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Long-term Allograft Survival (long-term + allograft_survival)
Selected AbstractsNeutralizing IL-7 Promotes Long-Term Allograft Survival Induced by CD40/CD40L Costimulatory BlockadeAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2006Y. Wang Memory T cells are somewhat resistant to immunosuppresion. They therefore pose a threat to inducing long-term allograft survival. IL-7 is essential for memory T-cell generation. Here, we investigated whether neutralizing IL-7 promotes allograft survival. We found that neutralizing IL-7 alone did not significantly prolong allograft survival. However, blocking both IL-7 and CD154 signaling synergistically prolonged allograft survival. In contrast, neutralizing IL-2 failed to further prolong allograft survival induced by CD40/CD154 costimulatory blockade. Allospecific memory CD8+ T-cell generation was severely impaired under the treatment of anti-IL-7 plus anti-CD154 Ab while administering recombinant IL-7 enhanced CD8+ memory generation even under donor-specific transfusion plus anti-CD154 Ab treatment. Neutralizing IL-7, but not IL-2, together with blocking CD154 synergistically suppressed the proliferation of naïve/effector CD8+ T cells infiltrating grafts. Nevertheless, neutralizing IL-7 did not alter regulatory T-cell generation while neutralizing IL-2 suppressed their generation. Hence, targeting IL-7 represents a new strategy to prolong allograft survival by acting on both naïve and memory T cells. Long-term allograft survival may be achieved by neutralizing IL-7 plus CD40/CD154 blockade, since CD40/CD154 costimulatory blockade prevents acute rejection while neutralizing IL-7 suppresses the generation of memory T cells that persist and mediate late or chronic rejection. [source] Induction therapy: Why, when, and which agent?PEDIATRIC TRANSPLANTATION, Issue 3 2010Leah Krischock Krischock L, Marks SD. Induction therapy: Why, when, and which agent? Pediatr Transplantation 2010: 14:298,313. © 2010 John Wiley & Sons A/S. Abstract:, The long-term outcome of paediatric transplantation has improved over the last decade with an increase in the armamentarium of immunosuppressive agents. However, the battle against the hostile immune response at the time of and after transplantation continues. Induction therapy can reduce early injury, to optimize the long-term allograft survival. The goal of induction immunosuppression in paediatric transplantation is to permit the use of lower doses of maintenance immunosuppressive agents without increased rates of acute allograft rejection and chronic allograft damage. The aim of this review is to summarize the current literature relating to the use of antibody agents for induction in paediatric solid organ transplantation. [source] Changing trends in pediatric transplantation: 2001 Annual Report of the North American Pediatric Renal Transplant Cooperative StudyPEDIATRIC TRANSPLANTATION, Issue 4 2003Mark R. Benfield This cooperative group now includes over 150 participating medical centers in the United States, Canada, Mexico, and Costa Rica. This report covers the years from 1987 through 2001 and includes data on 7545 renal transplants in 6878 patients. This report demonstrates changing trends in many areas of pediatric transplantation including increasing numbers of African American and Hispanic children receiving transplantation, remarkable improvements in the rate of acute rejection, rejection reversal, and short- and long-term allograft survival. In the most recent cohorts of patients, we now see that 1-yr allograft survival is no different in cadaver donor compared to living donor recipients and in infants compared to all other age groups. However, this analysis also reveals areas of continued challenges including inferior outcomes in African American and adolescent populations, chronic rejection, and the adverse effects of immunosuppression. [source] Molecular Markers and Targeted Therapy of Skin Rejection in Composite Tissue AllotransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010T. Hautz Skin rejection remains a major hurdle in reconstructive transplantation. We investigated molecular markers of skin rejection with particular attention to lymphocyte trafficking. Skin biopsies (n = 174) from five human hand transplant recipients were analyzed for rejection, characteristics of the infiltrate and lymphocytic adhesion markers. The cellular infiltrate predominantly comprised CD3+ T cells. CD68, Foxp3 and indoleamine 2, 3-dioxygenase expression and the CD4/CD8 increased with severity of rejection. Lymphocyte adhesion markers were upregulated upon rejection, intercellular adhesion molecule-1 and E-selectin correlated best with severity of rejection. Guided by the findings, a specific E- and P-selectin inhibitor was investigated for its effect on skin rejection in a rat hind limb allotransplant model. While efomycine M (weekly s.c. injection into the graft) alone had no effect, long-term allograft survival was achieved when combined with antithymocyte globulin and tacrolimus (control group without efomycine M rejected at postoperative day [POD] 61 ± 1). Upregulation of lymphocyte trafficking markers correlates with severity of skin rejection and time after transplantation in human hand transplantation. Blocking E- and P-selectin in the skin holds potential to significantly prolong limb allograft survival. [source] Baseline Donor-Specific Antibody Levels and Outcomes in Positive Crossmatch