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1.
J Exp Med ; 220(12)2023 12 04.
Article in English | MEDLINE | ID: mdl-37906166

ABSTRACT

Due to their suppressive capacity, regulatory T cells (Tregs) have attracted growing interest as an adoptive cellular therapy for the prevention of allograft rejection, but limited Treg recovery and lower quality of adult-derived Tregs could represent an obstacle to success. To address this challenge, we developed a new approach that provides large quantities of Tregs with high purity and excellent features, sourced from thymic tissue routinely removed during pediatric cardiac surgeries (thyTregs). We report on a 2-year follow-up of the first patient treated worldwide with thyTregs, included in a phase I/II clinical trial evaluating the administration of autologous thyTreg in infants undergoing heart transplantation. In addition to observing no adverse effects that could be attributed to thyTreg administration, we report that the Treg frequency in the periphery was preserved during the 2-year follow-up period. These initial results are consistent with the trial objective, which is to confirm safety of the autologous thyTreg administration and its capacity to restore the Treg pool.


Subject(s)
Heart Transplantation , T-Lymphocytes, Regulatory , Adult , Humans , Infant , Graft Rejection , Transplantation, Homologous
2.
Am J Transplant ; 20(10): 2652-2668, 2020 10.
Article in English | MEDLINE | ID: mdl-32342639

ABSTRACT

The purpose of the STAR 2019 Working Group was to build on findings from the initial STAR report to further clarify the expectations, limitations, perceptions, and utility of alloimmune assays that are currently in use or in development for risk assessment in the setting of organ transplantation. The goal was to determine the precision and clinical feasibility/utility of such assays in evaluating both memory and primary alloimmune risks. The process included a critical review of biologically driven, state-of-the-art, clinical diagnostics literature by experts in the field and an open public forum in a face-to-face meeting to promote broader engagement of the American Society of Transplantation and American Society of Histocompatibility and Immunogenetics membership. This report summarizes the literature review and the workshop discussions. Specifically, it highlights (1) available assays to evaluate the attributes of HLA antibodies and their utility both as clinical diagnostics and as research tools to evaluate the effector mechanisms driving rejection; (2) potential assays to assess the presence of alloimmune T and B cell memory; and (3) progress in the development of HLA molecular mismatch computational scores as a potential prognostic biomarker for primary alloimmunity and its application in research trial design.


Subject(s)
Isoantibodies , Kidney Transplantation , Graft Rejection/diagnosis , Graft Rejection/etiology , Group Processes , HLA Antigens , Histocompatibility
3.
Cytotherapy ; 21(12): 1216-1233, 2019 12.
Article in English | MEDLINE | ID: mdl-31810768

ABSTRACT

Regulatory T cells (Tregs) are a promising therapy for several immune-mediated conditions but manufacturing a homogeneous and consistent product, especially one that includes cryopreservation, has been challenging. Discarded pediatric thymuses are an excellent source of therapeutic Tregs with advantages including cell quantity, homogeneity and stability. Here we report systematic testing of activation reagents, cell culture media, restimulation timing and cryopreservation to develop a Good Manufacturing Practice (GMP)-compatible method to expand and cryopreserve Tregs. By comparing activation reagents, including soluble antibody tetramers, antibody-conjugated beads and artificial antigen-presenting cells (aAPCs) and different media, we found that the combination of Dynabeads Treg Xpander and ImmunoCult-XF medium preserved FOXP3 expression and suppressive function and resulted in expansion that was comparable with a single stimulation with aAPCs. Cryopreservation tests revealed a critical timing effect: only cells cryopreserved 1-3 days, but not >3 days, after restimulation maintained high viability and FOXP3 expression upon thawing. Restimulation timing was a less critical process parameter than the time between restimulation and cryopreservation. This systematic testing of key variables provides increased certainty regarding methods for in vitro expansion and cryopreservation of Tregs. The ability to cryopreserve expanded Tregs will have broad-ranging applications including enabling centralized manufacturing and long-term storage of cell products.


