Basta Milan
National Institutes of Health, NINDS, Bethesda, Maryland 20892, USA.
Mol Immunol. 2008 Oct;45(16):4073-9. doi: 10.1016/j.molimm.2008.07.012. Epub 2008 Aug 15.
Pathogen and self-specific antibodies are known for their ability to trigger generation of active complement fragments that then serve as effectors of cell damage. The remainder of the immunoglobulin pool of the host has the capacity to quench harmful effects of activated complement cascade by preventing active complement fragments from binding to their specific receptors. This scavenging function is mediated by different acceptor sites within the immunoglobulin molecule. Large fragments, such as C3b and C4b are preferentially bound to the Fc region, while biologically potent C3a and C5a anaphylatoxins get neutralized by low-affinity interaction with the constant domain of the F(ab)(2.) The ambivalent effect of immunoglobulins on the complement system implies their role in homeostasis as well as expansion of use of high-dose intravenous immunoglobulins in diseases and states mediated by inappropriate complement activation.
病原体特异性抗体和自身特异性抗体以其触发活性补体片段生成的能力而闻名，这些活性补体片段随后充当细胞损伤的效应物。宿主免疫球蛋白库的其余部分有能力通过阻止活性补体片段与其特异性受体结合来消除活化补体级联反应的有害影响。这种清除功能由免疫球蛋白分子内的不同受体位点介导。大的片段，如C3b和C4b优先与Fc区域结合，而具有生物活性的C3a和C5a过敏毒素则通过与F(ab)(2)恒定域的低亲和力相互作用而被中和。免疫球蛋白对补体系统的矛盾作用意味着它们在体内平衡中的作用，以及在由不适当的补体激活介导的疾病和状态中扩大高剂量静脉注射免疫球蛋白的使用。
