[Toll-like receptors: recognition receptors of the innate immune system and target structures for therapeutical intervention].

Toll-like receptors (TLR) are pattern recognition receptors of the innate immune system that recognize microbial ligands preferentially derived from bacteria and viruses. Activation of TLR results in an immediate pro-inflammatory response of the innate immune system. TLR located on the cell surface recognize bacterial cell wall components, while intracellular TLR recognize viral or bacterial nucleic acids. Due to their stimulatory activity, TLR ligands can act as adjuvants for vaccine development but are also used for local immunotherapy of certain types of skin lesions. On the other hand, TLR ligand antagonists are under development as an approach to dampen excessive innate immune responses.