, anemia, altered trafficking of B cells and CD8 T cells, loss of NK cells, and a 10-fold increase in bone marrow (BM) cells bearing the phenotype of hemopoietic stem cells. These events were dependent on CD8 T cells, TNF-alpha, IFN-gamma, and type I IFNs. BM cells up-regulated Fas, and there was a significant increase in the number of CD8+ T cells that correlated with a loss of CD19+ and Ab-secreting cells in the BM. TCR Valphabeta usage was random and polyclonal among liver-infiltrating CD8 T cells, and multifocal CD8+ T cell infiltrates were resolved upon termination of anti-CD137 treatment. Anti-CD137-treated mice developed lymphopenia, thrombocytopenia, and anemia, and had lowered levels of hemoglobin and increased numbers of reticulocytes.
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Affiliation(s)
- Liguo Niu
- Emory Vaccine Research Center, Emory University School of Medicine, Atlanta, GA 30329
| | - Simona Strahotin
- Emory Vaccine Research Center, Emory University School of Medicine, Atlanta, GA 30329
| | - Becker Hewes
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30329
| | - Benyue Zhang
- Emory Vaccine Research Center, Emory University School of Medicine, Atlanta, GA 30329
| | - Yuanyuan Zhang
- Emory Vaccine Research Center, Emory University School of Medicine, Atlanta, GA 30329
| | - David Archer
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30329
| | - Trent Spencer
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30329
| | - Dirck Dillehay
- Department of Animal Resources, Emory University School of Medicine, Atlanta, GA 30329
| | - Byoung Kwon
- The Immunomodulation Research Center, University of Ulsan, Ulsan, Republic of Korea
| | - Lieping Chen
- Johns Hopkins University School of Medicine, Department of Dermatology, Baltimore, MD 21205
| | - Anthony T. Vella
- Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030
| | - Robert S. Mittler
- Emory Vaccine Research Center, Emory University School of Medicine, Atlanta, GA 30329
- Department of Surgery, Emory University School of Medicine, Atlanta, GA 30329
- Address correspondence and reprint requests to Dr. Robert S. Mittler, Emory Vaccine Center, 954 Gatewood Road, Atlanta, GA 30329. E-mail address:
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Seaman S, Stevens J, Yang MY, Logsdon D, Graff-Cherry C, St. Croix B. Genes that distinguish physiological and pathological angiogenesis. Cancer Cell 2007; 11:539-54. [PMID: 17560335 PMCID: PMC2039723 DOI: 10.1016/j.ccr.2007.04.017] [Citation(s) in RCA: 309] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Revised: 03/23/2007] [Accepted: 04/24/2007] [Indexed: 01/13/2023]
Abstract
To unravel the normal vasculature transcriptome and determine how it is altered by neighboring malignant cells, we compared gene expression patterns of endothelial cells derived from the blood vessels of eight normal resting tissues, five tumors, and regenerating liver. Organ-specific endothelial genes were readily identified, including 27 from brain. We also identified 25 transcripts overexpressed in tumor versus normal endothelium, including 13 that were not found in the angiogenic endothelium of regenerating liver. Most of the shared angiogenesis genes have expected roles in cell-cycle control, but those specific for tumor endothelium were primarily cell surface molecules of uncertain function. These studies reveal striking differences between physiological and pathological angiogenesis potentially important for the development of tumor-specific, vascular-targeted therapies.
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Affiliation(s)
- Steven Seaman
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Janine Stevens
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Mi Young Yang
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Daniel Logsdon
- Basic Research Program, SAIC, NCI-Frederick, Frederick, MD 21702, USA
| | - Cari Graff-Cherry
- Basic Research Program, SAIC, NCI-Frederick, Frederick, MD 21702, USA
| | - Brad St. Croix
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
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57
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Giscombe R, Wang XB, Kakoulidou M, Lefvert AK. Characterization of the expanded T-cell populations in patients with Wegener's granulomatosis. J Intern Med 2006; 260:224-30. [PMID: 16918819 DOI: 10.1111/j.1365-2796.2006.01688.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Wegener's granulomatosis (WG) is a chronic inflammatory disease characterized by granulomatosis inflammation, systemic vasculitis and glomerulonephritis. In patients, the peripheral T cells are characterized by mono/oligoclonal CD4+/CD8+ T-cell AV/BV receptor expansions, with aberrant expression of activation markers. This study was designed to characterize the phenotypic differences between the expanded and nonexpanded T-cell populations. Expression of markers for activation, costimulation and adhesion molecules was examined. As earlier studies have shown aberrant expression of CD28/CD152, we also analysed the expression of another costimulatory system, the tumour necrotic factor receptor (TNFR) superfamily proteins. DESIGN Fluorocrome-conjugated monoclonal antibodies and flow cytometry was used to analyse the expression of the different markers on the surface of the expanded and nonexpanded subsets of T cells. SETTING The Karolinska Hospital and Karolinska Institutet in Stockholm, Sweden. SUBJECTS Nine patients with WG (six men and three women) had 16 TCRAV/BV CD4+/CD8+ expanded populations that were characterized. RESULTS The expanded TCRA/BV CD4+ and CD8+ cells had lower percentages of cells expressing CD28 and higher of those expressing CD152 (CTLA-4). The expanded CD4+ population had more cells expressing HLA-DR, CD57 and CCR5 (CD195), whilst the expression of CD25 was present on fewer of the expanded cells. The expanded CD8+ population contained more cells expressing CD137 (4-1BB), CD137 (4-1BBL), CD30 (Ki-1), CD40 and CD134 (OX40). CONCLUSIONS There were marked differences in the phenotypes of expanded and nonexpanded T-cell populations.
