Distinct parameters of the basophil activation test reflect the severity and threshold of allergic reactions to peanut

Abstract

Background: The management of peanut allergy relies on allergen avoidance and epinephrine autoinjector for rescue treatment in patients at risk of anaphylaxis. Biomarkers of severity and threshold of allergic reactions to peanut could significantly improve the care for patients with peanut allergy.

Objective: We sought to assess the utility of the basophil activation test (BAT) to predict the severity and threshold of reactivity to peanut during oral food challenges (OFCs).

Methods: The severity of the allergic reaction and the threshold dose during OFCs to peanut were determined. Skin prick tests, measurements of specific IgE to peanut and its components, and BATs to peanut were performed on the day of the challenge.

Results: Of the 124 children submitted to OFCs to peanut, 52 (median age, 5 years) reacted with clinical symptoms that ranged from mild oral symptoms to anaphylaxis. Severe reactions occurred in 41% of cases, and 57% reacted to 0.1 g or less of peanut protein. The ratio of the percentage of CD63(+) basophils after stimulation with peanut and after stimulation with anti-IgE (CD63 peanut/anti-IgE) was independently associated with severity (P = .001), whereas the basophil allergen threshold sensitivity CD-sens (1/EC₅₀ × 100, where EC₅₀ is half maximal effective concentration) value was independently associated with the threshold (P = .020) of allergic reactions to peanut during OFCs. Patients with CD63 peanut/anti-IgE levels of 1.3 or greater had an increased risk of severe reactions (relative risk, 3.4; 95% CI, 1.8-6.2). Patients with a CD-sens value of 84 or greater had an increased risk of reacting to 0.1 g or less of peanut protein (relative risk, 1.9; 95% CI, 1.3-2.8).

Conclusions: Basophil reactivity is associated with severity and basophil sensitivity is associated with the threshold of allergic reactions to peanut. CD63 peanut/anti-IgE and CD-sens values can be used to estimate the severity and threshold of allergic reactions during OFCs.

Keywords: Basophil activation test; CD-sens; CD203c; CD63; double-blind; peanut; peanut allergy; placebo-controlled food challenge; sensitivity; severity; threshold.

Fig 1

Peanut dose response of basophil activation in patients with severe versus nonsevere reactions (A) and in patients with low versus high threshold of reactivity (B) to peanut. *P < .05 and **P < .01 for the comparison between groups by using the Mann-Whitney U test.

Fig 2

Best BAT parameters to distinguish between patients with severe versus nonsevere reactions (A) and patients with low versus high threshold of reactivity (B) to peanut. **P < .01 and ***P < .001 for the comparison between groups by using the Mann-Whitney U test.

Fig 3

A, Proportion of patients with severe reactions according to the 75th percentile of basophil reactivity (measured by CD63 peanut/anti-IgE). B, Proportion of patients with lower threshold of reactivity to peanut according to the 75th percentile of basophil sensitivity (measured by using CD-sens). *P = .05 and **P < .01 for the comparison between groups by using the Mann-Whitney U test.