New research points to a potential wrinkle in a promising treatment for severe peanut allergies: Reactions can return if the treatments stop.
Roughly 1.25 million children in the U.S. have peanut allergies. Their immune systems go into overdrive when they encounter peanuts, producing antibodies that kickstart a process of inflammation and other allergic responses like swelling and hives.
Exposure Therapy
The only current solution is avoiding peanuts. But recent clinical trials have explored a treatment intended to make recipients more peanut-tolerant. By eating tiny amounts of peanut protein powder every day, patients with strong allergies can eat more of the legume without breaking out in hives, vomiting or enduring other difficult allergic reactions. But new lab analyses suggest that if people finish therapy and go too long without consuming any peanut products, they might lose some of the immunity they had built up.
The results, published in The Journal of Allergy and Clinical Immunology, suggest that patients trying this therapy might need custom follow-up care to hold on to any allergy resistance they acquire. Periodic testing to see how allergic patients are to peanuts “could help monitor responses to this treatment and support families giving it a try,” says study coauthor Alexandra Santos.
Santos, an immunologist at King’s College London, had already done some work designing a test that could use blood samples to identify the scale of someone’s peanut allergy. On the basis of that research, she set out to figure out why some children whose allergies seemed under control seemed to relapse.
When Santos’ lab exposed blood samples from allergic patients to peanuts, they saw the signs of an allergic reaction. As expected, blood from patients who had been exposed to peanut oil as part of the therapy developed antibody blockers that appeared to stop the reaction.
But when the lab removed the antibody blockers and then exposed the post-treatment samples to peanuts, the reaction kicked back in. This mimics what happens when children who had undergone the treatment hadn’t had peanut in a while, Santos says. “If we remove them, the antibodies are as reactive as before.”
These results support the theory that this therapy doesn't eliminate peanut allergies, it merely suppresses them.
Treating, Not Curing
It’s possible some allergies return because the patient has stopped eating peanuts daily and their antibody blockers dropped off, Santos says. Those patients might have to ingest peanuts every day — even when the official therapy regimen is over — to keep resistance, while others might get by with just the initial treatment. Regular use of the blood serum test Santos developed could determine who falls in which camp, she says.
If these results make patients or parents extra nervous about a therapy that involves intentionally eating a food they know can cause problems, Santos says it’s important for a patient to weigh the pros and cons and remember an important caveat: “This is a treatment that can confer protection, but it is not curative.”
