Why children like to eat dirt? Researchers provides a surprising answer

February 13, 2013 5:35 pm

Why children like to eat dirt? Researchers provides a surprising answer

Why-children-like-to-eat-dirt--Researchers-provides-a-surprising-answerImmune cells never forgets. This is the reason for which vaccines become immune function: immune cells “remember” the pathogen and build an alert system that allows to identify and fight it where it is. A new study by researchers at Stanford University adds a new element to the old theory of immunity. It seems that immune cells can develop these “memories” even pathogens that have not met before. This might be due to exposure to microbes harmless, or it is possible that these memories are borrowed from other cells, more experienced.

The discovery could explain why babies and very young children are susceptible to infectious diseases. They were not exposed to enough germs harmless so that their immune systems to develop the “precognition” that allows them to fight against pathogens. “Our findings could provide even a hint on why evolutionary children eat dirt,” said study author Mark Davis, a microbiologist and immunologist at Stanford. Children are attracted to the earth because they feel the need to express their fragile immune systems from microbes to build a defense system.

Davis and his colleagues studied a group of cells called CD4 T cells, the same cells that are attacked by HIV. CD4 cells are found in our blood stream where they stand “guard”, initiating an alarm signal when the cell identifies a foreign agent. CD4 cells are divided into two classes: naive cells that were not exposed to a pathogen and need some time to react, and memory cells, which have already fought a pathogen and are already in quest. Memory cells can respond in a few hours, while naive cells may require days or even weeks, during which we get sick.

Decades ago, Davis found that CD4 cells rearrange their DNA when they divide, creating an army of T cells that are capable of highly specific recognition of pathogens. According to this new study, this ability could help to identify cells and pathogens that have not met.

The researchers studied blood samples from 26 healthy adults and identified T cells that react to different pathogens. Half of the cells seemed to be able memory, that seemed to be met in the past that pathogen. Then, Davis and colleagues tested people, discovering that in fact had never been exposed to these diseases. Then, the researchers tried the same thing newborns using blood taken from the umbilical cord and discovered that babies were naive cells.

To further test this hypothesis, researchers turned to two adults who are not anti-influenza vaccinaseră the last 5 years and who have received the vaccine. After being invaded by this deadly virus, which aims to provide one nine memory CD4 cells, memory CD4 cells spread in their body. Interestingly, some cells have “remembered” by different bacterial cell structures that had nothing to do with flu.

How naive cells manage this? Environment is key. Humans are constantly exposed to numerous bacteria and viruses. “These” memories “of pathogens which our immune system has not never met might be due to our constant exposure to microorganisms harmless in soil, food, skin, the door handle on the phones and headphones for iPod “explains Davis.

So do not worry about the billions of bacteria, mostly harmless, with whom we come into contact every moment. It helps the immune system to be ready to fight pathogens.