Determination of Biological Activity of Three Allergen Extracts

Study Overview
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Brief Summary
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Allergen extracts are complex mixtures of proteins and contain varying amounts of allergenic and non-allergenic components. Many factors such as the variability, differences in extraction process and subsequent handling of allergens can affect the final composition, potency, and stability of allergen preparations. Genetic diversity of affected people adds another level of complexity. In order to control variability and to achieve consistency and reproducibility for optimal safety and sensitivity/specificity, it is essential to standardize the amount of allergen used in prick tests. Therefore, the system for biological standardization mainly used in Europe still is the biological calibration of in-House Reference Preparations (IHRP). The method has been adopted by the Nordic Council on Medicines as the Nordic Biological Unit, Histamine Equivalent Potency (HEP) or Skin Prick Test (SPT) value. The aim of this procedure is to estimate the biological activity of allergen extracts. The activity of an allergen extract is defined as 1 SPT per ml, when the extract provokes a specific skin reaction with a wheal of the same size as a wheal provoked by reference histamine at a concentration of 10 mg/ml, when both solutions are administrated using the same technique (prick testing) on at least 20 individuals who are sensitized to the allergen concerned. The present study aims to standardize the allergen extracts of Artemisia vulgaris, Platanus acerifolia, Dermatophagoides farinae by using this method.

Detailed Description
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The present study aims to standardize the allergen extracts of Artemisa vulgaris, Platanus acerifolia and Dermatophagoides farinae by using this method. Standardized extracts will then be used for diagnostics and treatment of allergies as mentioned above.

Official Title
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Biological Standardization of Artemisia Vulgaris and/or Platanus Acerifolia Pollen Extract and Dermatophagoides Farinae Mite Extract in Patients Sensitized to Them

Conditions
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Hypersensitivity

Intervention / Treatment
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* Biological: Skin Prick Test - Atopic subjects
* Biological: Skin Prick Test - Non Atopic subjects
* Biological: Skin Prick Test - Allergic subjects


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: A. Subjects sensitized to one or more allergen extracts: Positive clinical history with inhalant allergy to at least one of the allergen to be standardized. At least one positive prick test (mean wheal diameter greater or equal than 3mm) Positive prick test (wheal diameter greater or equal to 3 mm) to Histamine 10 mg/ml Age: 18-60 years Written informed consent Patients will be:preferably be monosensitized, or with clinically relevant sensitization , or with primary sensitization (maximum cutaneous reactivity) to the extracts under investigation.Patient who belongs to one of the following group: Monosensitized patient to one of the extracts under investigation Patient with clinically relevant sensitization to the extracts under investigation. Patient with primary sensitization to one of the extracts under investigation Women of child-bearing potential must have a negative urine pregnancy test at the time they begin the study. B. Atopic Subjects: Age: 18-60 years Written informed consent Positive prick test (wheal diameter greater or equal to 3 mm) to Histamine 10 mg/ml Negative prick test (mean wheal diameter less or equal to 3mm) when tested with already standardized extracts of the allergens under investigation or with cross reactive extracts. Women of child-bearing potential must have a negative urine pregnancy test at the time they begin the study. C. No Atopic Subjects: Age: 18-60 years. Written informed consent Positive prick test (wheal diameter greater or equal to 3 mm) to Histamine 10 mg/ml Wheal diameter greater or equal to 3 mm for: Any allergen, except pollen for the cases of Artemisia vulgaris and/or Platanus acerifolia pollen extracts. Any allergen, except mites for the case of Dermatophagoides farinae mite extract. In order to dismiss sensitization to other allergens, the wheal diameter should be less than 3 mm for: Any pollen (for the cases of Artemisia vulgaris and/or Platanus acerifolia pollen extracts) Any mites(for the case of Dermatophagoides farinae mite extract) Women of child-bearing potential must have a negative urine pregnancy test at the time they begin the study. Exclusion Criteria (shared by the 3 groups): Immunotherapy in the 5 years prior to the study against either the allergen to be tested or an allergen which is cross-reactive. (it is not applicable to no atopic patients) Any drug which may interfere with the cutaneous test or with its result. Any medical condition that from investigator's point of view the skin prick test cannot be done . Women who are pregnant or breast-feeding or are child-bearing age and who have not demonstrated that they have been surgically sterilized or have other means of not bearing children. Subjects who have participated in another clinical trial within 3 months prior to this study.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Atopic subjects<br>Patients sensitized to other allergenic sources but the allergen extracts under investigation. | Biological: Skin Prick Test - Atopic subjects<br>* Skin prick test of 4 concentrations of each allergenic source, together with a positive and negative control, using 10 mg/ml histamine dihydrochloride solution and a glycerinated phenol saline solution, respectively, will be tested in every patient in duplicate on the volar surface of the forearm. Assessment of the wheal size after 15 minutes.<br>|
| Active Comparator: Non atopic subjects<br>Healthy volunteers | Biological: Skin Prick Test - Non Atopic subjects<br>* Skin prick test of 4 concentrations of each allergenic source, together with a positive and negative control, using 10 mg/ml histamine dihydrochloride solution and a glycerinated phenol saline solution, respectively, will be tested in every subjects in duplicate on the volar surface of the forearm. Assessment of the wheal size after 15 minutes.<br>|
| Other: Allergic Subjects<br> | Biological: Skin Prick Test - Allergic subjects<br>* Skin prick test of 4 concentrations of each allergenic source, together with a positive and negative control, using 10 mg/ml histamine dihydrochloride solution and a glycerinated phenol saline solution, respectively, will be tested in every patient in duplicate on the volar surface of the forearm. Assessment of the wheal size after 15 minutes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Wheal size area | The primary efficacy variable will be the wheal size area at the site of the puncture of the immediate phase reaction in mm2. | 15 minutes after skin prick test | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Allergy