簡要描述：Activation of the complement system plays a key role in normal inflammatory response to injury but may cause substantial injury when activated inappropriately. The complement system is activated either through the classical (antibody induced) or the alternative (microbial surface, polysacharride induced) pathway, both leading to the formation of the C5b9 complex. Fluid phase binding of the multifunctional glycoprotein S protein (vitronectin) to C5b9 leads to the formation of a cytolytically ina