Subject(s)
Cryopreservation/methods , T-Lymphocytes, Regulatory/cytology , T-Lymphocytes, Regulatory/transplantation , Thymus Gland/cytology , Tissue Engineering/methods , Cell Culture Techniques/methods , Cell Culture Techniques/standards , Cell Proliferation , Cell- and Tissue-Based Therapy/methods , Cell- and Tissue-Based Therapy/standards , Cells, Cultured , Child, Preschool , Cryopreservation/standards , Culture Media/chemistry , Culture Media/pharmacology , Humans , Infant , Lymphocyte Activation , Manufactured Materials/standards , T-Lymphocytes, Regulatory/immunology , Time Factors
5.
J Heart Lung Transplant ; 35(4): 491-9, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26856666

ABSTRACT

BACKGROUND: Young children show better survival after heart transplant compared with older individuals and can receive heart transplants safely from ABO-incompatible donors. Children develop immunologic tolerance to donor ABH antigens reflected in persistent absence of specific antibodies. We hypothesized that immature T-independent B-cell response and lack of B-cell memory play a crucial role in tolerance of ABH antigens after ABOi transplants. METHODS: We determined phenotypes of splenic lymphocytes from adults and children and peripheral blood from ABO-incompatible or ABO-compatible heart transplant recipients and control subjects by flow cytometry. In vitro immune response to T-independent stimulation, erythrocytes, and ABH antigens was assessed using proliferation assays. RESULTS: A predominant role for CD27(+) B cells in T-independent activation was demonstrated; these cells were significantly less frequent in infants than older subjects. Only IgM(+)CD27(+) B cells proliferated in response to non-self erythrocytes. In blood, IgM(+) and switched IgM(-) memory B cells were rare in infants, increasing to near-adult levels in children 5 years old. IgM(+)CD27(+) B cells were significantly fewer in ABO-incompatible transplant recipients than in ABO-compatible recipients. CONCLUSIONS: CD27(+) cells play a key role in T-independent B-cell activation. Response to ABH antigens is mediated by IgM(+)CD27(+) B cells, and donor ABO-specific tolerance after ABO-incompatible transplantation in children is facilitated by low prevalence of these cells. The pattern of B-cell memory development is altered after ABO-incompatible transplant. Memory B cells may be quantified to assess eligibility for ABO-incompatible transplant and represent a potential therapeutic target to extend the benefits of the immature immune system to older age groups.


Subject(s)
B-Lymphocytes/immunology , Blood Group Incompatibility/immunology , Graft Rejection/immunology , Graft Survival , Heart Transplantation , Immune Tolerance , Lymphocyte Activation/immunology , ABO Blood-Group System/immunology , Adolescent , Adult , B-Lymphocytes/pathology , Blood Group Incompatibility/epidemiology , Canada/epidemiology , Cell Proliferation , Child , Child, Preschool , Flow Cytometry , Graft Rejection/blood , Graft Rejection/epidemiology , Humans , Incidence , Infant , Infant, Newborn , Middle Aged , Survival Rate/trends , Tissue Donors , Young Adult
6.
Bioconjug Chem ; 27(3): 705-15, 2016 Mar 16.
Article in English | MEDLINE | ID: mdl-26816334

ABSTRACT

Silica microparticles were functionalized with A and B blood group carbohydrate antigens (A type I, A type II, B type I, and B type II) to enable the detection and monitoring of ABO antigen-specific B cells. Microparticles were prepared via the Stöber synthesis, labeled with an Alexafluor fluorescent dye, and characterized via TEM and fluorescence microscopy. The silica microparticles were functionalized with (3-aminopropyl)trimethoxysilane (APTMS), followed by the use of an established fluorenylmethyloxycarbonyl (Fmoc)-protected PEG-based linker. The terminal Fmoc moiety of the PEG-based linker was then deprotected, yielding free amino groups, to which the A and B antigens were coupled. The carbohydrate antigens were synthesized with a p-nitrophenol ester to enable conjugation to the functionalized silica microparticles via an amide bond. The number of free amine groups available for coupling for a given mass of PEG-functionalized silica microparticles was quantified via reaction with Fmoc-glycine. The antigen-functionalized microparticles were then evaluated for their specificity in binding to A and B antigen-reactive B-cells via flow cytometry, and for blocking of naturally occurring antibodies in human serum. Selective binding of the functionalized microparticles to blood group-reactive B cells was observed by flow cytometry and fluorescence microscopy. The modular approach outlined here is applicable to the preparation of silica microparticles containing any carbohydrate antigen and alternative fluorophores or labels. This approach therefore comprises a novel, general platform for screening B cell populations for binding to carbohydrate antigens, including, in this case, the human A and B blood group antigens.


