Scientific Study

Abstract BACKGROUND: Open-label oral immunotherapy (OIT) protocols have been used to treat small numbers of patients with peanut allergy. Peanut OIT has not been evaluated in double-blind; placebo-controlled trials. OBJECTIVE: To investigate the safety and effectiveness of OIT for peanut allergy in a double-blind; placebo-controlled study. METHODS: In this multicenter study; children ages 1 to 16 years with peanut allergy received OIT with peanut flour or placebo. Initial escalation; build-up; and maintenance phases were followed by an oral food challenge (OFC) at approximately 1 year. Titrated skin prick tests (SPTs) and laboratory studies were performed at regular intervals. RESULTS: Twenty-eight subjects were enrolled in the study. Three peanut OIT subjects withdrew early in the study because of allergic side effects. During the double-blind; placebo-controlled food challenge; all remaining peanut OIT subjects (n = 16) ingested the maximum cumulative dose of 5000 mg (approximately 20 peanuts); whereas placebo subjects (n = 9) ingested a median cumulative dose of 280 mg (range; 0-1900 mg; P < .001). In contrast with the placebo group; the peanut OIT group showed reductions in SPT size (P < .001); IL-5 (P = .01); and IL-13 (P = .02) and increases in peanut-specific IgG(4) (P < .001). Peanut OIT subjects had initial increases in peanut-specific IgE (P < .01) but did not show significant change from baseline by the time of OFC. The ratio of forkhead box protein 3 (FoxP3)(hi): FoxP3(intermediate) CD4+ CD25+T cells increased at the time of OFC (P=04) in peanut OIT subjects. CONCLUSION: These results conclusively demonstrate that peanut OIT induces desensitization and concurrent immune modulation. The current study continues and is evaluating the hypothesis that peanut OIT causes long-term immune tolerance.