Stability of the Regulatory T Cell Lineage in Vivo

Self-Renewing T Cells The homeostasis of cell populations within an organism can be achieved through a variety of mechanisms, including the differentiation of precursor populations, self-renewal of terminally differentiated cells, or by programming cells to be extremely long-lived. Regulatory T cells that express the transcription factor Foxp3 are critical for maintaining immune tolerance by preventing excessive inflammation and autoimmunity. Rubtsov et al. (p. 1667 ) now use genetic fate mapping and cell transfer studies in vivo to demonstrate that Foxp3-expressing cells are remarkably stable under both basal and inflammatory conditions. Thus, regulatory T cells appear to be maintained through self-renewal and should maintain their identity if used in adoptive cell therapies for treatment of autoimmunity or other inflammatory disorders.