Natural killer (NK) cells can kill cancer cells via antibody-dependent cell-mediated cytotoxicity (ADCC): a tumor-associated IgG antibody binds to the Fc receptor CD16 on NK cells via the antibody Fc region and activates the cytotoxic functions of the NK cell. Here, we used PET imaging to assess NK cell migration to human epidermal growth factor receptor 2 (HER2)–positive HCC1954 breast tumors, examining the influence of HER2-targeted trastuzumab antibody treatment on NK cell tumor accumulation. Methods: Human NK cells from healthy donors were expanded ex vivo and labeled with [⁸⁹Zr]Zr-oxine. In vitro experiments compared the phenotypic markers, viability, proliferation, migration, degranulation, and ADCC behaviors of both labeled (⁸⁹Zr-NK) and unlabeled NK cells. Female mice bearing orthotopic human breast HCC1954 tumors were administered ⁸⁹Zr-NK cells alongside trastuzumab treatment or a sham treatment and then scanned using PET/CT imaging over 7 d. Flow cytometry and -counting were used to analyze the presence of ⁸⁹Zr-NK cells in liver and spleen tissues. Results: ⁸⁹Zr cell radiolabeling yields measured 42.2% ± 8.0%. At an average specific activity of 16.7 ± 4.7 kBq/10⁶ cells, ⁸⁹Zr-NK cells retained phenotypic and functional characteristics including CD56 and CD16 expression, viability, migration, degranulation, and ADCC capabilities. In vivo PET/CT studies indicated predominant accumulation of ⁸⁹Zr-NK cells in the liver and spleen. Ex vivo analyses of liver and spleen tissues indicated that the administered human ⁸⁹Zr-NK cells retained their radioactivity in vivo and that ⁸⁹Zr did not transfer to cells of murine soft tissues, thus validating this ⁸⁹Zr PET method for NK cell tracking. Notably, ⁸⁹Zr-NK cells migrated to HER2-positive tumors, both with and without trastuzumab treatment. Trastuzumab treatment was associated with an increased ⁸⁹Zr-NK cell signal at days 1 and 3 after injection. Conclusion: In vitro, ⁸⁹Zr-NK cells maintained key cellular and cytotoxic functions. In vivo, ⁸⁹Zr-NK cells trafficked to HER2-postive tumors, with trastuzumab treatment correlating with enhanced ⁸⁹Zr-NK infiltration. This study demonstrates the feasibility of using PET to image ⁸⁹Zr-NK cell infiltration into solid tumors.

自然杀伤（NK）细胞可以通过抗体依赖性细胞介导的细胞毒性（ADCC）杀死癌细胞：肿瘤相关的 IgG 抗体通过抗体 Fc 区与 NK 细胞上的 Fc 受体 CD16 结合，激活 NK 的细胞毒功能细胞。在这里，我们使用 PET 成像来评估 NK 细胞向人表皮生长因子受体 2 (HER2) 阳性 HCC1954 乳腺肿瘤的迁移，检查 HER2 靶向曲妥珠单抗抗体治疗对 NK 细胞肿瘤积累的影响。方法：来自健康供体的人 NK 细胞离体扩增并用 [ ⁸⁹ Zr]Zr-oxine 标记。体外实验比较了标记 ( ⁸⁹ Zr-NK) 和未标记 NK 细胞的表型标记、活力、增殖、迁移、脱颗粒和 ADCC 行为。携带原位人乳腺 HCC1954 肿瘤的雌性小鼠在曲妥珠单抗治疗或假治疗的同时接受⁸⁹ Zr-NK 细胞治疗，然后使用 PET/CT 成像进行扫描超过 7 天。使用流式细胞术和计数来分析肝和脾组织中^89个Zr-NK细胞的存在。结果： ⁸⁹ Zr 细胞放射性标记产率为 42.2% ± 8.0%。在平均比活性为 16.7 ± 4.7 kBq/10 ^{6 个}细胞时， ^{89 个}Zr-NK 细胞保留了表型和功能特征，包括 CD56 和 CD16 表达、活力、迁移、脱颗粒和 ADCC 能力。体内 PET/CT 研究表明⁸⁹ Zr-NK 细胞主要积聚在肝脏和脾脏中。 肝和脾组织的离体分析表明，所施用的人⁸⁹ Zr-NK 细胞在体内保留了其放射性，并且⁸⁹ Zr 没有转移到小鼠软组织细胞中，从而验证了这种用于 NK 细胞追踪的⁸⁹ Zr PET 方法。值得注意的是，无论是否接受曲妥珠单抗治疗，都有^{89 个}Zr-NK 细胞迁移至 HER2 阳性肿瘤。曲妥珠单抗治疗与注射后第 1 天和第 3 天的⁸⁹ Zr-NK 细胞信号增强相关。结论：在体外， ^{89 个}Zr-NK 细胞保持了关键的细胞和细胞毒功能。在体内， ⁸⁹ Zr-NK 细胞被转运至 HER2 阳性肿瘤，曲妥珠单抗治疗与增强的⁸⁹ Zr-NK 浸润相关。本研究证明了使用 PET 对⁸⁹ Zr-NK 细胞浸润实体瘤进行成像的可行性。