K cell

例句：

1. 1.The K cells in the blood are responsible for fighting off infections.
   血液中的K细胞负责抵抗感染。
2. 2. Researchers are studying how K cells can be used to treat cancer.
   研究人员正在研究如何利用K细胞治疗癌症。
3. 3. The immune system relies on K cells to fight off foreign invaders.
   免疫系统依赖于K细胞来抵御外来入侵者。