Polyinosinic-polycytidylic acid [Poly(I:C)] Endotoxin-free (sterile), AdipoGen Life Sciences. Chemical. CAS: 31852-29-6. MW: High molecular weight (>1.5kb). Toll-like receptor (TLR) 3 is an endosomal TLR that mediates immune responses against viral infections upon activation by its ligand double-stranded RNA, a replication intermediate of most viruses. TLR3 is expressed widely in the body and activates both the innate and adaptive immune systems. Toll-like receptor 3 (TLR3), melanoma differentiation-associated gene 5 (MDA5), and retinoic acid-inducible gene-I (RIG-I), all sensors of double-stranded RNA (dsRNA) are potent inducers of antiviral activity. Recently, poly (I:C)-induced cell death recently gained considerable attention as a tool to study the 'Ripoptosome' or 'Necrosome' complex, a novel intracellular signaling complex, thought to induce regulated necrosis, also called 'Necroptosis'.