Pentraxins are a complex superfamily of multifunctional molecules characterized by a multimeric structure. C-reactive protein and pentraxin 3 (PTX3) are prototypic molecules of the short and long pentraxin family, respectively. PTX3 is conserved in evolution and produced by innate immune cells. Evidence suggests that PTX3 acts as a non-redundant component of the humoral arm of innate immunity, downstream of, and complementary to, cellular recognition, as well as a tuner of inflammation.