Joseph R Leventhal

Northwestern Memorial Hospital, Chicago, Illinois, United States

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Publications (154)579.17 Total impact

  • Suzanne T. Ildstad · Joseph Leventhal · Yujie Wen · Esma Yolcu
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    ABSTRACT: For over 50 years the association between hematopoietic chimerism and tolerance has been recognized. This originated with the brilliant observation by Dr. Ray Owen that freemartin cattle twins that shared a common placental blood supply were red blood cell chimeras, which led to the discovery that hematopoietic chimerism resulted in actively acquired tolerance. This was first confirmed in neonatal mice by Medawar et al. and subsequently in adult rodents. Fifty years later this concept has been successfully translated to solid organ transplant recipients in the clinic. The field is new, but cell-based therapies are being used with increasing frequency to induce tolerance and immunomodulation. The future is bright. This review focuses on chimerism and tolerance: past, present and prospects for the future.
    No preview · Article · Jan 2016 · Chimerism
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    ABSTRACT: We previously described early results of a nonchimeric operational tolerance protocol in human leukocyte antigen (HLA)-identical living donor renal transplants and now update these results. Recipients given alemtuzumab, tacrolimus/MPA with early sirolimus conversion were multiply infused with donor hematopoietic CD34(+) stem cells. Immunosuppression was withdrawn by 24 months. Twelve months later, operational tolerance was confirmed by rejection-free transplant biopsies. Five of the first eight enrollees were initially tolerant 1 year off immunosuppression. Biopsies of three others after total withdrawal showed Banff 1A acute cellular rejection without renal dysfunction. With longer follow-up including 5-year posttransplant biopsies, four of the five tolerant recipients remain without rejection while one developed Banff 1A without renal dysfunction. We now add seven new subjects (two operationally tolerant), and demonstrate time-dependent increases of circulating CD4(+) CD25(+++) CD127(-) FOXP3(+) Tregs versus losses of Tregs in nontolerant subjects (p < 0.001). Gene expression signatures, developed using global RNA expression profiling of sequential whole blood and protocol biopsy samples, were highly associative with operational tolerance as early as 1 year posttransplant. The blood signature was validated by an external Immune Tolerance Network data set. Our approach to nonchimeric operational HLA-identical tolerance reveals association with Treg immunophenotypes and serial gene expression profiles. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.
    Full-text · Article · Jul 2015 · American Journal of Transplantation
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    ABSTRACT: The new national Kidney Allocation System of the Organ Procurement and Transplantation Network (OPTN), effective as of December 4, 2014, was designed to improve the chances of transplanting the most highly sensitized patients on the waitlist, those with calculated panel reactive antibody values of 98%, 99% and 100%. Recently, it was suggested that these highly sensitized patients will experience inequitable access, given the reported high prevalence of antibodies to HLA-DP, and the fact that only about 1/3 of deceased donors are typed for HLA-DP antigens. Here we report that 320/2948 flow cytometric crossmatches performed for the Northwestern transplant program over the past 28 months were positive solely due to HLA-DP donor-specific antibodies (11%; 16.5% of patients with HLA antibodies-sensitized patients). We further show that 58/207 (12%) HLA-DR serologically matched donor-recipient pairs had a positive B cell flow crossmatch due to donor-specific HLA class II antibodies, and 2/34 (6%) serologic zero-HLA-A-B-DR mismatch had a positive flow crossmatch due to HLA-DSA. We therefore provide information regarding the necessity and importance of complete donor HLA typing including both chains of the HLA-DP antigen (encoded by HLA-DPA1 and HLA-DPB1) at the time of organ offer. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.
