How much peanut is too much—modified oral challenges give the answer
Published Online: May 15, 2014
Since precautionary allergen labeling is voluntarily, its accuracy is doubtful. The food industry increasingly uses labeling with “may contain peanut,” which is not helpful for the peanut allergic customer. For accurate labeling practices and standardization of policies, threshold levels need to be developed that will indicate when an allergic reaction will occur in a certain number of peanut allergic individuals. For this purpose, eliciting doses (EDs) of peanut allergic patients during oral challenges are determined. The problem is that during an oral food challenge doses are given within a 30-minute time interval. This might be too short to determine the correct ED.
In a prospective study recently published in The Journal of Allergy and Clinical Immunology, Blumchen and colleagues used a modified oral challenge protocol in sixty-three peanut-allergic children with high risk for severe allergic reactions. Instead of using the standard protocol, with a 30-minute interval between dose steps, titrated peanut doses were given to the children every two hours. The authors speculated that by using this modified protocol more realistic EDs would be established. Furthermore, they correlated the EDs, as well as the severity of the allergic reaction under challenge, with multiple biomarkers for sensitization and allergic immune reactions.
Forty-five children showed objective symptoms during oral challenge after greater than 30 minutes, with a median latency of 55 minutes between receiving the last peanut-dose (ED) and the allergic reaction. Therefore, commonly used challenge protocols with 30-minute time intervals between the doses would be suboptimal for calculating EDs. The authors calculated that 5% of their population would react to peanut doses as low as 2 mg peanut protein, which equals 8 mg of peanut. The EDs could be correlated to the tested biomarkers, whereas the severity of the reaction could not be correlated.
Using a modified protocol—with two-hour intervals between dose steps—during oral challenges in peanut allergic children might minimize cumulative effects and thus generate more realistic thresholds than using a standard protocol. Furthermore, in using this modified protocol biomarkers seem to predict threshold levels.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.