Induction of tolerogenic DCs: ‘you are what you eat’

Dendritic cells (DCs) take up antigens using antigen receptors that can be divided into three major classes: C-type lectins, integrins and Fc receptors. These receptors facilitate effective presentation of MHC–peptide complexes to T cells, resulting in the induction of immune responses. However, we discuss recent evidence that some receptors also cause induction of tolerance. Signaling motifs within the receptors either block maturation of DCs or induce signals that render DCs tolerogenic. These DCs then either induce regulatory T cells or cause deletion of effector T cells, resulting in the induction of tolerance. Antigen receptors expressed by DCs might therefore have an important role in the induction and maintenance of peripheral tolerance.