先前对 FMS 样酪氨酸激酶 3 配体 (FLT3L) 的研究主要集中于它们从骨髓祖细胞生成树突状细胞 (DC) 的潜力，但对这些细胞如何影响 CD8 T 细胞功能的了解有限。在本研究中，我们进一步研究了FLT3L对CD8 T细胞免疫调节能力的体内作用。白蛋白缀合的FLT3L（Alb-FLT3L）被生成并应用于转化医学目的；此处，它用于治疗初始 C57BL/6 和 OT1 小鼠，以进行 CD8 T 细胞反应分析。采用同基因 B16ova 和 E.G7ova 小鼠模型进行过继细胞转移，以评估 Alb-FLT3L 预处理 CD8 T 细胞对肿瘤进展的影响。为了揭示 Alb-FLT3L 调节的潜在机制，我们对 CD44high CD8 T 细胞进行了批量 RNA 测序分析。使用 STAT1 缺陷小鼠来阐明 Alb-FLT3L 在 T 细胞调节中的功能作用。最后，进行一型干扰素信号传导的抗体阻断以及浆细胞样 DC (pDC) 与初始 CD8 T 细胞的体外共培养，以确定 pDC 在介导 CD44high CD8 T 细胞调节中的作用。CD44high CD8 T 细胞在 C57BL/ 中得到增强。 6只小鼠接受Alb-FLT3L给药。这些CD8 T细胞表现出虚拟记忆特征，并具有更强的增殖和有效功能。值得注意的是，将 CD44high 幼稚 CD8 T 细胞过继转移到患有 B16ova 肿瘤的 C57BL/6 小鼠中，导致肿瘤显着消退。对 CD44high 幼稚 CD8 T 细胞的 RNA-seq 分析显示，FLT3L 以 JAK-STAT1 信号通路依赖性方式诱导 CD44high CD8 T 细胞，结果表明 FLT3L 在 STAT1 缺陷中增强 CD8 T 细胞增殖的能力下降。小鼠与野生型对照小鼠相比。此外，抗体阻断一型干扰素信号传导限制了FLT3L诱导的CD44high CD8 T细胞的产生，而与来自FLT3L处理小鼠的pDC共培养的幼稚CD8 T细胞能够诱导CD44表达。这表明 pDC 在介导 FLT3L 对 CD44high CD8 T 细胞的调节中发挥着至关重要的作用。这些发现提供了重要的见解并支持 Alb-FLT3L 作为免疫调节剂在癌症免疫治疗中预处理初始 CD8 T 细胞的治疗潜力。© 2024。是美国政府作品，在美国不受版权保护；外国版权保护可能适用。

Previous research in FMS-like tyrosine kinase 3 ligands (FLT3L) has primarily focused on their potential to generate dendritic cells (DCs) from bone marrow progenitors, with a limited understanding of how these cells affect CD8 T cell function. In this study, we further investigated the in vivo role of FLT3L for the immunomodulatory capabilities of CD8 T cells.Albumin-conjugated FLT3L (Alb-FLT3L) was generated and applied for translational medicine purposes; here it was used to treat naïve C57BL/6 and OT1 mice for CD8 T cell response analysis. Syngeneic B16ova and E.G7ova mouse models were employed for adoptive cell transfer to evaluate the effects of Alb-FLT3L preconditioning of CD8 T cells on tumor progression. To uncover the underlying mechanisms of Alb-FLT3L modulation, we conducted bulk RNA-seq analysis of the CD44high CD8 T cells. STAT1-deficient mice were used to elucidate the functional roles of Alb-FLT3L in the modulation of T cells. Finally, antibody blockade of type one interferon signaling and in vitro coculture of plasmacytoid DCs (pDCs) with naive CD8 T cells was performed to determine the role of pDCs in mediating regulation of CD44high CD8 T cells.CD44high CD8 T cells were enhanced in C57BL/6 mice administrated with Alb-FLT3L. These CD8 T cells exhibited virtual memory features and had greater proliferative and effective functions. Notably, the adoptive transfer of CD44high naïve CD8 T cells into C57BL/6 mice with B16ova tumors led to significant tumor regression. RNA-seq analysis of the CD44high naïve CD8 T cells revealed FLT3L to induce CD44high CD8 T cells in a JAK-STAT1 signaling pathway-dependent manner, as supported by results indicating a decreased ability of FLT3L to enhance CD8 T cell proliferation in STAT1-deficient mice as compared to wild-type control mice. Moreover, antibody blockade of type one interferon signaling restricted the generation of FLT3L-induced CD44high CD8 T cells, while CD44 expression was able to be induced in naïve CD8 T cells cocultured with pDCs derived from FLT3L-treated mice. This suggests the crucial role of pDCs in mediating FLT3L regulation of CD44high CD8 T cells.These findings provide critical insight and support the therapeutic potential of Alb-FLT3L as an immune modulator in preconditioning of naïve CD8 T cells for cancer immunotherapy.© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.