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Abstract
PURPOSE OF REVIEW Immunological barriers still preclude clinical xenotransplantation. The protective role of CD4(+)CD25(+)Foxp3(+) T-regulatory cells (Treg) in allotransplantation is well described and, therefore, could represent a promising therapeutical tool for xenotransplantation. This review addresses the latest findings on Treg in xenotransplantation research. RECENT FINDINGS In vivo, costimulation blockade-based strategies including anti-CD154 monoclonal antibodies (mAbs) in combination with rapamycin or anti-LFA-1 mAb prolonged both concordant and discordant islets xenografts survival in a Treg-dependent manner. In vitro, IL-10 secretion was shown to be critical for the suppression of xenogeneic responses mediated by Treg. Moreover, transgenic expression of inducible costimulator-immunoglobulin or PD-L1 on porcine endothelial cells inhibited human T-cell proliferation in vitro and was associated with the induction of Treg and IL-10 secretion. CXCR3 mediated the recruitment of Treg to pig endothelium. Finally, the recruitment of human Treg was enhanced by the immobilization of human CCL17 on pig endothelium. SUMMARY There is increasing evidence for the potential of CD4(+)CD25(+)Foxp3(+) Treg to protect xenografts. Induction of Treg in recipients and/or recruitment of human Treg to pig endothelium may represent novel strategies to prevent cell-mediated rejection in pig-to-human xenotransplantation.
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Kim CH, Oh K, Kim DE, Lee SB, Yang JH, Lee G, Cho J, Lee DS. Both CD45RA+ and CD45RO+ human CD4+ T cells drive direct xenogeneic T-cell responses against porcine aortic endothelial cells. Xenotransplantation 2010; 17:224-32. [PMID: 20636543 DOI: 10.1111/j.1399-3089.2010.00582.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Xenogeneic cellular immune responses are mediated by either direct or indirect pathways depending on the participation of donor or host antigen presenting cells, respectively. The contribution of direct response of human T cells, especially memory T cells, to porcine antigen presenting cells is currently unknown. Here, we sought to determine whether human peripheral blood memory/activated phenotype T cells are directly responsive to porcine endothelial cells. METHODS Porcine aortic endothelial cells (PAECs) were prepared from Yorkshire or miniature pigs. Highly purified human T cells, including naïve and memory/activated phenotype cells, were incubated with PAECs with or without the addition of exogenous cytokines. T-cell proliferation and T-cell receptor (TCR) Vbeta usage in response to PAECs were analyzed. RESULTS Both CD8(+) and CD4(+) T cells responded directly to PAECs and exhibited exclusive responsiveness to SLA class I and class II molecules, respectively. Naïve and memory/activated phenotype CD4(+) T cells responded against PAECs, whereas only naïve phenotype CD8(+) T cells contributed to such a response. In addition, both populations of xenogeneic human CD4(+) T cells exhibited similar and diverse V beta usage. CONCLUSION Due to the considerable contribution of human CD45RO(+)CD4(+) T cells to the xenoreactivity against PAECs, effective control of xenogeneic memory/activated T-cell responses would significantly affect long-term survival of transplanted grafts.
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Affiliation(s)
- Chi Hwa Kim
- Laboratory of Immunology, Department of Anatomy, College of Medicine, Seoul National University, Seoul, Korea
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Ladhoff J, Fleischer B, Hara Y, Volk HD, Seifert M. Immune privilege of endothelial cells differentiated from endothelial progenitor cells. Cardiovasc Res 2010; 88:121-9. [PMID: 20388638 DOI: 10.1093/cvr/cvq109] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
AIMS The application of autologous endothelial progenitor cells (EPC) is a promising approach in cardiovascular regeneration, but the availability of cells in appropriate numbers is the limiting factor. Allogeneic EPC would be an alternative, and we therefore analysed the immunogenicity of EPC-derived endothelial cells (EC) to evaluate their potential usefulness. METHODS AND RESULTS Circulating EPC from rat were differentiated into EC and characterized phenotypically and functionally. Major histocompatibility complex (MHC) expression in response to interferon-gamma was determined compared with rat aortic EC, and in vitro humoral and cellular allogeneic responses were analysed. To determine the in vivo effects, acellular aortic grafts were endothelialized in vitro with EPC-derived EC and transplanted in a complete allogeneic mismatch rat aortic interposition model. EPC-derived EC expressed endothelial-specific markers and low levels of MHC class I (MHC I), but no constitutive MHC class II (MHC II). When stimulated with interferon-gamma, they upregulated MHC I and moderately upregulated MHC II. They were protected against alloantibody/complement-mediated lysis and allospecific cytotoxic T lymphocyte activity. They were less potent in allogeneic stimulation of CD4 T cells than aortic EC. Seeding of EPC-derived EC into acellular grafts led to excellent endothelialization, and allogeneic aortic transplantation induced only mild inflammatory responses without signs of rejection. CONCLUSION EPC-derived EC are protected against allospecific cellular immune responses and humoral-mediated attacks in vitro. When transplanted in vivo as a component of vascular grafts, these cells are not rejected, which makes them useful in therapeutic applications, especially vascular reconstruction.
