By Stephen Daniells, 20-Jul-2009

Scottish scientists have reported a breakthrough that could slash the numbers of fatal cases of serious allergic reactions to peanuts and other foods.

According to findings published in the Proceedings of the National Association of Sciences (PNAS) a molecule called interleukin-33 amplifies allergic reactions. Researchers from the University of Glasgow also report a development of a biological agent to reduce the symptoms.
“In basic terms, without the IL33 molecule, the allergic reaction experienced would be far less severe, greatly reducing the risk of death,” explained researcher Dr Alirio Melendez.
With food allergies on the rise, the news will be welcomed by the food industry. An estimated eight per cent of children in the EU suffering from food allergies, according to the European Federation of Allergy and Airways Diseases Patients' Associations.
The most common food allergen ingredients and their derivatives are cereals containing gluten, fish, crustaceans, egg, peanut, soybeans, milk and dairy products including lactose, nuts, celery, mustard, sesame seed, and sulphites.
There is no current cure for food allergy and vigilance by an allergic individual is the only way to prevent a reaction but a peanut allergy can be so severe that only very tiny amounts can be enough to trigger a response.
With peanut allergy potentially fatal for some people, food manufacturers are already bound by certain regulations, depending on the country, to highlight possible allergens in a food product, such as the EU’s Labelling Directive 2000/13/EC.



Unlocking anaphylaxis
The Glasgow-based researchers, led by Dr Alirio Melendez and Professor Eddy Liew, identified interleukin-33 after looking at a number of patients who experienced anaphylaxis during surgery and found that they had very high levels of the molecule.
“IL-33 is a relatively new discovery and its part in anaphylaxis (or any pathology) has not been greatly understood,” said Dr Melendez.
“Our study showed that IL-33 plays a pivotal role in hugely increasing the inflammation experienced during a period of anaphylactic shock and led us to understand how to intervene to reduce its impact.”
Using a mouse model, the researchers showed that blocking the IL-33 molecule could reduce the severity of the attack.
“This approach does not stop the allergic reaction altogether. It blocks the amplification of the reaction triggered by IL-33, not the allergic response itself.
“We are now further studying the role of IL-33 in anaphylaxis and similar disorders, and our plans are to further these studies on food, venoms and drugs-mediated anaphylaxis,” said Dr Melendez.



Independent comment
Lynne Regent, chief executive of The Anaphylaxis Campaign, welcomed the results as “encouraging”.
“We would hope to see this work developed further to a point where it could be of real benefit to people living with anaphylaxis or at risk of severe allergic reaction,” she said.
Source: PNAS
Volume 106, Number 24, Pages 9773-9778, doi: 10.1073/pnas.0901206106
"The cytokine interleukin-33 mediates anaphylactic shock"
Authors: P.N. Pushparaj, H.K. Tay, S.C. H'ng, N. Pitman, D. Xu, A. McKenzie, F.Y. Liew, A.J. Melendez



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