Peanut allergy affects approximately 1% of children and adults in the United States and the prevalence is increasing. Peanut allergy causes the majority of life-endangering or fatal allergic reactions to foods in this country. Fear of accidental peanut exposures has a very negative impact on the quality of life for allergic individuals and their families.
Recent research indicates that many individuals with peanut allergy can be desensitized, protecting them from severe allergic reactions from accidental peanut exposure. After increasing doses of peanut are given by mouth, a maintenance dose is needed regularly to maintain the desensitized state. The allergy is suppressed by the constant presence of peanut materials in the body, but the allergy is still present.
On March 1, 2014, three experts in this field (Dr. Hugh Sampson from Mount Sinai in New York, Dr. Kari Nadeau from Stanford, and Dr. Giovanni Pajno from the University of Messina, Italy) presented a symposium on oral immunotherapy at the American Academy of Allergy, Asthma, and Immunology meeting. They agreed that considerable progress has been made in peanut desensitization, but all agreed that optimization of desensitization protocols is needed.
There has been one reported death from anaphylaxis during peanut desensitization. As many as 93% of subjects in experimental trials had an allergic reaction during the build-up days. Most reactions were mild, such as abdominal pain, itchy throat, hoarseness, gritty eyes, watery eyes, sneezing, and skin reactions. Drop-out rates as high as 30% have been reported because of severe reactions such as nasal inflammation, shortness of breath, hives, and decreased blood pressure.
During the maintenance phase, severe allergic reactions to previously tolerated doses of peanut have been associated with exercise, viral infections, or poorly controlled asthma. If patients stop taking maintenance peanut doses, and then resume peanut ingestion, severe allergic reactions can occur.
Another complication of oral immunotherapy is eosinophilic esophagitis, a gastrointestinal reaction that has been reported in 0% to over 20 % of patients in different studies. Eosinophilic esophagitis is an allergic inflammation of the esophagus leading to difficulty swallowing, food becoming lodged in the esophagus, and pain. Dr. Nadeau indicated that they perform upper gastrointestinal endoscopy on all patients with any gastrointestinal symptoms to make certain their esophaguses are normal before enrolling patients in their studies. They have had no cases eosinophilic esophagitis complicating peanut desensitization so far. Other investigators have seen a significant number of eosinophilic esophagitis complications.
All of the panelists expressed optimism that more effective desensitization protocols can be devised. They were optimistic that methods to minimize allergic reactions during maintenance oral immunotherapy can be devised. Screening of candidates may avoid eosinophilic esophagitis.
The need for better standard protocols and safety concerns were the reasons cited to regard oral peanut desensitization still an experimental procedure, best performed in controlled trials in specialized medical centers.
Attempting to induce some degree of peanut tolerance isn’t a cure of peanut allergy, and, as cited by the experts, not ready for prime time.
By Vicki J. Lyons, MD
and Timothy J. Sullivan, MD
Advanced Allergy and
Asthma Clinic, Ogden, UT