Background:Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a potentially curative treatment for high-risk acute myeloid leukemia and myelodysplastic neoplasms (AML/MDS). However, AML/MDS relapse post-transplant is driven by immune escape mechanisms, limiting treatment options and contributing to poor prognosis. Granulocyte–Macrophage Colony-Stimulating Factor (GM-CSF) and Prostaglandin-E1 (PGE-1) (termed “Kit M”) induce dendritic cells of leukemic origin (DCleu) that have been shown to induce antileukemic immune responses.Methods:Using flow cytometry, we analyzed ICM/ICML-expressing uncultured T-cells/blasts in whole blood (WB) samples from patients with AML/MDS relapse post-allo-HCT who had received salvage treatment. Using Kit M, DCleuwere generated ex vivo. T-cell-enriched mixed-lymphocyte cultures (MLC) were performed for functional assessment of DC/DCleuto stimulate (leukemia specifically) patients’ immune cells. After MLC, ICM/ICML-expressing cells and immune activation were assessed. The experimental results were correlated with patients’ clinical responses to salvage treatment.Results: WB samples from 15 patients were analyzed. On average, high frequencies of ICM (CTLA4/PD1)-co-expressing blasts and high frequencies of ICM (CTLA4/PD1/TIGIT/TIM3/2B4)-co-expressing T-cells were found in uncultured WB, compared to the frequencies of healthy ICM-expressing T-cells. Treatment with Kit M induced DC/DCleu, which, after MLC, downregulated ICM-expressing T-cells and enhanced activated and memory T-cells. High frequencies of ICM-co-expressing uncultured T-cells/blasts correlated negatively with the blast lysis capacity and patients’ clinical response to relapse treatment. However, post-MLC, Kit-mediated modulation of ICM-expressing T cells did not correlate with blast lysis, nor with patients’ clinical response to treatment.Conclusions:We conclude that Kit M contributes to overcoming impaired antileukemic reactions, independent of the presence of ICM-expressing T-cells in relapsed AML patients after allo-HCT ex vivo.
背景：异基因造血干细胞移植（allo-HCT）是治疗高危急性髓系白血病和骨髓增生异常肿瘤（AML/MDS）的一种潜在根治性疗法。然而，移植后AML/MDS的复发由免疫逃逸机制驱动，限制了治疗选择并导致预后不良。粒细胞-巨噬细胞集落刺激因子（GM-CSF）和前列腺素E1（PGE-1）（合称“Kit M”）可诱导白血病来源的树突状细胞（DCleu），该细胞已被证明能诱导抗白血病免疫反应。 方法：我们采用流式细胞术，分析了接受挽救治疗的allo-HCT后AML/MDS复发患者全血样本中未经培养的、表达免疫检查点分子（ICM）/免疫检查点配体（ICML）的T细胞/原始细胞。利用Kit M，我们在体外生成了DCleu。随后进行T细胞富集的混合淋巴细胞培养，以功能性地评估DC/DCleu刺激（特别是针对白血病）患者免疫细胞的能力。混合淋巴细胞培养后，我们检测了表达ICM/ICML的细胞及免疫活化状态。实验结果与患者对挽救治疗的临床反应进行了相关性分析。 结果：共分析了15例患者的全血样本。与健康人表达ICM的T细胞频率相比，在未经培养的全血样本中，平均发现了高频率共表达ICM（CTLA4/PD1）的原始细胞，以及高频率共表达ICM（CTLA4/PD1/TIGIT/TIM3/2B4）的T细胞。Kit M处理诱导产生了DC/DCleu，经混合淋巴细胞培养后，这些细胞下调了表达ICM的T细胞，并增强了活化及记忆性T细胞。高频率共表达ICM的未经培养T细胞/原始细胞与原始细胞裂解能力及患者对复发治疗的临床反应呈负相关。然而，混合淋巴细胞培养后，Kit介导的对表达ICM的T细胞的调节，与原始细胞裂解能力或患者对治疗的临床反应均无相关性。 结论：我们得出结论，Kit M有助于克服allo-HCT后复发AML患者体内受损的抗白血病反应，且该作用与体外环境中表达ICM的T细胞的存在无关。
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