Scientists have discovered a new type of immune cell in a small aquatic animal called a planarian flatworm. These special cells, named 'ruptoblasts,' act like tiny explosives. When they detect a threat, they rapidly self-destruct, destroying nearby bacteria and foreign tissue. This explosive cell death process is called 'ruptosis.'
The discovery was made by researchers at Stanford University while studying how flatworms heal. Planarian flatworms are known for their amazing ability to regrow lost body parts. The scientists were testing how these worms react to tissue from other worms. They found that when worms were given unfamiliar tissue, they had a strong inflammatory reaction and died.
During this process, the researchers noticed a large amount of a hormone called activin. When they injected activin into normal flatworms, it caused a similar strong inflammation. Using advanced imaging, they identified the ruptoblasts as the cells responsible for this reaction.
Unlike cell death in humans, which can take hours, ruptosis happens very quickly, within seconds to minutes. A single ruptoblast can destroy up to 70 surrounding cells, including bacteria like E. coli. The researchers were surprised by the speed and effectiveness of this defense mechanism. Interestingly, these exploding cells are not like human immune cells and are found only in very ancient animal groups. Scientists believe flatworms can use this explosive defense because they have many stem cells to quickly repair any damage to their own tissue, something humans cannot do as easily.