Blood Test Might Tell When Peanut Allergy Is Gone
Findings might one day benefit patients who go through therapy to build up resistance to allergen
By Robert Preidt
FRIDAY, Jan. 31, 2014 (HealthDay News) -- A type of treatment to help build up resistance in people with peanut allergy might leave telltale signs in the people's immune-system DNA, a new study reveals.
The findings suggest that a blood test for these DNA changes could be used to monitor the long-term effectiveness of so-called "immunotherapy" in patients allergic to peanuts, according to the researchers.
There is no cure for peanut allergy, but researchers are examining whether consuming increasing amounts of peanut powder helps desensitize people to the peanut allergen. After participating in this doctor-supervised therapy, patients typically are told to eat some peanuts every day for the rest of their lives.
However, it's not possible to test patients to determine if they can safely stop eating peanuts every day, study senior author Dr. Kari Nadeau, an associate professor of pediatrics at the Stanford University School of Medicine, said in a university news release.
"At first, eating two peanut butter cups a day might seem fun, but it gets a little boring and a lot of people might stop," said Nadeau, who also is an immunologist at Stanford Hospital and Clinics and the Lucile Packard Children's Hospital. "Our new finding can help us try to determine whether, for the long term, someone's allergy has truly been shut off so people can eat ad lib."
The study included 20 children and adults with peanut allergy who had spent two years building up their immunity. They were able to eat a 4-gram serving of peanuts each day without suffering a severe allergic reaction.
The participants were told to avoid peanuts for three months, and then the researchers gave them a small amount of peanut powder to determine if their allergy had returned. The allergy came back in 13 patients, while seven remained allergy-free, the study authors said.
The researchers then analyzed blood samples taken from these two groups, as well as from people with peanut allergy who had never received oral immunotherapy. The investigators found that the DNA in white blood cells, which help reduce allergy response, was different in each of the three groups of patients.
Nadeau said this test might one day help doctors in deciding whether a person "can safely go off of immunotherapy, or if they need to continue to eat the food every day." It could also help determine whether a person might benefit from a longer course of immunotherapy, she said, but more study is needed.
The study was published online Jan. 31 in the Journal of Allergy and Clinical Immunology.