The difference between extracts and components

If a patient is suspected of having an allergy, a diagnosis is made, consisting of a thorough anamnesis by means of a physical examination, a query of clinical symptoms and a skin and/or blood test.

The blood tests measure class E antibodies (IgE) directed against allergen extracts, e.g. against the total extract of birch pollen. This means that it is determined whether the immune system forms class E protein molecules (= antibodies) to combat birch pollen. Molecular allergy diagnostics goes one step further and determines IgE antibodies against individual allergen components, i.e. against individual allergenic molecules within the extracts. Figuratively speaking: Extracts are the cake, components the ingredients.

In summary, extracts help to identify the allergen sources that cause symptoms. Allergen components can provide additional essential information on risk and cross-reactivity and allow more targeted treatments.¹

Extracts

Allergen extracts are made from natural material (e.g. pollen from ragweed). They consist of both allergens and non-allergenic components. These extracts are used on the one hand for diagnosis of allergies via a skin or blood test and on the other hand for therapy. If allergen extracts are administered to the affected person slowly over a longer period of time, a reduced immune reaction to the trigger is produced. This form of treatment is called allergen-specific immunotherapy (SIT/SLIT) or hyposensitisation.

Example: Allergen extract from plant pollen

In order to produce extracts from plant pollen, these are soaked in alcohol. However, not all relevant components of the pollen are alcohol-soluble and are therefore not detected during the extraction process. To compensate for the absence of these components, some of the naturally produced extracts are enriched with recombinant allergens that are produced biotechnologically.²

Components

Allergen components are single molecules (mostly proteins such as Amb a 1, Amb a 4 from ragweed) that can trigger sensitisation (formation of allergen-specific antibodies). The testing of individual components serves as a supplement to IgE antibody tests with extracts and offers a more precise allergy diagnosis. Among other things, cross-reactions can be distinguished from primary sensitisations, which allows a more specific choice of immunotherapy.

Cross-reactive allergen components

These can be divided into allergen families. All allergens within an allergen family have a very high amino acid sequence identity and structural similarity. Due to this high similarity, the allergens are virtually confused by the immune system. IgE antibodies, which are originally directed against birch, also bind to similar allergens in food: This leads to a cross allergy.

Example: Birch pollen-associated food allergy

Many people who are allergic to birch pollen have specific IgE antibodies against the birch pollen main allergen Bet v 1. This component has a similar structure to other proteins of the so-called PR-10 family. This allergen family also includes many foods such as apple, hazelnut, soya or peanuts, which can lead to a cross-reaction. This means that many birch pollen allergy sufferers experience allergic symptoms in the mouth and throat area even after eating these foods.

If you know about your cross-reactions, you can remove the food from your diet and prevent symptoms.

The igevia-Allergy Test uses both extracts and components as allergen sources. The results are therefore based on the latest scientific findings.