背景资料:TLR7 belongs to the Toll-like receptor (TLR) family that plays a fundamental role in pathogen recognition and activation of innate immunity. TLRs are highly conserved from Drosophila to humans and share structural and functional similarities. TLRs recognize pathogen-associated molecular patterns (PAMPs) which are expressed on infectious agents, and mediate the production of cytokines necessary for the development of effective immunity. The various TLRs exhibit different patterns of expression. TLR7 is principally expressed in lung, placenta, and spleen, and lies in close proximity to TLR8, on chromosome X.