Treating peanut allergy is an arduous process. The only option is a still-experimental therapy, known as oral immunotherapy, in which a patient consumes tiny, gradually increasing doses of peanut powder under a doctor's supervision. After months or years of treatment, the patient can eat small amounts of peanuts in ordinary foods without provoking an allergic response.
People with severe peanut allergy may think the effort is worthwhile because it frees them from worry that a stray, peanut-containing cookie or stir-fry will trigger anaphylactic shock. But there's a catch. To maintain this hard-won tolerance, patients who have completed oral immunotherapy are told they must eat peanuts every day for the rest of their lives. If they don't, they may regain their allergy.
Now, Stanford researchers think they've come up with a better option: a potential blood test to see which patients can safely stop eating peanuts without losing their peanut tolerance. A new study led by Kari Nadeau, MD, PhD, found that differences in the DNA of certain white blood cells separated patients who kept their immune tolerance from those who lost it after oral immunotherapy. The study, published today in the Journal of Allergy and Clinical Immunology, followed 20 child and adult patients who completed two years of oral immunotherapy to treat their peanut allergies. They were asked to stop eating peanuts for three months. In that time, 13 regained their sensitivity to peanuts and seven stayed peanut-tolerant.
The researchers saw epigenetic differences between the groups - genetic changes that affect the structure of the chromosome but not the gene sequence itself. The differences could be detected in small blood samples with commonly-available lab equipment, pointing the way to a possible clinical test. FDA approval is needed before the test could be clinically used for this purpose.
From our press release about the study:
"It’s interesting that the change we saw is at the epigenetic level," Nadeau said, referring to changes in gene activity and expression caused by factors other than DNA sequence. "This might help us tell people if they can safely go off of immunotherapy, or if they need to continue to eat the food every day." The test could also help researchers determine whether some individuals would benefit from longer courses of immunotherapy, she added.
Interestingly, the new research answers some questions that physicians posed about another just-released study of oral immunotherapy for the treatment of peanut allergies.
Previously: Eating nuts during pregnancy may protect baby from nut allergies, Ask Stanford Med: pediatric immunologist answers your questions about food allergy research and A mom's perspective on a food-allergy trial
Photo by Muy Yum