NK cells are thought to develop primarily in the bone marrow during adult life. However, increasing evidence shows that NK cell developmental intermediates can be found in different peripheral tissues with unique characteristics. Here, we identified a unique NK cell subset with the CD49a-CD49b- phenotype in the spleen. These cells displayed an immature phenotype and weak abilities in cytotoxicity and cytokine production. Adoptive transfer experiments revealed that they could develop into mature conventional NK (cNK) cells. Transcriptome analysis further confirmed their immature features. Parabiosis experiments revealed that these cells maintained tissue-resident properties in the spleen. Moreover, T-bet deficiency intrinsically impaired the ability of these cells to develop into mature cNK cells. Thus, our study identified a spleen-resident immature NK cell subset that could undergo extramedullary maturation in a T-bet dependent manner.

中文翻译：

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新型的脾脏未成熟NK细胞亚群及其以T-bet依赖的方式成熟。

人们认为NK细胞在成年后主要在骨髓中发育。但是，越来越多的证据表明，可以在不同的外周组织中发现具有独特特征的NK细胞发育中间体。在这里，我们确定了脾脏具有CD49a-CD49b-表型的独特NK细胞亚群。这些细胞表现出不成熟的表型和细胞毒性和细胞因子产生的能力较弱。过继转移实验表明它们可以发育成成熟的常规NK（cNK）细胞。转录组分析进一步证实了它们的不成熟特征。共生实验表明，这些细胞在脾脏中具有组织保留特性。此外，T-bet缺陷本质上削弱了这些细胞发育成成熟cNK细胞的能力。因此，