The present invention provides in vitro and in vivo diagnostic tests and methods for determining the safety, efficacy, or outcome of allergen-specific immunotherapy (SIT) in a patient. The present invention also provides for the measurement of allergen specific IgG and IgE in a patient tissue sample, or extract thereof, or in a biological fluid or blood sample, and determining whether the allergen-specific immunoglobulins contained in the patient sample(s), upon injection into an allergen-sensitized animal, will protect the animal following challenge with the allergen. The invention also provides methods for determining whether a patient suffering from an allergy is responsive to therapy with one or more therapeutic antibodies specific for the allergen.