Cures for a wide range of food allergies are less than a decade away, scientists said today.
By modifying the proteins in foods that cause the allergic reactions, researchers have created treatments that can safely desensitise the body's immune system to allergic triggers.
"Therapies for food allergy will be on the market within seven to 10 years," said Ronald van Ree of the University of Amsterdam, who is leading work in the development of these allergy treatments.
An allergy is an overreaction of the immune system cells called Immunoglobulin E (IgE) to proteins that should normally pose no problems. Examples of these proteins, known as allergens, are found in cats, horses, nuts, milk and pollen.
According to a report by the Royal College of Physicians (RCP), 30% of adults and 40% of children in Britain suffer from some sort of allergy. And the numbers are increasing. In 1990, peanut allergy was extremely rare but six years later, it affected one in 200 children. The figure may now be as high as one in 50.
In 2003, the RCP concluded that the British population had the highest prevalence of allergy in Europe and ranked it among the highest in the world.
"For food allergy, the only treatment is avoidance and rescue medication if you're not successful in avoiding the food you're allergic to," said Dr Van Ree. People suffering a major allergic reaction usually need an immediate injection of adrenaline to recover.
The best long-term treatment available for IgE-related allergy is a technique called allergen-specific immunotherapy. This involves injecting a patient with the allergen they react to, in a bid to desensitise their immune system. But it is expensive and slow - treatment can often involve regular injections for up to five years.
There is also a safety issue - the treatment cannot be used against food allergies because it almost always induces a severe reaction, requiring a dose of emergency medicine after each injection.
"We need to change the treatment for food allergies in such a way that we can do it more safely and in a shorter period," said Dr Van Ree.
Because the allergens in many foods are well-known, Dr Van Ree was able to artificially produce them, but with a difference. "We can change the molecules in such a way that IgE antibodies do not bind to the allergen any more," he said.
Dr Van Ree produced altered versions of the allergen present in apples and found that reactions to it dropped by a factor of 10. In the United States, similar work has been done to create mutated versions of the allergens in peanuts but, as yet, the experiments have not left the laboratory.
Researchers are also studying the reasons why people develop allergies, to improve subsequent treatments. "We know that if we grow up in an environment where there is a lot of bacterial and parasite infections, the number of patients who get allergies is much lower," said Dr Van Ree.
Scientists have also observed children growing up in farms in Bavaria who regularly drink unpasteurised milk and are exposed to microbes in barns and stables. These children are 10 times less likely to develop allergies in later life when compared with others.
Dr Van Ree said that, if the molecules in the milk that are protecting the Bavarian children can be identified, they could be added to the recombinant allergens to further improve the treatment.
"If we can fool the immune system in such a way that we can mimic chronic exposure by taking microbic or parasitical factors and adding them, then we might be able to shorten the treatment," he said.
