Furthermore, although the full implication of complement system activation in atherosclerosis is not understood, C5a has been shown in in vitro studies to induce adhesion molecule expression by endothelial cells [51] and to be a potent chemotactic for several inflammatory cells including monocytes [52], and could, therefore, play an important role in immune cell accumulation in the arterial wall [53]. Here, C5 is linked to atherosclerosis.