TLR3(Toll-like receptor 3) also known as CD283 (cluster of differentiation 283) is a protein that in humans is encoded by the TLR3 gene. mapped the TLR3 gene is mapped to chromosome 4q35 by fluorescence in situ hybridization. TLR3 is a member of the Toll-like receptor family of pattern recognition receptors of the innate immune system. TLRs are highly conserved from Drosophila to humans and share structural and functional similarities. They recognize pathogen-associated molecular patterns (PAMPs) that 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. This receptor is most abundantly expressed in placenta and pancreas, and is restricted to the dendritic subpopulation of the leukocytes. It recognizes dsRNA associated with viral infection, and induces the activation of NF-κB and the production of type I interferons. It may thus play a role in host defense against viruses. TLR3 recognizes double-stranded RNA, a form of genetic information carried by some viruses such as retroviruses. Upon recognition, TLR 3 induces the activation of NF-κB to increase production of type I interferons which signal other cells to increase their antiviral defenses. Double-stranded RNA is also recognised by the cytoplasmic receptors RIG-I and MDA-5. TLR3 displays a protective role in mouse models of atherosclerosis.[4] In addition, TLR3 activators show effects on human vascular cells.