Given the multitude of effects that complement can exert, there are mechanisms in place to limit complement activation where and when it occurs. For example, the phlogistic potential of both C3a and C5a is quickly reduced by plasma carboxypeptidases that cleave the C-terminal Arginine, resulting in C3a des-Arg and C5a des-Arg, each of which has less than 10% of their original biological activity. C3a des-Arg, which is also known as acylationstimulating protein (ASP), is thought to induce triglyceride synthesis in adipocytes (Kalant et al. 2005) . C3b and C4b are also quickly inactivated by proteolytic cleavage into fragments iC3b, C3dg, C3c, C4c, C4d by the serine protease Factor I in the presence of cofactors: membrane cofactor protein (MCP) and complement receptor 1 (CR1, CD35) that are membrane bound and Factor H which is bound to host surfaces. CR1 promotes phagocytosis, helping to clear immune complexes by binding to C3b in immune complexes. Failure to clear these complexes leads to deposition of complexes in tissues and activation via Fc receptors, resulting in tissue injury. CR2 (CD21) binds iC3b, C3dg and C3d (Holers and Kulik 2007) . Further-more, C1 inhibitor (C1-INH) inactivates C1r, C1s and MASP2 (Davis et al. 2008) . Complement activation is also regulated either by preventing the assembly of the C3 convertase or, once it is formed, by inhibiting its activity due to actions of decay acceleration factor (DAF, CD55), C4 binding protein (C4BP), Factor H and a membranebound protein found only in rodents, Crry. In addition, the MAC complex formation on cell surfaces or lysis is negatively regulated by S protein (a plasma glycoprotein synthesized by endothelial cells), vimentin (a cytoskeletal protein), and CD59 by interfering with the assembly of the MAC (Huang et al. 2006 ).