The Foxp3+ regulatory T cell: a jack of all trades, master of regulation

Abstract

The function of regulatory T cells (T(reg) cells) has been attributed to a growing number of diverse pathways, molecules and processes. Seemingly contradictory conclusions regarding the mechanisms underlying T(reg) cell suppressive activity have revitalized skeptics in the field who challenge the core validity of the idea of T(reg) cells as central immune regulators. However, we note that a consensus may be emerging from the data: that multiple T(reg) cell functions act either directly or indirectly at the site of antigen presentation to create a regulatory milieu that promotes bystander suppression and infectious tolerance. Thus, the versatility and adaptability of the Foxp3+ T(reg) cells may in fact be the best argument that these cells are 'multitalented masters of immune regulation'.

Figures

Figure 1

A three-tiered model of the functions of Treg cells in maintaining normal immune homeostasis. This model shows mechanisms potentially used by Treg cells for homeostatic control in the steady state, during ‘damage control’ at the site of inflammation and for infectious tolerance after the resolution of an immune response. aTreg, adaptive Treg cell; TGF- βR, TGF-β receptor; nTreg, natural Treg cell; CO, carbon monoxide; IFN-γR, IFN-γ receptor.