Pentraxins in the activation and regulation of innate immunity

Summary Humoral fluid phase pattern recognition molecules ( PRM s) are a key component of the activation and regulation of innate immunity. Humoral PRM s are diverse. We focused on the long pentraxin PTX 3 as a paradigmatic example of fluid phase PRM s. PTX 3 acts as a functional ancestor of antibodies and plays a non‐redundant role in resistance against selected microbes in mouse and man and in the regulation of inflammation. This molecule interacts with complement components, thus modulating complement activation. In particular, PTX 3 regulates complement‐driven macrophage‐mediated tumor progression, acting as an extrinsic oncosuppressor in preclinical models and selected human tumors. Evidence collected over the years suggests that PTX 3 is a biomarker and potential therapeutic agent in humans, and pave the way to translation of this molecule into the clinic.