Basophil activation test (BAT) is a blood test used for the diagnosis of allergy to substances such as foods, drugs and inhalants.
A sample of blood of the patient is incubated with the suspect allergen. If the patient is sensitised, the basophils (a type of leukocyte/white blood cell) will be activated and release chemical mediators from the granules inside the cell. During this process the membrane of the basophil will show some specific molecules (CD63 or CD203c) that will allow the identification of the activated basophils.
BAT is a relatively new, sophisticated and laborious technique and is not widely available. Also, the number of allergens is not as ample as for the classical skin tests.
Results with BAT are very promising. One of the main advantages is the identification of allergies with a simple extraction of blood, thus avoiding food or drug challenges. These may pose patients at the risk of severe reactions.
Usually no specific preparation is needed for the test, which only requires a blood extraction. Some medication, such as anti-IgE monoclonal antibody omalizumab, may change the result of the test. If you are scheduled for a BAT you should inform your doctor of the medication you are receiving.
The results of BAT are measured by flow cytomery.
Angel Mazon MD, PhD