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Affiliation(s)
- Juliane Ladhoff
- Institute of Medical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany
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Low immunogenicity of endothelial derivatives from rat embryonic stem cell-like cells. Cell Res 2009; 19:507-18. [PMID: 19238174 DOI: 10.1038/cr.2009.21] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Embryonic stem cells (ESC) are suggested to be immune-privileged, but they carry the risk of uncontrolled expansion and malignancy. Upon differentiation they lose their tumor-forming capacity, but they become immunogenic by the expression of a normal set of MHC molecules. This immunogenicity might trigger rejection after application in regenerative therapies. In this study MHC expression of and immune responses to endothelial derivatives of rat embryonic stem cell-like cells (RESC) under inflammatory conditions were determined in comparison to primary rat aortic endothelial cells (ECs). Cellular as well as humoral allo-recognition was analyzed in vitro. In addition, immune reactions in vivo were assessed by allo-antibody production and determination of interferon-gamma (IFNgamma)-secreting allo-reactive T cells. RESC derivatives expressed low but significant levels of MHC class I, and no MHC class II. In response to IFNgamma MHC class I expression was enhanced, while class II transactivator induction failed completely in these cells; MHC class II expression remained consistently absent. Functionally, the RESC derivatives showed a reduced allo-stimulatory capacity, protection against humoral allo-recognition in vitro and a slightly diminished susceptibility to cytotoxic T cell lysis. Furthermore, in vivo experiments demonstrated that these cells do not trigger host immune reactions, characterized by no allo-antibody production and no induction of allo-reactive memory T cells. Our results show that endothelial derivatives of RESC have a distinctive reduced immunogenic potency even under inflammatory conditions.
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Atorvastatin down-regulates the primate cellular response to porcine aortic endothelial cells in vitro. Transplantation 2008; 86:733-7. [PMID: 18791456 DOI: 10.1097/tp.0b013e3181821cad] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Using mixed lymphocyte reaction (MLR), the effect of atorvastatin on proliferation of human and baboon peripheral blood mononuclear cells (PBMCs) and human CD4+ T cells in response to wild-type (WT) and alpha-1,3-galactosyltransferase gene-knockout (GTKO) porcine aortic endothelial cells (pAECs) was investigated. swine leukocyte antigen class-II (SLA II) expression on pAEC before and after porcine interferon gamma (pIFN-gamma) stimulation, and the effect of atorvastatin on this expression was assessed. Added to the MLR, atorvastatin reduced (i) the human PBMC response to unstimulated (P<0.05) and (ii) the human and baboon PBMC responses to stimulated (P<0.05) WT and GTKO pAEC. Atorvastatin treatment of human PBMC before MLR reduced their response to stimulated WT (P<0.05) and GTKO (P<0.05) pAEC. Stimulation of pAEC with pIFN-gamma increased SLA II expression 20- to 60-fold, which was down-regulated by atorvastatin. Atorvastatin treatment of stimulated pAEC before MLR reduced proliferation of human PBMC (P<0.05) and CD4+ T cells (P<0.05). Atorvastatin down-regulates the primate cellular xenoresponse, possibly through its antiproliferative effect on PBMCs and the reduction of SLA II on pAECs.
