Basophil activation testing in diagnosis and monitoring of allergic disease – an overview

Abstract

The nature of basophil activation as an ex vivo challenge makes it a multifaceted and promising tool for the allergist. Through the development of flow cytometry, discovery of activation markers such as CD63 and markers identifying basophil granulocytes, the basophil activation test (BAT) has become a pervasive test. BAT measures basophil response to allergen crosslinking IgE on between 150 and 2,000 basophil granulocytes with remarkable analytical sensitivity in < 0.1 ml fresh blood. Dichotomous activation is assessed as the fraction of reacting basophils. In patients with food-, insect venom-, and drug allergy and patients with chronic urticaria BAT can be part of the diagnostic evaluation in addition to history, skin prick testing, and specific IgE determination. BAT may also be helpful in determining the clinically relevant allergen. Basophil sensitivity may be used to monitor patients on allergen immunotherapy, anti-IgE treatment, or in the natural resolution of allergy. The test may use fewer resources and be more reproducible than oral, sting, nasal or bronchial challenge testing. BAT may be useful before challenge testing as it is less stressful for the patient and avoids severe allergic reactions. It may be useful before challenge testing. An important next step is to standardize BAT and make it available in diagnostic laboratories. This article provides an overview of the practical and technical details as well as the utility of BAT in diagnosis and management of allergic diseases.