Beschreibung:
<jats:title>Summary</jats:title><jats:p>Research on CD4<jats:sup>+</jats:sup> CD25<jats:sup>+</jats:sup> regulatory T cells (Treg) has gathered momentum over the last five years but many aspects of their fundamental biology remain elusive. Treg have been considered to be ‘naturally anergic’ based on their failure to proliferate in response to T‐cell receptor ligation <jats:italic>in vitro</jats:italic>. Several recent studies challenge this view and demonstrate a robust proliferative capacity for CD25<jats:sup>+</jats:sup> cells. The significance of this finding for Treg homeostasis and function is considered below.</jats:p>