    Full-text · Article · Jul 2015 · American Journal of Transplantation
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    ABSTRACT: The presence of donor-specific HLA antibodies before or after transplantation may have different implications based on the antibody strength. Yet, current approaches do not provide information regarding the true antibody strength as defined by antigen-antibody dissociation rate. To assess currently available methods, we compared between neat mean fluorescence intensity (MFI) values, C1q MFI values, ethylenediaminetetraacetic acid (EDTA)-treated samples, as well as titration studies and peak MFI values of over 7000 Luminex-based single-antigen HLA antibody data points. Our results indicate that neat MFI values do not always accurately depict antibody strength. We further showed that EDTA treatment (6%) does not always remove all inhibitory factors compared with C1q or titration studies. In this study of patients presenting with multiple antibody specificities, a prozone effect was observed in 71% of the cohort (usually not affecting all antibody specificities within a single serum sample, though). Similar to titration studies, the C1q assay was able to address the issue of potential inhibition; however, its limitation is its low sensitivity and inability to detect the presence of weak antibodies. Titration studies are the only method among the approaches used in this study to provide information suggesting antigen-antibody dissociation rates and are, therefore, likely to provide better indication of true antibody strength. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.
    No preview · Article · Apr 2015 · American Journal of Transplantation
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    ABSTRACT: Previously, we had reported the role of tacrolimus (TAC) versus sirolimus (SRL) on the generation of regulatory T cells (Tregs) in primary MLR assays with SRL, demonstrating a uniquely supportive effect. However, the mechanisms associated with their actions on alloreactive human are not fully understood. Therefore, we tested whether TAC and SRL differentially affect already alloactivated human CD4 T-cell subsets. Alloreactive CD4CD45RA/CD45RO T cells generated in 9-day MLR were cocultured with anti-CD3 and autologous antigen presenting cells plus interleukin (IL)-2 in presence of TAC, SRL, or both, and the Tregs generated after another 5 to 6 days were phenotypically, molecularly, and functionally characterized. Tacrolimus significantly and SRL modestly inhibited interferon (IFN)-γ (Th1) and IL-17 (Th17)-producing cells. At clinical therapeutic concentrations, SRL, however, significantly increased forkhead/winged helix transcription factor P3 (FOXP3) Tregs, whereas TAC inhibited this T-cell population dose dependently and significantly. When used in combination, TAC and SRL had additive effects on inhibition of IFN-γ- and IL-17-producing cells. This was in contrast to the ability of SRL to reverse TAC-mediated inhibition of FOXP3-expressing cells. Proinflammatory cytokines (IL-1β, IL-6, and tumor necrosis factor-α) added to cultures caused significant decrease in FOXP3 Tregs that was again reversed by SRL. Sirolimus-derived Tregs were phenotypically normal, anergic to allostimulation, and suppressed proliferation of allogeneic effector T-cells. Thus, although TAC inhibits all alloreactive T cells, SRL promotes the differentiation and expansion of donor-specific Tregs without secondary reprogramming to IFN-γFOXP3 and IL-17FOXP3 Treg subsets. These results, although performed in an artificial in vitro model, add clinically applicable information on how these agents affect T-cell subpopulations.
    No preview · Article · Apr 2015 · Transplantation
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    ABSTRACT: Nineteen subjects have more than 18 months follow-up in a phase IIb tolerance protocol in HLA-mismatched recipients of living donor kidney plus facilitating cell enriched hematopoietic stem cell allografts (FCRx). Reduced intensity conditioning preceded a kidney allograft, followed the next day by FCRx. Twelve have achieved stable donor chimerism and have been successfully taken off immunosuppression (IS). We prospectively evaluated immune reconstitution and immunocompetence. Return of CD4 and CD8 T central and effector memory cell populations was rapid. T-cell receptor (TCR) Excision Circle analysis showed a significant proportion of chimeric cells produced were being produced de novo. The TCR repertoires posttransplant in chimeric subjects were nearly as diverse as pretransplant donors and recipients, and were comparable to subjects with transient chimerism who underwent autologous reconstitution. Subjects with persistent chimerism developed few serious infections when off IS. The majority of infectious complications occurred while subjects were still on conventional IS. BK viruria and viremia resolved after cessation of IS and no tissue-invasive cytomegalovirus infections occurred. Notably, although 2 of 4 transiently or nonchimeric subjects experienced recurrence of their underlying autoimmune disorders, none of the chimeric subjects have, suggesting that self-tolerance is induced in addition to tolerance to alloantigen. No persistently chimeric subject has developed donor-specific antibody, and renal function has remained within normal limits. Patients were successfully vaccinated per The American Society for Blood and Marrow Transplantation guidelines without loss of chimerism or rejection. Memory for hepatitis vaccination persisted after transplantation. Chimeric subjects generated immune responses to pneumococcal vaccine. These data suggest that immune reconstitution and immunocompetence are maintained in persistently chimeric subjects.
