Toll-like receptors and innate immunity

J Mol Med (Berl). 2006 Sep;84(9):712-25. doi: 10.1007/s00109-006-0084-y.


The innate immune system is an evolutionally conserved host defense mechanism against pathogens. Innate immune responses are initiated by pattern recognition receptors (PRRs), which recognize specific structures of microorganisms. Among them, Toll-like receptors (TLRs) are capable of sensing organisms ranging from bacteria to fungi, protozoa, and viruses, and play a major role in innate immunity. However, TLRs recognize pathogens either on the cell surface or in the lysosome/endosome compartment. Recently, cytoplasmic PRRs have been identified to detect pathogens that have invaded cytosols. In this review, we focus on the functions of PRRs in innate immunity and their downstream signaling cascades.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Antiviral Agents
  • Humans
  • Immunity, Innate / immunology*
  • RNA Helicases / metabolism
  • Signal Transduction
  • Toll-Like Receptors / immunology*


  • Antiviral Agents
  • Toll-Like Receptors
  • RNA Helicases