补体第二途径的激活可以提供抗微生物感染的自然的非免疫性防御。早在1950年前后,Pillemer及其同事发现一种新蛋白,命名为备解素(Properdin)。若将其从人血清中移除,血清的一些不依赖抗体的杀菌作用、病毒中和作用及溶血作用即行受损。因为这一补体系统的激活不需要抗体-依赖性第一补体途径(经典途径)成份C1、C4及 Activation of the second pathway of complement may provide a natural non-immune defense against microbial infections. As early as around 1950, Pillemer and colleagues found a new protein, named Properdin. If it is removed from human serum, some of the sera do not rely on the bactericidal effect of the antibody, the virus neutralization and hemolysis are impaired. Because activation of this complement system does not require the antibody-dependent first complement pathway (classical pathway) components Cl, C4 and