Effect of biologic agents on regulatory T cells.

The balance between effector T cells and regulatory T cells (Tregs) is central to transplant tolerance. Therefore, the impact of immunosuppressive therapies on their fate is a major determinant of long-term allograft outcome. The biologic agents are new molecules that show promise as more selective therapies with less adverse effects. Because they target mostly surface markers or costimulatory pathways of lymphocytes, it is of critical importance to evaluate their effect on both effector T cells and Tregs. The present review provides a brief summary of Tregs physiology and then discusses actual knowledge on the impact of the biologic agents on the frequency of Tregs as well as their function in vitro and in vivo in humans.