Toll-like receptors.

The mammalian Toll-like receptor (TLR) family consists of 13 members, and recognizes specific patterns of microbial components, called pathogen-associated molecular patterns (PAMPs). TLR-dependent recognition of PAMPs leads to activation of the innate immune system, which subsequently leads to activation of antigen-specific adaptive immunity. The TLR-mediated signaling pathways consist of the MyD88-dependent pathway and TRIF-dependent pathway, both of which induce gene expression. This unit discusses mammalian TLRs (TLR1 to 13) that have an essential role in the innate immune recognition of microorganisms. Also discussed are TLR-mediated signaling pathways and antibodies that are available to detect specific TLRs.