Advances in immune regulation in transplantation.

In the last three decades, we have observed a substantial progress in the organ and cell transplantation. New immune suppressive agents including calcineurin blockers and mTOR inhibitors improved transplantation outcome, but two key problems -- rejection of transplanted organs and graft versus host disease (GVHD) -- continue to be main obstacles after transplantation. Immune response is regulated with coordination of a varying number of cells. T regulatory cells orchestrate other cell responses and eventually limit immune activation and induce immune tolerance. Stimulation of negative costimulatory molecules and adoptive transfer of immunosuppressive cells including regulatory cells are promising therapies that would improve outcome of patients with organ or cell transplantation.