Critical roles of Toll-like receptors in host defense

Crit Rev Immunol. 2000;20(5):393-405.


Drosophila Toll is involved not only in dorsoventral patterning of embryos but also in immune responses to microbial infection. Several Toll-like receptors (TLRs) have also been identified in mammals. They are expressed on macrophages or dendritic cells (DCs), which are essential sentinels for innate immunity. These cells utilize TLRs as a recognition and signal transducing receptor for microbial molecular components. The most characterized mammalian TLR, TLR4, is a receptor for lipopolysaccharides (LPS). TLR2 recognizes other components, such as peptideglycans (PGN). This recognition, called pattern recognition, is essential for the establishment of innate immunity, which is the basis for host defense. In this article, we review recent findings about this expanding receptor family.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Infections / immunology*
  • Drosophila Proteins*
  • Humans
  • Immunity, Innate / genetics
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / physiology*
  • Molecular Sequence Data
  • Multigene Family / immunology
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / physiology*
  • Sequence Homology, Amino Acid
  • Signal Transduction / immunology
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptors


  • Drosophila Proteins
  • Membrane Glycoproteins
  • Receptors, Cell Surface
  • TLR2 protein, human
  • TLR4 protein, human
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptors