ABSTRACT
Allergen immunotherapy is appropriately performed with vaccines of inhalant allergens and the venom or, in some cases, the whole body extract from stinging insects. The term vaccine is used to designate the solution administered to the patient. The materials used to prepare the vaccine are referred to as extracts. Allergen extract companies compare their extract to the Center for Biologies Evaluation and Research reference using enzyme-linked immunosorbent assay inhibition, and potency is assigned. The traditional expressions of extract potency are weight by volume and protein nitrogen units. Neither provides precise information regarding the allergenic potency of the extract. Grass pollen vaccines containing 15–20 mcg of the major grass allergen are effective, but there was only marginal improvement compared to placebo when the maintenance dose contained only 2 mcg of the major allergen. The most extensive experience with vaccines containing known amounts of the major allergens is with ragweed. Glycerin is the most effective preservative for allergen extracts.