Subject(s)
Antigens/immunology , B-Lymphocytes/immunology , Microspheres , Silicon Dioxide/chemistry , Microscopy, Electron, Transmission
7.
J Leukoc Biol ; 90(1): 123-32, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21486907

ABSTRACT

During MS, phagocytosing myelin-containing macrophages arise and lie in close proximity to T cells. To date, it has not been addressed whether these myelin-laden macrophages have the capacity to present antigens to T cells and whether this contributes to inflammation in disease. We demonstrate that in vitro-generated human and mouse myelin-laden macrophages expressed MHC class I and II and costimulatory molecules and are thus well equipped for antigen presentation. Human myelin-laden macrophages exhibited normal endocytosis of particulate and soluble antigens. In addition, human myelin-laden macrophages elicited active T cell proliferation of naïve as well as memory T cells. Furthermore, mouse myelin-laden macrophages induced primary antigen-specific CD4(+) T cell proliferation in vivo but transiently diminished IFN-γ release. Functionally, MOG peptide-loaded myelin-laden mouse macrophages modestly but significantly reduced the severity of MOG peptide-induced EAE. These data show that myelin uptake results in the induction of a population of macrophages that retains antigen-presenting capacity and limits autoimmune-mediated disease.


Subject(s)
Antigen-Presenting Cells/immunology , Lymphocyte Activation/immunology , Macrophages/immunology , Multiple Sclerosis/immunology , Myelin Sheath/immunology , Animals , Antigen Presentation/immunology , Encephalomyelitis, Autoimmune, Experimental/immunology , Female , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/immunology , Humans , Immunophenotyping , Lymphocyte Culture Test, Mixed , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , T-Lymphocytes/immunology
8.
Immunol Lett ; 129(2): 64-71, 2010 Apr 08.
Article in English | MEDLINE | ID: mdl-20167235

ABSTRACT

The members of the epidermal growth factor (EGF)-transmembrane (TM)7 family of adhesion class G-protein coupled receptors are abundantly expressed by cells of the myeloid lineage. A detailed investigation of their expression by functional subsets of activated macrophages is still lacking. Therefore, we determined the expression of CD97, EGF module-containing mucin-like receptor (EMR)2 and EMR3 by monocyte-derived macrophages experimentally polarized in vitro. This was compared to three types of disease-associated lipid-laden macrophages displaying an alternatively activated phenotype in situ. Polarization in vitro towards classically activated M1 versus alternatively activated M2 extremes of macrophage activation did not result in a congruent regulation of EGF-TM7 receptor mRNA and protein except for a down-regulation of CD97 by IL-10. In contrast, macrophages handling lipid overload in vivo displayed differences in the expression of CD97 and EMR2. While foamy macrophages in atherosclerotic vessels expressed both CD97 and EMR2, foam cells in multiple sclerosis brain expressed CD97, but only little EMR2. Foam cell formation in vitro by oxidized LDL and myelin did not affect CD97 or EMR2 expression. Gaucher spleen cells accumulating glucosylceramide expressed very high levels of CD97 and EMR2. These findings indicate that complex cellular expression programmes rather than activation modes regulate the expression of EGF-TM7 receptors in macrophages.


