determination of the sensitivity and specificity of prick test betula verrucosa

Conditions: Immune System Diseases

Summary: 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.

Keywords: immune system diseases prick test betula verrucosa