The highly conserved family of pentraxins (—short pentraxinsic, CRP and SAP) consists of approximately 25 000 (mW)proteins. Recently, several distinct larger proteins expressed in the brain and other tissues have been identified. PTX3 was the first cloned member of the long pentraxin family. From 1993, other —long pentraxinsis were identified, including NPR, XL-PXN1 from Xenopus laevis, rat and human neuronal pentraxin NP1, neuronal pentraxin NP2, which possibly represents the human homologue of guinea pig pentraxin apexin, and rat pentraxin Narp. In all these molecules a C-terminal pentraxin domain is clearly related to serum pentraxins, the N-terminal domain shows no strong homology to other known proteins. Long pentraxins exhibit structural and functional similarities as well as differences when compared with the classical pentraxins. Long pentraxins do not have the restricted liver inducibility typical of CRP and SAP (upon interleukin-6 stimulation) and show a more premiscuous pattern of expression in vitro and in vivo. PTX3 is inducible by TNF or IL-1 and is produced during the acute phase response. Other newly identified long pentraxins are constitutively expressed proteins. The function of long pentraxins is unknown. They may play important roles in the uptake of extracellular material in various tissues as well as in apoptosis of neuronal cells.

        Key words: apoptosis, tumour necrosis factor, interleukin-1, pentraxins.