killer cell

noun

, Immunology.

1. any of several types of lymphocyte or leukocyte capable of destroying cells that have acquired foreign characteristics, as a tumor cell or virus-infected cell.

killer cell

noun

1. a type of white blood cell that is able to kill cells, such as cancer cells and cells infected with viruses

Example Sentences

When it encounters a real infection, the entire immune military of trained antibodies and killer cells can then rapidly spur to life, nixing the invader before they have a chance to spread or reproduce.

From Singularity Hub 

So if you’re in a good mood, and your serotonin levels are healthy, that’s going to produce T cells and natural killer cells, which are like the James Bond of the immune system.

From Nautilus