Allergen Profile, Walnut, IgE With Component Reflex

Serum

0.6 mL

0.5 mL (Note: This volume does not allow for repeat testing.)

Red-top tube or gel-barrier tube

The measurement of specific immunoglobulin E (IgE) to individual components of an allergen, either purified native or recombinant, is referred to as component resolved diagnosis (CRD).^1-5 This approach represents an improvement over traditional measurement of IgE to allergen extracts that contain a mixture of proteins. The pattern of specific IgE reactivity to component allergens can predict which patients are at higher risk for systemic allergic reactions versus those who are sensitized but clinically tolerant. CRD can also be used to predict which patients are at risk for more severe reactions and which patients are likely to have milder symptoms.

Allergies to plant-derived foods can occur as the result of sensitization to relatively stable proteins, such as the seed storage or lipid transfer proteins. Sensitization to this type of protein can be associated with more severe, systemic reactions and a higher risk for anaphylaxis. Alternatively, allergies to plant-derived foods may occur in pollen-sensitized individuals due to pollen allergens that cross-react with food allergens. Examples of pollen-associated allergens are the profilins or PR10 proteins that are homologues of the major white birch pollen antigen Bet v 1. Allergy to this family of proteins is associated with symptoms that are generally limited to the oropharyngeal area (commonly referred to as the oral allergy syndrome of pollen food allergy syndrome).

Component resolved diagnostics can help to^1-5:

• Distinguish between allergy due to cross-reactivity and primary allergy.

• Improve the risk assessment using allergen components.

• Improve management of allergic patients.

Thermo Fisher ImmunoCAP® Allergen-specific IgE

Walnut Allergy

• Walnut is one of the most common causes of allergic reactions to tree nuts.^6-8

• Walnut allergy is potentially life-threatening, increasing in prevalence, and rarely outgrown.^8,9,11

• The estimated prevalence of walnut allergy in the general population is as high as 0.5% and in food allergic children as high as 4%.^8,10

• Walnut and pecan nut are botanically closely related and show extensive cross-reactivity.^8,11-13

• Walnut allergy can appear early in life, symptoms can be elicited on first known exposure, and the dose can be very low.^8,9,11

• Walnut can induce food-dependent anaphylaxis elicited by exercise or other cofactors such as NSAID drugs or alcohol.^14-16

• Molecular allergy diagnostics can help to identify primary walnut sensitization in nut allergic patients.^12,17

Walnut Components

Jug r 1

• Jug r 1 is a storage protein that serves as an energy source for the seed during growth of a new plant.

• Sensitization to 2S albumin proteins such as Jug r 1 is known to be associated with systemic food reactions.^7,8,18,19

• Sensitization to the storage protein Jug r 1 (2S albumin) indicates a primary walnut allergy.^6,7

• Walnut allergic patients with sensitization to Jug r 1 should also be investigated for allergy to other nuts or seeds, including pecan nut, hazelnut, and cashew nut, as coëxisting allergies may occur.^9,11

Jug r 3

• Walnut-allergic patients sensitized to Jug r 3 may react to other LTP-containing foods, such as peach, other nuts, apple, or grapes.^7,8,14,20

• The presence of IgE antibodies to Jug r 3 indicates that local symptoms, as well as systemic reactions, can occur.^8,14,20

• Walnut-allergic patients sensitized to Jug r 1 and/or Jug r 3 should avoid raw as well as roasted/heated walnuts.¹²

Link for further information on walnut CRD.