T细胞的抗原识别和活化可以直接影响整个免疫应答的性质、效能和结果, 在人体免疫反应中具有核心作用。细胞的形态结构和力学特性决定着细胞的功能的发挥。利用原子力显微镜(AFM)从纳米水平和皮牛顿量级探测分析静息的T细胞和不同刺激剂(超抗原SEA和植物凝集素PHA)活化的T细胞的形态结构和生物力学特性。研究发现静息的T细胞呈较为规则的圆形, 细胞表面相对光滑均一, 活化后细胞高度和体积明显增大, 体积增大为静息T细胞的2~3倍, 高度增加了约50%, 这是T细胞经过刺激剂活化后增殖、分化而增大的表现。同时发现活化后的T细胞表面粗糙度增大, 细胞表面形成100 nm~1 μm颗粒状团簇结构。这种微纳结构域的形成与T细胞经过活化后细胞表面分子表达和细胞因子的分泌有关, 并且与免疫突触的形成和功能发挥密切关联。经过PHA和SEA活化后的T细胞表面粘附力增大, 是静息的T细胞的3-6倍, 而细胞硬度明显减小, 这种力学特性的变化有利于T细胞与病原体的相关作用从而清除病原体。通过AFM的研究, 可以进一步的了解T淋巴细胞形态变化与细胞行为之间的关系, 为更好地理解T细胞的结构与功能提供了更多可视化的依据。

The antigen recognition and activation of T cells has a central role in the immune response, which can directly affect the efficiency and the result of immune response. Morphological structure and mechanical properties of cells determines their function. Using atomic force microscope (AFM), the morphological structures and biomechanical properties of the resting T cells, the PHA activated T cells and the SEA activated T cells were detected at the nanoscale and Newton level. It was indicated that the resting T cells with round shape, the cell surface was relatively smooth and uniform. The cell height and the volume were increased after being activated. The volume of activated T cells increased for 2~3 times of resting T cells and the height increases about 50%. Furthermore, high-resolution AFM images showed that the surface average roughness (Ra) of activated T cells also increased. Interestingly, some particle clusters (100 nm~1 μm) are found in the activated T cell membrane. Clustering of cell surface receptors into micro/nano-domains in the plasma membrane was an important mechanism for regulating cellular functions. Compared with resting T cells, the adhesion force of activated T cells increased significantly, but the stiffness decreased. The changes of mechanical properties of T cells are beneficial to eliminate pathogens. These findings provide new insights into the T cell structure, function and ultimate immune response.