食管癌（EC）是一种致命的恶性肿瘤。具有程序性死亡配体 1 (sEV-PDL1) 的小细胞外囊泡 (sEV) 诱导免疫逃逸，促进肿瘤进展。此外，循环滤泡辅助性T细胞（Tfh）和循环滤泡调节性T细胞（Tfr）之间的不平衡与许多恶性肿瘤的进展有关。然而，EC 衍生的 sEV-PDL1 在循环 Tfh/Tfr 中的作用尚不清楚。通过流式细胞术检测循环Tfh和Tfr细胞。通过差速离心分离 sEV，并培养用于细胞扩增测定。分离、刺激并用 sEV 培养幼稚 CD4 T 细胞，以评估 Tfh 和 Tfr 细胞的频率、表型和功能。 EC患者循环Tfh的比例低于健康供体（HD），而循环Tfr的比例则较高。与 HD 组相比，EC 组表现出显着较低的循环 Tfh/Tfr 和较高水平的 sEV-PDL1。值得注意的是，EC 组中 sEV-PDL1 与循环 Tfh/Tfr 呈负相关。体外试验中，sEV-PDL1 抑制 Tfh 扩增，提高细胞毒性 T 淋巴细胞相关抗原 4 (CTLA4) Tfh 细胞百分比，降低白细胞介素 (IL)-21 和干扰素-γ 水平，并增加 IL-10。 sEV-PDL1促进循环Tfr的扩增和免疫抑制功能； CTLA4 Tfr 和诱导型 T 细胞共刺激剂 Tfr 百分比的增加伴随着高 IL-10。然而，应用抗 PDL1 抗体显着逆转了这一情况。我们的结果提示了 EC 中 sEV-PDL1 介导的免疫抑制的新机制。抑制 sEV-PDL1 以恢复循环 Tfh/Tfr 平衡为 EC 提供了一种新颖的治疗方法。© 2023。作者获得 Springer-Verlag GmbH 德国（Springer Nature 旗下公司）的独家许可。

Esophageal cancer (EC) is a deadly malignancy. Small extracellular vesicles (sEVs) with programmed death ligand 1 (sEV-PDL1) induce immune escape to promote tumor progression. Furthermore, the imbalance between circulating follicular helper T (Tfh) and circulating follicular regulatory T (Tfr) cells is related to the progression of many malignant tumors. However, the role of the EC-derived sEV-PDL1 in circulating Tfh/Tfr is unknown. Circulating Tfh and Tfr cells were detected by flow cytometry. sEVs were isolated through differential centrifugation and cultured for cell expansion assays. Naïve CD4+ T cells were isolated, stimulated, and cultured with sEVs to evaluate the frequencies, phenotypes, and functions of Tfh and Tfr cells. The proportion of circulating Tfh in patients with EC was lower than that in healthy donors (HDs), whereas that of circulating Tfr was higher. The EC group showed significantly lower circulating Tfh/Tfr and a higher level of sEV-PDL1 than HDs. Notably, sEV-PDL1 was negatively correlated with circulating Tfh/Tfr in the EC group. In vitro assays, sEV-PDL1 inhibited Tfh expansion, enhanced the cytotoxic T lymphocyte-associated antigen 4+ (CTLA4+) Tfh cell percentage, decreased the levels of interleukin (IL)-21 and interferon-γ, and increased IL-10. sEV-PDL1 promoted the expansion and immunosuppressive functions of circulating Tfr; the increased percentages of CTLA4+ Tfr and inducible T cell co-stimulator+ Tfr were accompanied with high IL-10. However, applying an anti-PDL1 antibody significantly reversed this. Our results suggest a novel mechanism of sEV-PDL1-mediated immunosuppression in EC. Inhibiting sEV-PDL1 to restore circulating Tfh/Tfr balance provides a novel therapeutic approach for EC.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.