Key test principles
The AllergyScreen® and the AlleisaScreen® systems are quantitative in vitro systems to determine the presence of allergen-specific IgE antibodies in human serum. A blood sample from the patient is necessary for this test. Liquid allergens, produced for in vitro diagnostic purposes, are passively bound as test lines to a nitrocellulose membrane and the membrane strips are glued into the reaction troughs.
Customers can select up to 20 allergens using AllergyScreen® and up to 60 different allergens using AlleisaScreen®.
1. Different allergens are bound as test lines to the surface of a nitrocellulose membrane.
2. To determine allergen-specific IgE antibodies, patients’ sera (250 µl for Allergyscreen® and 300 µl for AlleisaScreen®) is pipetted into the reaction trough and incubated for 45 minutes at room temperature. During this time the allergen-specific IgE antibodies bind to the specific allergens on the membrane. Nonbound IgE antibodies are removed by washing.
3. In a next step, polyclonal anti-human IgE antibody (AllergyScreen®) or a mix of a monoclonal and a polyclonal anti-human IgE antibody (AlleisaScreen®) is pipetted into the reaction trough and incubated for another 45 minutes at room temperature. These biotin coupled detector antibodies bind to the allergen-specific IgE from the patient serum. Nonbound detector antibodies are removed by washing.
4. The membrane is then incubated with a streptavidin tagged alkaline phosphatase (streptavidin-conjugate) for 20 minutes at room temperature. The streptavidin tag binds to the biotin of the detector antibody. Nonbound streptavidin-conjugate is removed by washing.
5. Now the substrate (colour solution) is added to the membrane and incubated at room temperature for 20 minutes. An enzymatic reaction of the alkaline phosphatase takes place, resulting in a blue band on the respective allergen line. The reaction is stopped by washing. The colouration is directly proportional to the amount of the specific antibody in the serum sample.
6. After thoroughly drying the membrane, an evaluation of the colouration of the allergen lines is carried out by one of our systems: Improvio scanners, CubeScreen Reader or RapidReader. The concentration of specific IgE in the serum sample is determined and results are given in classes (from 0 to 6) and iU/ml (range 0 to 100 iU/ml).