Standardization of Chortoglyphus Arcuatus Allergenic Extract. Determination of Biological Activity in HEP Units

The skin testing procedure, based on the Nordic Guidelines is the reference method for the biological calibration of in-House Reference Preparations (IHRP). The method is not intended for routine testing of allergen extracts. The use of this procedure is the basis for the definition of biological activity units: "the activity of an allergen extract is 10,000 Biological Units (BU) per ml (10 HEP per ml), when the extract provokes an specific skin reaction in the median sensitive patient with a wheal of the same size as a wheal provoked by a positive reference solution consisting of histamine 54.3 mmol/l (for example histamine dihydrochloride 10 mg/ml), when both solutions are administrated using the same technique (prick testing) on at least 20 individuals who are clinically allergic and cutaneously reactive to the allergen concerned".

Inclusion criteria

• Voluntarily signed informed consent form by the patient
• Patients should live in a geographic zone where allergy caused by Chortoglyphus arcuatus is a relevant problem.
• Patients should not be excluded due to low or high sensitivity to the allergen, when they otherwise fulfil the inclusion criteria.
• A positive case history with inhalant allergy related to exposure to the allergen to be tested.
• A positive prick test (mean wheal diameter > 3 mm) when tested with a standardized extract prepared from the allergen source in question and/or a positive test for specific IgE.
• A mean wheal diameter > 7 mm2 obtained in a prick test with histamine dihydrochloride 10 mg/ml.
• Age: 18-50 years.
• Both genders

Exclusion criteria

• Immunotherapy in the past 2 years with an allergen preparation known to interfere with the allergens to be tested.
• Use of drugs that may interfere with the skin reactions.
• Pregnancy
• Dermographism
• Atopic dermatitis (locally at the test site)
• Urticaria.