Kate Johnson

November 14, 2013

BALTIMORE — The first case of a bone marrow transplant curing a peanut allergy has been reported in the United States, but researchers warn that the reverse is also possible.

"If a recipient has a food allergy, they should be screened after bone marrow transplant to determine if they still have the allergy," said lead investigator Yon Luo, MD, from North Shore–Long Island Jewish Hospital Health System in Great Neck, New York. "There is a chance their allergy will be gone."

However, "there are several reports of a donor with a food allergy passing it on to the recipient," he told Medscape Medical News. "If that is the case, those recipients should be screened after they recover from the transplant to determine the risk of food allergic reaction or anaphylaxis," he noted.

Although the findings might be of peripheral interest to transplant experts, they are of central importance to allergy specialists, Dr. Luo said.

He described the patient — who was first evaluated for peanut allergy at 15 months of age and was unexpectedly free of the allergy 9 years later — here at the American College of Allergy, Asthma & Immunology (ACAAI) 2013 Annual Scientific Meeting.

Generalized urticaria and vomiting after peanut ingestion led to the initial diagnosis of peanut allergy. There was no respiratory compromise, and symptoms improved with oral diphenhydramine (Benadryl, McNeil-PPC, Inc), so no epinephrine was required. A positive skin-prick test confirmed the allergy, and the patient was prescribed strict peanut avoidance and an epinephrine injector.

"We followed him for several years with no accidental ingestions," said Dr. Luo.

The patient was diagnosed with acute lymphocytic leukemia when he was 4 years old.

The patient experienced chemotherapy-induced remission for approximately 2.5 years, but then relapsed. He was treated with myeloablative conditioning and stem cell bone marrow transplantation from an unrelated nonallergic donor when he was approximately 8.5 years old.

A little more than 1 year after the transplant, his IgE antibody level to peanut was undetectable on ImmunoCAP testing (<0.35 kUa/L). Nine months later, both a skin-prick test and oral challenge to peanut were negative.

"That confirmed resolution of his peanut allergy," said Dr. Luo.

Allergy Reversal

"One of the most challenging issues with this case was determining the patient's allergic condition before the bone marrow transplant, because people could suggest this allergy just resolved," said Dr. Luo.

Although other explanations are possible for the allergy reversal, 80% of peanut allergies do not resolve. In addition, while the patient was receiving chemotherapy, which suppresses IgE production, results of ImmunoCAP testing to peanut was 0.87 kUa/L, he reported. "We feel pretty confident that the patient was still allergic to peanut before the bone marrow transplant."

This case "indicates that genetic modifications during the early stages of immune cell development in bone marrow may play a large role in causing allergy," said Dr. Luo's coauthor, Steven Weiss, MD, from ProHEALTH Care Associates in Syosset, New York, who specializes in pediatric and adult allergy, asthma, and immunology.

Dr. Luo noted that there are several published reports of transfer of peanut allergy after bone marrow transplantation from atopic donors to patients who had no previous history of food allergy.

The first case of peanut allergy cure after bone marrow transplantation was reported by Jonathan Hourihane, MD, from University College Cork in Ireland, and his team (Allergy 2005;60:536-537).

Dr. Hourihane was asked by Medscape Medical News to comment on this latest report. "It places allergy firmly in the field of immune regulation, where many clinicians do not think of it. The indications for transplant widen all the time, but no one is advocating it for food allergy. Such cures will remain a nice bonus of major therapies for life-limiting diseases, which food allergy currently isn't," Dr. Hourihane said.

American College of Allergy, Asthma & Immunology (ACAAI) 2013 Annual Scientific Meeting: Abstract 6. Presented November 10, 2013.

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