Tyagi S, Klickstein L B, Nicholson-Weller A
Department of Medicine, and Charles A. Dana Research Institute and Harvard-Thorndike Laboratory, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA.
J Leukoc Biol. 2000 Nov;68(5):679-86.
Isolated human polymorphonuclear neutrophils (PMN) responded to human C5a with an immediate, transient release of superoxide lasting from 0.5 to 5 min. This was followed by a second release of superoxide, which began at 10 min after addition of C5a, was sustained for more than 30 min, and required ICAM-1 immobilized in the wells. F(ab')2 monoclonal antibody (mAb) preparations were used to dissect the role of individual beta2 integrins and to avoid the confounding effects of ligating Fc receptors. Anti-CD18 mAb treatment of the PMN had no effect on the immediate first phase but completely inhibited the second, adhesion-dependent phase of superoxide production. Anti-CR3 mAb only inhibited the adhesion phase of superoxide production partially, implying that other beta2 integrins were involved. A mixture of anti-CD11a, anti-CD11b, and anti-CD11c was not able to block superoxide production completely, suggesting a role for alphad/beta2. Surprisingly, blocking anti-LFA-1 mAb had no effect on superoxide production. Consistent with this observation, immobilized, purified ICAM-2, a specific counter-receptor for LFA-1, did not support the adhesion-dependent phase of-superoxide production. Thus, PMN treated with C5a used signals via CR3, P150/95, and alphad/beta2, but not LFA-1, to support superoxide production. LFA-1 has been shown by others to mediate most of the adhesion necessary for transendothelial migration in vivo. The inability of LFA-1 ligation to stimulate superoxide production may be an important means of preventing blood-vessel damage when PMN migrate across the endothelium.
分离出的人多形核中性粒细胞（PMN）对人C5a产生反应，立即短暂释放超氧化物，持续时间为0.5至5分钟。随后是第二次超氧化物释放，在加入C5a后10分钟开始，持续超过30分钟，且需要固定在孔中的细胞间黏附分子-1（ICAM-1）。使用F(ab')2单克隆抗体（mAb）制剂来剖析各个β2整合素的作用，并避免连接Fc受体带来的混淆效应。用抗CD18 mAb处理PMN对超氧化物产生的第一阶段即时反应没有影响，但完全抑制了第二阶段，即超氧化物产生的黏附依赖性阶段。抗CR3 mAb仅部分抑制超氧化物产生的黏附阶段，这意味着其他β2整合素也参与其中。抗CD11a、抗CD11b和抗CD11c的混合物不能完全阻断超氧化物的产生，提示αd/β2起作用。令人惊讶的是，阻断性抗淋巴细胞功能相关抗原-1（LFA-1）mAb对超氧化物产生没有影响。与这一观察结果一致，固定化的纯化ICAM-2（LFA-1的特异性反受体）不支持超氧化物产生的黏附依赖性阶段。因此，用C5a处理的PMN通过CR3、P150/95和αd/β2而非LFA-1利用信号来支持超氧化物产生。其他人已表明LFA-1介导体内跨内皮迁移所需的大部分黏附作用。LFA-1连接不能刺激超氧化物产生可能是PMN跨内皮迁移时防止血管损伤的重要方式。
