In addition, pentraxins (PTX) can recognize pathogens and eliminate them by directly binding to C1q. Based on their subunit structure, PTX are divided into two subfamilies: the short PTX family to which belong the acute phase proteins SAP and CRP and the long PTX family to which belongs the prototype protein PTX3 (Sjöberg et al. 2009; Bottazzi et al. 2010) . Pentraxins are synthesized in the liver and other tissues in response to an infection (Bottazzi et al. 2010) . The C3 convertases C4bC2a of CP and LP and C3bBb of the AP further cleave C3 to release C3a and C3b. C3b acts as an opsin and helps to further amplify complement activation as well as help in phagocytosis. In addition, C3b complexes with the C3 convertases to form the C5 convertases: C3bBbC3b and C4bC2aC3b (Fig. 1) . The C5 convertases cleave C5 to form C5a and C5b. The membrane attack complex (C5b-9, MAC), also called the terminal complement complex (TCC), is then initiated by C6 and C7 binding to C5b and then C8 and multiple molecules of C9 binding to the C5bC6C7 complex. The MAC complex forms a pore by inserting itself into cell membranes, resulting in cell lysis.