    Full-text · Article · Jan 2015 · Transplantation
  • Esma S Yolcu · Joseph R Leventhal · Suzanne T Ildstad
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    ABSTRACT: To describe the clinical outcomes and science behind a CD8/TCR facilitating cell-based hematopoietic stem cell transplant approach (termed FCRx) to induce tolerance to renal allografts without graft-versus-host disease (GVHD) and avoidance of long-term immunosuppressant drugs in living donor kidney transplant recipients. Successful solid organ transplantation currently requires the life-long use of medications to suppress the immune system to prevent transplant rejection. Drug-based immunosuppression significantly increases the risk of infection and cancer, as well as being very costly. Development of new therapies to minimize or eliminate entirely the need for antirejection drugs is of great interest to the transplant community. Therapeutic cell transfer for the control of the human immune system represents a compelling approach to reduce or eliminate the need for antirejection drugs. Establishment of durable hematopoietic macrochimerism under nonmyeloablative conditioning is achievable in mismatched recipients using facilitating cells and stem cells obtained from donor mobilized peripheral blood mononuclear cells. Persistently chimeric recipients developed donor-specific tolerance and were weaned off of immunosuppressive drugs over 12 months. They maintained stable renal function without development of acute or chronic GVHD.
    No preview · Article · Dec 2014 · Current Opinion in Organ Transplantation
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    ABSTRACT: The cellular immune response is the most important mediator of allograft rejection and is a major barrier to transplant tolerance. Delineation of the depth and breadth of the alloreactive T cell repertoire and subsequent application of the technology to the clinic may improve patient outcomes. As a first step toward this, we have used MLR and high-throughput sequencing to characterize the alloreactive T cell repertoire in healthy adults at baseline and 3 months later. Our results demonstrate that thousands of T cell clones proliferate in MLR, and that the alloreactive repertoire is dominated by relatively high-abundance T cell clones. This clonal make up is consistently reproducible across replicates and across a span of three months. These results indicate that our technology is sensitive and that the alloreactive TCR repertoire is broad and stable over time. We anticipate that application of this approach to track donor-reactive clones may positively impact clinical management of transplant patients.
    Full-text · Article · Nov 2014 · PLoS ONE
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    ABSTRACT: Tacrolimus and sirolimus are commonly used maintenance immunosuppressants in kidney transplantation. As their effects on immune cells and allograft molecular profiles have not been elucidated, we characterized the effects of tacrolimus to sirolimus conversion on the frequency and function of T cells, and on graft molecular profiles. Samples from renal transplant patients in a randomized trial of 18 patients with late sirolimus conversion and 12 on tacrolimus maintenance were utilized. Peripheral blood was collected at 0, 6, 12, and 24 months post randomization, with T-cell subpopulations analyzed by flow cytometry and T-cell alloreactivity tested by IFN-γ ELISPOT. Graft biopsy samples obtained 24 months post randomization were used for gene expression analysis. Sirolimus conversion led to an increase in CD4(+)25(+++)Foxp3(+) regulatory T cells. While tacrolimus-maintained patients showed a decrease in indirect alloreactivity over time post transplant, sirolimus conversion increased indirect alloreactive T-cell frequencies compared with tacrolimus-maintained patients. No histological differences were found in graft biopsies, but molecular profiles showed activation of the antigen presentation, IL-12 signaling, oxidative stress, macrophage-derived production pathways, and increased inflammatory and immune response in sirolimus-converted patients. Thus, chronic immune alterations are induced after sirolimus conversion. Despite the molecular profile being favorable to calcineurin inhibitor-based regimen, there was no impact in renal function over 30 months of follow-up.Kidney International advance online publication, 29 October 2014; doi:10.1038/ki.2014.350.
