title: Lentivirally Transduced Recipient-derived Dendritic Cells Serve to Ex Vivo Expand Functional FcRγ-sufficient Double-negative Regulatory T Cells.
abstract: αβTCR+CD4-CD8-double-negative (DN) T regulatory (Treg) cells have recently been shown to suppress antigen-specific immune responses mediated by CD8+and CD4+T cells in mice and humans. In this study, we developed a system to expand DN Treg cells for transplantation therapy that exclusively uses recipient-derived immune cells and confers a high degree of safety as the protocol does not involve the direct injection of lentiviral vectors. Recipient-derived dendritic cells (DCs) were transduced with lentiviral vectors that express major histocompatibility complex class I Ldantigen (LV-Ld), which is expressed by the donor graft but is allogeneic to the graft recipient. LV-Ld-transduced mature DCs (mDCs) were able to expand effectively both FcRγ-/-and FcRγ+/+DN T cells. After expansion with LV-Ld-transduced mDCs, only the FcRγ+/+DN Treg cells maintained their ability to suppress CD8+T cells in vitro. In addition, adoptive transfer of the FcRγ+/+ex vivo expanded DN Treg cells significantly prolonged the survival of Ld+skin grafts. This study is the first description of successful ex vivo expansion of antigen-specific DN Treg cells using genetically modified syngeneic DCs for adoptive immunotherapy and demonstrates that although FcRγ-/-DN T cells can be expanded, they do not gain regulatory ability.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Multi Organ Transplantation Program, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Thomson
authors.affiliation: Division of Stem Cell and Developmental Biology, Department of Medical Biophysics, Ontario Cancer Institute and the Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Miriam E
authors.initials: ME
authors.lastname: Mossoba
authors.affiliation: Division of Stem Cell and Developmental Biology, Department of Medical Biophysics, Ontario Cancer Institute and the Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Siatskas
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Multi Organ Transplantation Program, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Wenhao
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Multi Organ Transplantation Program, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: April
authors.initials: A
authors.lastname: Sung
authors.affiliation: Division of Stem Cell and Developmental Biology, Department of Medical Biophysics, Ontario Cancer Institute and the Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Medin
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Multi Organ Transplantation Program, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Immunology, University of Toronto, Toronto, Ontario, Canada. Electronic address: lzhang@transplantunit.org.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang