NK cells kill their target cells by releasing cytotoxic granules in their cytoplasm directly into the target cell.

NK细胞通过释放胞质内的细胞毒颗粒直接进入靶细胞内，来杀死靶细胞。

If the pathogen was a virus, NK cells would help destroy the infected cells at this point.

如果病原体是病毒，此时NK细胞会帮助摧毁被感染的细胞。

B and T cells make up the adaptive immune system, while NK cells are part of the innate immune system.

B细胞和T细胞组成了适应性免疫系统，而NK细胞是固有免疫系统的一部分。

NK cells are large lymphocytes with granules and they target cells infected with intracellular organisms, like viruses, as well as cells that pose a threat like cancer cells.

NK细胞是有颗粒的大淋巴细胞，它们靶向被细胞内病原体（如病毒）感染的细胞，还有像癌细胞这样构成威胁的细胞。

B cells and NK cells complete their development where they started - in the bone marrow, whereas some lymphoid progenitor cells migrate to the thymus where they develop into T cells.

B细胞和NK细胞在它们产生的地方（骨髓中）完成发育，而一些淋巴系组细胞会迁移到胸腺，在那里它们发育成为T细胞。