Date of this Version
Clinical and Experimental Allergy 33:11 (November 2003), pp. 1581–1585.
Background: Characterization of fatal and nonfatal reactions to food indicates that the majority of reactions are due to the ingestion of prepared foods rather than the nonprocessed allergen. In an ongoing study that used a double-blind placebo-controlled food challenge to investigate peanut allergy and clinical symptoms, the observed reaction severity in four of the first six subjects was greater than anticipated. We hypothesized that this was due to differences in the composition of the challenge vehicle. Objective: The aim was to investigate whether the severity of observed challenge reactions would be repeated on rechallenge with a lower fat challenge vehicle. Methods: Peanut-allergic subjects were rechallenged with a lower fat recipe after reacting more severely than was anticipated to an initial peanut challenge. Similar challenge vehicle recipes were used, the only difference being the lower fat content (22.9% compared with 31.5%). The peanut content of the two recipes was analyzed using RAST inhibition studies and ELISA tests. Results: Three of four subjects reacted to much smaller doses of peanut protein on rechallenge (mean dose equivalence –23 times less peanut) with the lower fat recipe. RAST inhibition showed that neither recipe altered epitope recognition. The higher fat recipe required twice as much peanut to cause 50% inhibition. ELISA detected far lower levels of peanut in the higher fat recipe (220 000 parts per million [ppm]) than in the lower fat recipe (990 000 ppm). Conclusion: The fat content of a challenge vehicle has a profound effect on the reaction experienced after allergen ingestion. This is another factor to be considered in assessing the risk of certain foods to food-allergic consumers and adds another dimension to clinical, research, and regulatory practice.