This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'The primary function of Toll-like Receptors is? \nSelect and explain. \nA. Activation of Immune System, B. Vasodilation, C. Regulation of Calcium channel, D. Second Messenger', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In the late 1990s and early 2000s, researchers identified mammalian analogs of the Drosophila Toll\xa0receptor, cloned the mammalian Toll-like receptor 4 (TLR4), identified TLR4 as the receptor for lipopolysaccharide (LPS) and the membrane transducer for LPS signaling in mononuclear phagocytes\xa0and other cells, and identified other TLRs as receptors for other microbial components.\nCD 14 binds bacterial LPS (endotoxin) and, as a component of a multimolecular complex, plays an\xa0important role in LPS-induced activation, inflammatory response, and innate immunity. LPS is captured by a serum LPS-binding protein and is transported to CD14, which binds the complex.\xa0CD14, however, cannot trigger activation because it lacks an intracellular region.\xa0This function is mediated by one of a group of molecules known as Toll-like receptors (TLR), as they are structurally\xa0homologous to the Toll receptors of the fruit fly Drosophila melanogaster.', 'role': 'assistant'}]