Determination of the Sensitivity and Specificity of Prick Test Betula Verrucosa

The main objective is to evaluate the concentration of allergen extract of Betula verrucosa that elicit a papule equivalent to that produced by a solution of histamine dihydrochloride 10 mg / ml in size.

Open, prospective, unblinded and non-randomized biological assay. Each patient was tested with four concentrations of allergen and with a histamine and saline solution as positive and negative controls, respectively.

Eligibility Criteria:
General inclusion criteria for both groups:

* Positive skin prick test with the positive control (Histamine HCl at 10 mg/mL). The length of the largest diameter of the wheal induced by this control should be ≥ 3 mm.
* Negative skin prick test with the negative control. The length of the largest diameter of the wheal induced by this control should be \< 3 mm.
* All ages and both genders.

For the group of patients CH+ (true positive to Betula verrucosa): All these patients had a previous diagnosis of allergy to the birch pollen:

* A positive case history with inhalant allergy related to exposure to birch pollen.
* A positive skin prick test (mean wheal diameter ≥ 3 mm) when tested with a biologically standardized extract prepared from birch pollen. This preparation, from another manufacturer, was the one used in the routine in the Hospital.
* Positive test for specific IgE (CAP value \> 0.35 IU/mL). For the group of patients CH- (true negative to Betula verrucosa): All these patients had a previous diagnosis of allergy to agents unrelated to birch pollen.
* A negative case history with inhalant allergy related to exposure to birch pollen or to pollen with known cross-reactivity with the birch pollen. These patients could be allergic to other pollen or other allergens, such mites.
* A negative prick test (largest diameter of the wheal ≥ 3 mm) when tested with a standardized extract prepared from the allergen source in question.
* A negative test for specific IgE (CAP value \< 0.35 IU/mL) to birch pollen or to pollen with known cross-reactivity with birch pollen: Corylus avellana, Quercus verrucosa, Fagus sylvatica, Castanea satavia, Carpinus betelus and Alnus glutinosa.

Exclusion criteria for both groups:

* Patients that were using drugs that may interfere with the skin prick tests.
* Patients using the following drugs 24 hours before the test: theophylline, systemic corticosteroids.
* Patients in which the largest diameter of the wheal induced by the positive control was \< 3 mm.
* Patients in which the largest diameter of the wheal induced by the negative control was ≥ 3 mm.
* Pregnancy, dermographism, atopic dermatitis (locally at the test site), urticaria.
* Patients who suffer disease in which the use of adrenaline is not allowed.
* Patients with any severe psychiatric disease.

For the patients CH+:

• Patients that received or are treated with immunotherapy with an allergenic extract of birch pollen and/or with allergen extracts with known cross-reactivity to birch pollen (Corylus avellana, Quercus verrucosa, Fagus sylvatica, Castanea satavia, Carpinus betelus and Alnus glutinosa).

For the patients CH-:

* Patients sensitized to pollen with demonstrated cross-reactivity with the pollen of Betula verrucosa. These pollen included Corylus avellana, Quercus verrucosa, Fagus sylvatica, Castanea satavia, Carpinus betelus and Alnus glutinosa.