Key test principles
The AllergyScreen®/AlleisaScreen® test kits are semi-quantitative in vitro diagnostics to determine the presence of allergen-specific IgE antibodies in human serum/plasma. A blood sample from the patient is necessary for this test. Liquid crude allergen extracts, produced for in vitro diagnostic purposes, are passively bound as allergen lines to a nitrocellulose membrane and the test membranes are glued into the troughs.
Customers can choose between up to 20 allergen lines using AllergyScreen® test kit and up to 60 different allergen lines using AlleisaScreen® test kit.
1. Different natural crude allergen extracts are bound as allergen lines to the surface of a nitrocellulose membrane.
2. To determine allergen-specific IgE antibodies, patients’ sera/plasmas (250 µl for AllergyScreen® and 300 µl for AlleisaScreen®) is pipetted onto the test strip and incubated for 45 minutes at room temperature. During this time the allergen-specific IgE antibodies bind to the specific allergens on the test strip. Unbound 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 onto the test strip and incubated for another 45 minutes at room temperature. The biotin coupled detector antibodies bind to the allergen-specific IgE from the patient serum/plasma. Unbound detector antibodies are removed by washing.
4. The test strip 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. Unbound streptavidin conjugate is removed by washing.
5. Finally the staining solution is added to the test strip 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 allergen-specific IgE antibody in the serum/plasma sample.
6. After thoroughly drying the test strip, an evaluation of the colouration of the allergen lines is carried out by an Improvio scanner. The concentration of allergen-specific IgE in the serum/plasma sample is determined and results are given in classes (from 0 to 6) and IU/ml (range 0 to 100 IU/ml).