McGettrick Helen M, Hunter Kirsty, Moss Paul A, Buckley Christopher D, Rainger G Ed, Nash Gerard B
The Medical School, The University of Birmingham, Birmingham B15 2TT, UK.
J Leukoc Biol. 2009 Jan;85(1):98-107. doi: 10.1189/jlb.0508301. Epub 2008 Oct 23.
The kinetics and regulatory mechanisms of T cell migration through the endothelium have not been fully defined. In experimental, filter-based assays in vitro, transmigration of lymphocytes takes hours, compared with minutes, in vivo. We cultured endothelial cell (EC) monolayers on filters, solid substrates, or collagen gels and treated them with TNF-alpha, IFN-gamma, or both prior to analysis of lymphocyte migration in the presence or absence of flow. PBL, CD4+ cells, or CD8+ cells took many hours to migrate through EC-filter constructs for all cytokine treatments. However, direct microscopic observations of EC filters, which had been mounted in a flow chamber, showed that PBL crossed the endothelial monolayer in minutes and were highly motile in the subendothelial space. Migration through EC was also observed on clear plastic, with or without flow. After a brief settling without flow, PBL and isolated CD3+ or CD4+ cells crossed EC in minutes, but the numbers of migrated cells varied little with time. Close observation revealed that lymphocytes migrated back and forth continuously across endothelium. Under flow, migration kinetics and the proportions migrating back and forth were altered little. On collagen gels, PBL again crossed EC in minutes and migrated back and forth but showed little penetration of the gel over hours. In contrast, neutrophils migrated efficiently through EC and into gels. These observations suggest a novel model for lymphoid migration in which EC support migration but retain lymphocytes (as opposed to neutrophils), and additional signal(s) are required for onward migration.
T细胞穿过内皮细胞迁移的动力学和调节机制尚未完全明确。在基于滤膜的体外实验检测中，淋巴细胞的迁移需要数小时，而在体内则只需几分钟。我们在滤膜、固体基质或胶原凝胶上培养内皮细胞（EC）单层，并在分析有无流动情况下淋巴细胞迁移之前，用肿瘤坏死因子-α（TNF-α）、干扰素-γ（IFN-γ）或两者对其进行处理。对于所有细胞因子处理，外周血淋巴细胞（PBL）、CD4⁺细胞或CD8⁺细胞穿过EC-滤膜构建体都需要数小时。然而，对安装在流动腔室中的EC滤膜进行直接显微镜观察发现，PBL在数分钟内就能穿过内皮单层，并且在内皮下空间具有高度的运动性。在有或无流动的透明塑料上也观察到了穿过EC的迁移。在无流动的短暂沉降后，PBL以及分离的CD3⁺或CD4⁺细胞在数分钟内就能穿过EC，但迁移细胞的数量随时间变化不大。仔细观察发现，淋巴细胞在内皮细胞上持续来回迁移。在流动条件下，迁移动力学以及来回迁移的比例变化不大。在胶原凝胶上，PBL同样在数分钟内穿过EC并来回迁移，但数小时内对凝胶的穿透很少。相比之下，中性粒细胞能有效地穿过EC并进入凝胶。这些观察结果提示了一种淋巴细胞迁移的新模式，即EC支持迁移但保留淋巴细胞（与中性粒细胞相反），并且向前迁移需要额外的信号。
