Basophils orchestrate inflammatory reactions in immune responses and are hyperactive in allergic responses. Therefore, determining the influence of your drug on basophil activation can be of interest when you want to determine the anti-inflammatory action of anti-allergy drugs or want to screen for unwanted inflammatory/allergic side effects of your drug. 

The basophil activation test (BAT) is a whole blood assay used to investigate allergen-induced activation of basophilic granulocytes. Allergen activation is mimicked by incubation with anti-IgE. This anti-IgE crosslinks the IgE that is present on the basophil cell membrane, thereby activating the basophils. This activation can be assessed by measuring upregulation of CD63 (glycoprotein gp53), an indicator of degranulation, on CD123⁺HLA-DR^- basophils. If desired, also upregulation of CD203c, an early activation marker, can be assessed.

Advantages of the whole blood basophil activation assay

• 450 µl of whole blood per donor/subject is sufficient for read-out
• Assay has been set up according to ISO15189 regulations and can therefore directly be used in clinical trials
• Can be performed on blood from healthy donors in the presence of your compound, or any other blood sample provided by you (i.e. blood from in vitro dosed healthy donors)
• High-throughput measurement of many samples possible
• No pre-selection of cells necessary, which is especially useful for fragile cell populations such as basophils

Example of basophil activation assessment via BAT

Using BAT to assess the ex vivo effect on basophil activation of in vivo dosing of an immunomodulatory compound

Heparinized blood was collected before healthy subjects received an anti-inflammatory compound or placebo, and at indicated time points after dosing. After blood collection, basophils in whole blood were stimulated with anti-IgE (n=2), or left unstimulated (n=2). After 45 minutes of incubation, the samples were stained with anti-CD123, anti-HLA-DR and basophil activation marker anti-CD63. Subsequently, the erythrocytes were lysed to clean up the sample for flow cytometry. The white blood cells were fixed and analyzed by flow cytometry. % basophil activation is expressed as the percentage of CD63⁺ cells within the CD123⁺HLA-DR^- basophil gate.