Walnut allergy L27.-, T78.0, T78.1

Sensitizations against walnut are rather rare. In the past, walnuts, like hazelnuts , were considered a potent food allergen, to which patients with birch pollen - pollinosis (see below tree pollen) are particularly sensitive. Since no Bet-v-1-like allergens are found in the walnut, this is not true.

So far identified allergens of Juglans regia (Walnut, English walnut)

• Jug r 1 2S Albumin( seed storage protein): Major allergen, indicator of risk sensitization
• Jug r 2 Vicilin, seed storage protein: Major allergen, indicator of risk sensitization
• Jug r 3 Non-specific lipid transfer protein type 1 (nsLTP1): Major allergen, varying cross-reactivity with allergens of other members of the lipid transfer protein family.
• Jug r 4 11S Leguminous seed storage protein
• Jug r 5 PR-10 protein

The major allergens of the walnut Jug r 1 (2S-albumin), Jug r 2 (7S globulin) both storage proteins as well as Jug r 3(lipid transfer protein) can lead to systemic reactions when sensitized accordingly.

Nuts are the second most common cause of food-related anaphylaxis in children. The order of allergen frequencies is: hazelnut, cashew, almond, walnut. The frequency of sensitization varies widely across Europe. In tests with the extracts, sensitisation was 7.7% in Spain and 0.1% in Iceland. In tests with the primary allergens Jug r 2 and Jug r 4, both storage proteins, sensitisation was < 0.5%. There is a cross-reactivity between walnut and pecan nut.

1. Burney PG et al (2014) The prevalence and distribution of food sensitization in European adults. Allergy 69:365-371.
2. Kleine-Tebbe J et al (2016) Molecular allergy diagnostics with IgE single determinations (singleplex): Methodological and practical aspects In: Kleine-Tebbe JK et al (Hrsg) Molecular allergy diagnostics. Springer Publishing House GmbH S91-138
3. Lange L et al (2015) Molecular diagnostics for peanut allergy: Lipid transfer proteins. In: Kleine-Tebbe J et al. Hrsg Molecular allergy diagnostics. Springer Verlag Berlin-Heidelberg S 217-227.
4. WHO/IUS Allergen Nomenclature Sub-Committee