主讲：肖　健 Complement 龚非力教授

Jules Bordet (1870-1961), discoverer of complement Belgian bacteriologist and immunologist who received the Nobel Prize for Physiology or Medicine in 1919 for his discovery of immunity factors in blood serum; this was a development vital to the diagnosis and treatment of many dangerous contagious diseases. Jules Bordet  (1870-1961), discoverer of complement

结论: 细胞性抗原的裂解既需要抗体也需要补体的参与。 Bordet (1895), discovery of complement补体的发现 ① Fresh antiserum + SRBC lysis ② Fresh noral serum + SRBC No lysis Agglutination ③ Heated antiserum SRBC + No lysis ② + ③ lysis 结论: 细胞性抗原的裂解既需要抗体也需要补体的参与。

Definition定义及概述 一 Complement补体 补体系统 存在于脊椎动物血清中的一组不耐热的具有酶促反应活性的糖蛋白. 一个由超过30种血浆蛋白构成的具有精密调控作用的反应系统。

补体系统组成 血清补体成分 固有成分 调节蛋白 补体受体 名 称 分子量 （ kDa ） 血清浓度 （ m g/l ） 经典途径 C1q 460 80 C1r 83 50 C1s 83 50 C4 200 600 C2 102 20 C3 185 1300 旁路途径 D 因子 24 1 B 因子 90 210 凝集素途径 MBL 30 x 3 1 终端成分 C5 204 70 C6 120 65 C7 120 55 C8 160 55 C9 70 60 调节因子 105 200 C1-INH C4-bp 550 250 H 150 480 I 88 35 P 4 x 56 20

补体的理化性质与来源 不耐热 肝细胞 （Hepatocytes ） 单核/巨噬细胞 （Monocyte/Macrophage） 造血细胞 （Hematopoietic cells） 纤维母细胞 （Fibroblasts） 内皮细胞 （Endothelial） 生殖细胞 （Reproductive） 脂肪细胞 （Adipocytes） 星细胞 （Astrocytes） 神经细胞 ( Neurons )

Complement Activation 二 Complement Activation 补体激活 1，Classical Pathway经典途径 – Ag-Ab Complexes 2， Alternative Pathway旁路途径 – LPS, 酵母多糖，葡聚糖 3， Mannose-Binding Protein Pathway甘露糖结合凝集素途径 – Mannose, N- acetylglucosamine

Terminal activation

Ⅰ. The Classic Pathway经典途径 The binding of antibody to its specific antigen often triggers the complement system through the so-called classical pathway. It can occur in solution or when the antibodies have bound to antigens on a cell surface. 抗原抗体结合激发的补体活化称之。

C1s C1q C1r The C1 protein is composed of three proteins: C1q, which binds to the Fc portion of the Ab molecule; C1s, which can enzymatically cleave the next complement component, C4 and C2; and C1r, which acts as a bridge connecting C1q to C1s. Ca++ C1r C1s C1q Chelating agents dismantle the C1 complex and are anti-complementary. Heat destroys the C2 component. Sample for C measurement should be drawn in a green-top vial (no EDTA), must be kept cold and tested as soon as possible. C1 complex

Generation of C3-convertase C4a b Ca++ C1r C1s C1q

C2 C2 a C2b a C4a Ca++ C1r C1s C1q Mg++ C4b2a is C3 convertase C4b

Generation of C5-convertase C2b C4a Ca++ C1r C1s C1q C3a b C4b2a3b is C5 convertase; it leads into the Membrane Attack Pathway Mg++ C4b C3 C2 a

C5-activation b C5a C5 C3b C4b C2 a

assembly of the lytic complex(MAC)

insertion of lytic complex into cell membrane 9 C 9 C 9 C 9 C 9 C 9 C 9 C 9 C 9

e

经典途径的特点 1，cellular antigens细胞性抗原 2，Ag-Ab complex triggers C system.抗原抗体复合物 3，be activated from C1, C4, C2, C3, to C5, C6, C7, C8, C9.活化顺序 4, formation of C3 and C5 convertase.形成两个转化酶 5, assembly of the lytic complex (MAC)。组装MAC

2.The Alternative Pathway旁路途径 There is a spontaneous conversion of C3 to C3b. Ordinarily the C3b is quickly inactivated: the C3b binds to inhibitory proteins and sialic acid present on the surface of body's own cells, and the process is aborted.

the Structure of C3 Molecule C3结构 C3 is the most abundant protein of the complement system (1~1.3 mg/ml). Because of its abundance and its ability to activate itself, it greatly magnifies the response. C3的自发活化 a 链 C- b 链 CR1 N- N- P C- CR3 CR2 -S-S- -S-S-

旁路途径的活化 C3 自发活化 LPS 多糖 葡聚糖 MAC

3.MBL途径 MBL途径的成份 C4 MASP2 甘露聚糖 C2 MASP1 MBL

Mannose-binding lectin pathway C4b C4a C2b C2a C4b2a is C3 convertase; it will lead to the generation of C5 convertase C4b C4 C2a C2 MASP2 MASP1 MBL

三 补体活化的调节 The explosive potential of the complement system requires that it be kept under tight control. At least 12 proteins are known that do this.至少12种蛋白参与

C1INH 抑制C1r/C1s和MASP的活性 C1r C1s C1r C1s C1q C1inh

C1-inhibitor deficiency: angioedema血管神经性水肿

C4bp C4bp与C4b的结合能力比C2高27倍

Factor H 哺乳动物细胞表面 微生物细胞表面 C3b C3b 唾液酸 Bb 灭活 哺乳动物细胞表面 微生物细胞表面 C3b C3b 唾液酸 Bb H 灭活 H H因子与哺乳细胞表面的唾液酸结合之后被活化，抑制替代途径的补体活化。没有丰富的唾液酸的微生物细胞表面不能吸附H因子，容易成为补体系统的攻击对象。

CD46和 CD55 CD55 CD46 NH2 NH2 CD55（DAF：Decay Accelerating Factor， 补体衰变加速因子）是经GPI锚固于胞膜表面的75 kDa 糖蛋白，能够与C3b结合并且降解C3/C5转化酶。 CD46是一个分子量为56-66 kDa的共二聚体膜蛋白，与CD55、CR1和CR2等具有同源性。能够与C3b和C4b结合并使之被I因子降解。 CL CL CL CL CL CL CL CL 胞膜 胞浆区 GPI锚固

C8bp Inhibition of C9 binding CD59 （C8bp） C5b-8 C9

S protein 与C5b67结合，妨碍其插入靶细胞脂质双层

CR CR1 和 CR2 CR1（CD35）—— C4b；C3b CR2（CD21）—— C3d；iC3b NH2 C C4b CR1（CD35）—— C4b；C3b C C A B C D C C CR2（CD21）—— C3d；iC3b C C C3b C C CR3（Mac-1）—— iC3b CR4（CD11c/CD18）——iC3b C5aR（CD88）—— C5a C CR2 C NH2 C C C C3d EBV C C3b C C C C A B C D C C C C C C C C C C C C C C C C C C C C C C C C C C C COOH COOH

The function of Complement 1, lyse the target cells 细胞毒作用 2, opsonization:C3b,C4b 调理作用 3, Immune adherence 免疫粘附，清除免疫复合物 and the removal complex:C3b,C4b 4, Neutralizing virus 中和病毒 5, Inflammantory mediators 炎症介质 Kinin-like action(激肽样作用): C2b Anaphylatoxins（过敏毒素）:C3a,C5a Chemokine-like action(趋化作用):C3a,C5a,C567

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