The immune system protects the host from invading pathogens, is involved in tumor defense and initiates repair mechanisms upon tissue damage. Innate immune cells express germ-line encoded signaling receptors that can sense microbial products or altered or misplaced self molecules.

Several classes of innate immune signaling receptors have been identified. Toll-like receptors (TLRs) are transmembrane signaling receptors that recognize extracellular microbial products as well as ligands derived from host molecules. Nod-like receptors (NLRs) are intracellular signaling molecules of which some can form multimolecular  signalosome complexes termed inflammasomes. Another intracellular receptor family are the Rig-I like receptors (RLRs) which can recognize nucleic acids in the cytosol of cells. The C-type lectin receptors (CLRs) are carbohydrate binding transmembrane receptors that function in the recognition of glycosylated of host molecules or invading pathogens. In addition to these receptor families, a host of other receptors contribute to innate immune cell function.

 

 

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