Thank you for your inquiry.
Your interpretation of the literature is correct in that “classically” the pattern of specific IgE to peanut components seen in your patient would be more likely to predict that only oral symptoms, and not a systemic reaction, would occur upon ingestion of peanuts. However, it is important to understand that this classical interpretation is based only on statistical probabilities. By this I mean that children demonstrating only specific IgE to Ara h 8 are less likely to exhibit a systemic reaction than children exhibiting specific IgE to Ara h 2, for example. Nonetheless, systemic reactions can occur with isolated sensitivity to Ara h 8.
As you can see from the abstract (Asarnoj, et al.) copied below, systemic reactions can occur in children with isolated Ara h 8 sensitivity. This is seen clearly in Figure 3 of this article.
The most reliable test to discern whether a child will exhibit a systemic reaction to peanut is an actual oral challenge. In essence, the reaction exhibited by the child described in your inquiry should be taken at “face value,” and the child, at least for the present, should be considered allergic to peanuts. It is clear that patients who have negative skin tests as well as serum specific IgE to foods may still exhibit allergic reactions upon oral food challenge (see Journal of Allergy and Clinical Immunology reference copied below).
Thus, in summary, the results of serum specific IgE testing both in testing to “whole” and component testing, simply serve as guidelines, pointing out the relative risks of a reaction upon ingestion. They are not intended to confer 100 percent predictability as to whether or not a patient will react to the ingestion of the food in question.
Thank you again for your inquiry and we hope this response is helpful to you.
Allergy. 2010 Sep;65(9):1189-95. doi: 10.1111/j.1398-9995.2010.02334.x. Epub 2010 Feb 8.
IgE to peanut allergen components: relation to peanut symptoms and pollen sensitization in 8-year-olds.
Asarnoj A, Movérare R, Ostblom E, Poorafshar M, Lilja G, Hedlin G, van Hage M, Ahlstedt S, Wickman M.
National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Background: Allergen-specific IgE testing is often performed with crude peanut extract, but the results may be difficult to interpret because of cross-reactions between peanut and other plant allergens. The aim was to investigate IgE reactivity to peanut allergen components in children from a birch-rich region in relation to pollen sensitization and peanut symptoms.
Methods: From a birth cohort, clinical parameters were obtained through questionnaires and IgE antibody levels to peanut and birch pollen were measured. Different peanut/birch sensitization phenotypes were defined among 200 selected children. IgE reactivity to peanut and pollen allergen components was analysed using microarray technique.
Results: Peanut symptoms were reported in 87% of the children with IgE reactivity to any of the peanut allergens Ara h 1, 2 or 3 but not to Ara h 8 (n = 46) vs 17% of children with IgE reactivity to Ara h 8 but not to Ara h 1, 2 or 3 (n = 23), P < 0.001. Furthermore, symptoms were more severe in children with Ara h 1, 2 or 3 reactivity. Children with IgE reactivity both to Ara h 2 and to Ara h 1 or 3 more often reported peanut symptoms than children with IgE only to Ara h 2 (97%vs 70%, P = 0.016), particularly respiratory symptoms (50%vs 9%, P = 0.002).
Conclusions: IgE analysis to peanut allergen components may be used to distinguish between peanut-sensitized individuals at risk of severe symptoms and those likely to have milder or no symptoms to peanut if sensitized to pollen allergens and their peanut homologue allergens.
J Allergy Clin Immunol. Author manuscript; available in PMC 2012 November 1.
Published in final edited form as:
J Allergy Clin Immunol. 2011 November; 128(5): 1120–1122.
Published online 2011 August 11. doi: 10.1016/j.jaci.2011.07.012
Outcomes of office-based, open food challenges in the management of food allergy
Jay A Lieberman, MD, Amanda L Cox, MD, Michelle Vitale, RN, and Hugh A Sampson, MD
Phil Lieberman, M.D.