Pexelizumab

Although inflammation is a normal response, continued exposure to foreign surfaces, toxic antigens, and tissue injury results in pathologic local and systemic inflammation (SIRS). This response involves multiple humoral and cellular components, including the coagulation (Factor XII, thrombin, Proteins C and S, platelets) and complement systems, cytokines (TNF-alpha, interleukins), leukocytes, monocytes, adhesion molecules (ICAM-1), and endothelial cells, among others. The complement system is a group of glycoproteins, which, when activated, results in the formation of C3-convertase, which converts C3 to C3a and C3b. C3a cleaves C5 to C5a and C5b. C5b, in conjunction with C6, C7, C8, and C9, forms the membrane attack or terminal complement complex (TCC) C5b-9. Both C5a and C5b-9 activate, promote, and amplify inflammatory components, and likely play central roles in the development of SIRS, tissue injury, reperfusion injury, and apoptosis. Pexelizumab, a recombinant humanized single chain monoclonal antibody to C5, blocks the conversion of C5 to C5a and C5b-9.