CD26, acting as a costimulator of T cell activation, plays an important role in the immune system. However, the role of CD26 in the differentiation of T cell subsets, especially of new paradigms of T cells, such as Th17 and Tregs, is not fully clarified. In the present study, the role of CD26 in T cell differentiation was investigated in vitro. CD26 expression was analyzed in the different subsets of human peripheral blood T lymphocytes after solid-phase immobilized specific anti-CD3 mAb stimulation. Here, the percentage of CD4⁺ cells significantly increased and most of these cells were coexpressed with CD26, suggesting a close correlation of CD26 expression with the proliferation of CD4⁺ cells. Subsequently, after immobilized anti-CD3 mAb stimulation, CD26 high-expressing cells (CD26^high) were separated from CD26 low-expressing cells (CD26^low) by magnetic cell sorting. We found that the percentages of cells secreting Th1 typical cytokines (IL-2, IFN-γ) and Th17 typical cytokines (IL-6, IL-17, and IL-22) or expressing Th17 typical biomarkers (IL-23R, CD161, and CD196) in the CD26^high group were markedly higher than in those in the CD26^low group. In addition, a coexpression of CD26 with IL-2, IFN-γ, IL-17, IL-22, and IL-23R in lymphocytes was demonstrated by fluorescence microscopy. These results provide direct evidence that the high expression of CD26 is accompanied by the differentiation of T lymphocytes into Th1 and Th17, indicating that CD26 plays a crucial role in regulating the immune response.

中文翻译：

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CD26 参与 T 淋巴细胞 Th1 和 Th17 亚群的分化和功能

CD26 作为 T 细胞活化的共刺激物，在免疫系统中发挥重要作用。然而，CD26 在 T 细胞亚群分化中的作用，尤其是 T 细胞的新范式，如 Th17 和 Tregs，尚未完全阐明。在本研究中，CD26 在 T 细胞分化中的作用进行了体外研究。在固相固定的特异性抗 CD3 mAb 刺激后，分析了不同亚群人外周血 T 淋巴细胞中的 CD26 表达。在这里，CD4 ⁺细胞的百分比显着增加，并且这些细胞中的大多数与 CD26 共表达，表明 CD26 表达与 CD4 ⁺增殖密切相关细胞。随后，在固定化抗 CD3 mAb 刺激后，通过磁性细胞分选将CD26 高表达细胞 (CD26 ^high ) 与 CD26 低表达细胞 (CD26 ^low )分离。我们发现分泌 Th1 典型细胞因子（IL-2、IFN- γ）和 Th17 典型细胞因子（IL-6、IL-17 和 IL-22）或表达 Th17 典型生物标志物（IL-23R、CD161、 CD26^高组和 CD196)显着高于 CD26^低组。此外，CD26 与 IL-2、IFN- γ的共表达淋巴细胞中的 IL-17、IL-22 和 IL-23R 通过荧光显微镜证实。这些结果提供了直接证据表明 CD26 的高表达伴随着 T 淋巴细胞向 Th1 和 Th17 的分化，表明 CD26 在调节免疫反应中起着至关重要的作用。