1. Selecting Allergen for BAT
Box 1
Selecting Allergen for BAT
Start with patient history, attempt to identify the culprit allergen,
if possible, perform prick-test or determine sIgE,
sensitizing allergen might be replaced be analogous allergen
Use standardized allergen reagent if available
In the case of a response to allergen, attempt to identify individual
sensitising molecules to predict cross-reactions and determine
sensitising agents by establishing sensitisation to allergen molecules
Preparation of a standardized crude extract, if the allergen is not
available as standardized reagent:
10 g allergen in 100 ml PBS,
blending to homogeneity,
centrifugation of 15 ml at 600 g and 4°C for 8 min,
use of allergen extract at 10%, 1% and 0.1%,
in case of a positive results, include one to three controls

2. BAT in Allergy Diagnosis
Box 2
BAT in Allergy Diagnosis
Taking a structured patients history including severity of symptoms
Comfirmation of the allergen identity by an objective test
Prick test or measurement of sIgE
Consideration of an intradermal test in drug and insect venom allergy
Consideration of a BAT
In case the allergen is known to produce false positive results in skin testing
In case there is no allergen source to use for skin or sIgE testing
In case of discordance between the patient history and sIgE or skin tests (i.e. in case of IgE-mediated allergy, but negative sIgE due to extremely low total IgE)
In case of expecting a systemic response in skin testing
Before considering a challenge test to confirm culprit allergen

3. BAT in Monitoring Allergy
Box 3
BAT in Monitoring Allergy
Taking a structured patients history including severity of symptoms
Demonstration of the allergen identity by an objective test
Prick test or measurement of sIgE
Consideration of an intradermal test in drug and insect venom allergy
Measurement of basophil sensitivity
Start treatment/allow for natural tolerance development
Measurement of basophil sensitivity
In case BAT is negative
A challenge can be performed
Reintroduce allergen e.g. food

4. Potential Clinical Utility of BAT
Box 4
Support in diagnosis of allergy
Drugs (supplement for β-lactam antibiotics/quinolones, unique for muscle relaxants, radio contrast media and pyrazolones)
Food (reduction of number of OFC required possible)
Occupational allergens (unique)
Insect venom (supplement for insect venom allergen detection)
Autoimmune urticaria (replacement of ASST possible)
Local allergic rhinitis (possibly due to extraordinary analytical sensitivity of BAT)
Dichotomous decision: % pos, SI, AUC
Monitoring allergic disease
Reproducible ex vivo cor-relation to clinical allergy
Identification of clinical relevant allergen in insect venom allergy
Monitoring natural and induced resolution of food allergy
Predicting success of allergen immunotherapy
Monitoring anti-IgE-treatment
Change in sensitivity: EC50 – CD-sens