PURPOSE OF THE STUDY.
To evaluate whether environmental peanut exposure is a risk for peanut sensitization and allergy and whether this risk is modified by an impaired skin barrier.
Subjects were 359 atopic children, aged 3 to 15 months, who had been recruited to the National Institutes of Health-sponsored Consortium of Food Allergy Research (CoFAR) Observational Study and had dust samples available for analysis. Participants had a clinical history of cow’s milk and/or egg allergy with a positive skin prick test (SPT) to these allergens or had moderate to severe atopic dermatitis and a positive SPT and with no known peanut allergy.
At recruitment into the CoFAR study, subjects were evaluated for history and severity of atopic dermatitis, peanut sensitization, and likely allergy based on peanut-specific immunoglobulin (Ig)E ≥5 kUA/mL. Peanut protein in household dust (micrograms per gram) was measured.
An exposure-response relationship was observed between peanut protein in household dust and peanut skin prick sensitization and likely allergy based on peanut-specific IgE. The odds of peanut SPT sensitization were increased with an increase in 4 log2 environmental peanut exposure (EPE; 1.71-fold; 95% confidence interval [CI], 1.13- to 2.59-fold, P = .01) in the final multivariate model. The same was true for likely peanut allergy (2.10-fold; 95% CI, 1.2- to 3.67-fold, P < .01). In subjects with a history of atopic dermatitis, the effect of EPE on peanut SPT sensitization was enhanced (odds ratio [OR], 1.97; 95% CI, 1.26–3.09; P < .01) and even more so in those with history of severe atopic dermatitis (OR, 2.41; 95% CI, 1.30–4.47; P < .01). The effect of EPE on likely peanut allergy was also increased in these children with a history of atopic dermatitis (OR, 2.34; 95% CI, 1.31–4.18; P < .01), but the further increased effect was not seen with severe atopic dermatitis as it was with peanut SPT sensitization.
This study demonstrates a positive association between exposure to peanut protein in household dust and peanut sensitization and allergy in children with atopic dermatitis, providing further evidence that environmental exposure through an impaired skin barrier increases risk.
These findings indicate that when young children with atopic dermatitis are exposed to peanut antigen through transcutaneous contact, the risk for peanut sensitization and allergy are increased. Results further support the dual-allergen exposure hypothesis, which proposes that oral exposure at young ages may lead to tolerance whereas transcutaneous exposure, particularly through an inflamed skin barrier, can lead to sensitization (Lack G. J Allergy Clin Immunol. 2012;129:1187–1197). Additional research is needed to determine if the same association is present with other food antigens. Furthermore, this study highlights the need for additional research to delineate the risks versus benefits of different routes of exposure (ie, oral vs transcutaneous) of peanut allergens and the timing and balance of that exposure to prevent or to reduce the risk of peanut allergy.
- Copyright © 2015 by the American Academy of Pediatrics