Some children can handle scarf peanuts, but only one nut can kill others. A new study suggests one reason why children develop life-threatening food allergies. At birth, their blood is rich with cells that can promote a hyperactive immune response.
Previous studies of some of the approximately 6 million young Americans who develop food allergies suggest that abnormalities begin to brew earlier. By sampling the baby's blood from the umbilical cord, researchers can get a quick overview of the immune system of the child. They found that the blood of children who later develop food allergies contains more chemical signals that promote inflammation, and lower than normal concentrations of natural regulatory T cells, the immune system responses low tone.
To understand what changes could be key to the development of allergy, Zhang Yuxia immunologist of the Walter and Eliza Hall Institute of Medical Research in Parkville, Australia, and colleagues recruited over 1,000 new -nés. The researchers analyzed the immune cells in blood samples from the umbilical cord of children. Then when the children were aged 1 year, the team tested whether they were allergic to a range of foods, including eggs, cow's milk, and peanuts.
The young children who had food allergies also showed a higher number of a type of white blood cells called monocytes at birth. Monocytes form the reserves of the immune system. When we get sick, they turn into cells such as macrophages that fight pathogens. Zhang and his colleagues found that children prone allergies monocytes are not only more numerous, they were also hyperactive, react more vigorously to bacterial molecule that makes monocytes children with allergies. In other words, they responded more aggressively to apparent threats made monocytes in toddlers who develop allergies.
Previous studies have not linked hyperactive monocytes food allergies in childhood, the researchers tested the cells' effects on other immune cells. In culture dishes, the signals emitted by monocytes of allergic children caused natural regulatory T cells that normally suppress allergic reactions to the contrary; they turned into T helper cells that drive these reactions. monocytes molecular messages also stimulate the "undecided" T helper cells to convert into T helper cells allergy-promotion, the researchers report online today in Science Translational Medicine .
What do these results, Zhang suggests, is that the immune system of some children "at birth has already begun" to develop allergies. Why allergy-prone children are born with hyperactive monocytes is not clear, said Zhang. A mother may be exposed to something during pregnancy, perhaps in his food, which changes the developing immune system of children. Genetic differences could also influence the sensitivity of monocytes.
"There is a mechanism highlighting somewhat different from that which has been shown before," said immunologist Oliver Burton Children's Hospital Boston, who was not connected to the 'study. But the large number of children in the study and careful analysis the authors make credible results, he said.
"The document provides laboratory tests to show that infants who develop food allergies may be different from newborns who don 't," says allergist and clinical immunologist Marshall Plaut of the Institute National allergy and infectious diseases in Bethesda, Maryland. He cautions, however, that researchers have yet to confirm that monocytes in the release of the body the same chemical signals than those released by the monocytes in the laboratory.
Because the chemical signals released by hyperactive monocytes promote inflammation, the study implies that the suppression of inflammation may curb allergies. Scientists suggest that we need more research on the measures, such as changing the food system of the mother, which could reduce inflammation.
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