Kidney TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2010J. M. Gloor Renal transplant candidates with donor-specific alloantibody (DSA) have increased risk of antibody-mediated allograft injury. The goal of this study was to correlate the risk of antibody-mediated rejection (AMR), transplant glomerulopathy (TG) and graft survival with the baseline DSA level (prior to initiation of pretransplant conditioning). These analyses include 119 positive crossmatch (+XM) compared to 70 negative crossmatch (,XM) transplants performed between April 2000 and July 2007. Using a combination of cell-based crossmatch tests, DSA level was stratified into very high +XM, high +XM, low +XM and ,XM groups. In +XM transplants, increasing DSA level was associated with increased risk for AMR (HR = 1.76 [1.51, 2.07], p = 0.0001) but not TG (p = 0.18). We found an increased risk for both early and late allograft loss associated with very high DSA (HR = 7.71 [2.95, 20.1], p = 0.0001). Although lower DSA recipients commonly developed AMR and TG, allograft survival was similar to that of ,XM patients (p = 0.31). We conclude that the baseline DSA level correlates with risk of early and late alloantibody-mediated allograft injury. With current protocols, very high baseline DSA patients have high rates of AMR and poor long-term allograft survival highlighting the need for improved therapy for these candidates. [source] CCR5 Is Required for Regulation of Alloreactive T-Cell Responses to Single Class II MHC-Mismatched Murine Cardiac GraftsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2009T. Nozaki The effector CD4 T-cell response in wild-type C57BL/6 recipients of single class II MHC-disparate B6.H-2bm12 cardiac allografts is restricted by CD4+CD25+ regulatory T cells (Tregs) resulting in long-term allograft survival. To investigate the role chemokine receptors might play in Treg function, this study tested the requirement for CCR5 on Tregs to suppress the alloimmune response in C57BL/6 recipients of B6.H-2bm12 cardiac allografts. In contrast to the long-term survival of B6.H-2bm12 allografts in wild-type recipients (>100 days), the allografts were acutely rejected within 25 days in CCR5,/, recipients with intense infiltration of CD4 T cells. Numbers and duration of donor-reactive CD4 T cells producing IFN-, and IL-4 were markedly increased in spleens of B6.CCR5,/, versus wild-type recipients. Wild-type and B6.CCR5,/, mice had equivalent numbers of splenic FoxP3+ Tregs before and following transplantation, and these Tregs were equivalently suppressive in vitro. However, diminished numbers of FoxP3+ Tregs infiltrated B6.H-2bm12 allografts in B6.CCR5,/, recipients. Adoptive transfer of wild-type, but not CCR5-deficient, CD4+CD25+ Tregs to CCR5,/, recipients restored long-term survival of B6.H-2bm12 cardiac grafts. Collectively, these results indicate that CCR5 expression is required for the regulatory functions of Tregs that restrict alloreactive CD4 T-cell responses to single class II MHC-mismatched cardiac allografts. [source] Reassessing the Impact of Donor HLA-C Genotype on Long-Term Liver Transplant SurvivalAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2009T. H. Tran HLA-C is the major inhibitory ligand for killer immunoglobulin-like receptors (KIRs) that are expressed on natural killer (NK) cells. Based on their KIR specificity, HLA-C alleles can be divided into two groups, termed HLA-C1 and HLA-C2. Donor HLA-C group has recently been identified by Hanvesakul et al. (Am J Transplant 2008) as a critical determinant of clinical outcome following liver transplantation: Possession of at least one HLA-C group 2 allele by the donor was associated with significantly improved long-term graft and patient survival, presumably due to an inhibition of host NK cell function. To verify this study, we performed genotyping of 913 deceased liver donors for the relevant KIR epitopes of HLA-C and correlated the presence or absence of donor HLA-C2 genotype with graft and patient survival. In our study, donor HLA-C2 genotype had no impact on 10-year graft or patient survival. We cannot confirm a major role of donor HLA-C2 genotype on long-term allograft survival after liver transplantation. [source] CD8+ T-Cell Depletion and Rapamycin Synergize with Combined Coreceptor/Stimulation Blockade to Induce Robust Limb Allograft Tolerance in MiceAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2008Z. Li The growing development of composite tissue allografts (CTA) highlights the need for tolerance induction protocols. Herein, we developed a mouse model of heterotopic limb allograft in a stringent strain combination in which potentially tolerogenic strategies were tested taking advantage of donor stem cells in the grafted limb. BALB/c allografts were transplanted into C57BL/6 mice treated with anti-CD154 mAb, nondepleting anti-CD4 combined to either depleting or nondepleting anti-CD8 mAbs. Some groups received additional rapamycin. Both depleting and nondepleting mAb combinations without rapamycin only delayed limb allograft rejection, whereas the addition of rapamycin induced long-term allograft survival in both combinations. Nevertheless, robust donor-specific tolerance, defined by the acceptance of a fresh donor-type skin allograft and simultaneous rejection of third-party grafts, required initial CD8+ T-cell depletion. Mixed donor-recipient chimerism was observed in lymphoid organs and recipient bone marrow of tolerant but not rejecting animals. Tolerance