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In Spain Ara h 9, also known as a lipid transfer protein (LTP), was associated with
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“true” peanut allergy in a cohort of mostly adults . Twenty-two of the 26 peanut allergic
individuals also reported symptoms after eating peaches. Peach, hazelnut, and
mugwort all contain LTP allergens and are included in the test panel to help detect
specific IgE to this protein that may be relevant to “true” peanut allergy, especially in
people who are allergic to peaches.

Peanut allergens Ara h 8, hazelnut allergen Cor a 1 and birch allergen Bet v 1 are all
cross-reactive and belong to a pathogenesis related protein family. Ara h 5, Cor a 2
and Bet v 2 are cross-reactive and are members of the profilin family which includes
allergens from grasses such as timothy and other plants. In a recent study of children
in Sweden, the presence of Ara h 8 specific IgE without detectable specific IgE to Ara
h 1, Ara h 2 or Ara h 3, was associated with no or mild reactions to peanut challenges.
This family of allergens tends to be labile to digestion and when relevant to clinical
reactivity is most often associated with oral allergy syndrome (OAS). The profilins like
Ara h 5, Cor a 2 and Bet v 2 are rarely associated with clinical allergic reactions, but
may be involved in OAS.

Patients with pollen specific IgE often have IgE antibodies directed against a
carbohydrate antigen found in many pollens including timothy grass and birch pollen
as well as peanut. The carbohydrate antigens have been designated cross-reactive
carbohydrate determinants (CCD) and specific IgE to CCDs are found in 20 – 60 % of
pollen sensitive people. The clinical relevance of CCD specific IgE is not totally
understood, but it has generally been thought to have little clinical relevance to peanut
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allergy .

The diagnosis of “true” peanut allergy must include the patient clinical history, clinical
findings, and symptoms as well as laboratory findings. The use of the Allermetrix
peanut panel will help physicians identify patients who may be at higher risk of
developing or having strong clinical reactions to peanuts. Several studies have
demonstrated that a high level of peanut specific IgE (15- 57 kU/L) is highly predictive
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of anaphylaxis . This cutoff was developed as a tool to identify patients in whom a
peanut challenge could be life threatening. It is not a very sensitive cutoff as many
patients who have peanut specific IgE at lower concentrations have clinical peanut
allergy.

The Allermetrix peanut panel can help stratify the risk of patients reacting to peanuts.
The presence of specific IgE to Ara h 2 appears to identify those at highest risk of
being clinically sensitive to peanut. A negative Ara h 2 finding with elevated specific
IgE to Ara h 1, peach, hazelnut, or mugwort may represent an intermediate risk level
for the patient to have clinical reactions to peanut. Patients with positive peanut
specific IgE that are not reactive to Ara h 2, Ara h 1, and peach but demonstrate
reactivity to any of the pollen allergens in the peanut panel most likely have cross-
reactive antibodies. These patients represent the lowest laboratory risk for a clinical

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