Toll-like receptors (TLRs) play a fundamental role in the induction of immune responses. They are richly represented in these places the body, which are a potential gateway infection. The locations of these TLRs, mainly present on antigen presenting cells (APC) and certain non-immune cells, especially epithelial cells, are able to recognize molecular patterns (PAMP) infiltrating the local pathogens and initiate the defensive response. TLRs are therefore an important component of the innate response.