specificity was confirmed by the inability to produce IL-2, IFN-, and TNF-, in MLC with donor antigen while significant alloreactivity persisted against third- party alloantigens. Collectively, these results show that robust CTA tolerance and mixed donor-recipient chimerism can be achieved in response to the synergizing combination of rapamycin, transient CD8+ T-cell depletion and costimulation/coreceptor blockade. [source] Neutralizing IL-7 Promotes Long-Term Allograft Survival Induced by CD40/CD40L Costimulatory BlockadeAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2006Y. Wang Memory T cells are somewhat resistant to immunosuppresion. They therefore pose a threat to inducing long-term allograft survival. IL-7 is essential for memory T-cell generation. Here, we investigated whether neutralizing IL-7 promotes allograft survival. We found that neutralizing IL-7 alone did not significantly prolong allograft survival. However, blocking both IL-7 and CD154 signaling synergistically prolonged allograft survival. In contrast, neutralizing IL-2 failed to further prolong allograft survival induced by CD40/CD154 costimulatory blockade. Allospecific memory CD8+ T-cell generation was severely impaired under the treatment of anti-IL-7 plus anti-CD154 Ab while administering recombinant IL-7 enhanced CD8+ memory generation even under donor-specific transfusion plus anti-CD154 Ab treatment. Neutralizing IL-7, but not IL-2, together with blocking CD154 synergistically suppressed the proliferation of naïve/effector CD8+ T cells infiltrating grafts. Nevertheless, neutralizing IL-7 did not alter regulatory T-cell generation while neutralizing IL-2 suppressed their generation. Hence, targeting IL-7 represents a new strategy to prolong allograft survival by acting on both naïve and memory T cells. Long-term allograft survival may be achieved by neutralizing IL-7 plus CD40/CD154 blockade, since CD40/CD154 costimulatory blockade prevents acute rejection while neutralizing IL-7 suppresses the generation of memory T cells that persist and mediate late or chronic rejection. [source] Transplantation of ABO Group A2 Kidneys from Living Donors into Group O and B Recipients,AMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2001John B. Sorensen Fifteen blood group O and B recipients have been transplanted with kidneys from subtype A2 living donors since April 1992. ABO red cell grouping was performed by local licensed blood banks with A2 subtype determined using an anti-A1 lectin and, retrospectively, by a polymerase chain reaction (PCR)-based molecular method. All grafts functioned immediately and no patient has required dialysis. Three patients each experienced one reversible rejection episode. With the exception of one cardiac death at 9 months and one patient with profound toxicity to calcineurin inhibitors, all allografts continue to function normally. One donor, mistyped as a group A2 using lectin, was by PCR typing an A1O1 nonsecretor; the graft continues to function normally at 30 months. Transplantation of living donor A2 renal allografts into non-A recipients produces excellent long-term allograft survival and expands the potential living donor pool for nonblood group A recipients. [source] The kinetics of CD154 (CD40L) expression in peripheral blood mononuclear cells of healthy subjects in liver allograft recipients and X-linked hyper-IgM syndromeCLINICAL TRANSPLANTATION, Issue 6 2000A Bartlett The costimulatory pathways play a key role in T cell activation during allograft rejection (AR). Inhibition of the T cell costimulatory molecule CD154 (CD40 ligand) has been effective in producing long-term allograft survival in rodents and non-human primates. The role of the CD40-CD154 pathway in human orthotopic liver transplantation (OLT) has not been examined. Aim: To describe the patterns of CD154, CD69 and CD152 (CTLA4) expression in OLT recipients and to determine their temporal relationship to AR. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 15 OLT allograft recipients just prior to and for seven consecutive days postoperatively. Gene and protein expression of CD154, CD69 and CD154 were examined by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry (FC), respectively. Results: FC failed to demonstrate an up-regulation of CD154 and CD152 protein expression during the first postoperative week. Intracellular FC did not increase the sensitivity. There was an increased level of CD3+CD8+ T cells expressing CD69 at the time of rejection compared to that on day 0. RT-PCR demonstrated a sporadic expression of CD154 and CD69 mRNA, with no correlation to episodes of acute cellular rejection. In vitro stimulation of PBMCs revealed an impaired up-regulation of CD154 in patients receiving conventional immunosuppression compared to healthy controls. The assays were validated using positive and negative controls, including a family with X-linked hyper-IgM syndrome. Conclusion: We found no evidence of spontaneous CD154 gene or protein expression in PBMCs associated with acute rejection episodes following OLT. Immunosuppression resulted in impaired responses to ex vivo stimulation. Lymphocyte costimulatory pathways play a critical role in mediating acute allograft rejection. However, we found no evidence of spontaneous CD154 gene or protein expression in PBMCs associated with acute rejection episodes following OLT. Furthermore, stimulation in vitro resulted in less up-regulation of CD154 than for healthy controls. [source] | ||||||||||