Laird Harrison

March 06, 2014

SAN DIEGO — Avoiding peanuts after oral immunotherapy can reverse the effects of the treatment, a new study shows.

Only 1 of 4 patients maintained their tolerance for peanuts when they completely avoided them for 3 months, said senior investigator Wesley Burks, MD, from North Carolina Children's Hospital in Chapel Hill.

He presented the study results during a news conference here at the American Academy of Allergy, Asthma & Immunology 2014.

It is understandable that patients want to avoid foods such as peanuts after they have developed tolerance. "They don't like to eat peanuts," said Scott Commins, MD, an allergist at the University of Virginia in Charlottesville, who presented a related study at the meeting.

Dr. Burks and his team wanted to determine how long patients could maintain their tolerance for peanuts while avoiding them. They evaluated 20 patients who had received oral immunotherapy.

The patients with allergies ate peanuts in doses too small to cause a reaction. That dose was increased until they could eat a dose large enough that they were not likely to react if they were accidentally exposed.

The patients passed a double-blind placebo-controlled food challenge showing they could tolerate peanuts.

They don't like to eat peanuts.

All 16 patients who avoided peanuts for 1 month passed another food challenge. Of the 4 who avoided peanuts for 3 months, only 1 passed the challenge.

Immune system changes were confirmed with basophil activation and skin prick tests to peanut.

In the 1-month avoidance group, peanut-induced basophil activation was minimal at the first food challenge. When those patients were challenged at 3 months, there was no change.

In the 3-month avoidance group, peanut-induced basophil activation was minimal at the first food challenge. However, at the second food challenge, activation was increased and the wheal size on the skin prick test had increased.

"It was going back to what it looked like 3-and-a-half years before," said Dr. Burks.

Although these results might seem like bad news for people contemplating oral immunotherapy for peanut allergy, Dr. Commins had some good news. His team demonstrated that 1 or 2 peanuts a day is enough to maintain tolerance.

A Peanut a Day

They evaluated 17 people allergic to peanuts who had successfully completed a year of oral immunotherapy and passed a food challenge.

The subjects were 4 to 19 years of age. Their initial median serum peanut-specific immunoglobulin (Ig)E was 285.4 IU/mL (range, 22.1 to 795.0 IU/mL).

After completing the immunotherapy, all 17 patients continued to eat 1 or 2 peanuts a day until their peanut-specific IgE dropped below 15 IU/mL. For the 10 patients who passed a second food challenge, that took a median of 8.7 months (range, 4 to 17 months).

At study completion, 7 patients were continuing to consume 1 or 2 peanuts a day and their IgE had not dropped below 15 IU/mL.

"Maybe in the long run, we won't need a large dose to maintain tolerance," said Dr. Commins.

Dr. Burks said he agrees, noting that this is "in line with what other studies have shown."

Dr. Burks has disclosed no relevant financial relationships. Dr. Commins reports receiving an honorarium from UptoDate.

American Academy of Allergy, Asthma & Immunology (AAAAI) 2014: Abstracts 360 and 536. Presented March 2, 2014.


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