Objective Vaccination against hepatitis B virus (HBV) confers protection from subsequent infection through immunological memory that is traditionally considered the domain of the adaptive immune system. This view has been challenged following the identification of antigen-specific memory natural killer cells (mNKs) in mice and non-human primates. While the presence of mNKs has been suggested in humans based on the expansion of NK cells following pathogen exposure, evidence regarding antigen-specificity is lacking. Here, we demonstrate the existence of HBV-specific mNKs in humans after vaccination and in chronic HBV infection. Design NK cell responses were evaluated by flow cytometry and ELISA following challenge with HBV antigens in HBV vaccinated, non-vaccinated and chronic HBV-infected individuals. Results NK cells from vaccinated subjects demonstrated higher cytotoxic and proliferative responses against autologous hepatitis B surface antigen (HBsAg)-pulsed monocyte-derived dendritic cells (moDCs) compared with unvaccinated subjects. Moreover, NK cell lysis of HBsAg-pulsed moDCs was significantly higher than that of hepatitis B core antigen (HBcAg)-pulsed moDCs (non-vaccine antigen) or tumour necrosis factor α-activated moDCs in a NKG2D-dependent manner. The mNKs response was mediated by CD56dim NK cells coexpressing CD57, CD69 and KLRG1. Further, mNKs from chronic hepatitis B patients exhibited greater degranulation against HBcAg-pulsed moDCs compared with unvaccinated or vaccinated patients. Notably, mNK activity was negatively correlated with HBV DNA levels. Conclusions Our data support the presence of a mature mNKs following HBV antigen exposure either through vaccination or infection. Harnessing these antigen specific, functionally active mNKs provides an opportunity to develop novel treatments targeting HBV in chronic infection.

中文翻译：

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HBV疫苗接种和HBV感染诱导HBV特异性自然杀伤细胞记忆

目的 乙型肝炎病毒 (HBV) 疫苗接种可通过传统上被认为是适应性免疫系统领域的免疫记忆来防止随后的感染。在小鼠和非人类灵长类动物中鉴定出抗原特异性记忆自然杀伤细胞 (mNK) 后，这一观点受到了挑战。虽然根据病原体暴露后 NK 细胞的扩增，已经表明人类中存在 mNK，但缺乏关于抗原特异性的证据。在这里，我们证明了人类接种疫苗后和慢性 HBV 感染中存在 HBV 特异性 mNK。在接种 HBV 疫苗、未接种疫苗和慢性 HBV 感染者中用 HBV 抗原攻击后，通过流式细胞术和 ELISA 评估设计 NK 细胞反应。结果 与未接种疫苗的受试者相比，接种疫苗受试者的 NK 细胞对自体乙型肝炎表面抗原 (HBsAg) 脉冲的单核细胞衍生树突细胞 (moDC) 表现出更高的细胞毒性和增殖反应。此外，HBsAg 脉冲的 moDCs 的 NK 细胞裂解显着高于乙型肝炎核心抗原 (HBcAg) 脉冲的 moDCs（非疫苗抗原）或肿瘤坏死因子 α 激活的 moDCs，以 NKG2D 依赖性方式。mNKs 反应由共表达 CD57、CD69 和 KLRG1 的 CD56dim NK 细胞介导。此外，与未接种疫苗或接种疫苗的患者相比，来自慢性乙型肝炎患者的 mNKs 对 HBcAg 脉冲的 moDCs 表现出更大的脱颗粒作用。值得注意的是，mNK 活性与 HBV DNA 水平呈负相关。结论我们的数据支持在通过疫苗接种或感染接触 HBV 抗原后存在成熟的 mNK。利用这些抗原特异性、功能活跃的 mNKs 提供了开发针对慢性感染中 HBV 的新型治疗方法的机会。