Sensing the hybrid - A novel PAMP for TLR9

Abstract

The host immune response is initiated by pattern recognition receptors (PRR) when triggered by specific ligands known as pathogen-associated molecular patterns (PAMP). Toll-like receptor 9 is highly expressed in plasmacytoid dendritic cells and is well described as a PRR for CpG DNA which induce the production of cytokines and type I interferons. In this issue of The EMBO Journal, Rigby et al identify RNA-DNA hybrids as a novel PAMP specifically recognized by TLR9 in dendritic cells. RNA:DNA hybrids represent a new type of pathogen-associated molecular pattern, which signals via TLR9 to regulate cytokine and IFN responses in dendritic cells. © 2014 The Authors.