Allergies are now the 5th leading cause of chronic disease. This growing epidemic currently affects more than 50 million Americans at a cost of ~$18B/yr. Diagnosing allergies traditionally has relied on in vivo testing whereby a patient is exposed to a series of allergens by skin pricks, or challenged systemically with a single allergen. This research aims to develop a quantitative in vitro assay using mononuclear cells that will accurately predict the in vivo outcome upon exposure to an allergen. The diagnostic test would be less painful, and would minimize the risks associated with traditional challenge tests, such as anaphylaxis.