髓系来源的抑制细胞（MDSCs）是病理活化的中性粒细胞和单核细胞，负向调节对癌症和慢性感染的免疫反应。异常的骨髓生成和髓系细胞的病理活化产生了这种异质性的髓系来源的抑制细胞。它们特征在于其不同的转录、表型、生化和功能特征。在肿瘤微环境（TME）中，髓系来源的抑制细胞代表了一个重要的免疫抑制细胞类别，与肿瘤负担、分期和不良预后相关。髓系来源的抑制细胞通过阻止淋巴细胞寄主、增加活性氧和氮氧自由基的产生、促进多种细胞因子、趋化因子和免疫调节分子的分泌、刺激其他免疫抑制细胞、耗竭各种代谢产物和上调免疫检查点分子，对T细胞和其他免疫细胞产生强烈的免疫抑制作用。此外，髓系来源的抑制细胞在肿瘤中的异质性使其鉴定具有挑战性。总的来说，它们是许多癌症免疫疗法的重大障碍，针对它们可能是改善免疫治疗干预效果的有利策略。然而，在血液系统恶性肿瘤中，特别是B细胞恶性肿瘤，针对这些髓系来源的抑制细胞的临床结果还有待探索。本文综述了髓系来源的抑制细胞的复杂生物学，重点介绍了这些细胞用于调节血液系统恶性肿瘤T细胞功能的免疫抑制途径。此外，我们描述了在这些疾病中针对髓系来源的抑制细胞的挑战、治疗策略和临床相关性。版权所有©2023 Bhardwaj和Ansell。

Myeloid-derived suppressor cells (MDSCs) are pathologically activated neutrophils and monocytes that negatively regulate the immune response to cancer and chronic infections. Abnormal myelopoiesis and pathological activation of myeloid cells generate this heterogeneous population of myeloid-derived suppressor cells. They are characterized by their distinct transcription, phenotypic, biochemical, and functional features. In the tumor microenvironment (TME), myeloid-derived suppressor cells represent an important class of immunosuppressive cells that correlate with tumor burden, stage, and a poor prognosis. Myeloid-derived suppressor cells exert a strong immunosuppressive effect on T-cells (and a broad range of other immune cells), by blocking lymphocyte homing, increasing production of reactive oxygen and nitrogen species, promoting secretion of various cytokines, chemokines, and immune regulatory molecules, stimulation of other immunosuppressive cells, depletion of various metabolites, and upregulation of immune checkpoint molecules. Additionally, the heterogeneity of myeloid-derived suppressor cells in cancer makes their identification challenging. Overall, they serve as a major obstacle for many cancer immunotherapies and targeting them could be a favorable strategy to improve the effectiveness of immunotherapeutic interventions. However, in hematological malignancies, particularly B-cell malignancies, the clinical outcomes of targeting these myeloid-derived suppressor cells is a field that is still to be explored. This review summarizes the complex biology of myeloid-derived suppressor cells with an emphasis on the immunosuppressive pathways used by myeloid-derived suppressor cells to modulate T-cell function in hematological malignancies. In addition, we describe the challenges, therapeutic strategies, and clinical relevance of targeting myeloid-derived suppressor cells in these diseases.Copyright © 2023 Bhardwaj and Ansell.