    Full-text · Article · Oct 2014 · Kidney International
  • Article: OR26

    No preview · Article · Oct 2014
  • Article: P011

    No preview · Article · Oct 2014
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    ABSTRACT: Background: Human leukocyte antigen (HLA)-DQ has emerged as the alloantibody most frequently associated with the generation of de novo donor-specific antibody (DSA), antibody-mediated-rejection, and unfavorable transplantation outcome. Methods: The generation of HLA-DQ de novo DSA was interrogated in 40 transplant recipients who were immunologically naive before their failed transplantation. Eplet and epitope analyses were performed using HLAMatchmaker and Cn3D software. Results: Ten DQA and thirteen DQB eplets or eplet combinations were identified. All but one revealed an epitope footprint that includes both the DQα and DQβ chains. Four examples are illustrated in detail, representing a range of different epitope landscapes. A disparity between antigen density and mean fluorescence intensity values for some alleles within an eplet group was noted, with mean fluorescence intensity values of the lowest fluorescence bead being one tenth of the highest fluorescence bead, despite the fact that the amount of antigen on these beads were not significantly different. Conclusion: Our data support the need for changing the manner in which HLA-DQ antigens and antibodies are evaluated for organ transplantation. The current nomenclature system does not reflect the true nature of HLA-DQ polymorphism. Moreover, epitope immunogenicity likely involves more than the mere presence of a specific eplet. Because our field contemplates the use of epitope matching as an approach to improve organ allocation and overall outcomes, it is imperative to have accurate characterization of the immunogenicity of each epitope. This will pave the way to identifying acceptable mismatches and will allow risk stratification for generating de novo HLA-DSA after transplantation.
    No preview · Article · Jul 2014 · Transplantation
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    ABSTRACT: Recently, The Transplantation Society convened a workshop to address the question, "What do we need to have in place to make tolerance induction protocols a 'standard of care' for organ transplant recipients over the next decade?" In a productive 2-day meeting, there was wide-ranging discussion on a broad series of topics, resulting in five consensus recommendations as follows: (1) establish a registry of results for patients enrolled in tolerance trials; (2) establish standardized protocols for sample collection and storage; (3) establish standardized biomarkers and assays; (4) include children 12 years and older in protocols that have been validated in adults; and (5) establish a task force to engage third-party payers in discussions of how to fund tolerance trials. Future planned workshops will focus on progress in implementing these recommendations and identifying other steps that the community needs to take.
    No preview · Article · Jun 2014 · Transplantation
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    ABSTRACT: Traditionally, chronic calcineurin inhibitor (CNI) nephrotoxicity has been considered to be one of the main nonimmune mechanisms causing chronic renal allograft dysfunction. CNI minimization and withdrawal strategies have yielded inconsistent results. Few studies address the feasibility of CNI elimination in a prednisone-free regimen. We report a prospective, randomized trial in 200 patients evaluating the impact on renal function and incidence of acute rejection after conversion from tacrolimus (Tac) to sirolimus (SRL). Patients with recent (<3 months) acute rejection episodes or with >0.5 g/day of proteinuria were excluded. All were induced with alemtuzumab, underwent rapid steroid elimination and were maintained on mycophenolate mofetil and Tac. At 12 months posttransplant, patients were randomized 2:1 to SRL (n = 123) or maintained on Tac (n = 64). Mean follow-up was 41.1 ± 15.8 months in the SRL group and 40.7 ± 14.4 months in the Tac group. Biopsy-proven acute rejection at 24 months postrandomization was similar between the groups. Patient survival, graft survival and estimated GFR were also not statistically different. Our study demonstrates that in a prednisone-free immunosuppressive regimen, conversion from Tac to SRL at 12 months posttransplantation is not associated with increased rates of acute rejection and graft loss. However, despite CNI elimination, renal allograft function is equally maintained in both groups.
