Close

Log In

Login to continue where you left off or register to access the accredited modules

Peanut and tree nut allergies

Learning objectives

After this module, participants will be able to:

  • Identify and describe which components can be used in component-resolved diagnostics (CRD) to aid the diagnosis and management of peanut and tree nut allergies.
  • Explain the different cross-reactions that can occur between peanuts, tree nuts and other allergen sources.

 

Nut allergies

  • Nuts are a major food in all diets worldwide. In Europe, they are primarily consumed in a roasted form, eaten whole, as nut butters or as ingredients in food products.1
  • Peanuts are classified as legumes (as opposed to nuts) and respective allergies have been shown to affect 2% of children in the UK.2
  • Allergies can also be induced by tree nuts, such as hazelnuts, cashew nuts and walnuts.3
  • Generally, there are two types of nut allergy: 4
    • Primary nut allergy – a systemic, often severe reaction to nuts in patients sensitised to major storage proteins
    • Pollen food syndrome – a distinct disorder with generally mild oral/pharyngeal symptoms due to a pollen sensitisation, which can be triggered by nuts
    • In northern and central European countries, reactions to hazelnut are often driven by birch pollen.5
  • The allergenicity of nuts can be altered through processing. For example, roasting at high temperatures has been shown to increase the allergenicity of Ara h 1 (peanut) by inducing the formation of globular protein aggregates.6

Allergens in peanut, hazelnut and cashew nut1

PR, pathogenesis-related; nsLTP, non-specific lipid transfer protein 
 

Allergenicity of nut allergens

 

Cross-reactivities of nut allergens

The following cross-reactions have been identified for peanuts, hazelnuts and cashew nuts:

 

 

Component-resolved diagnostics in nut allergy

The potential of component-resolved diagnostics (CRD) in routine diagnostics for peanut and tree nut allergies has been extensively studied.5,28,29

Generally, CRD may offer:

  • Detection of species-specific marker allergens which can indicate primary sensitisation, e.g. Cor a 14 (hazelnut) and Ara h 2 (peanut)20
  • Discrimination between cross-reactivities which may be causing clinical symptoms, e.g. Bet v 1 (birch) and Cor a 1 (hazelnut) cross-reactivity (very common in birch pollen allergic subjects). This can differentiate pollen-food syndrome from true nut allergy20
  • Reduce the number of oral food challenges.28,29

All results must be interpreted with the patient’s medical history and symptoms.30

 

CRD in peanut and tree nut allergies

Peanuts (Arachis hypogaea)

  • Ara h 1, Ara h 2 and Ara h 3 can be used as primary, species-specific sensitisation markers as long as specific IgE to storage proteins from other legumes are negative or significantly lower20. However, in some Mediterranean populations, sensitisation to Ara h 9 may be more prevalent.10
    • For example, a cross-sectional study performed in children and adolescents showed that Ara h 9 sensitisation was more frequent in older children (age 6–10) and adolescents (age 11–20) and less frequent in younger children (age 1–5). The opposite trend was observed with Ara h 2.11
  • IgE sensitisation to Ara h 5 and Ara h 8 is associated with profilin and PR-10 Bet v 1 cross-reactions, respectively.20

Hazelnuts (Corylus avellane)20

  • IgE sensitisation to Cor a 9 and Cor a 14 in hazelnut allergy can be used as primary species-specific allergen markers if specific IgE to storage proteins (2S albumins, 7S and 11S globulins) in other tree nuts, legumes or seeds are significantly lower.
  • IgE to sensitisation to Cor a 8 in a food allergic patient (from southern Europe) with systemic reactions can be associated with primary Cor a 8-associated sensitisation or an nsLTP-cross reaction.
  • In birch pollen allergic patients (e.g. from central or northern Europe) with mostly mild oral symptoms, cross-reactivity to Cor a 1 is common.

Cashew nuts (Anacardium occidentale)

  • Specific IgE to Ana o 3 can be used to predict clinically relevant allergy to cashew nuts.18

 

Are there scenarios in which CRD results provide clues for predicting the severity of nut allergy response?

