The OX40-OX40L molecule system in leukemia: Expression, function and modulation of NK cell reactivity

NK细胞在恶性肿瘤，特别是白血病的免疫监视中起着重要作用。它们的反应性由来自各种激活和抑制受体的信号平衡指导，TNF家族的几个成员也有同样的作用。通常，TNF家族的许多分子在肿瘤和免疫效应细胞的活化、增殖和凋亡中起重要作用。其他研究人员最近报道，在活化时，NK细胞可以表达TNF家族成员OX 40配体（OX 40 L），已知其主要由抗原呈递细胞（APC）表达，其中其充当T细胞上OX 40的配体。与TNF家族的许多其他配体一样，OX 40 L能够阻断双向信号，并且发现通过OX 40 L的这种反向信号传导影响APC的免疫调节特性。OX 40 L对NK细胞的功能作用以及它们与肿瘤细胞的相互作用尚不清楚。在该项目的初步工作中，我们发现通过不同方案产生的用于过继转移至癌症患者的临床用途的多克隆NK细胞差异表达OX 40 L。经由0X 40 L向NK细胞中的信号传导导致NK细胞的活化（CD 69和NKp 44的上调）和增强的IFN-γ产生。此外，我们已经产生了针对同源受体OX 40的单克隆抗体并对其进行了功能表征。使用这些抗体，我们可以表明OX 40在患者白血病细胞上以高百分比表达，主要在AML中。OX 40的刺激导致释放病理生理学相关的细胞因子并增加白血病细胞的代谢活性。关于NK细胞对恶性细胞的免疫监视中分子系统的功能相关性，进一步的初步数据显示，OX 40-OX 40 L相互作用增加了NK细胞对靶细胞的反应性。拟议的项目现在旨在全面分析来自各种白血病实体患者的更大样本队列中OX 40的表达，以及其作为疾病的预后标志物的适合性。此外，我们计划研究OX 40是否以及如何影响白血病细胞的增殖，凋亡，细胞因子的产生和免疫原性。最后，OX 40 L对NK细胞反应性的影响将被彻底研究，特别强调其在与恶性造血细胞相互作用中的作用。因此，该项目的总体目标是表征OX 40及其配体在白血病细胞的NK细胞免疫监视中的功能，目的是在患者中进行潜在的治疗调节。

NK cells play an important role in the immunosurveillance of malignancies, especially in leukemia. Their reactivity is guided by a balance of signals from a variety of activating and inhibitory receptors, and several members of the TNF family contribute to the same. In general, many molecules of the TNF family play an important role in the activation, proliferation, and apoptosis of both tumor and immune effector cells. Other investigators reported recently, that upon activation NK cells can express the TNF family member OX40 ligand (OX40L), which primarily is known to be expressed by antigen presenting cells (APC), where it serves as ligand for OX40 on T cells. Alike many other ligands of the TNF family, OX40L is capable to transduce bidirectional signals, and such reverse signaling via OX40L was found to affect the immunomodulatory properties of APC. The functional role of OX40L on NK cells in general and their interaction with tumor cells in particular is yet unknown. In the preliminary work for this project we found that polyklonal NK cells, generated by different protocols for clinical use in adoptive transfer to cancer patients, differentially express OX40L. Signaling via OX40L into NK cells led to activation (upregulation of CD69 and NKp44) and enhanced IFN-gamma production of the NK cells. Furthermore, we already generated and functionally characterized monoclonal antibodies against the cognate receptor OX40. Using these antibodies we could show that OX40 is expressed in a high percentage on patient leukemia cells, predominantly in AML. Stimulation of OX40 lead to release of pathophysiologically relevant cytokines and increased metabolic activity of the leukemia cells. With regard to the functional relevance of the molecule system in the immunosurveillance of malignant cells by NK cells, further preliminary data revealed that OX40-OX40L interaction increased the reactivity of NK cells against target cells.The proposed project now aims to comprehensively analyze the expression of OX40 in a larger cohort of samples from patients with various leukemia entities, and also its suitability as a prognostic marker in the disease. Furthermore we plan to study whether and how OX40 affects proliferation, apoptosis, cytokine production and immunogenicity of leukemia cells. Finally, the influence of OX40L on the reactivity of NK cells will be thoroughly examined with particular emphasis on its role in their interaction with malignant hematopoietic cells. The overall objective of this project thus is to characterize the function of OX40 and its ligand in NK cell immunosurveillance of leukemia cells with the aim of a potential therapeutic modulation in patients.