U. Darsow et al., ATOPY PATCH TEST WITH DIFFERENT VEHICLES AND ALLERGEN CONCENTRATIONS - AN APPROACH TO STANDARDIZATION, Journal of allergy and clinical immunology, 95(3), 1995, pp. 677-684
Background: In some patients with atopic eczema, eczematous skin lesio
ns can be induced by patch testing with aeroallergens. Methods: To est
ablish a standardized system for the atopy patch tet (APT), 36 patient
s with atopic eczema, four patients with rhinoconjunctivitis and 10 he
althy control subjects were epicutaneously tested with allergen extrac
ts from house dust mite, cat dander, and grass pollen. APTs were perfo
rmed on nonabraded, uninvolved skin with 1000 and 10,000 protein nitro
gens units (PNU)/gm allergen in petrolatum or hydrogel. Reactions were
evaluated after 48 and 72 hours and compared with skin prick and spec
ific serum IgE (CAP-RAST; Pharmacia, Uppsala, Sweden). Results: After
48 hours, 57 clear-cut positive reactions with eczematous, often folli
cle-bound, appearance were diagnosed from a total of 432 test sites. S
eventy-two percent of these positive reactions in patients with atopic
eczema developed with 10,000 PNU/gm and 28% with 1000 PNU/gm. Sixty-s
even percent of reactions were elicited with allergens in petrolatum v
ersus 33% when hydrogel was used as vehicle. Allergen-specific concord
ances of APT (10,000 PNU/gm, petrolatum) ranged from 0.39 to 0.53 (pri
ck tet) and 0.42 to 0.69 (CAP-RAST). In healthy control subjects and p
atients with rhinoconjunctivitis without atopic eczema, no clear-cut p
ositive APT reaction was seen. Conclusions: Petrolatum as vehicle and
an allergen concentration higher than 1000 PNU/gm may lead to improved
APT results on unchanged skin. In the future, the clinical relevance
of an IgE-mediated sensitization for eczematous skin lesions may be ev
aluated by the APT.