Walnut allergen proteins (Jug r) (Jug r)

Walnut allergen proteins are a group of seed storage and defense-related proteins found in the English walnut (Juglans regia) that are responsible for triggering IgE-mediated hypersensitivity reactions (WHO/IUIS Allergen Nomenclature). The most clinically significant components include Jug r 1 (a 2S albumin), Jug r 2 (a 7S vicilin-like globulin), Jug r 3 (a non-specific lipid transfer protein), and Jug r 4 (an 11S legumin-like globulin) (UniProt). These proteins are characterized by their high stability against thermal denaturation and proteolytic digestion, which allows them to maintain their allergenicity even after cooking or passing through the acidic environment of the stomach. In sensitized individuals, exposure to these proteins can lead to a range of symptoms, from mild oral itching to life-threatening systemic anaphylaxis (StatPearls). In the context of modern allergy medicine, these proteins serve as the primary targets for component-resolved diagnostics, which help clinicians assess the risk of severe reactions based on specific protein sensitization (e.g., Jug r 1 and Jug r 3 are often associated with systemic reactions). Furthermore, they are the active components in experimental and emerging allergen-specific immunotherapy (AIT) protocols, such as oral immunotherapy (OIT). These treatments aim to increase the patient's threshold for reaction by inducing a state of clinical desensitization, often utilizing biologics like Omalizumab as an adjunct to improve safety during the build-up phase (PMID: 31178037).

Other names

Juglans regia allergensWalnut seed storage proteinsEnglish walnut allergens

Walnut allergen proteins act as antigens that cross-link allergen-specific IgE on the surface of mast cells and basophils, triggering the release of inflammatory mediators like histamine and leukotrienes. Therapeutic strategies such as oral immunotherapy (OIT) involve the controlled, gradual administration of these proteins to induce immunological desensitization, shifting the immune response from a Th2-dominated allergic profile to a more tolerant state mediated by regulatory T cells (Tregs) and IgG4 antibodies (PMID: 31178037).