Sublingual immunotherapy shows promise as treatment for peanut allergy
Peanuts are one of the most common triggers of severe food-induced allergic reactions, which can be fatal, and the prevalence of peanut allergy is increasing. However, there is currently no clinical treatment available for peanut allergy other than strict dietary elimination and, in cases of accidental ingestion, injections of epinephrine.
But a new multicenter clinical trial shows promise for sublingual immunotherapy (SLIT), a treatment in which patients are given daily doses, in gradually increasing amounts, of a liquid containing peanut powder. The patients first hold the liquid under the tongue for 2 minutes and then swallow it.
The two lead authors of the study, published in the January 2013 issue of the Journal of Allergy and Clinical Immunology, are David M. Fleischer, MD, of National Jewish Health in Denver, Colo., and Wesley Burks, MD, Curnen Distinguished Professor and Chair of the Department of Pediatrics in the University of North Carolina School of Medicine.
“These results are encouraging,” Burks said. “The immune response was stronger than we thought it might be, and the side effects of this treatment were relatively small. However, the magnitude of the therapeutic effect was somewhat less than we had anticipated. That’s an issue we plan to address in future studies.”
In the study, 40 people with peanut allergy, ages 12 to 37 years, were randomized to receive daily peanut or placebo SLIT. All were given a baseline oral food challenge of up to 2 grams of peanut powder to test how much peanut powder they could consume without symptoms.
After 44 weeks, all were given a second oral food challenge. Those who were able to consume either 5 grams, or at least 10-fold more peanut powder than their baseline amount, were considered to be responders (i.e., desensitized to peanut). At 44 weeks, 70 percent of those who received peanut SLIT were responders, compared to 15 percent of those receiving placebo. Among the peanut-SLIT responders, the median amount of peanut powder they could successfully consume increased from 3.5 to 496 milligrams. After 68 weeks, that amount increased significantly, to 996 milligrams.
Of 10,855 peanut doses given through week 44 of the study, 63.1 percent were symptom-free. When oral/pharyngeal symptoms were excluded from the analysis, 95.2 percent of doses were symptom-free.
What is a peanut allergy?
A peanut allergy is a reaction that occurs when your body mistakenly identifies peanuts as harmful substances. When you eat peanuts or food containing peanuts, your immune system-the body’s natural defense system that fights infections and diseases-overreacts and can cause a serious, even life-threatening response.
What causes a peanut allergy?
An allergic reaction occurs when your immune system overreacts and releases chemicals, including histamine, into your blood. These chemicals can affect different tissues in the body, such as the skin, eyes, nose, airways, intestinal tract, lungs, and blood vessels. It’s not clear why peanuts trigger this response in some people.
The study concluded that peanut SLIT safely induced desensitization in a majority of participants compared to placebo, and that longer duration of therapy led to significant increases in the amount of peanut powder people could safely consume.
However, Burks cautions, this is not a treatment that people should try on their own. For now it’s a treatment that should only be given by medical professionals in a carefully monitored clinical trial, he said.
Which foods may contain peanuts?
Besides peanut butter and peanut oil, some foods that may contain peanuts include:
Arachis oil (another name for peanut oil)
Many ethnic foods, including Chinese, Mexican, Thai and Vietnamese
Many candies, especially chocolate (which often is made on machinery that also processes candies made with nuts)
Some cereals, including granola
Marzipan
Pesto sauce
Some veggie burgers
Some health food bars
Should a pregnant woman eat peanuts or peanut products?
Women who are allergic to peanuts should not eat peanuts or peanut products during pregnancy or at any other time. Studies suggest that women who are not allergic to peanuts can safely eat peanuts during pregnancy (3).
Because peanut allergy tends to run in families, health care providers have been seeking ways to help prevent this allergy in babies from affected families. Until recently, experts recommended that women who aren’t allergic to peanuts but who have a family history of peanut allergy avoid peanuts during pregnancy (3, 4). However, recent studies have found no evidence that avoiding peanuts in pregnancy helps prevent peanut allergies in the child (3, 5).
Peanuts can be healthy food choices for pregnant women. Peanuts are a good source of protein and folate. Folate is the form of folic acid that is found naturally in foods. Taking folic acid before and during early pregnancy helps prevent certain serious birth defects of the brain and spine. The March of Dimes recommends that all women who could become pregnant take a multivitamin containing 400 micrograms of folic acid daily, and make healthy food choices that include foods rich in folic acid.
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Study participants were recruited from five U.S. sites: New York, N.Y.; Baltimore, Md.; Little Rock, Ark.; Denver, Colo.; and Durham, N.C. Study co-authors include researchers from the University of Arkansas for Medical Sciences and Arkansas Children’s Hospital, Johns Hopkins University School of Medicine, Mount Sinai School of Medicine, the EMMES Corp. in Rockville, Md., and the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health (NIH).
The study was funded by grants from the NIAID and the NIH’s National Center for Research Resources.
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Tom Hughes
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919-966-6047
University of North Carolina Health Care