Test Details
Methodology
Thermo Fisher ImmunoCAP® Allergen-specific IgE
Result Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Test Includes
The walnut component profile includes allergen-specific IgE to walnut extract. This test reflexes to two molecular components described below.
Use
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 to1-5:
• Distinguish between allergy due to cross-reactivity and primary allergy.
• Improve the risk assessment using allergen components.
• Improve management of allergic patients.
Footnotes
Custom Additional Information
• 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 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
• 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
Specimen Requirements
Specimen
Serum
Volume
0.6 mL
Minimum Volume
0.5 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 604600 | IgE Walnut w/Component Reflex | 602444 | Class Description | N/A | ||
| 604600 | IgE Walnut w/Component Reflex | 606845 | F256-IgE Walnut | kU/L | 6273-7 | |
| Order Code | 604600 | |||||
| Order Code Name | IgE Walnut w/Component Reflex | |||||
| Order Loinc | ||||||
| Result Code | 602444 | |||||
| Result Code Name | Class Description | |||||
| UofM | ||||||
| Result LOINC | N/A | |||||
| Order Code | 604600 | |||||
| Order Code Name | IgE Walnut w/Component Reflex | |||||
| Order Loinc | ||||||
| Result Code | 606845 | |||||
| Result Code Name | F256-IgE Walnut | |||||
| UofM | kU/L | |||||
| Result LOINC | 6273-7 |
| Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
|---|---|---|---|---|---|---|
| Reflex 1 | 604721 | Panel 604721 | 604719 | F441-IgE Jug r 1 | kU/L | 81790-8 |
| Reflex 1 | ||||||
| Order Code | 604721 | |||||
| Order Name | Panel 604721 | |||||
| Result Code | 604719 | |||||
| Result Name | F441-IgE Jug r 1 | |||||
| UofM | kU/L | |||||
| Result LOINC | 81790-8 | |||||
| Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
|---|---|---|---|---|---|---|
| Reflex 1 | 604721 | Panel 604721 | 604720 | F442-IgE Jug r 3 | kU/L | 81789-0 |
| Reflex 1 | ||||||
| Order Code | 604721 | |||||
| Order Name | Panel 604721 | |||||
| Result Code | 604720 | |||||
| Result Name | F442-IgE Jug r 3 | |||||
| UofM | kU/L | |||||
| Result LOINC | 81789-0 | |||||