Predicting reactivity threshold in children with anaphylaxis to peanut
T Reier-Nilsen1,2, M M Michelsen1,2, K C Lødrup Carlsen1,2
1Division of Paediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway.
Insights
Basophil activation, peanut skin prick tests, and peanut-specific IgE levels predict peanut allergy reactivity thresholds in children. These markers do not predict the severity of allergic reactions during oral food challenges.
Area of Science:
- Allergy and Immunology
- Pediatric Allergy
- Clinical Immunology
Background:
- Peanut allergy management often requires dietary restrictions, ideally guided by individual reactivity thresholds determined via oral food challenges (OFC).
- Severe peanut allergy in children can pose risks, often precluding OFC due to potential systemic reactions.
Purpose of the Study:
- To identify clinical and immunological factors associated with peanut allergy reactivity thresholds in children experiencing anaphylaxis.
- To investigate if these factors correlate with the severity of allergic reactions during OFC.
Main Methods:
- A double-blinded placebo-controlled food challenge (DBPCFC) was conducted on 96 children (aged 5-15) with a history of severe peanut reactions or sensitization.
- Pre-challenge assessments included interviews, skin prick tests (SPT), lung function tests, serological IgE/IgG/IgG4 levels, basophil activation tests (BAT), and conjunctival allergen provocation tests (CAPT).
Main Results:
- All 96 children experienced anaphylaxis during the DBPCFC.
- Basophil activation, peanut SPT, and the peanut-specific IgE/total IgE ratio were significantly linked to reactivity thresholds and the lowest observed adverse event levels (LOAEL).
- Basophil activation effectively predicted very low peanut thresholds (<3 mg), with a 75.8% cut-off yielding a 93.5% negative predictive value.
Conclusions:
- In children with peanut anaphylaxis, basophil activation, peanut SPT, and peanut-specific IgE/total IgE ratio correlate with reactivity thresholds and LOAEL.
- These immunological and clinical markers were not associated with the severity of allergic reactions during OFC.
Background:
Peanut allergy necessitates dietary restrictions, preferably individualized by determining reactivity threshold through an oral food challenge (OFC). However, risk of systemic reactions often precludes OFC in children with severe peanut allergy.
Objective:
We aimed to determine whether clinical and/or immunological characteristics were associated with reactivity threshold in children with anaphylaxis to peanut and secondarily, to investigate whether these characteristics were associated with severity of the allergic reaction during OFC.
Methods:
A double-blinded placebo-controlled food challenge (DBPCFC) with peanut was performed in 96 5- to 15-year-old children with a history of severe allergic reactions to peanut and/or sensitization to peanut (skin prick test [SPT] ≥3 mm or specific immunoglobulin E [s-IgE] ≥0.35 kUA/L). Investigations preceding the DBPCFC included a structured interview, SPT, lung function measurements, serological immunology assessment (IgE, IgG and IgG4 ), basophil activation test (BAT) and conjunctival allergen provocation test (CAPT). International standards were used to define anaphylaxis and grade the allergic reaction during OFC.
Results:
During DBPCFC, all 96 children (median age 9.3, range 5.1-15.2) reacted with anaphylaxis (moderate objective symptoms from at least two organ systems). Basophil activation (CD63+ basophils ≥15%), peanut SPT and the ratio of peanut s-IgE/total IgE were significantly associated with reactivity threshold and lowest observed adverse events level (LOAEL) (all P < .04). Basophil activation best predicted very low threshold level (<3 mg of peanut protein), with an optimal cut-off of 75.8% giving a 93.5% negative predictive value. None of the characteristics were significantly associated with the severity of allergic reaction.
Conclusion And Clinical Relevance:
In children with anaphylaxis to peanut, basophil activation, peanut SPT and the ratio of peanut s-IgE/total IgE were associated with reactivity threshold and LOAEL, but not with allergy reaction severity.
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