Toll-like receptor facts for kids

Toll-like receptors (TLRs) are special proteins found in your body. Think of them as tiny guards on the outside of your cells. They are part of your body's natural defense system, called the innate immune system. They also play a role in your digestive system.

These TLRs stretch from the outside of a cell to the inside, like a bridge. Their main job is to spot tiny invaders, like germs (microbes). When germs get past your body's first defenses, like your skin or the lining of your intestines, TLRs are there to recognize them.

Once a TLR spots a germ, it sends a signal inside the cell. This signal tells your immune cells to start fighting. It can turn on or off thousands of genes that help control how your body reacts to the infection. TLRs are super important for starting your body's defense. They also help connect your quick, natural immune response to your more specific, long-term defense, called adaptive immunity. They do this by being present in special cells called dendritic cells.

Many Types of TLRs

Most mammals, including humans, have about ten to fifteen different kinds of Toll-like receptors. Humans and mice have thirteen types, from TLR1 to TLR13. Other mammals have similar ones.

However, not all TLRs are exactly the same in every mammal. For example, humans have a TLR10, but mice have a damaged version of that gene. On the other hand, mice have TLRs 11, 12, and 13, which humans do not have. Other animals might have TLRs that are not found in humans at all. Animals that are not mammals, like insects, can also have different types of TLRs.

How They Were Discovered

Toll-like receptors got their name from a gene called "Toll" found in the fruit fly, Drosophila. In 1985, a scientist named Christiane Nüsslein-Volhard discovered this gene. When the gene was changed, the flies looked very unusual. The scientists were so surprised that they shouted in German, "Das ist ja toll!" which means "That's great!"

Later, in 1996, another scientist, Jules A. Hoffmann, and his team found that the "Toll" gene was very important for the fly's defense against fungal infections. It helped the fly make special peptides, which are like tiny germ-fighting chemicals. Scientists also found similar proteins in plants, like rice in 1995 and Arabidopsis in 2000.

A scientist named Bruce A. Beutler and his team discovered how TLR4 works. They found that TLR4 helps the body sense a specific part of bacteria called lipopolysaccharide (LPS). They proved this by showing that mice with a broken TLR4 gene could not react to LPS. This discovery showed that TLR4 is a key part of the system that detects LPS.

Images for kids

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  The Toll immunity pathway as found in the fruit fly

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  The history of Toll-like receptors

See also

In Spanish: Receptor de tipo Toll para niños