Subject(s)
Antigens, CD/immunology , Atherosclerosis/immunology , Gaucher Disease/immunology , Gene Expression Regulation , Macrophages/immunology , Membrane Glycoproteins/immunology , Multiple Sclerosis/immunology , Receptors, G-Protein-Coupled/immunology , Atherosclerosis/genetics , Carotid Arteries/immunology , Flow Cytometry , Gaucher Disease/genetics , Immunohistochemistry , Multiple Sclerosis/genetics , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction
9.
Curr Opin Organ Transplant ; 14(5): 577-82, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19620867

ABSTRACT

PURPOSE OF REVIEW: As the knowledge of CD4+CD25bright+FoxP3+ regulatory T cells in experimental transplant models grows, we need to understand how and to what extent these suppressor cells regulate donor-directed immune events in the transplantation clinic. This review focuses on the function of regulatory T cells in the peripheral blood and the transplanted organ of patients after heart transplantation during immunological quiescence and rejection. RECENT FINDINGS: Here, we present data that peripheral CD4+CD25bright+FoxP3+ T cells of heart transplant patients who experience acute rejection have inadequate immune regulatory function in vitro compared with those of nonrejecting patients. During rejection, potent donor-specific T-cell suppressors are present in the transplanted organ. SUMMARY: The studies in transplant patients' show that the function of CD4+CD25bright+FoxP3+ regulatory T cells in alloimmunity is to inhibit the activation of effector T cells, to prevent rejection, and to control the antidonor response at the graft itself at later stages of immune reactivity.


Subject(s)
Graft Rejection/immunology , Heart Transplantation/immunology , Immunity, Cellular/immunology , T-Lymphocytes, Regulatory/immunology , Graft Rejection/drug therapy , Humans , Immunosuppressive Agents/therapeutic use , T-Lymphocytes, Regulatory/drug effects , Transplantation, Homologous
10.
Arterioscler Thromb Vasc Biol ; 29(8): 1220-7, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19520974

ABSTRACT

OBJECTIVE: Atherosclerotic plaque rupture can lead to severe complications such as myocardial infarction and stroke. Myeloid related protein (Mrp)-14, Mrp-8, and Mrp-8/14 complex are inflammatory markers associated with myocardial infarction. It is, however, unknown whether Mrps are associated with a rupture-prone plaque phenotype. In this study, we determined the association between Mrp-14, -8, -8/14 plaque levels and plaque characteristics. METHODS AND RESULTS: In 186 human carotid plaques, levels of Mrp-14, -8, and -8/14 were quantified using ELISA. High levels of Mrp-14 were found in lesions with a large lipid core, high macrophage staining, and low smooth muscle cell and collagen amount. Plaques with high levels of Mrp-14 contained high interleukin (IL)-6, IL-8, matrix metalloprotease (MMP)-8, MMP-9, and low MMP-2 concentrations. Mrp-8 and Mrp-8/14 showed a similar trend. Within plaques, a subset of nonfoam macrophages expressed Mrp-8 and Mrp-14 and the percentage of Mrp-positive macrophages was higher in rupture-prone lesions compared to stable ones. In vitro, this subset of macrophages does not acquire a foamy phenotype when fed oxLDL. CONCLUSIONS: Mrp-14 is strongly associated with the histopathologic features and the inflammatory status of rupture-prone atherosclerotic lesions, identifying Mrp-14 as a local marker for these plaques.


Subject(s)
Atherosclerosis/metabolism , Calgranulin B/metabolism , Carotid Arteries/pathology , Carotid Artery Diseases/metabolism , Atherosclerosis/pathology , Atherosclerosis/surgery , Biomarkers/metabolism , Calgranulin A/metabolism , Carotid Arteries/metabolism , Carotid Artery Diseases/pathology , Carotid Artery Diseases/surgery , Endarterectomy, Carotid , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , Humans , Immunohistochemistry , Macrophages/metabolism , Macrophages/pathology , Retrospective Studies , Rupture, Spontaneous
11.
Transplantation ; 87(8): 1191-200, 2009 Apr 27.
Article in English | MEDLINE | ID: mdl-19384166

ABSTRACT

BACKGROUND: CD4CD25FoxP3 regulatory T cells are suppressors of antigen-activated immune reactivity. Here, we assessed the clinically relevant role of these cells in the control of immune responses directed to a transplanted heart. METHODS: We investigated the phenotype and function of peripheral CD4CD25FoxP3 T cells in heart transplant patients free from acute rejections (n=9) and in rejectors (n=12) before and during acute cellular rejection. RESULTS: Between rejectors and nonrejectors, the proportion of CD4CD25 T cells and of FoxP3 cells within this population was comparable. Yet, CD4CD25FoxP3 T cells of rejectors had a higher CD127 expression than those of nonrejectors (P<0.0001). Depletion of CD4CD25 T cells from peripheral blood mononuclear cells increased the antidonor proliferative response of both nonrejectors (P=0.0005) and rejectors (P=0.03). In rejectors, however, only a 2-fold increase was measured, whereas the nonrejectors' response became 14 times higher (P=0.002). Reconstitution of CD4CD25 T cells only suppressed the overall antidonor proliferative response of CD25 responder cells of nonrejectors significantly (P=0.001). Moreover, the percentage inhibition of the response was higher in nonrejectors than in rejectors (P=0.02). Analyses of pretransplant samples revealed that CD4CD25 T cells of rejectors already had a lower suppressive capacity than those of nonrejectors before transplantation (P=0.04). CONCLUSION: CD4CD25FoxP3 T cells of heart transplant patients who experience acute rejection had an up-regulated CD127 expression and an inadequate regulatory function compared with those of nonrejecting patients. Our observations suggest that the function of circulating CD4CD25FoxP3 regulatory T cells may be pivotal for the prevention of acute cellular rejection after clinical heart transplantation.


Subject(s)
CD4 Antigens/immunology , Forkhead Transcription Factors/immunology , Graft Rejection/immunology , Heart Transplantation/immunology , Interleukin-2 Receptor alpha Subunit/immunology , T-Lymphocytes, Regulatory/immunology , T-Lymphocytes/immunology , Acute Disease , Adult , Antigens, CD/immunology , Female , Forkhead Transcription Factors/genetics , Graft Rejection/epidemiology , Graft Rejection/prevention & control , Humans , Lymphocyte Activation , Lymphocyte Culture Test, Mixed , Male , Middle Aged
12.
Hum Immunol ; 69(7): 389-98, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18638654

ABSTRACT

Regulatory T cells are considered to be pivotal for the induction of tolerance to donor antigens. In the past decades, several regulatory T-cell subsets have been identified, such as CD4(+)CD25(+) regulatory T cells and the CD8(+)CD28(-) suppressor T cells. Although many studies have investigated the role of these regulators in transplant tolerance, relatively little attention has focused on the exact place where these cells suppress immune responses directed to donor antigens. The localization of regulatory T cells may influence their effect on allogeneic immune responses. More insight into the localization and migration of regulatory T cells in transplant recipients is therefore important, especially when these cells are to be used for monitoring purposes and for cellular immune therapy. In the present review we summarize current knowledge about the presence of functional donor-directed regulatory T cells in the secondary lymphoid organs, peripheral blood, and the transplanted organ itself. In addition, we discuss the importance of the appropriate localization for the control of anti-donor immune reactivity.


Subject(s)
Organ Transplantation , T-Lymphocytes, Regulatory/immunology , Animals , CD28 Antigens/immunology , CD8 Antigens/immunology , Humans , Isoantigens/immunology , Lymphocyte Activation , Lymphoid Tissue/immunology , Lymphoid Tissue/pathology , Transplantation Immunology , Transplantation Tolerance , Transplantation, Homologous
13.
Transpl Immunol ; 18(3): 250-4, 2008 Jan.
Article in English | MEDLINE | ID: mdl-18047933

