Background/Objectives: Circulating tumor cells (CTCs) and large extracellular vesicles (LEVs) are key components of the liquid biopsy that provide minimally invasive access to tumor biology. A clinically relevant subset of CTCs coexpressing epithelial and immune markers (im.CTCs) has been described, yet the origin of this phenotype remains unclear. In this study, we investigated the cellular and molecular context underlying the emergence of immune marker expression on CTCs and LEVs. Methods: Using high-resolution immunofluorescence microscopy of patient-derived blood samples, we identified direct physical interactions between white blood cells (WBCs) and both im.CTCs and im.LEVs, exclusively in patients harboring im.CTCs. Results: In several cases, WBCs partially encapsulated CTCs and LEVs, and quantitative analysis revealed localized enrichment of immune membrane markers at the contact interface, distinguishing these events from random proximity. Proteomic profiling further identified CD4+ T cells as the predominant interacting immune cell type and confirmed the presence of CD45, CD3, and CD4 on the interacting CTCs and LEVs, matching their WBC counterparts. Conclusion: These findings support membrane transfer as a potential mechanism for the acquisition of immune markers by CTCs and LEVs and provide in vivo evidence of contact-dependent tumor-immune interactions in circulation with implications for immune modulation and clinical interpretation of the im.CTC phenotype.
背景/目的：循环肿瘤细胞（CTCs）与大细胞外囊泡（LEVs）是液体活检的关键组成部分，为肿瘤生物学研究提供了微创途径。临床相关的一类同时表达上皮标志物与免疫标志物的CTCs（im.CTCs）已被报道，但其表型起源尚不明确。本研究旨在探究CTCs和LEVs表达免疫标志物现象背后的细胞与分子学背景。方法：通过对患者血液样本进行高分辨率免疫荧光显微成像，我们在存在im.CTCs的患者样本中观察到白细胞（WBCs）与im.CTCs及im.LEVs之间存在直接物理相互作用。结果：在多个病例中，白细胞部分包裹CTCs和LEVs，定量分析显示接触界面处免疫膜标志物局部富集，从而将这些事件与随机邻近现象区分开来。蛋白质组学分析进一步确定CD4+ T细胞为主要相互作用的免疫细胞类型，并证实相互作用的CTCs和LEVs表面存在CD45、CD3和CD4标志物，与其相互作用的白细胞表型相匹配。结论：这些发现支持膜转移是CTCs和LEVs获得免疫标志物的潜在机制，为循环系统中接触依赖性肿瘤-免疫相互作用提供了体内证据，这对im.CTC表型的免疫调节及临床解读具有重要意义。
肿瘤(癌症)患者之家