

Victorian researchers have found newborn babies with hyperactive immune cells in their cord blood are more likely to develop allergies to milk, eggs, peanuts, wheat and other common foods by the age of one.

It is hoped the finding could lead to future treatments during or before pregnancy to prevent childhood food allergies, which are on the rise in Australia and affect 10% of babies in Melbourne before they are 12 months old.

Researchers have struggled to pinpoint why allergies are rising, with a number of factors suspected to be behind the phenomenon.

The research was led by the Walter and Eliza Hall Institute, which used food allergy information and cord blood stores collected from 1,000 women and their babies through the Barwon Infant Study.

Professor Len Harrison, a co-author of the study from the University of Melbourne, said there was a lot of interest in cord blood because it provided a rich source of stem cells, which develop into many different cell types in the body during early life and growth.

“Through analysing the cord blood we showed there was this relationship between food allergies in the babies and the activation of the monocytes in their cord blood,” Harrison said.

“Monocytes are the less specialised types of immune cells which respond immediately to things like infections and the activation of these were a signifier of future high risk of food allergy.”

The researchers also showed that the activation of these monocytes could change the character of T-cells, a type of white blood cell that plays a central role in immunity, so that they were predisposed to cause allergic reactions to some foods.

“Now we’ve pinpointed this, the question is: what’s driving it, what is priming the immune system to be more reactive?” Harrison said. “Is it something that occurred during birth or before?

“The incidence of food allergy has been increasing over the years so it can’t be just genes. It must be to do with how the environment is also influencing and changing gene expression.”

The researchers will now go back to their data on the mothers and examine factors such as their diet, lifestyles and exposure to environmental toxins to see if they might be involved in triggering the hyperactive immune cells.

“There’s a whole host of factors that might impact on this state of inflammation that we have to work through,” Harrison said.

The findings were published in the medical journal Science Translational Medicine on Thursday.

Associate Professor Peter Vuillermin, a paediatrician who leads the Barwon Infant Study, said childhood food allergies were not only becoming more common in Australia but more severe.

“The evidence for that is fairly unequivocal,” he said. “There has been a threefold increase in hospital presentations due to food allergy over recent decades and most of this increase has been among children under five years of age.

“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.”

Dr Robert Loblay, a clinical immunologist and the director of the Royal Prince Alfred hospital’s allergy unit in Sydney, described the study findings as interesting.

“It is plausible that they have provided in their findings a mechanistic explanation for susceptibility to food allergy and I await further results with interest,” he said.