ABSTRACT

Previously, we demonstrated in heart transplant patients that FOXP3, a gene required for the development and function of regulatory T cells, was highly expressed in the graft during an acute cellular rejection. In this study, we analyzed whether the FOXP3 gene expression in the peripheral blood also reflects anti-donor immune responses, and therefore may provide clues for non-invasive detection of non-responsiveness or acute rejection. We examined the FOXP3 expression patterns of peripheral blood mononuclear cells (PBMC; n=69) of 19 heart transplant patients during quiescence and rejection in comparison with those of endomyocardial biopsies (EMB; n=75) of 24 heart transplant patients. While the FOXP3 mRNA levels were abundantly expressed in rejecting EMB (ISHLT rejection grade>1R) compared with EMB without histological evidence of myocardial damage (ISHLT rejection grade 0R-1R; p=0.003), no association with rejection or non-responsiveness was found for the FOXP3 mRNA levels in the peripheral blood. Thus, in contrast to intragraft FOXP3 gene expression, the peripheral FOXP3 mRNA levels lack correlation with anti-donor immune responses in the graft, and, consequently, FOXP3 does not appear to be a potential candidate gene for non-invasive diagnosis of non-responsiveness or rejection.


Subject(s)
Forkhead Transcription Factors/genetics , Graft Rejection , Heart Transplantation/immunology , Leukocytes, Mononuclear/metabolism , Adult , Aged , Biopsy , Female , Forkhead Transcription Factors/blood , Gene Expression , Graft Survival/immunology , Humans , Male , Middle Aged , Myocardium/pathology , RNA, Messenger/blood , RNA, Messenger/genetics
14.
Transplantation ; 83(11): 1477-84, 2007 Jun 15.
Article in English | MEDLINE | ID: mdl-17565321

ABSTRACT

BACKGROUND: Regulatory FOXP3+ T cells control immune responses of effector T cells. However, whether these cells regulate antidonor responses in the graft of cardiac allograft patients is unknown. Therefore, we analyzed the gene expression profiles of regulatory and effector T-cell markers during immunological quiescence and acute rejection. METHODS: Quantitative real-time polymerase chain reaction was used to analyze mRNA expression levels in time-zero specimens (n=24) and endomyocardial biopsies (EMB; n=72) of cardiac allograft patients who remained free from rejection (nonrejectors; n=12) and patients with at least one histologically proven acute rejection episode (rejectors; International Society for Heart and Lung Transplantation [ISHLT] rejection grade>2; n=12). RESULTS: For all analyzed regulatory and effector T-cell markers, mRNA expression levels were increased in biopsies taken after heart transplantation compared with those in time-zero specimens. Posttransplantation, the FOXP3 mRNA levels were higher in EMB assigned to a higher ISHLT rejection grade than the biopsies with grade 0: the highest mRNA levels were detected in the rejection biopsies (rejection grade>2; P=0.003). In addition, the mRNA levels of CD25, glucocorticoid-induced TNF receptor family-related gene, cytotoxic T lymphocyte-associated antigen 4, interleukin-2, and granzyme B were also significantly higher in rejecting EMB than in nonrejecting EMB (rejection grade

Subject(s)
Forkhead Transcription Factors/genetics , Heart Transplantation/immunology , Myocardium/metabolism , RNA, Messenger/metabolism , Acute Disease , Adolescent , Adult , Aged , Antigens, CD/genetics , Antigens, Differentiation/genetics , CTLA-4 Antigen , Endocardium/metabolism , Female , Gene Expression , Glucocorticoid-Induced TNFR-Related Protein/genetics , Graft Rejection/genetics , Graft Rejection/metabolism , Graft Rejection/pathology , Granzymes/genetics , Humans , Interleukin-2/genetics , Interleukin-2 Receptor alpha Subunit/genetics , Male , Middle Aged , Postoperative Period , Severity of Illness Index , Tissue Donors , Transplantation, Homologous
15.
Transplantation ; 83(11): 1485-92, 2007 Jun 15.
Article in English | MEDLINE | ID: mdl-17565322