    No preview · Article · Sep 2013 · American Journal of Transplantation
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    ABSTRACT: Panel-reactive antibody (PRA) testing provides assessment of the breadth of sensitization a patient might have against human leukocyte antigen (HLA) antigens. The evolution of calculated PRA (cPRA) reflects the commitment of the transplant community to increase accessibility and promote equity to all patients awaiting kidney transplantation. Recent data from our center and others, however, suggested that a significant diversity of HLA-DQ antigens is not captured, which may lead to inequity in allocating cPRA points. HLA-DRB1-DQA1-DQB1 typing of 2182 individuals was evaluated for this study using Luminex-based sequence-specific oligonucleotide typing. A total of 3182 haplotypes were confirmed to have the level of resolution required for this study. The diversity of HLA-DQαβ alleles is greater than what is apparent using the serologic equivalents. The distribution of these alleles within a serologic group varies, with some alleles being more frequent than others; therefore, their representation within the current cPRA system is inaccurate. Three informative examples are given. Haplotypes of DR antigens with DQαβ alleles did not always follow the common published linkage disequilibrium, especially in populations where there is greater genetic diversity. The current cPRA system does not take into account the distribution of molecular equivalents within DQ serologic specificities. This can result is inequitable allocation of sensitization points and disadvantaging the more sensitized patients. To ameliorate this situation, the United Network for Organ Sharing system should allow inputting HLA-DQαβ alleles both for donor typing and as antibody specificities, which will lead to better representation of unacceptable DQ alleles and improve organ allocation equity.
    Full-text · Article · Aug 2013 · Transplantation
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    ABSTRACT: The ability to achieve immunologic tolerance after transplantation is a therapeutic goal. Here, we report interim results from an ongoing trial of tolerance in HLA-identical sibling renal transplantation. The immunosuppressive regimen included alemtuzumab induction, donor hematopoietic stem cells, tacrolimus/mycophenolate immunosuppression converted to sirolimus, and complete drug withdrawal by 24 months post-transplantation. Recipients were considered tolerant if they had normal biopsies and renal function after an additional 12 months without immunosuppression. Of the 20 recipients enrolled, 10 had at least 36 months of follow-up after transplantation. Five of these 10 recipients had immunosuppression successfully withdrawn for 16-36 months (tolerant), 2 had disease recurrence, and 3 had subclinical rejection in protocol biopsies (nontolerant). Microchimerism disappeared after 1 year, and CD4(+)CD25(high)CD127(-)FOXP3(+) regulatory T cells and CD19(+)IgD/M(+)CD27(-) B cells were increased through 5 years post-transplantation in both tolerant and nontolerant recipients. Immune/inflammatory gene expression pathways in the peripheral blood and urine, however, were differentially downregulated between tolerant and nontolerant recipients. In summary, interim results from this trial of tolerance in HLA-identical renal transplantation suggest that predictive genomic biomarkers, but not immunoregulatory phenotyping, may be able to discriminate tolerant from nontolerant patients.
    No preview · Article · Jun 2013 · Journal of the American Society of Nephrology
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    ABSTRACT: Background: The United Network for Organ Sharing algorithm for deceased-donor kidney allocation considers only the human leukocyte antigen (HLA)-A, HLA-B, and HLA-DR loci. Although HLA-DQ serologic specificities can be entered as unacceptable antigens, they are assigned only by the identity of the DQβ chain, disregarding the role of the similarly polymorphic α chain. DQα/β combinations result in unique antigenic epitopes, which serve as targets to different antibodies. Therefore, the presence of HLA antibodies to one DQα/β combination should not preclude negative crossmatch (XM) against another combination. In this retrospective analysis, patients were allowed XM against a particular donor if they had antibodies to some, but not all, DQα/β allele combinations with the donor serologic HLA-DQ antigens. Methods: HLA antibody signature was obtained using solid-phase Luminex-based antibody analysis. Results were captured at the high-resolution level (as provided by the positive beads). Potential donors were typed to include information on both HLA-DQA and HLA-DQB alleles. Results: Of the 1130 flow XM assays performed, 147 patients had antibodies to donor serologic HLA-DQ antigens. Thirty-five of those patients had antibodies to an allelic DQα/β combination within the donor serologic DQ specificity that were different from the donor's DQα/β, leading to negative flow XM results (24%). Virtual XM, accounting for donor DQα/β combinations, successfully predicts more than 98% of XM outcomes. Conclusions: In patients with allelic DQα/β antibodies, denying the opportunity for XM based on serologically defined unacceptable antigens can disadvantage the patient. Larger cohort studies are required to substantiate our observation. Introducing DQα/β combination information may increase virtual XM accuracy and organ allocation equity.
    No preview · Article · Jan 2013 · Transplantation
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    ABSTRACT: Immunosuppression (IS) withdrawal from calcineurin inhibitors is only possible in ∼20% of liver transplant recipients. However, mammalian target of rapamycin inhibitors (e.g., sirolimus; SRL) appear to be more immunoregulatory and might promote a tolerant state for withdrawal. Our aim was to determine whether systemic (i.e., blood, marrow, and allograft) signatures of immunoregulation are promoted by conversion from tacrolimus (TAC) to SRL. We therefore performed the following serial assays before and after SRL conversion in liver transplant recipients to test for enhanced markers of immunoregulation: (1) flow-cytometry immunophenotyping of peripheral blood mononuclear cells (PBMCs) and bone marrow aspirates for regulatory T cells (Tregs) (e.g., CD4(+) CD25(+++) FOXP3(+) ) and regulatory dendritic cells (DCregs) (immunoglobulin-like transcript 3(+) /4(+) ); (2) liver biopsy immunohistochemical staining (e.g., FOXP3:CD3 and CD4:CD8 ratios) and immunophenotyping of biopsy-derived Tregs after growth in culture; (3) effects of pre- versus postconversion sera on Treg generation in mixed lymphocyte reactions; (4) peripheral blood nonspecific CD4 responses; and (5) peripheral blood gene transcripts and proteomic profiles. We successfully converted 20 nonimmune, nonviremic recipients (age, 57.2 ± 8.0; 3.5 ± 2.1 years post-liver transplantation) from TAC to SRL for renal dysfunction. Our results demonstrated significant increases in Tregs in PBMCs and marrow and DCregs in PBMCs (P < 0.01) after conversion. In biopsy staining, FOXP3:CD3 and CD4:CD8 ratios were significantly higher after conversion and a number of biopsy cultures developed new or higher FOXP3(+) cell growth. Nonspecific CD4 responses did not change. Both pre- and postconversion sera inhibited mixed lymphocyte reactions, although only TAC sera suppressed Treg generation. Finally, 289 novel genes and 22 proteins, several important in immunoregulatory pathways, were expressed after conversion. Conclusions: TAC to SRL conversion increases systemic Tregs, DCregs, and immunoregulatory proteogenomic signatures in liver transplant recipients and may therefore facilitate IS minimization or withdrawal. (HEPATOLOGY 2012).
