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The glossary contains definitions and explanations of industry-specific and scientific terminology used within Extractopedia. Click one of the letters above to find terms beginning with that letter.



A substance that enhances the body’s immune response to an antigen. Can be found in vaccines.

Allergen extract

A biologic preparation derived from the extraction of a raw biological source material with an appropriate extracting fluid. The four common formulations of allergen extracts include: glycerinated, lyophilized, aqueous, and alum-precipitated.


A potency unit that expresses the relative biologic activity of an allergenic extract compared to an FDA-issued standard. House Dust Mite extracts are the only extracts that are standardized using AU.


A condition of hyperreactive airways. This includes bronchial constriction, inflammation and hypersecretion of mucus. Asthma is a common co-morbidity associated with allergic rhinitis. Pediatric allergic rhinitis, especially that driven by perennial allergens (e.g., House Dust Mite, Mold), commonly progresses to allergic asthma of varying severity.

Aqueous extract

An extract of allergen in an aqueous (i.e. water-based) solution. This is in contrast to a glycinerated extract, which is formulated in a glycerin-based solution. Aqueous extracts contain a saline solution and 0.4% phenol, which functions as a bacteriostatic agent.


A water-based solution, typically saline-derived. In the case of allergen extracts, aqueous solutions must include a bacteriostatic agent, such as phenol, to maintain sterility.


Any natural or synthetic substance capable of eliciting a cellular-signaling response. All allergens are antigens, but the reverse is not true. Antigens bind different classes of Ig receptors (e.g., IgA, IgG, IgM, IgE). Allergens specifically provoke an IgE antibody response (Type I hypersensitivity) in sensitized individuals, while non-sensitized individuals clear the allergen, typically symptom-free, via an allergen-IgG-mediated response.


An immediate, severe hypersensitivity reaction caused by a systemic (full body) allergic response. One or more of the following symptoms may occur: sneezing, mild to severe generalized urticaria, itching (other than at the skin test site), extensive or generalized edema, wheezing, asthma, dyspnea, cyanosis, hypotension, syncope, and upper airway obstruction. Symptoms may progress to shock and death. Patients should always be observed for at least 20 – 30 minutes after testing. Volume expanders and vasopressor agents may be required to reverse hypotension. Inhalational bronchodilators and parenteral aminophylline may be required to reverse bronchospasm. Severe airway obstruction unresponsive to bronchodilator may require tracheal intubation and use of oxygen. In the event of a marked systemic reaction, application of a tourniquet above the injection site and the administration of 0.2 mL to 1.0 mL of epinephrine injection (1:1,000) is recommended. Maximum recommended dose for children between 2 and 12 years of age is 0.3 mL. The tourniquet should not be left in place without loosening for 90 seconds every 15 minutes. Adverse events should be reported via MedWatch (1-800-FDA1088), Adverse Event Reporting, Food and Drug Administration, 5600 Fishers Lane, Rockville, MD 20852-9787

Amb a 1

A major allergen contained in short ragweed pollen. Short ragweed extracts are labeled with AgE concentrations (now called Amb a 1) The concentration of AgE (i.e., Amb a 1) is measured for each manufactured lot of extract, using a standardized assay. Clinical studies have been conducted, which established a therapeutic dose range for Ragweed allergy immunotherapy. Guidelines for dosing are outlined in the Allergy Immunotherapy Practice Parameters.


A process whereby an aqueous allergen extract is allowed to complex with an aluminum salt complex (e.g., aluminum hydroxide). Alum-precipitation functions as an adjuvant, which enables the extract to elicit an immunological response. In addition, the alum-allergen complex produces a depot effect, where the allergen is more slowly released into the body. This slow release formulation improves treatment tolerability, especially among highly sensitive patients.