Minimal but essential doses of immunosuppression: a more realistic approach to improve long-term outcomes for pediatric living-donor liver transplantation.

1 Department of Surgery; Graduate School of Medicine; Kyoto University; Kyoto, Japan (Ohe, Nafady-Hego, Uemoto, Koshiba) 2 Department of Experimental Pathology; Institute for Frontier Medical Science; Kyoto University; Kyoto, Japan (Li, Sakaguchi) 3 Department of Ubiquitous Health Informatics; Graduate school of Medicine; The University of Tokyo; Tokyo, Japan (Kayo) 4 Transplantation Research Immunology Group; Nuffield Department of Surgery; University of Oxford; John Radcliffe Hospital; Headington, Oxford, United Kingdom (Wood) 5 Department of Surgery & Medicine; University of Cambridge; United Kingdom and National University of Singapore, Singapore (Calne).
Transplantation (Impact Factor: 3.78). 04/2011; 91(7):808-10. DOI: 10.1097/TP.0b013e31820f07de
Source: PubMed
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    ABSTRACT: BACKGROUND: T-cell receptor Vδ2 γδ T cells (Vδ2 cells) participate in host defense, whereas Vδ1 γδ T cells (Vδ1 cells) may regulate immune responses. Vδ1 cells appear to play a role in fetomaternal tolerance and our aim was to examine their role in liver transplant tolerance. METHODS: To determine whether Vδ1 cells increase within accepted grafts after semiallogeneic pediatric liver transplantation, the Vδ1/Vδ2 ratio was assessed at the transcriptional level and the complementarity-determining region 3 loop of the δ chain of Vδ1 cells was sequenced in biopsies from immunosuppression-free (n=6) or almost free (n=3) liver transplant recipients, referred to as group tolerance (Gr-Tol; n=9). The results were compared with biopsies from grafts of recipients on maintenance immunosuppression due to concern of rejection (Gr-IS; n=11). Chronically rejected grafts (Gr-CR; n=6) and normal livers (Gr-NL; n=8) were also examined. RESULTS: The Vδ1/Vδ2 ratio was the highest in Gr-Tol (0.07±0.06) compared with Gr-IS (0.03±0.02; P=0.04), Gr-CR (0.01±0.02; P=0.008), and Gr-NL (0.02±0.04; P=0.01). There was an identical complementarity-determining region 3 sequence (100% homologous) among all recipients in Gr-Tol, which was dominant in six of nine recipients. This sequence was not seen in Gr-IS or Gr-CR, although it was observed in five of six normal livers. CONCLUSIONS: A unique Vδ1-bearing T-cell clone accumulates within accepted human liver grafts. It might be useful as a biomarker of tolerance and the identification of its ligand might aid in the development of a novel strategy for tolerance induction.
    Transplantation 12/2012; · 3.78 Impact Factor
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    ABSTRACT: To outline the rationale of powerful depleting induction therapy with alemtuzumab and minimal maintenance immunosuppression after organ transplantation. The original observations in principle have been confirmed by many independent centres. Follow-up of the 'prope tolerance' protocol has confirmed a low incidence of rejection, infection and post transplant lymphoproliferative disorder (PTLD). Especially, encouraging results were obtained in African-Americans. There were few side effects and the regimen was well tolerated by patients. Treg cells were observed in the circulation, which could be an important factor in the mechanisms of graft acceptance using a prope tolerance regimen. There was a considerable reduction in the costs of the transplantation procedure. It is suggested that this minimalisation of maintenance immunosuppression is the best therapy currently available that we can offer to our patients.
    Current opinion in organ transplantation 06/2011; 16(4):353-8. · 3.27 Impact Factor
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    ABSTRACT: Obstacles to morbidity-free long-term survival after liver transplantation (LT) include complications of immunosuppression (IS), recurrence of the original disease and malignancies, and unexplained chronic hepatitis and graft fibrosis. Many programs attempt to minimize chronic exposure to IS by reducing dosages and stopping steroids. A few programs have successfully weaned a highly select group of recipients from all IS without apparent adverse consequences, but long-term follow-up is limited. Patients subjected to adjustments in IS are usually followed by serial liver chemistry tests, which are relatively insensitive methods for detecting allograft damage. Protocol biopsy has largely been abandoned for hepatitis C virus-negative recipients, at least in part because of the inability to integrate routine histopathological findings into a rational clinical management algorithm. Recognizing a need to more precisely categorize and determine the clinical significance of findings in long-term biopsy samples, the Banff Working Group on Liver Allograft Pathology has reviewed the literature, pooled the experience of its members, and proposed working definitions for biopsy changes that (1) are conducive to lowering IS and are compatible with operational tolerance (OT) and (2) raise concern for closer follow-up and perhaps increased IS during or after IS weaning. The establishment of guidelines should help us to standardize analyses of the effects of various treatments and/or weaning protocols and more rigorously categorize patients who are assumed to show OT. Long-term follow-up using standardized criteria will help us to determine the consequences of lowering IS and to define and determine the incidence and robustness of OT in liver allografts. Liver Transpl 18:1154-1170, 2012. © 2012 AASLD.
    Liver Transplantation 05/2012; 18(10):1154-70. · 3.94 Impact Factor