Regulatory T cells, derived from naive CD4+ CD25- T cells by in vitro foxp3 gene transfer, can induce transplantation tolerance

Background. Regulatory T (Treg) cells, generated in vitro by Foxp3 gene transfer into naive CD4(+)25(-) T cells, have been shown to inhibit the development of inflammation and autoimmune disease, but it is not known whether they are able to prevent allograft rejection. This study investigated whether Treg cells generated from naive CD4(+) T cells by Foxp3 gene transfer could induce transplantation tolerance. Methods. HY-specific, T-cell receptor (TCR) -transgenic CD4(+)25(-) T cells were retrovirally transduced with the Foxp3 gene. The phenotype, function, and cytokine profiles of the transduced cells were examined in vitro by fluorescence-activated cell sorter, T-cell proliferation assays, enzyme-linked immunosorbent assay, and intracellular cytokine staining. Adoptive transfer and skin grafting experiments were conducted to assess whether Foxp3-transduced HY-specific T cells could prevent the rejection of syngeneic male grafts. Results. CD4(+)25(-) T cells retrovirally transduced with Foxp3 express a panel of cell surface and intracellular molecules closely associated with Treg activity. This Treg phenotype was stable during in vitro culture with some further maturation. In vitro, Foxp3-transduced cells were functionally anergic and suppressive T cells. In vivo adoptive transfer of Foxp3-transduced HY-specific TCR-transgenic CD4(+) T cells protected male skin grafts from rejection by syngeneic females. Retroviral transduction of the Foxp3 gene into non-TCR-transgenic CD4(+)25(-) T cells, however, had no influence on male skin graft rejection. Conclusion. This study provides the first evidence that Foxp3-transduced T cells can control the rejection of an allogeneic transplant and suggests that T-cell Foxp3 gene transfer may have therapeutic value in clinical transplantation.