Definition:
A "killer cell" is a type of immune system cell, specifically a T cell that has a special marker called the CD8 receptor. These cells play a crucial role in the body’s defense against infections, especially viruses. When a virus infects a cell, the killer cell can recognize this infected cell by finding specific signs (called antigens) on its surface. Once it identifies the infected cell, the killer cell binds to it and destroys it to help keep the body healthy.
In more advanced discussions, you might encounter terms like "cytotoxic T lymphocytes," which is another name for killer cells. Researchers study killer cells to develop better treatments for diseases like cancer, where these cells can be used to target and destroy cancerous cells.
In a non-scientific context, "killer" can also be used informally to mean something that is very impressive or excellent. For example: - "That movie was a killer!" (meaning it was fantastic).
While "killer cell" does not have specific idioms or phrasal verbs associated with it, the word "killer" can appear in various idiomatic expressions: - "Killer instinct": The ability to act decisively and effectively, often in competitive situations. - "Killer app": A software application that is so useful or desirable that it drives sales of the product it is associated with.
Understanding "killer cell" helps you appreciate how our immune system works to protect us from illnesses.