固有免疫淋巴细胞系列自然杀伤细胞（NK细胞）浸润肿瘤环境，并能识别和消灭肿瘤细胞。NK细胞肿瘤浸润与患者预后密切相关。然而，目前尚不清楚是否有部分抗肿瘤NK细胞离开肿瘤环境。在血液源性癌症中，与白血病细胞发生相互作用的NK细胞可通过共表达两种CD45亚型（CD45RARO细胞）和/或肿瘤抗原（Ag）的细胞膜表达来识别，而NK细胞通过吞噬作用获得这些抗原。我们通过体外共培养的方法评估了NK细胞对固体肿瘤抗原的吞噬作用。我们通过无监督维度缩减技术在乳腺肿瘤（BC）患者和健康供体（HD）的血样中分析了NK细胞亚群。我们证实NK细胞在体外能够通过固体癌细胞进行吞噬作用。吞噬作用的程度取决于靶细胞和抗原的类型，而不取决于靶细胞上表达的抗原数量或对NK细胞杀伤的敏感性。我们通过流式自组织映射（FlowSOM）鉴定了几个在BC患者和HD之间差异丰度的NK细胞群集，包括表型为CD45RARO + CD107a +的抗肿瘤NK亚群。这些分析显示，在患者中，真正进行去颗粒化的NK细胞增加，并且这些NK细胞表面具有固体肿瘤抗原的吞噬作用。然而，吞噬的NK细胞频率非常低，远远低于血液性癌症患者的频率，这表明离开肿瘤环境的NK细胞数量很少。据我们所知，这是首次描述在乳腺肿瘤患者的外周循环NK亚群中存在固体肿瘤标记物的报道。这种NK细胞免疫分析可能有助于开发补充已有BC治疗方法的新策略，或者在固体癌症患者治疗后使用外周血NK细胞进行治疗监测和治疗诊断。版权所有©2023 Campos-Mora, Jacot, Garcin, Depondt, Constantinides, Alexia, Villalba.

The innate immune lymphocyte lineage natural killer (NK) cell infiltrates tumor environment where it can recognize and eliminate tumor cells. NK cell tumor infiltration is linked to patient prognosis. However, it is unknown if some of these antitumor NK cells leave the tumor environment. In blood-borne cancers, NK cells that have interacted with leukemic cells are recognized by the co-expression of two CD45 isoforms (CD45RARO cells) and/or the plasma membrane presence of tumor antigens (Ag), which NK cells acquire by trogocytosis. We evaluated solid tumor Ag uptake by trogocytosis on NK cells by performing co-cultures in vitro. We analyzed NK population subsets by unsupervised dimensional reduction techniques in blood samples from breast tumor (BC) patients and healthy donors (HD). We confirmed that NK cells perform trogocytosis from solid cancer cells in vitro. The extent of trogocytosis depends on the target cell and the antigen, but not on the amount of Ag expressed by the target cell or the sensitivity to NK cell killing. We identified by FlowSOM (Self-Organizing Maps) several NK cell clusters differentially abundant between BC patients and HD, including anti-tumor NK subsets with phenotype CD45RARO+CD107a+. These analyses showed that bona-fide NK cells that have degranulated were increased in patients and, additionally, these NK cells exhibit trogocytosis of solid tumor Ag on their surface. However, the frequency of NK cells that have trogocytosed is very low and much lower than that found in hematological cancer patients, suggesting that the number of NK cells that exit the tumor environment is scarce. To our knowledge, this is the first report describing the presence of solid tumor markers on circulating NK subsets from breast tumor patients. This NK cell immune profiling could lead to generate novel strategies to complement established therapies for BC patients or to the use of peripheral blood NK cells in the theranostic of solid cancer patients after treatment.Copyright © 2023 Campos-Mora, Jacot, Garcin, Depondt, Constantinides, Alexia and Villalba.