Tolerogenic dendritic cells: key regulators of peripheral tolerance in health and disease.

Dendritic cells (DCs) as professional antigen-presenting cells are able to induce immunity and tolerance in different conditions, which leads to strong immune responses against hostile agents or tolerance to self-antigens. Although for subsets of DCs, a regulatory function has been shown, the role of the microenvironment is momentous to generate tolerogenic DCs (tDCs). Different microorganisms and tumor cells escape from immune responses by producing mediators and components that influence DCs to show tolerogenic characteristics. In this review, tDC induction was explained in steady state and disease conditions. Moreover, an overview was presented on the efforts to generate in vitro tDCs, their clinical applications and the problems which remain to be solved in this field.