A team led by a researcher at the Stanford University School of Medicine has developed vaccines that vastly reduce or eliminate dogs' allergic reactions to three major food allergens: peanuts, milk and wheat. The vaccines' benefits lasted at least three months.
The research, published in the Nov. 12 online edition of the journal Allergy and completed jointly with scientists at UC-San Francisco, UC-Davis and UC-Berkeley, is the first to reverse pre-existing food allergies in an animal other than a mouse. The vaccines provide new hope to the millions of people who suffer from food allergies.
"Food allergy is an important problem for which there is no good treatment," said Dale Umetsu, MD, PhD, professor of pediatrics at Stanford and chief of the division of allergy and immunology at Lucile Packard Children's Hospital. "Developing a cure for this growing problem will help millions of people and save lives."
According to Anne Munoz-Furlong, founder and CEO of the Food Allergy and Anaphylaxis Network, a nonprofit patient advocacy group, "This study takes us one step closer to finding a treatment that will allow people to live without fear of having a reaction that could kill them."
Of the nine dogs in the study, four had peanut allergies and five had both milk and wheat allergies. Ten weeks after the dogs were vaccinated for the relevant allergenic foods, significantly greater amounts of the foods had to be used to generate a telltale allergic bump on the skin (called a wheal) in standard allergy skin tests.
In addition, all four of the peanut-allergic dogs tolerated eating much larger quantities of ground peanut after vaccination. As a group, they went from tolerating, on average, about one peanut to tolerating more than 37 peanuts. In fact, three of the four vaccinated dogs could eat a handful of peanuts - the maximum amount they were offered (about 57 peanuts) - without developing any symptoms. One of these dogs had a more than a hundred-fold increase in peanut tolerance - from half of one peanut to 57 peanuts.
Similarly, when milk-allergic dogs were fed 0.2 grams of milk two to four months after vaccination, they exhibited a 100 percent reduction in vomiting and a 60 percent reduction in diarrhea compared to their reactions prior to vaccination. The results for every test were statistically significant.
The dogs were cared for according to nationally accepted guidelines, and the tests performed were no different from those that are commonly used in human subjects. And, as in human research, dogs that had allergic reactions were immediately treated with antihistamines and recovered.
Food allergies occur in 1 to 2 percent of adults and up to 8 percent of children age 8 or younger. "Currently, the only treatment is to avoid the relevant food," said Umetsu. "Unfortunately, that's often difficult." Accidental exposures happen because peanut and milk products are present in many processed foods.
About 100 people, mostly children, die annually as a result of accidental exposures that produce a systemic allergic reaction called anaphylaxis, according to the National Institute of Allergy and Infectious Diseases. At its most severe, anaphylactic shock involves cardiac arrest and/or airway swelling so severe that a person can suffocate if not immediately treated with epinephrine, a strong antihistamine. Peanuts are the most common culprit.
Peanut and tree nut allergies have been on the rise in recent years, and the NIAID estimates that about 3 million Americans are affected annually. According to one study, these allergies' prevalence in children doubled from 1997 to 2002. The so-called "hygiene hypothesis" attributes this escalation to too much cleanliness in modern life. Under this theory, infections are critical to help protect people from allergies.