Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA.
J Exp Med. 2010 Nov 22;207(12):2733-49. doi: 10.1084/jem.20091201. Epub 2010 Nov 1.
The real-time dynamics of the T cell receptor (TCR) reflect antigen detection and T cell signaling, providing valuable insight into the evolving events of the immune response. Despite considerable advances in studying TCR dynamics in simplified systems in vitro, live imaging of subcellular signaling complexes expressed at physiological densities in intact tissues has been challenging. In this study, we generated a transgenic mouse with a TCR fused to green fluorescent protein to provide insight into the early signaling events of the immune response. To enable imaging of TCR dynamics in naive T cells in the lymph node, we enhanced signal detection of the fluorescent TCR fusion protein and used volumetric masking with a second fluorophore to mark the T cells expressing the fluorescent TCR. These in vivo analyses and parallel experiments in vitro show minimal and transient incorporation of TCRs into a stable central supramolecular activating cluster (cSMAC) structure but strong evidence for rapid, antigen-dependent TCR internalization that was not contingent on T cell motility arrest or cSMAC formation. Short-lived antigen-independent TCR clustering was also occasionally observed. These in vivo observations demonstrate that varied TCR trafficking and cell arrest dynamics occur during early T cell activation.
T 细胞受体 (TCR) 的实时动态反映了抗原检测和 T 细胞信号转导，为了解免疫反应的演变事件提供了有价值的信息。尽管在简化的体外系统中研究 TCR 动力学取得了相当大的进展，但在完整组织中以生理密度表达的亚细胞信号复合物的活体成像一直具有挑战性。在这项研究中，我们生成了一种转基因小鼠，其 TCR 与绿色荧光蛋白融合，以深入了解免疫反应的早期信号事件。为了能够在淋巴结中的幼稚 T 细胞中成像 TCR 动力学，我们增强了荧光 TCR 融合蛋白的信号检测，并使用第二个荧光标记物进行体积掩蔽来标记表达荧光 TCR 的 T 细胞。这些体内分析和体外平行实验表明，TCR 很少且短暂地整合到稳定的中央超分子激活簇 (cSMAC) 结构中，但有强有力的证据表明 TCR 快速、抗原依赖性内化，这与 T 细胞运动阻滞或 cSMAC 形成无关。偶尔也观察到短暂的抗原非依赖性 TCR 聚集。这些体内观察表明，在早期 T 细胞激活过程中会发生不同的 TCR 运输和细胞阻滞动力学。
