Peanut allergy could be switched off

By Dr. Ananya Mandal, MDOct 12 2011

Now researchers may have discovered how to switch off food allergies. Researchers from Northwestern University found a way to tweak the immune system so that it doesn’t react when foods like peanuts and eggs are encountered – in mice.

This is encouraging since there is a rise in food allergies for the past decade or so. Food allergies can be deadly leading to a life-threatening allergic reaction, called anaphylaxis. National Institutes of Health scientists estimate that about 4.7 percent of children younger than 5 years old and 3.7 percent of children aged 5 to 17 suffer from food allergies. Each year there are some 15,000 to 30,000 episodes of food-related anaphylaxis, according to the NIH. Currently there is no reliable therapy for food allergies, other than avoiding the food.

Paul J. Bryce, an assistant professor of medicine at the Northwestern University Feinberg School of Medicine, whose study was published in the Journal of Immunology explained that the idea is to convince the body’s immune system that these foods are safe. “The key concept here is that we are supposed to be able to eat foods,” Bryce said. “Allergies to peanuts and other foods occur when the immune system goes wrong. We’ve been trying to understand how the immune system tells the difference between what it should and should not respond to.”

Allergic people react to peanuts and other edibles because their bodies interpret proteins in these foods as pathogens that must be killed. Once a person is sensitized to a food, like peanuts, immune cells called T helper cells go into action. These cells are constantly on patrol looking for the protein they’ve determined is dangerous. When they find it, they bring on other immune cells and start a massive immune reaction that can be so severe that it can kill.

Bryce and his colleagues discovered that they could block that reaction by taking a bit of peanut protein, wrapping a white blood cell around it and then injecting the altered cell into an allergic mouse’s body.  Once the immune system spots the protein lodged in a white blood cell it recalibrates, now designating the protein as safe.

“There are many differences between immune responses in mice and humans,” Bryce said. “There are also many similarities.” The same principle applies to autoimmune diseases – like rheumatoid arthritis and multiple sclerosis – which work very much in the same way as allergies do, Bryce said. The only difference is that the protein being attacked is part of the person’s own body, rather than a food that is consumed.

“This approach to inducing tolerance is in early clinical trials for multiple sclerosis,” Bryce said. “We are hopeful that any success there would justify further trials, including those designed to test its use for food allergy.”

Dr. Mary Tobin, director of allergy at Rush University Medical Center, who was not involved in the study, said that right now the only sure treatment for people with food allergies is avoidance.
“Now, to be able to inhibit the immune system or change the messaging at a basic level is really key, because then you can turn off these aberrant responses to peanuts or shellfish, which are the most common allergens,” she said.

Tobin said the presence of food allergies and the awareness of anaphylaxis has surfaced in the public consciousness within the past decade, and emergency rooms see more cases of allergy-induced illness than before. “These families live in a huge amount of fear that a kind person will unwittingly expose their child to a peanut and the child will die,” she said, noting that children also deal with social pressure to eat any and all foods.

Meghann Talkington, a registered dietician who was not involved in the study, said there are several unanswered questions. She would want to know how safe the treatment would be if it were administered in humans, whether it took a pill form or an injection and whether it would be easier for people simply to abstain from peanuts. But she said the researchers’ hypothesis would be a great benefit. “The research is important to allow people to have more food options,” she said. “Depending on how bad their allergy is, they might not be able to touch the nut versus being able to directly eat them, so the research might make things easier and more convenient for them.”

Dr. Clifford Basset, medical director at Allergy and Asthma Care of New York however says, “Bottom line: There is no cure for food allergies, at least in 2011, and in the foreseeable future. It’s all about education, prevention and preparedness.”