    Full-text · Article · Jan 2013 · Hepatology
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    ABSTRACT: In this chapter, we describe studies on non-chimeric human leukocyte antigen (HLA) identical tolerance and chimeric HLA disparate tolerance brought about by infusions of hematopoietic stem cells from the renal donor (DHSC). In our HLA identical series, 4 DHSC infusions were administered during the first 9 months posttransplant in a highly immunoregulatory environment using alemtuzumab induction and rapid conversion from early tacrolimus to mycophenolate and sirolimus. This resulted in the generation of recipient T regulatory cells accompanied by genomic indicators, but only transient chimerism. Seven of the first 12 recipients have been immunosuppression-free between 1 1/2 - 4 years with transplant biopsies free of rejection one year after immunosuppression withdrawal. The HLAdisparate group was treated by non-myeloablative conditioning consisting of: 200cGy whole body irradiation; fludarabine; cyclophosphamide; and, perioperative infusion of a product termed FCRx that contained DHSC, T cells, and a unique fraction of bone marrow derived CD8+TCR-alphabeta-negative cells. Five of the first 8 subjects became 100% chimeric in the peripheral blood and have been immunosuppression-free for 2 to 4 years without graft-versus-host-disease and with normal function and transplant biopsies. An additional 12 recipients with shorter follow-up have had similar courses. Those with non-durable chimerism have not been able to have immunosuppression withdrawn but maintain normal renal transplant function. We conclude that non-HLA disparities in renal transplants between HLA identical pairs may not need durable chimerism to induce tolerance provided by DHSC and temporary immunosuppression supporting the development of regulatory T cells. However, more intense conditioning and infusion of FCRx leading to durable chimerism in the absence of graft versus host disease is necessary to induce tolerance in HLA disparate pairs.
    No preview · Article · Jan 2013 · Clinical transplants
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    ABSTRACT: Background: We recently reported that durable chimerism can be safely established in mismatched kidney recipients through nonmyeloablative conditioning followed by infusion of a facilitating cell (FC)-based hematopoietic stem cell transplantation termed FCRx. Here we provide intermediate-term follow-up on this phase II trial. Methods: Fifteen human leukocyte antigen-mismatched living donor renal transplant recipients underwent low-intensity conditioning (fludarabine, cyclophosphamide, 200 cGy TBI), received a living donor kidney transplant on day 0, then infusion of cryopreserved FCRx on day +1. Maintenance immunosuppression, consisting of tacrolimus and mycophenolate, was weaned over 1 year. Results: All but one patient demonstrated peripheral blood macrochimerism after transplantation. Engraftment failure occurred in a highly sensitized (panel reactive antibody [PRA] of 52%) recipient. Chimerism was lost in three patients at 2, 3, and 6 months after transplantation. Two of these subjects had received either a reduced cell dose or incomplete conditioning; the other two had PRA greater than 20%. All demonstrated donor-specific hyporesponsiveness and were weaned from full-dose immunosuppression. Complete immunosuppression withdrawal at 1 year after transplantation was successful in all patients with durable chimerism. There has been no graft-versus-host disease or engraftment syndrome. Renal transplantation loss occurred in one patient who developed sepsis following an atypical viral infection. Two subjects with only transient chimerism demonstrated subclinical rejection on protocol biopsy despite donor-specific hyporesponsiveness. Conclusions: Low-intensity conditioning plus FCRx safely achieved durable chimerism in mismatched allograft recipients. Sensitization represents an obstacle to successful induction of chimerism. Sustained T-cell chimerism is a more robust biomarker of tolerance than donor-specific hyporeactivity.
    No preview · Article · Dec 2012 · Transplantation

Publication Stats

3k Citations
579.17 Total Impact Points


  • 2007-2016
    • Northwestern Memorial Hospital
      Chicago, Illinois, United States
  • 2015
    • University of Louisville
      Louisville, Kentucky, United States
  • 1999-2015
    • Northwestern University
      • • Department of Surgery
      • • Division of Organ Transplantation
      Evanston, Illinois, United States
    • University of Illinois at Chicago
      Chicago, Illinois, United States
  • 2006
    • Duke University
      Durham, North Carolina, United States
  • 2005
    • The University of Chicago Medical Center
      • Department of Surgery
      Chicago, Illinois, United States
  • 2004
    • Dalhousie University
      • Department of Biology
      Halifax, Nova Scotia, Canada
  • 2000
    • University of Texas at Dallas
      Richardson, Texas, United States
  • 1992-1996
    • University of Minnesota Duluth
      • Laboratory Medicine and Pathology
      Duluth, Minnesota, United States
  • 1993
    • American Heart Association
      Dallas, Texas, United States