HRA is an in vitro assessment of allergic response that closely resembles the in vivo situation. The test require only small amount of whole blood and allows measurement of basophil functional response both for allergy diagnosis and for clinical monitoring (immunotherapy). This assay measure the release of histamine which occurs upon stimulation of basophilic granulocytes depending upon their sensitivity to a specific allergen.


Figure: Troubleshooting adverse effect reactions of compound in Phase I.

Figure: Cross-validation between histamine readout with CD63+ expression by basophils IN fMLP stimulated controls.


Beside allergens the histamine release assay is also applicable for the analysis of pathophysiological responses to drugs, chemicals and other compounds which have not been evaluated for adverse side effects.