Successful oral tolerance induction in severe peanut allergy.

BACKGROUND: Peanut allergy is common, potentially severe and rarely resolves causing impaired quality of life. No disease-modifying treatment exists and there is therefore a need to develop a therapeutic intervention.

AIMS OF THE STUDY: The aim of this study was to investigate whether peanut oral immunotherapy (OIT) can induce clinical tolerance to peanut protein.

METHODS: Four peanut-allergic children underwent OIT. Preintervention oral challenges were performed to confirm clinical allergy and define the amount of protein required to cause a reaction (dose thresholds). OIT was then administered as daily doses of peanut flour increasing from 5 to 800 mg of protein with 2-weekly dose increases. After 6 further weeks of treatment, the oral challenge was repeated to define change in dose threshold and subjects continued daily treatment.

RESULTS: Preintervention challenges confirmed peanut allergy and revealed dose thresholds of 5-50 mg (1/40-1/4 of a whole peanut); one subject had anaphylaxis during challenge and required adrenaline injection. All subjects tolerated immunotherapy updosing to 800 mg protein and i.m. adrenaline was not required. Each subject tolerated at least 10 whole peanuts (approximately 2.38 g protein) in postintervention challenges, an increase in dose threshold of at least 48-, 49-, 55- and 478-fold for the four subjects.

CONCLUSIONS: We demonstrated a substantial increase in dose threshold after OIT in all subjects, including the subject with proven anaphylaxis. OIT was well tolerated and conferred protection against at least 10 peanuts, more than is likely to be encountered during accidental ingestion.