allergenicity

Allergenicity is the property of a substance to provoke an allergic immune response in susceptible individuals. Allergens are typically proteins or glycoproteins that can trigger IgE-mediated type I hypersensitivity after sensitization. The likelihood and severity of reactions depend on factors such as the route of exposure (inhalation, ingestion, skin contact) and individual atopic predisposition. Common sources include pollen, dust mites, animal dander, foods, and certain insect venoms.

Mechanisms of allergenicity involve sensitization and effector responses. Dendritic cells process and present allergen epitopes to T helper cells, often steering a Th2 response with cytokines like IL-4 and IL-13. This promotes IgE class switching in B cells, leading to IgE production that binds to mast cells and basophils. Upon subsequent exposure, cross-linking of surface-bound IgE triggers release of histamine and other mediators, causing symptoms from sneezing and wheezing to anaphylaxis. Cross-reactivity can occur when different allergens share similar protein epitopes. Protein stability, proteolytic activity, and dose influence the degree of allergenicity, and non-IgE-mediated immune mechanisms can also contribute in some conditions.

Assessment and management of allergenicity focus on diagnosis, avoidance, and treatment. Diagnostic tools include skin prick testing, serum-specific IgE measurement, and, when appropriate, supervised oral food challenges. Management emphasizes exposure reduction, environmental controls, and accurate allergen labeling. Pharmacotherapy addresses symptoms, and emergency plans with epinephrine are essential for at-risk individuals. Immunotherapy, such as sublingual or subcutaneous routes, may reduce sensitivity for certain inhalant and venom allergies. Regulatory frameworks often require labeling and standardized allergen tests to aid risk communication.

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