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Affiliation(s)
- R Giscombe
- Immunological Research Laboratory, Center for Molecular Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
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58
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Abstract
CD137 is a member of the tumor necrosis factor receptor family and a potent regulator of T cell activities. Agonists of CD137 have been used widely and successfully to treat cancer in animal models, and recently, it has become evident that CD137 agonists can also be used to treat autoimmune disease. An aspect of the CD137 receptor/ligand system, which has been comparatively little-explored, is its ability of reverse signaling. Just as is CD137, the CD137 ligand is also expressed as a cell membrane protein, and it too can transduce signals into the cells on which it is expressed. This bidirectional signaling capacity allows the CD137 receptor/ligand system to mediate extensive cross-talk between immune cells and between immune and nonimmune cells. This review summarizes the known activities of the CD137 ligand on the different leukocyte subsets and on cancer cells and discusses their influence on the course of immune responses.
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Affiliation(s)
- Herbert Schwarz
- National University of Singapore, 2 Medical Drive, MD 9, Singapore 117597.
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59
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Abstract
The activation of T cells plays a central role in antitumor immunity. In order to activate naïve T cells, two key signals are required. Signal one is provided through the T-cell receptor (TCR) while signal two is that of costimulation. The CD28:B7 molecules are one of the best-studied costimulatory pathways, thought to be the main mechanism through which primary T-cell stimulation occurs. However, a number of molecules have been identified which serve to amplify and diversify the T-cell response, following initial T-cell activation. These include the more recently described 4-1BB:4-1BB ligand (4-1BBL) molecules. 4-1BB:4-1BBL are a member of the TNFR:TNF ligand family, which are expressed on T cells and antigen-presenting cells (APCs), respectively. Therapies utilizing the 4-1BB:4-1BBL signaling pathway have been shown to have antitumor effects in a number of model systems. In this paper, we focus on the 4-1BB:4-1BBL costimulatory molecules. In particular, we will describe the structure and function of the 4-1BB molecule, its receptor and how 4-1BB:4-1BBL costimulation has and may be used for the immunotherapy of cancer.
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Affiliation(s)
- Adam T C Cheuk
- Leukaemia Science Laboratories, Department of Haematological Medicine, Guy's, King's & St Thomas' School of Medicine, King's College London, Rayne Institute, 123 Coldharbour Lane, London SE5 9NU, UK
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60
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Abstract
Human vascular endothelial cells (EC) basally display class I and II MHC-peptide complexes on their surface and come in regular contact with circulating T cells. We propose that EC present microbial antigens to memory T cells as a mechanism of immune surveillance. Activated T cells, in turn, provide both soluble and contact-dependent signals to modulate normal EC functions, including formation and remodeling of blood vessels, regulation of blood flow, regulation of blood fluidity, maintenance of permselectivity, recruitment of inflammatory leukocytes, and antigen presentation leading to activation of T cells. T cell interactions with vascular EC are thus bidirectional and link the immune and circulatory systems.
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Affiliation(s)
- Jaehyuk Choi
- Interdepartmental Program in Vascular Biology and Transplantation, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536-0812, USA
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61
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Palma C, Binaschi M, Bigioni M, Maggi CA, Goso C. CD137 and CD137 ligand constitutively coexpressed on human T and B leukemia cells signal proliferation and survival. Int J Cancer 2003; 108:390-8. [PMID: 14648705 DOI: 10.1002/ijc.11574] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
CD137, a member of the tumor necrosis factor receptor family, provides expansion and survival signal to T cells. Its ligand, CD137L, in addition to its ability to costimulate T cells, signals back into antigen presenting cells promoting their activation and differentiation. Recently, CD137 has been proposed as a therapeutic target to improve and sustain anticancer immune response. Several activated T leukemia and B lymphoma cell lines expressed CD137 or CD137L, respectively, and soluble CD137L has been found in sera of leukemia patients. However, the functionality and role of these costimulatory molecules in hematologic malignancies are until now unknown. Interestingly, we observed constitutive CD137 and CD137L coexpression on both human T and B leukemia cell lines. The constitutive CD137 expression on unstimulated T or B leukemia cells presents some differences compared to CD137 expressed on PMA/ionomycin-activated T leukemia cells. Surprisingly, in spite of the low expression level, both tumor CD137 and CD137L molecules signaled in T and B leukemia cells inducing proliferation and prolonging survival. In addition, CD137/CD137L system ligation opposed the anticancer drug cytotoxic effects, reducing the apoptotic DNA fragmentation and stimulating proliferation of doxorubicin-escaped leukemia cells. Although the role of leukemia CD137/CD137L system in vivo is unknown, these data suggest that these costimulatory molecules might confer an advantage to hematologic tumors promoting survival, sustaining cellular growth and contributing to drug resistance.