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Mulley WR, Li YQ, Wee JL, Dodge N, Christiansen D, Simeonovic C, Ierino FL, Sandrin MS. Local expression of IDO, either alone or in combination with CD40Ig, IL10 or CTLA4Ig, inhibits indirect xenorejection responses. Xenotransplantation 2008; 15:174-83. [DOI: 10.1111/j.1399-3089.2008.00472.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Xu Y, McDonald J, Perloff E, Butticè G, Schreiber BM, Smith BD. Collagen and major histocompatibility class II expression in mesenchymal cells from CIITA hypomorphic mice. Mol Immunol 2006; 44:1709-21. [PMID: 16982097 DOI: 10.1016/j.molimm.2006.07.294] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 07/27/2006] [Accepted: 07/28/2006] [Indexed: 11/23/2022]
Abstract
Major histocompatibility class II (MHC II) transactivator (CIITA) is critical for interferon-gamma (IFN-gamma)-induced repression of collagen [Xu, Y., Wang, L., Buttice, G., Sengupta, P.K., Smith, B.D., 2004. Major histocompatibility class II transactivator (CIITA) mediates repression of collagen (COL1A2) transcription by interferon gamma (IFN-gamma). J. Biol. Chem. 279, 41319-41332] and activation of MHC II transcription. To better understand the role of CIITA and IFN-gamma induced repression of collagen, mesenchymal cells (lung fibroblasts, adventitial fibroblasts, and smooth muscle cells) were isolated from a CIITA deficient mouse (C2ta(tm1Ccum)). IFN-gamma induced MHC II expression and repressed collagen type I expression in all three cell types isolated from the wild type background. As expected, IFN-gamma treatment of cells isolated from CIITA deficient mice did not induce MHC II production or activate the MHC II promoter. Interestingly, collagen gene expression and promoter activity was similar to that of wild type. Moreover, IFN-gamma induced CIITA mRNA and a truncated form of CIITA protein in all cells isolated from CIITA deficient mice. Most importantly, truncated CIITA occupied the collagen alpha 2(I) gene (col1a2) transcription start site during IFN-gamma treatment, but it did not occupy the MHC II promoter as judged by chromatin immunoprecipitation assays. Exogenous expression of a similar truncated form of CIITA maintained its ability to repress col1a2 transcription, but lost its ability to activate MHC II gene transcription suggesting a role for the CIITA C-terminal domain in activation, but not repression. IFN-gamma induced primarily types I and IV CIITA isoforms in the mouse cells. All three isoforms of CIITA were capable of repressing col1a2 and activating MHC II gene transcription. These data suggest that the previously described CIITA knockout mouse carries a hypomorphic mutation, rather than a null mutation. The removal of the leucine rich region in CIITA blocks activation of MHC II without altering repression of collagen transcription.
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Affiliation(s)
- Yong Xu
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
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Geissler I, Collins L, Schofield R, Fabre JW. In Vivo Suppression of Major Histocompatibility Complex Class II Expression on Porcine Vascular Endothelial Cells by an HMG-CoA Reductase Inhibitor. Transplantation 2006; 81:922-6. [PMID: 16570018 DOI: 10.1097/01.tp.0000179154.17329.68] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Vascular endothelial cells of man and pig, but not rodents, strongly express major histocompatibility complex (MHC) class II antigens in vivo, probably via the inducible promoter IV of the class II transactivator. There is abundant in vitro evidence that MHC class II positive vascular endothelial cells can activate T cells. Peripheral antigen presentation by endothelial cells is potentially important for organ-specific immunity, for allograft rejection, and possibly for immune responsiveness in general. Given the reported effects of statins on promoter IV of the class II transactivator, we evaluated in vivo expression of MHC class II antigens in pigs treated with atorvastatin calcium. METHODS Pigs were given 3 mg/kg/day of atorvastatin orally daily for 16 days, and then killed 24 hr after the last dose. Heart, kidney, and liver were removed for immunohistological and quantitative absorption analysis. RESULTS Double-labeling studies using immunofluorescence on frozen section for Factor VIII and MHC class II showed a marked suppression of MHC class II on vascular endothelial cells in all 4 treated pigs, in comparison with untreated pigs. This was confirmed using immunoperoxidase techniques on frozen sections. Quantitative absorption analysis showed up to 25-fold reduction in MHC class II expression. CONCLUSIONS Statins substantially suppress endothelial cell MHC class II expression in vivo. This is likely to inhibit organ-specific immune responses, and possibly also general immune responsiveness. In a transplantation setting, in addition to other regulatory effects on the recipients immune system, statins might reduce the long-term capacity of the donor organ to activate rejection mechanisms.
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Affiliation(s)
- Ina Geissler
- Department of Clinical Sciences, Guy's, King's & St. Thomas' School of Medicine, The Rayne Institute, King's Denmark Hill Campus, 123 Coldharbour Lane, London SE5 9NU, United Kingdom
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Abstract
The benefit of HMG-CoA reductase inhibitors (statins) to the cardiovascular system is now well established and these drugs are being used extensively to treat hypercholesterolaemia clinically. However, as clinical outcomes become available it appears that statins are proving more beneficial than expected and thus it is being proposed that the actions of statins go beyond their ability to lower serum cholesterol levels. The report that statins can interact directly with lymphocyte function-associated antigen (LFA)-1 and prevent it engaging with the intracellular adhesion molecule (ICAM)-1 receptor on T cells is a novel mechanism of statin action and provides convincing evidence that these compounds can regulate biological systems other than by the cholesterol synthesis pathway. Immunosuppression to prevent organ transplant rejection is one application for which statins are currently being assessed. The clinical evidence is conflicting and does not convincingly reflect whether statins are beneficial as immunomodulators. However, in vivo studies investigating the cellular actions of statins have identified two mechanisms by which statins can potentially modulate an in vivo immune response. Firstly, statins regulate inducible class II major histocompatibility complex (MHC) expression on macrophages and endothelial cells. Secondly, statins can inhibit LFA-1 adhesion to ICAM-1 and thus regulate T cell activation. These findings suggest that statins have the potential to regulate an immune response in vivo and that more investigation is essential in order to explain the opposing clinical data.
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Affiliation(s)
- Liza J Raggatt
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, USA
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Yazawa T, Ito T, Kamma H, Suzuki T, Okudela K, Hayashi H, Horiguchi H, Ogata T, Mitsui H, Ikeda M, Kitamura H. Complicated mechanisms of class II transactivator transcription deficiency in small cell lung cancer and neuroblastoma. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 161:291-300. [PMID: 12107114 PMCID: PMC1850684 DOI: 10.1016/s0002-9440(10)64181-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Small cell lung cancer (SCLC) and neuroblastoma (NB), the most aggressive adult and infant neuroendocrine cancers, respectively, are immunologically characterized by a severe reduction in major histocompatibility complex (MHC) that is indispensable for anti-tumor immunity. We had reported that the severe reduction of MHC in SCLC was caused by a deficient interferon (IFN)-gamma-inducible expression of class II transactivator (CIITA) that is known as a very important transcription factor for IFN-gamma-inducible class II and class I MHC expression (Yazawa T, Kamma H, Fujiwara M, Matsui M, Horiguchi H, Satoh H, Fujimoto M, Yokohama K, Ogata T: Lack of class II transactivator causes severe deficiency of HLA-DR expression in small cell lung cancer. J Pathol 1999, 187:191-199). Here, we demonstrate that the reduction of MHC in NB was also caused by a deficient IFN-gamma-inducible expression of CIITA and that the deficiency in SCLC and NB was caused by similar mechanisms. Human achaete-scute complex homologue (HASH)-1, L-myc, and N-myc, which are specifically overexpressed in SCLC and NB, bound to the E-box in CIITA promoter IV and reduced the transcriptional activity. Anti-sense oligonucleotide experiments revealed that overexpressed L-myc and N-myc lie upstream in the regulatory pathway of HASH-1 expression. The expression of HASH-1 was also up-regulated by IFN-gamma. Our results suggest that SCLC and NB have complicated mechanisms of IFN-gamma-inducible CIITA transcription deficiency through the overexpressed HASH-1, L-myc, and N-myc. These complicated mechanisms may play an important role in the escape from anti-tumor immunity.
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Affiliation(s)
- Takuya Yazawa
- Department of Pathology, Yokohama City University School of Medicine, Kanagawa, Japan.
