Atopy patch test reactions are associated with T lymphocyte-mediated allergen-specific immune responses in atopic dermatitis.

BACKGROUND

Positive test reactions to epicutaneous application of aeroallergens served as a model of 'early' eczema in atopic dermatitis (AD) in a number of dermato-immunological studies. However, no quantitative evaluation has been performed so far comparing specific T-cell activation parameters in the peripheral blood of AD patients with positive or negative atopy patch tests (APT).

OBJECTIVE

The purpose of this study was to investigate specific immunological parameters in patients with atopic dermatitis showing positive or negative atopy patch tests reactions.

METHODS

APT results (n = 96) were compared with allergen-specific IgE, specific lymphocyte proliferation, and the expression of 'activation' markers on peripheral blood T-cells upon in vitro stimulation with house dust mite, cat or grass pollen allergens.

RESULTS

Only a subpopulation (48%) of patients sensitized to aeroallergens (i.e. specific IgE > 0.7 kU/L) developed APT-reactions to the corresponding allergen. APT reactions were, however, significantly associated with allergen specific lymphocyte proliferation (p < 0.0001), and a higher number of CD54+ or CD30+ T-cells (p < 0.05) upon in vitro stimulation.

CONCLUSION

The association of delayed skin reactions with allergen specific T-cell parameters in the blood points to an immunologically mediated mechanism leading to positive reactions in the APT.