"This helper T cell is like the busboy on the cruise line. He takes a look at the piece of shark, takes a little nibble, realizes it's a shark for sure, and runs off to tell a cook about what he found! The cook, a white blood cell called a B cell, listens to the little helper T cell, realizes that it is indeed a unique shark, and turns into another white blood cell called a plasma cell that is like the head chef on the ship. Basically, the cook got promoted to head chef because he realized there's a unique species of shark in the water that can be caught and used for dinner."

The article relates the immune system and a cruise ship.