Summary

  • Sensitisation to Ara h 2 is considered to be the best predictor for peanut allergy; however, Ara h 9 may be a better predictive marker in southern European populations
  • Sensitisation to peanut allergens Ara h 8 and Ara h 5 can be indicators of cross-reactivity
  • Cor a 9 and Cor a 14 are primary species-specific allergen markers for hazelnut; however, sensitisation to Cor a 8 may also be of relevance to southern European patients
  • Sensitisation to hazelnut allergen Cor a 1 can be an indicator of cross-reactivity
  • Sensitisation to Ana o 3 is considered the best predictor for cashew nut allergy
  • CRD can be used to detect sensitisation to species-specific allergen markers for each nut and can be used to distinguish primary nut allergy from pollen-food syndrome.
  • CRD may also help reduce the number of oral food challenges carried out.

 

References

  1. Matricardi PM et al. (Editors). Molecular Allergology User’s Guide. 2016. Zurich: European Academy or Allergy and Clinical Immunology.
  2. Allergy UK. https://www.allergyuk.org/information-and-advice/conditions-and-symptoms/778-peanut-allergy (accessed July 2019)
  3. Weinberger T, Sicherer S. J Asthma Allergy. 2018;11:41–51
  4. Stiefel G et al. Clin Exp Allergy. 2017;47(6):719–739
  5. Datema MR et al. J Allergy Clin Immunol. 2015; 136(2):382–391
  6. Vissers YM et al. Clin Exp Allergy. 2011; 41(11):1631–1642
  7. Agabriel C et al. Pediatr Allergy Immunol. 2014; 25(7):662– 667
  8. Suratannon N et al. Pediatr Allergy Immunol. 2013; 24(7):665–670
  9. Ebisawa M et al. Pediatr Allergy Immunol. 2012; 23(6):573–581
  10. Vereda A et al. J Allergy Clin Immunol. 2011; 127(3):603–607
  11. Garica-Blanca A et al. Pediatr Allergy Immunol. 2015; 26(6):497–502
  12. Nicolaou N et al. J Allergy Clin Immunol. 2010; 125(1):191–197
  13. Lange L et al. Allergo J Int. 2014; 23(5):158–163
  14. Lauer I et al. Clin Exp Allergy. 2009; 39(9):1427–1437
  15. Beck SC et al. J Clin Pathol. 2018; 71(3):239–245
  16. Garnier L et al. Clin Transl Allergy. 2014; 4(Suppl 2):O15
  17. Scala E et al. Allergy. 2015; 70(8):933–943
  18. Lange L et al. Allergy. 2017; 72(4):598–603
  19. Mittag D et al. J Allergy Clin Immunol. 2004; 114(6):1410–1417
  20. Kleine-Tebbe J, Jakob T (Editors). Molecular Allergy Diagnostics. Springer Nature. 2017
  21. Arkwright PD et al. Biomed Res Int. 2013; 746507
  22. Cabanos C et al. Protein Expr Purif. 2010; 73(1):36–45
  23. De Leon MP et al. Mol Immunol. 2007; 44(4):463–471
  24. Hofmann C et al. J Allergy Clin Immunol. 2013; 131(5):1384–1392
  25. Schocker et al. J Allergy Clin Immunol. 2004;113(1):141–147
  26. Villalata D et al. Int Arch Allergy Immunol. 2019; 178(1):89–92
  27. Archila LD et al. Clin Exp Allergy. 2016; 46(6):871–883
  28. Eller E, Bindslev-Jensen C. Allergy. 2013; 68(2):190–194
  29. Dang TD et al. J Allergy Clin Immunol. 2012; 129(4):1056–1063
  30. Portnoy JM. Mo Med. 2011; 108(5):339–343
 
PCM Scientific Logo
This independent educational activity is supported by funding from Thermo Fisher Scientific. PCM Scientific is the medical education company acting as scientific secretariat and organiser for this programme. The activity is run independently of the financial supporter and all content is created by the faculty. No funder has had input into the content of the activity.
1 Giltspur Street, London EC1A 9DD