Myeloid-derived suppressor cells (MDSCs) are a heterogenous population of cells that have been implicated in the development of an immunosuppressive environment, which promotes tumorigenesis and tumor progression. Numerous studies have reported expansion of MDSCs in circulation and the tumor microenvironment (TME) of cancer patients. However, due to the heterogenic nature of MDSCs and the different approaches for their identification, their detailed characterization and impact on disease progression in cancer patients are warranted. In this study, we investigated the levels of different myeloid cell subsets and antigen-presenting cells (APCs) using flow cytometry in unfractionated whole blood (WB), peripheral blood mononuclear cells (PBMCs), tumor tissue (TT), and adjacent normal tissue (NT) of colorectal cancer (CRC) patients. We found high levels of granulocytic myeloid cells (GMCs) in whole blood, but their levels were significantly lower in PBMCs. Importantly, we found significantly higher levels of GMCs in the TME compared to NT. In addition, monocytic myeloid cells (MMCs) showed significantly higher levels in PBMCs of CRC patients, compared to healthy donors (HDs). Notably, patients with advanced disease stages showed significantly higher levels of GMCs compared to early stages in whole blood, but PBMCs and tumor-infiltrating myeloid cells did not show any significant differences. Lastly, we found that levels of GMCs decreased, while IMCs increased in the TME with tumor budding. Our results highlight the importance of investigating the levels of different myeloid cell subsets in PBMCs versus whole blood of cancer patients and improve current knowledge on the potential prognostic significance of myeloid cells in CRC patients.

中文翻译：

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患有早期和晚期疾病阶段的结直肠癌患者的循环和肿瘤微环境中的髓样细胞。

髓样来源的抑制细胞（MDSC）是异质性细胞群体，与免疫抑制环境的发展有关，该环境可促进肿瘤发生和肿瘤进展。大量研究报告了MDSCs在癌症患者的循环和肿瘤微环境（TME）中的扩展。但是，由于MDSC的异质性和鉴定方法的不同，必须对它们进行详细的表征以及对癌症患者疾病进展的影响。在这项研究中，我们使用流式细胞术研究了未分级全血（WB），外周血单核细胞（PBMC），肿瘤组织（TT）和邻近正常组织中不同髓样细胞亚群和抗原呈递细胞（APC）的水平（NT）大肠癌（CRC）患者。我们发现全血中的粒细胞性髓样细胞（GMC）含量很高，但在PBMC中它们的含量却明显较低。重要的是，与NT相比，我们发现TME中的GMC含量明显更高。此外，与健康供体（HD）相比，CRC患者的PBMC中单核细胞（MMC）的水平明显更高。值得注意的是，处于疾病晚期的患者与全血中的早期患者相比，其GMC的水平明显更高，但是PBMC和浸润肿瘤的髓样细胞没有任何显着差异。最后，我们发现TME中GMC的水平下降，而IMC则随着肿瘤萌芽而上升。