BasoFunction Test

Adverse reactions to drugs and chemicals may not be detected by specific IgE testing or skin tests. The BasoFunction test is an in vitro test that measures histamine released from a person’s basophils following challenge with a suspected allergen in patients. This test is indicated for patients with a history of adverse reactions who cannot be tested by conventional methods. 

The BasoFunction test that is offered by some reference laboratories such as Eurofins and Quest Diagnostics. Peripheral blood leukocytes are enriched from heparinized whole blood and stimulated with formyl-methionyl-leucyl-phenylalanine (fMLP), allergen or buffer alone. Following a brief incubation, the amount of histamine released from the basophils into the supernatant is measured by enzyme-linked immunoassay (ELISA).  FLMP is a nonspecific stimulator that determines the activation potential of the patient’s basophils. Buffer serves as a negative control. 

The amount of histamine (ng/mL) released following stimulation with a specific allergen is reported. Patients with histamine values above a predetermined threshold have hypersensitivity to the specific allergen. The sensitivity and the true predictive value of the test is unknown for most drugs. Caution should be exercised with regard to patients who are non-responders to a suspected allergen. The allergen may still cause a clinically significant adverse reaction in vivo.

Approximately 5 to 10% of individuals have a low response to fMLP, indicating hypo-responsive basophils.The test is not valid in these individuals. 

The list of potential allergens that can be tested include analgesics, anesthetics, antibiotics, food additives, contrast media and other chemicals. Reference ranges were determined on a population of healthy controls that had responsive basophils and no history of adverse reactions to the indicated allergens. Reference ranges vary for each allergen.

Specimen requirement is a green top tube of blood. Patients taking calcineurin inhibitors should stop their medication for 72 hours prior to draw.  Patients taking prednisone should stop medication for 2 weeks before draw.