Oral peanut immunotherapy in children with peanut anaphylaxis

Background: The only treatment option for peanut allergy is strict avoidance. Objective: To investigate efficacy and safety of oral immunotherapy (OIT) in peanut allergy. Methods: Twenty-three children (age, 3.2-14.3 years) with IgE-mediated peanut allergy confirmed by positive double-blind, placebo-controlled food challenge (DBPCFC) received OIT following a rush protocol with roasted peanut for 7 days. If a protective dose of at least 0.5 g peanut was not achieved, patients continued with a long-term buildup protocol using biweekly dose increases up to at least 0.5 g peanut. A maintenance phase for 8 weeks was followed by 2 weeks of peanut avoidance and a final DBPCFC. Immunologic parameters were determined. Results: After OIT using the rush protocol, patients tolerated a median dose of only 0.15 g peanut. Twenty-two of 23 patients continued with the long-term protocol. After a median of 7 months, 14 patients reached the protective dose. At the final DBPCFC, patients tolerated a median of 1 g (range, 0.25-4 g) in comparison with 0.19 g peanut at the DBPCFC before OIT (range, 0.02-1 g). In 2.6% of 6137 total daily doses, mild to moderate side effects were observed; in 1.3%, symptoms of pulmonary obstruction were detected. OIT was discontinued in 4 of 22 patients because of adverse events. There was a significant increase in peanut-specific serum IgG₄ and a decrease in peanut-specific IL-5, IL-4, and IL-2 production by PBMCs after OIT. Conclusion: Long-term OIT appears to be safe and of some benefit in many patients with peanut allergy. With an increase in threshold levels and a reduction of peanut-specific T_H2 cytokine production, the induction of tolerance may be feasible in some patients.