Regulatory Dendritic Cell (DCreg) Cell Infusion in Living Donor Liver Transplantation

    loading  Checking for direct PDF access through Ovid


BackgroundBased on strong preclinical data showing that regulatory dendritic cells (DCreg) of donor origin can promote long-term graft survival in rodents and suppress allograft rejection in non-human primates, we have embarked on a first-in-human phase I/II safety and preliminary efficacy trial of donor-derived DCreg in living donor liver transplantation (LTx).MethodsIn the study protocol, DCreg are generated from elutriated monocytes isolated from the leukapheresed donor,14-28 days (d) before transplant. The donor-derived DCreg are infused iv (target range 2.5-10.106/kg) 7 d before transplant (d −7), while a half dose of MPA is administered from d −7 to d 0. Standard-of-care immunosuppression (steroid, MPA, tacrolimus) is administered post-LTx, and in those patients that meet eligibility criteria for weaning, immunosuppressive therapy is gradually withdrawn, starting with MPA reduction 6 mths post-LTx. Sequential immunological analyses are conducted on recipient blood and tissue samples to track the donor-derived DCreg, evaluate anti-donor reactivity and examine potential mechanisms of immune hyporesponsiveness. In the first LTx recipient (HLA-B12+) to receive donor-derived (HLA-A3+) DCreg, peripheral blood samples were obtained before and after cell infusion; native liver tissue was obtained at the time of graft implantation.ResultsDonor-derived DCreg generated for infusion were HLA-DR+, CD1c, CD11c+, CD83, IRF4lo and expressed a high programed death ligand-1 (PD-L1):CD86 ratio. In parallel small scale in vitro functional analyses, the DCreg failed to respond to LPS, and induced donor-specific hyporesponsiveness of recipient CD4 and CD8 T cells. The donor-derived DCreg (HLA-A3+) displaying a similar phenotype to that exhibited pre-infusion, were detected in whole blood immediately after completion of the cell infusion that comprised 5.106 DCreg/kg (450.106 total DCreg). No infusion reaction or cytokine release response was observed. Three days post-infusion (d −4), HLA-A3+ donor-derived DC could no longer be detected in blood, although a small population of DC co-expressing both recipient (HLA-B12) and donor MHC (HLA-A3), ie cross-dressed DC, were evident in the circulation. At the time of transplant, before graft implantation, cross-dressed (HLA-A3+B12+) DC could also be detected in non-parenchymal cell populations isolated from the diseased native liver. Using a 14-color panel of mAbs, these tissue-resident cross-dressed DC were PD-L1hi, IRF4lo and Foxp3hiConclusionsAfter safe infusion of donor-derived DCreg into a prospective living donor LTx recipient, cross-dressed DC were detected in the peripheral blood within a few days and in the native diseased liver at the time of graft implantation. These cross-dressed DC, that appear to have acquired donor MHC from the infused DCreg, exhibit low levels of the DC transcription/maturation factor IRF4 and high levels of PD-L1 and Foxp3, suggesting possible in vivo regulatory function.

    loading  Loading Related Articles