Basophil activation test

The basophil activation test (BAT) is a method for the diagnosis of allergies of the immediate type (type I) or pseudoallergic reactions. It uses an in vitro method to represent the in vivo reaction to allergen exposure. It is therefore an important allergological diagnostic component in immediate reactions and closes a diagnostic gap in unclear or difficult cases where discrepancies between the patient's medical history and in vivo/vitro diagnostics have arisen or where serological IgE diagnostics are not available (Strohmmeier D et al. 2017). Furthermore, it represents a test alternative for patients in whom skin testing is not possible for various reasons (e.g. high degree of sensitization with the risk of shock fragments during testing). However, the test is not suitable for detecting delayed-type hypersensitivity reactions (type IV reactions).

For this in-vitro procedure, the basophilic granulocytes are incubated with the relevant allergens (e.g. drugs, insect venom). After allergen stimulation, the basophils are detected by means of an anti-IgE antibody and their degree of activation is determined by the expression of specific surface markers(CD63 or CD203c, see CD classification below) by flow cytometry (see flow cytometry); alternatively, after allergen stimulation, the"leukotriene release" can be measured by ELISA.

Basophil activation is determined from heparin blood. The test is particularly suitable for the quantification of allergic reactions to food components/contents and drugs for which no RAST diagnosis exists.

1. Strohmeier d et al (2017) Evaluation of the basophil activation test in the diagnosis of food and drug intolerances. Allerg J Int 26: 72-73