BasophilenAktivierungstest

Basophilen Aktivierung, or basophil activation, refers to the process by which basophils respond to stimuli such as allergens or other mediators, leading to cellular changes and mediator release. Basophils are circulating white blood cells involved in immune responses and allergic inflammation.

The activation mechanism primarily involves crosslinking of IgE bound to the FcεRI receptor on the basophil surface by an antigen. This triggers intracellular signaling that results in degranulation and the release of histamine, leukotrienes (C4, D4, E4), and cytokines such as IL-4 and IL-13. Basophils can also be activated by non-IgE stimuli, including complement components C3a and C5a, and certain pharmacologic agents, contributing to diverse inflammatory responses.

Basophil activation tests (BAT) are laboratory assays that assess basophil responsiveness using flow cytometry. After in vitro stimulation with suspected allergens or controls, the upregulation of activation markers such as CD63 and CD203c on the basophil surface is measured. Results are usually reported as the percentage of activated basophils or as shifts in marker expression. BAT is used as an adjunct diagnostic tool in IgE-mediated allergies, venom immunotherapy evaluation, and some drug allergies, particularly when skin testing or specific IgE results are inconclusive or impractical.

Practical considerations include pre-analytical handling and anticoagulation of blood, since basophil responsiveness is sensitive to time and conditions. Samples are commonly collected in heparin and analyzed within several hours. BAT results should be interpreted in the context of the patient’s clinical history and alongside other allergy tests, recognizing limitations such as variable sensitivity across allergens and the lack of universal standardization across laboratories.