IgE to specific peanut allergens (Ara h) may identify peanut-sensitized individuals at risk of severe symptoms

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.

From a birth cohort, IgE antibody levels to peanut and birch pollen were measured.

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 vs 17% of children with IgE reactivity to Ara h 8 but not to Ara h 1, 2 or 3.

Symptoms were more severe in children with Ara h 1, 2 or 3 reactivity.

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.


8 top allergens account for 90 percent of food allergies. Specific IgE levels (sIgE) that predict the likelihood of passing an oral food challenge are shown in the figure. (click to enlarge the image). Sensitivity of blood allergy testing is 25-30% lower than that of skin testing, based on comparative studies (CCJM 2011).

References:

IgE to peanut allergen components: relation to peanut symptoms and pollen sensitization in 8-year-olds. A. Asarnoj et al. Allergy, 2010.
http://www3.interscience.wiley.com/journal/123276060/abstract

Peanut allergy: Diagnostic accuracy of sIgE to Ara h 6 in adults is as good as Ara h 2 http://buff.ly/1uU314i

Food Allergy: A Short Review

Food Allergen Avoidance

Food Challenges

Mind Maps: Food Allergy

Mnemonics: Food Allergy

Pearls and Pitfalls of Allergen Testing - JCAAI http://goo.gl/6ThcC and http://goo.gl/Bfnhn

Comparison of diagnostic methods for peanut, egg, and milk allergy - skin prick test (SPT) vs. specific IgE (sIgE) (click to see the spreadsheet).

Overdiagnosis of Food Allergy: IgE and skin-prick testing should be confined to the realm of experts (allergists). Medscape, 2011.

Below is a marketing video from ImmunoCAP Peanut Component test. From the test manufacturer's YouTube channel: "The mother of a patient shared the story of her son who was diagnosed with multiple food allergies as an infant. After a peanut allergy diagnosis, the family's world was turned upside down. Recently, when starting Kindergarten, his doctor recommended the ImmunoCAP Peanut Component tests and, like 75% of all peanut sensitized individuals, the test results indicated he was not clinically allergic. He can now eat peanuts without fear."