Allergenic extracts are complex mixtures of bioactive molecules, the most important of which are the proteins that elicit a specific IgE-mediated immune response, the so-called “active ingredients” of an extract. The advent of improved biochemical methods has made it possible to more thoroughly evaluate the allergen content for a number of commercially available products. Subsequently, a defined allergen profile now represents one of the key features of an extract and it often serves as a fundamental parameter when assessing lot-to-lot consistency.
Characterization Assays
Most allergenic extract manufacturers employ a limited set of biochemical assays to evaluate the components of their extracts. At ALK, we utilize multiple assays as part of our extract characterization efforts:
Polyacrylamide Gel Electrophoresis (PAGE)
A qualitative method which separates proteins based on size and electrical charge to reveal the complex protein profile of an extract (e.g. species differentiation for pollens and venom).
Immunoelectrophoresis (IE)
A qualitative/quantitative gel assay that helps differentiate the antigenic proteins within an extract by confirming reactivity to patient serum. (e.g. Fel d 1 in cat hair/pelt extracts).
Enzyme-Linked Immunosorbent Assay (ELISA)
A quantitative colorimetric assay that is performed on a 96-well microtitre plate and utilizes polyclonal or monoclonal antibody binding principles to detect specific allergens.
Major Allergens People who suffer from allergies may produce IgE antibodies towards any number of proteins for a given allergen source. However, for most allergic individuals, one or two proteins can typically be identified as the immunodominant triggers. Consequently, certain immunologically important proteins are classified as Major Allergens. To be designated as a major allergen, the protein in question should demonstrate significant IgE reactivity in greater than 50% of patients who exhibit clinical symptoms to the allergen source material.
Given the importance of major allergens in the etiology of allergic disease, it has become our goal at ALK to track these proteins as part of our extract characterization process. To meet this objective, we continually dedicate scientific resources for the development and validation of major allergen assays.