Objective

Natural killer (NK) cells are part of the innate immune system which not only provides a primary response to pathogenic conditions but can also play an important regulatory role in immune responses. Furthermore, these cells can influence immune responses by affecting other involved cells. Human NK cells can be classified as CD56^dim and CD56^bright; the former demonstrates mostly cytotoxic effects, while the latter comprises mostly tolerant or regulatory NK cells. These cells participate in the immunopathogenesis of rheumatoid arthritis (RA) and their role remains still unclear.

Methods

We searched PubMed/MEDLINE and Scopus databases to review and analyze relevant literature on the impact of NK cells in the pathogenesis of RA.

Results

Although the percentage of NK cells increases in peripheral blood of RA patients compared to healthy individuals, the cytotoxic function of these cells is impaired. It is demonstrated by reduced “perforin⁺ NK cells” and decreased per-cell lytic function. These cytotoxic NK cells may control the pathogenic bone absorptive function of osteoclasts by directly targeting these cells.

Conclusion

Collectively, the evidence collected in the current review emphasizes the possible protective role of CD56^dim NK cells in the pathogenesis of RA.

中文翻译：

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NK细胞在类风湿关节炎中的作用

客观的

自然杀伤 (NK) 细胞是先天免疫系统的一部分，它不仅提供对致病条件的主要反应，而且还可以在免疫反应中发挥重要的调节作用。此外，这些细胞可以通过影响其他相关细胞来影响免疫反应。人类 NK 细胞可分为 CD56 ^dim和 CD56 ^bright；前者主要表现出细胞毒性作用，而后者主要包括耐受性或调节性 NK 细胞。这些细胞参与类风湿性关节炎 (RA) 的免疫发病机制，其作用仍不清楚。

方法

我们检索了 PubMed/MEDLINE 和 Scopus 数据库，以回顾和分析有关 NK 细胞在 RA 发病机制中影响的相关文献。

结果

尽管与健康个体相比，RA 患者外周血中 NK 细胞的百分比增加，但这些细胞的细胞毒性功能受损。它表现为“穿孔素⁺ NK 细胞”减少和每细胞溶解功能降低。这些细胞毒性 NK 细胞可以通过直接靶向这些细胞来控制破骨细胞的致病性骨吸收功能。

结论

总的来说，当前综述中收集的证据强调了 CD56^暗淡NK 细胞在 RA 发病机制中的可能保护作用。