Atopy patch test

Skin test procedure (epicutaneous test) as a diagnostic method for characterizing patients with aeroallergen-triggered atopic eczema. The epicutaneous test is performed with the allergens in question, which can trigger IgE-mediated reactions ( type I allergens). Positive ATP reactions are particularly frequent in persons with a freely carried eczema pattern.

Epicutaneous test with allergens that can trigger IgE-mediated reactions ( type I allergens ). The application is usually carried out with allergen lyophilisates in Vaseline by means of large Finnchambers (> 12 mm Ø) on clinically unaffected, non-abraded skin on the back. Change of the transepidermal water loss or the epidermal barrier function at the site of a positive patch test reaction. This provides a possible entry portal for further allergens which can lead to an intensification of the eczema reaction. In comparison, epicutaneous testing with contact allergens does not affect the epidermal barrier in positive patch areas. The reproducibility of triggered atopy patch reactions is about 90-95% within a period of 16 months. Reading of an eczematous skin reaction 48-72 hours after application of the allergen.

Development of an eczema reaction.

The reproducibility of the atopy patch test method is high when the test is performed on the back (significant association of ATP and specific IgE). Atopy patch testing with food allergens is still widely regarded as an experimental method. Allergens in vaseline vehicles cause twice as many clearly positive reactions in the same concentration as allergens in a hydrophilic vehicle!