Release of soluble immune complexes from immune adherence receptors on human erythrocytes is mediated by C3b inactivator independently of Beta 1H and is accompanied by generation of C3c.
Release of soluble immune complexes from immune adherence receptors on human erythrocytes is mediated by C3b inactivator independently of Beta 1H and is accompanied by generation of C3c.
复制标题
可溶性免疫复合物从人红细胞上的免疫粘附受体的释放是由独立于 Beta 1H 的 C3b 灭活剂介导的，并伴随着 C3c 的生成。
DOI：
10.1073/pnas.79.16.5047
复制
发表时间：
1982
影响因子：
11.1
通讯作者：
Mold,C
中科院分区：
文献类型：
--
作者：
Medof,ME;Prince,GM;Mold,C
用125 I标记的牛血清白蛋白和豚鼠抗白蛋白制备抗原·抗体复合物（Ag·Ab），在37°C下与正常人血清（1：16）孵育30 min，然后与自体红细胞（RBC）孵育。洗涤后，将带有抗原·抗体·补体复合物（Ag·Ab·C）的RBC重悬于血清试剂或纯化的补体组分溶液中，分析其解离动力学。Ag·Ab·C在56°C加热30 min（SΔ30）的血清中解离，而在120 min（SΔ120）的血清中不解离。抗-β1H或抗-C4结合蛋白（C4 bp）吸附后，SΔ30的解离明显减少，而加入C3 b灭活剂后，SΔ120的解离明显增加。溶血试验显示SΔ30保留灭活活性，而SΔ120缺乏显著活性。Ag·Ab·C在纯化的灭活剂或C3 b存在下解离，而β1H或C3不解离。灭活剂的解离比C3 b更快，并且在0°C和37°C下发生。灭活剂抑制剂处理可消除SΔ30的解离;灭活剂缺乏血清的解离显著降低。在灭活剂的有限稀释度下，加入β1H并不增强灭活剂介导的解离，用抗β1H吸附Ag·Ab·C或用吸附抗β1H的血清制备Ag·Ab·C并不减弱解离。用灭活剂解离后，Ag·Ab·C的大小不变，但不再能与新鲜红细胞结合，而与Raji和Daudi淋巴母细胞的结合增强。用~（125）I标记的C_3制备的Ag·Ab·C经NaDodSO_4/聚丙烯酰胺凝胶电泳显示，与红细胞结合后，用灭活剂解离，产生C_3c大小的C_3片段。用过量灭活剂预孵育Ag·Ab·C并不能阻止Ag·Ab·C随后与RBC结合，但结合后Ag·Ab·C迅速解离。这些结果表明，C3 b灭活剂可从人RBC上的免疫粘附受体释放免疫复合物，释放不依赖于β1H，改变免疫复合物的细胞结合特性，并涉及C3 b α′链的多次裂解，并且人RBC膜中的受体是C3 b灭活剂介导的分解所必需的。
Antigen·antibody complexes (Ag·Ab) prepared from125I-labeled bovine serum albumin and guinea pig anti-albumin were incubated at 37°C for 30 min with normal human serum diluted optimally for binding (1:16) and then with autologous erythrocytes (RBC). After washing, RBC-bearing antigen·antibody·complement complexes (Ag·Ab·C) were resuspended in serum reagents or solutions of purified complement components, and the kinetics of dissociation were analyzed. Ag·Ab·C dissociated in serum heated at 56°C for 30 min (SΔ30) but not in serum heated for 120 min (SΔ120). Dissociation in SΔ30 markedly decreased after adsorption with anti-C3b inactivator but not anti-β1H or anti-C4 binding protein (C4bp), and dissociation in SΔ120 markedly increased after addition of C3b inactivator. Hemolytic assays revealed that SΔ30 retained inactivator activity whereas SΔ120 lacked significant activity. Ag·Ab·C dissociated in the presence of purified inactivator or C3b but not β1H or C3. Dissociation was more rapid with inactivator than with C3b and occurred at 0°C as well as at 37°C. Treatment with inactivator inhibitor abolished dissociation in SΔ30; dissociation in inactivator deficient serum was markedly reduced. Addition of β1H did not enhance inactivator-mediated dissociation at limiting dilutions of inactivator, and adsorption of Ag·Ab·C with anti-β1H or preparation of Ag·Ab·C with serum adsorbed with anti-β1H did not diminish dissociation. After dissociation with inactivator, Ag·Ab·C were unchanged in size but were no longer able to bind to fresh RBC and gave enhanced binding to Raji and Daudi lymphoblastoid cells. NaDodSO4/polyacrylamide gel electrophoresis of Ag·Ab·C prepared with125I-labeled C3 revealed that, after binding to RBC, dissociation with inactivator was accompanied by generation of a C3 fragment the size of C3c. Preincubation of Ag·Ab·C with excess inactivator did not prevent subsequent binding of Ag·Ab·C to RBC but, immediately after binding, Ag·Ab·C dissociated rapidly. These findings indicate that C3b inactivator can release immune complexes from immune adherence receptors on human RBC, that release occurs independently of β1H, alters cell binding properties of immune complexes, and involves multiple cleavages of the C3b α′ chain, and that receptors in human RBC membrane are required for this C3b inactivator-mediated breakdown.