Pentraxin 2 (PTX2), also known as Serum amyloid P (SAP), is a highly conserved, naturally circulating plasma protein and a soluble pattern recognition receptor of the innate immune system. The unique binding activities indicated that it may play an important role in the removal of damaged tissue. PTX2 belongs to the pentraxin family, is universally present in amyloid deposits. Mouse with targeted deletion of the PTX2 gene shows retarded and reduced induction of experimental reactive systemic (AA type) amyloidosis confirmed that it does indeed contribute to pathogenesis of amyloidosis and is a valid therapeutic target. In recent discovery, PTX2 can be used as a powerful antifibrotic agent to regulate certain monocyte differentiation states.