In vivo imaging of T Cells using engineered antibodies and PET

描述(申请人提供)：炎症和免疫反应在大多数影响人类健康的主要疾病中发挥核心作用，包括癌症、心血管疾病、自身免疫、神经炎症过程、糖尿病和其他疾病。此外，免疫调节疗法和过继细胞疗法已被确定为癌症的有效治疗方法。监测和区分免疫细胞亚群(如T和B淋巴细胞、巨噬细胞、中性粒细胞等)的能力体内无创治疗将对有效治疗的发展具有不可估量的价值。正电子发射断层成像(PET)提供了高灵敏度、非侵入性和定量的成像，它可以与基于抗体的探针相结合，根据细胞表面的表型提供体内组织和细胞的分子成像。此外，已经开发出具有最佳动力学的工程化抗体片段(微抗体和半胱氨酸)，使免疫PET能够快速体内靶向和清除成像应用。在这项拟议的工作中，将开发免疫PET来解决免疫细胞亚群直接成像的挑战。工程抗体片段将被优化，用于体内检测、成像和定量表达CD8的T淋巴细胞，CD8是细胞毒性T细胞的标志。具体目标1将致力于生产稳定的、优化的抗CD8微抗体和来源于大鼠抗鼠单抗的Cys-diabies。特定目标2将建立正常(野生型)小鼠淋巴器官可视化的最佳显像剂、剂量和成像方案。具体目标3将侧重于对正常和免疫刺激小鼠的T细胞进行定量，以确定在小鼠模型中检测的参数和限度。一旦得到验证，CD8 T细胞的免疫PET探针将成为研究小鼠模型中免疫过程的宝贵工具，提供对生物体内免疫反应的更深入了解，并将为临床前模型以及最终人类中免疫细胞亚群的成像和定量打开大门。

DESCRIPTION (provided by applicant): Inflammation and immune responses play a central role in most of the major diseases that impact human health, including cancer, cardiovascular disease, autoimmunity, neuroinflammatory processes, diabetes and other diseases. In addition, immunomodulatory therapies and adoptive cell therapies have become established as powerful therapeutic approaches in cancer. The ability monitor and distinguish immune cell subsets (e.g. T and B lymphocytes, macrophages, neutrophils, etc.) noninvasively in vivo will be invaluable to the development of effective treatments. Positron emission tomography (PET) provides highly sensitive, non- invasive and quantitative imaging, which can be combined with antibody-based probes to provide molecular imaging of tissues and cells in vivo based on cell surface phenotype. Furthermore, engineered antibody fragments (minibodies and cys-diabodies) have been developed with optimal kinetics enabling rapid in vivo targeting and clearance for imaging applications by immunoPET. In the proposed work, immunoPET will be developed to address the challenge of direct imaging of immune cell subsets. Engineered antibody fragments will be optimized for in vivo detection, imaging, and quantitation of T lymphocytes that express CD8, a marker that is a hallmark of cytotoxic T cells. Specific Aim 1 will focus on production of stable, optimized anti-CD8 minibodies and cys-diabodies derived from rat anti-mouse monoclonal antibodies. Specific Aim 2 will establish the optimal imaging agent, dose, and imaging protocol for visualization of the lymphoid organs in normal (wild-type) mice. Specific Aim 3 will focus on quantitation of T cells in normal and immune-stimulated mice to determine the parameters and limits of detection in mouse models. Once validated, immunoPET probes for CD8 T cells will be valuable tools to study immune processes in mouse models, providing a deeper understanding of immune responses in living organisms, and will open the door to broad methods for imaging and quantitating immune cell subsets in preclinical models and eventually humans.