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MESH Headings
- 4-1BB Ligand
- Antigens, CD/metabolism
- Antineoplastic Agents/pharmacology
- Apoptosis/drug effects
- Cell Division/drug effects
- Cell Survival
- Doxorubicin/pharmacology
- Drug Resistance, Neoplasm
- Gene Expression Regulation/drug effects
- Humans
- Leukemia, B-Cell/metabolism
- Leukemia, B-Cell/pathology
- Leukemia, T-Cell/metabolism
- Leukemia, T-Cell/pathology
- Receptors, Nerve Growth Factor/metabolism
- Receptors, Tumor Necrosis Factor/metabolism
- Signal Transduction/drug effects
- Tumor Cells, Cultured/drug effects
- Tumor Cells, Cultured/metabolism
- Tumor Cells, Cultured/pathology
- Tumor Necrosis Factor Receptor Superfamily, Member 9
- Tumor Necrosis Factor-alpha/metabolism
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Affiliation(s)
- Carla Palma
- Department of Pharmacology, Menarini Ricerche SpA, Rome, Italy.
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62
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Kim KM, Kim HW, Kim JO, Baek KM, Kim JG, Kang CY. Induction of 4-1BB (CD137) expression by DNA damaging agents in human T lymphocytes. Immunology 2002; 107:472-9. [PMID: 12460192 PMCID: PMC1782822 DOI: 10.1046/j.1365-2567.2002.01538.x] [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: 01/10/2023] Open
Abstract
4-1BB(CD137) is a member of the tumour necrosis factor receptor superfamily and is expressed on activated T cells, monocytes and natural killer (NK) cells. The interaction of 4-1BB and 4-1BB ligand provides a costimulatory signal leading to T-cell activation. The expression of 4-1BB has been known to be activation dependent. Interestingly, we found that expression of 4-1BB increased in human peripheral blood mononuclear cells after exposure to mitomycin C. Thus, we tested whether the treatment with other DNA-damaging agents, such as doxorubicin, bleomycin, and gamma-irradiation, could induce 4-1BB expression. The data indicated that 4-1BB expression increased dose-dependently by these agents reaching maximum at 2-3 days after the exposure. We found that the major 4-1BB-expressing population was CD3+ T cells, although a moderate number of CD14+ cells and a few NKB1+ cells also expressed 4-1BB. The levels of 4-1BB expression induced by anticancer drugs, were relatively lower than that induced by CD3 ligation. Interestingly, at subcytotoxic concentrations, doxorubicin and bleomycin considerably enhanced 4-1BB expression induced by CD3 ligation in CEM cells. The ligation of the damage-induced 4-1BB by monoclonal antibody enhanced the viability and proliferating capacity of the cells. In conclusion, the expression of 4-1BB might be one of the cellular responses of the immune cells against various genotoxic stresses.
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Affiliation(s)
- Kwang-Mi Kim
- College of Pharmacy and College of Medicine, Seoul National University, Seoul 151-742, Korea
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63
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Wen T, Bukczynski J, Watts TH. 4-1BB ligand-mediated costimulation of human T cells induces CD4 and CD8 T cell expansion, cytokine production, and the development of cytolytic effector function. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:4897-906. [PMID: 11994439 DOI: 10.4049/jimmunol.168.10.4897] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
4-1BB (CD137) is a costimulatory member of the TNFR family expressed on activated T cells. Its ligand, 4-1BBL, is expressed on activated APC. In the mouse, CD8 T cells are preferentially activated by agonistic anti-murine 4-1BB Abs. However, murine 4-1BBL can stimulate both CD4 and CD8 T cells. To date, there are only limited data on the effects of 4-1BBL on human T cell responses. To further understand the role of 4-1BBL in human T cell responses, we compared human CD4 and CD8 T cell responses to transfected human 4-1BBL plus TCR-mediated stimulation. Both human CD4 and CD8 T cells responded to 4-1BBL. The presence of 4-1BBL on the APC led to increased expansion, cytokine production, and the development of cytolytic effector function by human T cells. In unfractionated T cell cultures, CD4 and CD8 T cells could expand to a similar extent in response to signals through the TCR and 4-1BB, as measured by CFSE labeling and by quantitating T cell numbers in the cultures. In contrast to the results with total T cells, isolated CD8 T cells produced less IL-2 and expanded to a lesser extent than isolated CD4 T cells responding to 4-1BBL. Thus, 4-1BBL is most effective when both CD4 and CD8 T cells are included in the cultures. CD28 and 4-1BB were found to synergize in the induction of IL-2 by human T cells, and CTLA-Ig partially blocked 4-1BBL-dependent IL-2 production. However, a portion of the 4-1BBL-mediated effects were independent of CD28-B7 interaction.
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Affiliation(s)
- Tao Wen
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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