Influence of Toll-Like-Receptor Ligands on the Dendritic Cell - T Cell Interactions: Therapeutic Options for Allergic Diseases? Mini-Review

Dendritic cells (DC) exert important functions both in the induction of protective T cell immunity, as well as in the induction of tolerance. The latter is essential in protection against the development of allergy. Exposure to pathogenassociated molecular patterns (PAMPs), that signal through different Toll-like receptor (TLR)s, modulates production by DC of several Interleukin(IL)-12 family members: IL-12p70, IL-23, IL-27 and IL-35. The production of those cytokines in turn differentially influences both T cell differentiation and effector T cell activation. We focus in this review on myeloid and plasmacytoid DC and their role in development of allergic diseases. In particular, we focus on differences in DC activation between healthy and allergic individuals. Furthermore we discuss the activation of DC by TLR-ligands and their differential cytokine induction. Finally, we discuss preclinical studies and potentially therapeutic options using TLRligands for allergic diseases.