Regulatory CD4⁺CD25⁺ T cells and macrophages: Communication between two regulators of effector T cells

Regulatory T cells (Tregs) play an essential role in the induction and maintenance of peripheral tolerance as well as prevention of autoimmunity by limiting the strength of the immune response of effector T cells. Macrophages, a heterogeneous population of phagocytes and professional antigen presenting cells (APCs), can also exert suppressive effects on effector T cells to keep the peripheral balance of immunity. The bi-directional interactions of dendritic cells (DCs) and Tregs have been cell studied. However, much less is known about the reciprocal interaction between macrophages and Tregs. In this review, we will discuss recent observations regarding the interplay of these two regulators of immunity.