A new study debunks the theory that peanut allergies are caused by an offending ingredient inherent in the nut. Instead, the research shows, the condition stems from a person's abnormal immune response.
Peanut allergies afflict an estimated 1.5 million Americans and are the cause of 200 deaths in the United States each year. The condition is particularly difficult to manage in young children, who aren't as vigilant about reading labels or asking about food ingredients. An absentminded bite of a peanut butter-and-jelly sandwich can result in a violent reaction that often requires a trip to the hospital.
Researchers from St. Mary's Hospital at Imperial College in London discovered that children with peanut allergies have an exceptional immune reaction at the cellular level, and that children with no peanut allergy or who outgrow their allergy no longer exhibit this response.
Using a novel technique, the scientists isolated the very rare immune cells involved in an allergic response to peanuts in three types of children: Those with peanut allergies, those who had outgrown their allergy, and those with no history of peanut allergies. They then amplified these cells in the lab and studied their behavior after exposure to a peanut extract.
After magnifying these immune cells, or T-cells, the researchers observed that the T-cells of allergic patients became excited after exposure to the peanut. Once the T-cells react to the peanut extract, a cascade of allergic responses ensue, from a skin rash to labored breathing.
"We have found a rapid way of taking very rare immune cells, amplifying these cells, and in a very short space of time identifying and separating them out to study their function with the minimal artificial manipulation," says co-author Dr. Gideon Lack, a consultant in pediatric allergy and immunology at St. Mary's.
The study's unique strategy will likely influence a broad range of future research, says Dr. Wesley Burks, a pediatrician at Arkansas Children's Hospital in Little Rock.
"The novel approach used by these authors to identify antigen-specific T-cells will likely have important implications for future studies of allergic disease, as well as autoimmune disease," he says.
The results, published in the April 1 issue of the Journal of Clinical Investigation, will also guide future treatments for food allergies, the authors contend.
"These findings will help us in clinical trials where there are existing treatments. We will be able to monitor the effect on the patient by doing blood tests and checking to see if immune cells are responding," Lack says.
"One could use this kind of a technique to identify people who continue to have a peanut allergy and to come up with a vaccine that can induce the non-allergic response," adds Dr. Donald Leung, director of the division of pediatric allergy immunology at the National Jewish Medical Research Center in Denver.