Donor-strain-derived immature dendritic cell pre-treatment induced hyporesponsiveness against allogeneic antigens

The maturation of antigen-presenting dendritic cells (DCs) serves as an important determinant for the regulation of immunity, and overall immune response. We hypothesized that a reduced immune response to donor alloantigens and improved allograft survival could be induced by pre-treating recipients with bone-marrow-derived donor-strain fixed immature DCs (FIDCs). Donor-strain-derived mature and immature DCs were fixed before grafting to ensure that they possessed a stable immunogenic phenotype. The fixed mature DCs effectively induced allogeneic T-cell proliferation in recipients, whereas FIDCs were unable to elicit an allogeneic T-cell response. T cells that had previously been exposed to FIDCs maintained naïve phenotypes and were unable to extensively divide after injection into lethally irradiated donor-strain mice. The pre-treatment of recipients with donor-strain FIDCs markedly prolonged the survival of islet as well as skin allografts. However, T-cell hyporesponsiveness induced by FIDC injection was abrogated by the depletion of CD4(+) CD25(+) T cells. Consequently, FIDC-induced T-cell hyporesponsiveness could reflect anergy rather than specific deletion. Our findings suggest that FIDCs of donor strain could be used to induce long-term graft survival.