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Mohacsi P, Rieben R, Sigurdsson G, Tschanz H, Schaffner T, Nydegger UE, Carrel T. Successful management of a B-type cardiac allograft into an O-type man with 3(1/2)-year clinical follow-up. Transplantation 2001; 72:1328-30. [PMID: 11602865 DOI: 10.1097/00007890-200110150-00026] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND In May 1997, a 19-year-old male patient of histo-blood group type O suffering from congenital end-stage heart failure accidentally received a cardiac allograft of type B and is still alive in fair condition. METHODS In addition to conventional immunosuppressive therapy, plasma exchange (PEX), extracorporeal immunoabsorption (EIA), intravenous immunoglobulins (IVIG), and C1 inhibitor were used. RESULTS Such treatment successfully reduced both IgM and IgG anti-B levels and complement hyperactivity and allowed to reach the state of accommodation without obvious signs of rejection. The patient has been surviving for 42 months; retransplantation with an O-type heart remained unnecessary. CONCLUSION Humoral rejection has been avoided in this patient, with PEX, EIA, IVIG, and C1 inhibitor substantially contributing to this success. With future availability of such combined therapies, preferably before transplantation, vascular rejection events caused by preformed antibodies and complement (ABO mismatch or anti-HLA) could be prevented or treated.
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Affiliation(s)
- P Mohacsi
- Department of Cardiology, University Hospital / Inselspital, Bern, Switzerland.
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Chardon P, Rogel-Gaillard C, Cattolico L, Duprat S, Vaiman M, Renard C. Sequence of the swine major histocompatibility complex region containing all non-classical class I genes. TISSUE ANTIGENS 2001; 57:55-65. [PMID: 11169259 DOI: 10.1034/j.1399-0039.2001.057001055.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A segment of 158,063 nucleotides of the pig major histocompatibility complex (SLA) and corresponding to the junction of the class I and class III regions was sequenced entirely. The centromeric part of the segment contained six class III genes including the three tumor necrosis factor genes, while the telomeric part contained three genes belonging to the class I region. The order and the molecular organization of these genes were exactly conserved in the SLA and HLA complexes, except for the SC1 gene which displayed a shift of the reading frame in swine. The cluster of the three SLA class I-related genes (Ib) and the MIC1 and MIC2 genes were located in the middle of the segment, in the following order from the centromeric side onwards, SLA-6, SLA-7, SLA-8, MIC-1 and MIC-2. All three SLA Ib genes displayed an overall molecular structure compatible with the expression of membrane-anchored glycoproteins. The SLA-7 and SLA-8 genes bear greater resemblance than to the SLA-6 gene. Six SLA-6 alleles have been previously defined differing each from the other by unique point mutations. One of them, appeared to have arisen through the occurrence of a gene conversion event in which the SLA-7 gene served as template. Only MIC-2 gene might be functional, the second MIC-1 gene being truncated. In all, the 14 genes characterized spans 37% of the total sequence. The remaining 63% nucleotides comprised a number of repeat DNA motives, including LINE fragments, SINEs, microsatellites, and also numerous nucleotide stretches not yet defined in swine.
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Affiliation(s)
- P Chardon
- Laboratoire de Radiobiologie et Etude du Génome, INRA CEA, Jouy en Josas, France.
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Lawson C, McCormack AM, Moyes D, Yun S, Fabre JW, Yacoub M, Rose ML. An epithelial cell line that can stimulate alloproliferation of resting CD4+ T cells, but not after IFN-gamma stimulation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:734-42. [PMID: 10878346 DOI: 10.4049/jimmunol.165.2.734] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It has previously been shown that IFN-gamma-induced up-regulation of HLA class II on the surface of epithelial cells is not sufficient to induce proliferation of allospecific CD4+ T cells in vitro. To further investigate this phenomenon, a human epithelial bladder carcinoma, T24, was induced to constitutively express HLA class II without IFN-gamma stimulation, by permanent transfection with the full-length class II transactivator (CIITA) gene. Proliferation of allospecific T cells to transfected and wild-type cells with and without prior activation with saturating levels of IFN-gamma for 4 days was examined. IFN-gamma-activated T24 did not induce any response from CD4+ T cells. However, T24.CIITA induced significant levels of alloproliferation, which could be abrogated by pretreatment of T24.CIITA with a mAb to LFA-3. Prestimulation of T24. CIITA with saturating levels of IFN-gamma for 4 days also prevented allospecific CD4+ T cell proliferation. These findings suggest that epithelial cells may be intrinsically able to process and present alloantigen and provide adequate costimulation. We propose that IFN-gamma has a secondary, as yet unidentified, effect that acts to negatively regulate this response, at least in some epithelial cells.
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Affiliation(s)
- C Lawson
- Transplant Immunology Group, Imperial College School of Medicine, National Heart and Lung Institute, Heart Science Centre, Harefield Hospital, Harefield, Middlesex, United Kingdom
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