raku pinnaretseptorid (eeskätt dendriitrakkudel, fagotsüütidel), mis eristavad mikroorganismidele iseloomulikke molekule, Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are single, membrane-spanning, non-catalytic receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes.