Another question is whether adults and children will respond differently over time to immunotherapies. Most of the studies so far have specifically enrolled children with food allergies, but research has shown that whether people are 60 or six, their immune systems seem to behave the same way. "Adults can get as much benefit as the children—and the results are very similar," says Kari Nadeau, director of allergy research at Stanford Medical Center.
Spoonful of herbs
Like the food allergens themselves, the oral treatment—even in the smallest doses—can cause the immune system to lash out with a stomachache, an itchy mouth, hives or more severe systemic reactions. And for 10 to 20 percent of people these symptoms are bad enough to make them drop out of the trials. Especially for children, getting through an uncomfortable reaction from the therapy is tough. "When you're a five-year-old kid, you're worried about your tummy pain now" more than decreased risks later, Nadeau says.
One possible way to get patients to stay with the program is to dampen their immune systems before they get the dose of allergens. So-called monoclonal antibody drugs, such as Omalizumab (Xolair), approved for asthma, could be the answer. They inhibit an antibody type known as immunoglobulin E (IgE), which is elevated in people who have the more severe allergic reactions. "IgE is kind of the match that lights the fire behind allergies," Nadeau explains. "So if you don't have the match, you won't have the fire." The suppressor drugs work "like a protective cover" for the immune system by binding to IgEs and blocking them, Nadeau says.
Researchers based in part at the Mount Sinai Medical Center in New York City are taking a more unconventional approach. They are investigating the use of a blend of Chinese herbs to disarm the body's response to food allergens. The formula that is currently in clinical trials is thought to work on a similar principle as the monoclonal antibody drugs. FAFH-2, as it is currently known, combines medicinal herbs from ling zhi—a blend used to reduce allergies and inflammation—and wu mei wan—a treatment for gastrointestinal problems.
With these mitigation approaches, Umetsu says, "we may be able to treat more of the patients—and do it more rapidly."
Close to a cure?
As long as people can tolerate the treatment, therapy seems to go over well, increasing exponentially the amount of a previously dangerous food that a patient can consume. But what happens when people stop taking the frequent doses currently required to boost immunity? "That's the next big question in this research: When can you get off this food therapy," Nadeau asks.
Even for approved allergy treatments, such as those for bee stings, the notion of indefinite protection remains controversial. After years of desensitization and maintenance shots for bee sting allergy some individuals might still revert to being allergic if they go off the therapy, Umetsu says. And the same could very well be true with food allergies.
In his group's milk allergy studies, he says, most of his patients are drinking milk and eating cheese and ice cream. But the research is still too new to determine if the subjects are cured—or if continued treatment will be needed to maintain their tolerance. About 10 to 20 percent of patients who have gone off the milk allergy therapy for a couple weeks or months had allergic reactions after ingesting milk proteins. "I don't think anyone would venture to say that we've cured anybody," Umetsu says.
So instead of a cure, "another goal is to get a patient to tolerate more of the food," he notes. As Burks points out, "for many parents, that's what they want"—just to know that an accidental dusting of peanut protein in a granola bar or bake sale cookie is not going to send their child to the emergency room. "They don't want the fear that one bite will kill them."
The peanut model
Much of the research so far has focused on the two most common food allergens: the dreaded peanut and dastardly milk. Peanuts are responsible for a quarter of all childhood food allergies, followed by milk at 21 percent (and shellfish at 17 percent). But the good news is that most specific food allergies seem to work in basically the same way.
"The peanut is basically a prototype by which we're going to use the same methodology to solve other foods," Nadeau says. So if a peanut prophylaxis proves effective, those for other foods might quickly follow.