Members of the Toll-like receptor (TLR) family, named for the closely related Toll receptor in Drosophila, play a pivotal role in innate immune responses. TLRs recognize conserved motifs found in various pathogens and mediate defense responses. TLR7, 8 and 9 form a group of structurally related TLR family members that are localized to intracellular endosomes . TLR7 shows highest expression in lung, placenta, and spleen. TLR7 mediates responses to a class of synthetic compounds, including imidazoquinolines, guanosine-based drugs that induce anti-viral responses.
