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Monday, 5 June, 2000, 23:13 GMT 00:13 UK
'Breakthrough' in battle against allergies
Allergy research
Research adds to knowledge about causes of allergies
The cause of some food allergies in children has been discovered, say scientists.

It is a small piece in a very large puzzle

Dr Hasan Arshad, David Hide Asthma and Allergy Centre
Researchers in the US say they have identified the role played by a key chemical and they believe the breakthrough could lead to the prevention of allergic reactions in children's guts.

The scientists at the Children's Hospital Medical Center of Cincinnati found that a chemical called eotaxin, a protein, controls inflammation of the intestine in allergic reactions.

Eotaxin draws a type of cell normally found in blood - eosinophils - into inflammatory tissue.

By genetically engineering mice without the eotaxin - a type of chemokine - the team led by Dr Marc Rothenberg eliminated the eosinophil cells from the small intestine.

Their accumulation in the blood increased at the same time.

Dr Rothenberg said: "This demonstrates a critical role for eotaxin specifically in regulating allergic responses in the gastrointestinal tract.

"Since agents that block eotaxin and similar chemokines are being actively developed by a number of pharmaceutical companies, these studies provide impetus for rapidly applying these new drugs to gut allergy."

He says up to 30% of people are affected by allergies - double the proportion of a few decades ago.

His research investigated allergies not related to anaphylaxis, a severe form of reaction which constricts breathing and can cause death in extreme cases.

'Alarming rate'

"We have not only seen a marked increase in the incidence of allergic diseases, but the emergence of allergic reactions to common environmental substances has also increased at an alarming rate," he added.

"Food allergies such as peanut anaphylaxis now affect about 5% of the population. These problems are particularly concerning at young ages when adverse reactions to new foods in the diets often becomes a challenging problem."

However, Dr Hasan Arshad at the David Hide Asthma and Allergy Centre at St Mary's Hospital, Isle of Wight, said the finding was a "small piece in a very large puzzle".

He added: "If you look at one study, it seems that chemical is doing lots of things.

"But there are at least 20 chemokines and 15 to 20 other chemicals involved and they all interact in a very complex way.

Blocking one chemical or another "has not shown a dramatic improvement, because the process is so complex. You block one pathway and the other pathway takes over".

It was, though, helpful to have more information about the chemical's role.

The research is published in the Proceedings of the National Academy of Sciences.

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