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Allergen Profile, Cashew Nut, IgE With Component Reflex
The cashew nut component profile includes allergen-specific IgE to cashew nut extract. This test reflexes to cashew nut component Ana o 3 when the cashew allergen-specific IgE is >0.10 kU/L.
The measurement of specific immunoglobulin E (IgE) to 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 risk assessment using allergen components.
• Improve management of allergic patients.
Thermo Fisher ImmunoCAP® Allergen-specific IgE
• Cashew nut allergy is increasing as consumption increases. Snacking on cashew nuts has become more popular, and their use as a common ingredient in Asian foods, baked goods, nut butters, and pestos is growing.6,7
• Cashew nut allergic patients have high risk of experiencing severe allergic reactions; the risk has been reported to be even higher than for peanut allergic patients (74% vs. 30%).6-11
• Cashew nut allergy is potentially life-threatening, can start early in life, and is rarely outgrown.8,10,12
• Symptoms can be elicited on first known exposure, and the dose is often very low (eg, smelling, touching without eating).6,10,12
• Cashew nut allergy is increasing in parallel with increased consumption as it's becoming a popular snack, a common ingredient of Asian and processed foods, such as nut butters, baked goods, and pesto.6,7
• Cashew nut and pistachio are botanically closely related and show extensive cross-reactivity.7,13-16
• Ana o 3, a major cashew nut allergen, is a storage protein that serves as an energy source for the seed during growth of a new plant.7,17
• Sensitization to Ana o 3 indicates a primary cashew nut allergy.7,8,17
• Sensitization to 2S albumins, such as Ana o 3, is known to be associated with systemic food reactions.7,13,17-20
• Cashew nut allergic patients sensitized to Ana o 3 should avoid raw as well as roasted/heated cashew nuts.13,19
• Cashew nut allergic patients with sensitization to Ana o 3 should also be investigated for allergy to other nuts or seeds, such as pistachio, walnut and peanut, as coëxisting allergies may occur.7,13,19
• Positive whole cashew IgE with negative Ana o 3 results may be explained by sensitization to:
− Other cashew nut storage proteins or lipid transfer protein (LTP).
− Pollen proteins like profilin or PR10 proteins.
− CCD (cross-reacting carbohydrate determinants).
0.5 mL (Note: This volume does not allow for repeat testing.)