Allergy or tolerance in children sensitized to peanut: Prevalence and differentiation using component-resolved diagnostics

Background

Not all peanut-sensitized children develop allergic reactions on exposure.

Objective

To establish by oral food challenge the proportion of children with clinical peanut allergy among those considered peanut-sensitized by using skin prick tests and/or IgE measurement, and to investigate whether component-resolved diagnostics using microarray could differentiate peanut allergy from tolerance.

Methods

Within a population-based birth cohort, we ascertained peanut sensitization by skin tests and IgE measurement at age 8 years. Among sensitized children, we determined peanut allergy versus tolerance by oral food challenges. We used open challenge among children consuming peanuts (n = 45); others underwent double-blind placebo-controlled challenge (n = 34). We compared sensitization profiles between children with peanut allergy and peanut-tolerant children by using a microarray with 12 pure components (major peanut and potentially cross-reactive components, including grass allergens).

Results

Of 933 children, 110 (11.8%) were peanut-sensitized. Nineteen were not challenged (17 no consent). Twelve with a convincing history of reactions on exposure, IgE ≥15 kUa/L and/or skin test ≥8mm were considered allergic without challenge. Of the remaining 79 children who underwent challenge, 7 had ≥2 objective signs and were designated as having peanut allergy. We estimated the prevalence of clinical peanut allergy among sensitized subjects as 22.4% (95% CI, 14.8% to 32.3%). By using component-resolved diagnostics, we detected marked differences in the pattern of component recognition between children with peanut allergy (n = 29; group enriched with 12 children with allergy) and peanut-tolerant children (n = 52). The peanut component Ara h 2 was the most important predictor of clinical allergy.

Conclusion

The majority of children considered peanut-sensitized on the basis of standard tests do not have peanut allergy. Component-resolved diagnostics may facilitate the diagnosis of peanut allergy.

Key words: Peanut allergy, oral food challenge, component-resolved diagnostics, Ara h 2, microarray, birth cohort

Abbreviations used: CRD, Component-resolved diagnostics, DBPCFC, Double-blind placebo-controlled food challenge, MWD, Mean wheal diameter, OFC, Oral food challenge, sIgE, Serum IgE, SPT, Skin prick test, UK, United Kingdom