Why Some Kids Have Allergies — and Some Don't

Beth Greenfield
Senior Editor

Kids’ allergies can seem so random. How else to explain why one child can inhale peanut butter by the spoonful while another can’t even be in the same room as the stuff? This week, a team of scientists believes they’ve found a way.

After studying more than 1,000 babies, immunologists led by Yuxia Zhang have discovered that those with so-called hyperactive immune cells at birth were more likely to develop allergies within their first year of life, noted press materials from the Walter + Eliza Hall Institute of Medical Research in Australia, where the researchers are based.

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For the study, published Thursday in the journal Science Translational Medicine, they began by analyzing the immune cells in the infants’ cord blood, then testing them at the age of 1 for allergies to eggs, cow’s milk, and peanuts.

“We found a link between children who had hyperactive immune cells at birth and the development of allergies to milk, eggs, peanuts, wheat, and other common foods in their first years of life,“ noted researcher Len Harrison.

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Added Zhang, “In at-risk babies, immune cells called monocytes were activated before or during birth. Signals from these cells encouraged the development of immune responses by specialized immune cells called T cells that were predisposed to cause allergic reactions to some foods.”

The finding could lead to future treatments for babies and infants to prevent childhood food allergies. But it did not shed any light on why so many kids seem to have allergies these days.

Associate Professor Vuillermin, a pediatrician who leads the Barwon Infant Study — a well-documented collection of data on childhood allergies that was used in Zhang’s study — said the uptick has been significant, at least in Australia. “There has been a three-fold increase in hospital presentations due to food allergy over recent decades, and most of this increase has been among children under 5 years of age,” he said. “In fact, up to 1 in every 10 babies in Melbourne develop food allergy during the first year of life.”

Still, he noted, “We don’t know why the increase in food allergy has occurred. The important thing about this study is that we’ve shown the immune systems of babies who develop food allergy are in a sense ‘primed’ for allergic disease by the time they are born.”

(Top photo: KidStock/Getty Images)

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