ABSTRACT

BACKGROUND: Interleukin (IL)-21 is the most recently described cytokine that signals via the common cytokine receptor (gammac), is produced by activated CD4+ T-cells, and regulates expansion and effector function of CD8+ T-cells. MATERIALS: To explore the actions of IL-21 with other gammac-dependent cytokines in alloreactivity, mRNA expression of IL-21, IL-21R alpha-chain, and IL-2 proliferation and cytotoxicity was measured after stimulation in mixed lymphocyte reactions. Additionally, IL-21 and IL-21R alpha-chain expression was studied in biopsies of heart transplant patients. RESULTS: Analysis of mRNA expression levels of allostimulated T-cells showed a 10-fold induction of IL-21 and IL-21R alpha-chain. Interestingly, induction of IL-21 was highly dependent on IL-2 (as in the presence of anti-IL-2, anti-IL-2R alpha-chain, and the immunosuppressive drugs cyclosporine A, tacrolimus, and rapamycin) the transcription of IL-21 was almost completely inhibited, whereas in the presence of exogenous IL-2 the mRNA expression of IL-21 was even more upregulated. IL-21 functioned as a costimulator for IL-2 to augment proliferation and cytotoxic responses, while blockade of the IL-2 route abrogated these functions of IL-21. Blockade of the IL-21 route by anti-IL-21R alpha-chain monoclonal antibodies inhibited the proliferation of alloactivated T-cells. Also, in vivo alloreactivity was associated with IL-21/IL-21R alpha-chain expression. After heart transplantation, the highest intragraft IL-21, IL-21R alpha-chain, and IL-2 mRNA expression levels were measured during acute rejection (P<0.001, P=0.01, P=0.03). CONCLUSION: IL-21 is a critical cytokine for IL-2 dependent immune processes. Blockade of the IL-21 pathway may provide a new perspective for the treatment of allogeneic responses in patients after transplantation.


Subject(s)
Graft Rejection/physiopathology , Heart Transplantation , Interleukin-2/metabolism , Interleukins/metabolism , Cell Proliferation , Cohort Studies , Cytotoxicity, Immunologic , Endocardium/metabolism , Graft Rejection/blood , Graft Rejection/genetics , Graft Rejection/metabolism , Humans , Immunosuppression Therapy , Interleukins/genetics , Lymphocyte Culture Test, Mixed , Myocardium/metabolism , Postoperative Period , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Messenger/metabolism , Receptors, Interleukin-21/genetics , Receptors, Interleukin-21/metabolism , T-Lymphocytes/pathology
16.
J Heart Lung Transplant ; 25(8): 955-64, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16890117

ABSTRACT

BACKGROUND: After transplantation, CD4+CD25+FOXP3+ and interleukin (IL) 10-producing regulatory cells might regulate immune responses toward donor antigens. In this study, we determined whether cardiac allograft recipients show donor-specific hyporesponsiveness and studied the underlying mechanisms. METHODS: We analyzed the donor-specific T-cell responses by mixed lymphocyte reactions and limiting dilution assays to define whether cardiac allograft recipients (n = 21) show proliferative and cytotoxic hyporesponsiveness to donor antigens long after transplantation (range, 1.5-7 years). The mechanisms controlling immune responses, that is, FOXP3+/GITR+ T cells, and IL-10-producing cells, were studied by quantitative real-time polymerase chain reaction. RESULTS: In the presence of a proliferative response to donor antigens, no cytotoxic responsiveness could be measured in a number of patients in the absence (73%) and presence of exogenous IL-2 (29%), IL-15 (31%), and IL-15 plus IL2Ralpha blockade (88%). Overall, the cytotoxic response to donor cells was significantly lower than the reactivity to third-party cells after the addition of IL-2 (p = 0.004) and IL-15 plus IL2Ralpha blockade (p < 0.001). After donor stimulation, the peripheral blood mononuclear cells expressed higher messenger RNA (mRNA) levels of IL-10, but not of FOXP3 or GITR, than after third-party stimulation (p = 0.003). Moreover, the IL-10 mRNA expression was inversely correlated with the donor-specific cytotoxic responsiveness (p = 0.01). CONCLUSIONS: A significant proportion of patients showed donor-specific cytotoxic hyporesponsiveness long after heart transplantation, which was associated with high mRNA levels of IL-10 but not of FOXP3 or GITR. This observation suggests that IL-10-producing cells participate in the donor-specific cytotoxic hyporeactivity.


Subject(s)
Heart Transplantation/immunology , Interleukin-10/genetics , Interleukin-10/immunology , RNA, Messenger/biosynthesis , T-Lymphocytes/immunology , Female , Humans , Male , Middle Aged , Tissue Donors
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