Allergen Profile, Walnut, IgE With Component Reflex*

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Turnaround Time: 3 - 5 days
CPT Code:


Test Type: 0.6mL Serum


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.

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

1. Chokshi NY, Sicherer SH. Interpreting IgE sensitization tests in food allergy. Expert Rev Clin Immunol. 2016 Apr; 12(4):389-403. PubMed 26666347

2. Canonica GW, Ansotegui IJ, Pawankar R, et al. A WAO - ARIA - GA2LEN consensus document on molecular-based allergy diagnostics. World Allergy Organ J. 2013 Oct 3; 6(1):17. PubMed 24090398

3. Incorvaia C, Rapetti A, Aliani M, et al. Food allergy as defined by component resolved diagnosis. Recent Pat Inflamm Allergy Drug Discov. 2014 Jan; 8(1):59-73. PubMed 24483212

4. Sampson HA, Aceves S, Bock SA, et al. Food allergy: A practice parameter update-2014. J Allergy Clin Immunol. 2014 Nov; 134(5):1016-1025. PubMed 25174862

5. Kattan JD, Sicherer SH. Optimizing the diagnosis of food allergy. Immunol Allergy Clin North Am. 2015 Feb; 35(1):61-76. PubMed 25459577

6. Roux KH, Teuber SS, Sathe SK. Tree nut allergens. Int Arch Allergy Immunol. 2003 Aug; 131(4):234-244. PubMed 12915766

7. Costa J, Carrapatoso I, Oliveira MB, Mafra I. Walnut allergens: molecular characterization, detection and clinical relevance. Clin Exp Allergy. 2014 Mar; 44(3):319-341. PubMed 24382327

8. Pastorello EA, Farioli L, Pravettoni V. Lipid transfer protein and vicilin are important walnut allergens in patients not allergic to pollen. J Allergy Clin Immunol. 2004 Oct; 114(4):908-914. PubMed 15480333

9. Rosenfeld L, Shreffler W, Bardina L, et al. Walnut allergy in peanut-allergic patients: significance of sequential epitopes of walnut homologous to linear epitopes of Ara h 1, 2 and 3 in relation to clinical reactivity. Int Arch Allergy Immunol. 2012; 157(3):238-245. PubMed 22042002

10. McWilliam V, Koplin J, Lodge C, Tang M, Dharmage S, Allen K. The prevalence of tree nut allergy: A systematic review. Curr Allergy Asthma Rep. 2015 Sep; 15(9):54. PubMed 26233427

11. Maloney JM, Rudengren M, Ahlstedt S, Bock SA, Sampson HA. The use of serum-specific IgE measurements for the diagnosis of peanut, tree nut, and seed allergy. J Allergy Clin Immunol. 2008 Jul; 122(1):145-151. PubMed 18502490

12. Sastre J. Molecular diagnosis in allergy. Clin Exp Allergy. 2010 Oct; 40(10):1442-1460. PubMed 20682003

13. Uotila R, Kukkonen AK, Pelkonen A, Mäkelä MJ. Cross-sensitization profiles of edible nuts in a birch-endemic area. Allergy. 2016 Apr; 71(4):514-521. PubMed 26706253

14. Romano A, Scala E, Rumi G, Gaeta F, et al. Lipid transfer proteins: The most frequent sensitizer in Italian subjects with food-dependent exercise-induced anaphylaxis. Clin Exp Allergy. 2012 Nov; 42(11):1643-1653. PubMed 23106665

15. Cardona V, Luengo O, Garriga T, et al. Co-factor-enhanced food allergy. Allergy. 2012 Oct; 67(10):1316-1318. PubMed 22845005

16. Pascal M, Muñoz-Cano R, Reina Z, et al. Lipid transfer protein syndrome: clinical pattern, cofactor effect and profile of molecular sensitization to plant-foods and pollens. Clin Exp Allergy. 2012 Oct; 42(10):1529-1539. PubMed 22994350

17. Ciprandi G, Pistorio A, Silvestri M, Rossi GA, Tosca MA. Walnut anaphylaxis: The usefulness of molecular-based allergy diagnostics. Immunol Lett. 2014 Sep; 161(1):138-139. PubMed 24928563

18. Pedrosa M, Boyano-Martínez T, García-Ara MC, Caballero T, Quirce S. Peanut seed storage proteins are responsible for clinical reactivity in Spanish peanut-allergic children. Pediatr Allergy Immunol. 2012 Nov; 23(7):654-659. PubMed 22830362

19. Robotham JM, Wang F, Seamon V, et al. Ana o 3, an important cashew nut (Anacardium occidentale L.) allergen of the 2S albumin family. J Allergy Clin Immunol. 2005 Jun; 115(6):1284-1290. PubMed 15940148

20. Egger M, Hauser M, Mari A, Ferreira F, Gadermaier G. The role of lipid transfer proteins in allergic diseases. Curr Allergy Asthma Rep. 2010 Sep; 10(5):326-335. PubMed 20582490

Collection Details:

Collection Instructions:

Red-top tube or gel-barrier tube.

Room Temperature.