Allergeenispesifisyys

Allergeenispesifisyys refers to the degree to which an individual’s allergic immune response is directed toward a particular allergen or allergen component rather than to other, related substances. It describes the specificity of the immune reaction, typically mediated by allergen-specific IgE antibodies and, in some cases, T cell responses.

In allergic disease, specific reactivity is most often assessed with IgE-mediated mechanisms. Tests include measuring allergen-specific IgE (sIgE) in serum and skin prick testing (SPT) with defined allergens. Advances in component-resolved diagnostics (CRD) detect IgE to individual allergen components (for example, Ara h2 in peanut or Bet v 1 in birch pollen), which can improve the discrimination between sensitization and clinically relevant allergy. Other tools, such as basophil activation tests, are used in research or complex diagnostic cases.

Allergen specificity is important because of cross-reactivity. Shared protein epitopes among related allergens can cause sensitization to one substance to appear as reactivity to others. Clinically, distinguishing true allergen specificity from cross-reactivity helps tailor avoidance strategies and informs decision-making about immunotherapy.

Limitations include that the presence of sIgE or a positive skin test does not always predict clinical allergy, and CRD results must be interpreted in the context of history and exposures. Specificity can vary by population and may change with age or environmental exposure.

Examples commonly discussed include peanut Ara h2 specificity associated with true peanut allergy and Bet v 1–related cross-reactivity with certain fruits and vegetables. Allergeenispesifisyys remains central to accurate allergy diagnosis and management.