Patch tests with house dust mite antigens in atopic dermatitis patients: methodological problems

Area of Science:

• Allergen immunotherapy
• Dermatology
• Immunology

Background:

• Atopic dermatitis (AD) is a chronic inflammatory skin condition often associated with allergies.
• House dust mite (HDM) is a common allergen implicated in AD exacerbations.
• Accurate diagnostic methods for identifying specific allergen triggers in AD are essential.

Purpose of the Study:

• To evaluate the methodology of patch testing for house dust mite allergens in patients with atopic dermatitis.
• To investigate the impact of allergen concentration, application duration, and tape-stripping intensity on patch test reactivity.
• To determine the occurrence of specific versus non-specific reactions in HDM patch testing.

Main Methods:

• Patch tests were conducted on 21 atopic dermatitis patients with confirmed HDM sensitivity (positive prick test and RAST).
• Varied concentrations of Dermatophagoides pteronyssinus (D. pteronyssinus) solutions and purified HDM antigen were used.
• Tests were applied to tape-stripped (8X or 15X) and normal skin, with application times of 24 and 48 hours.

Main Results:

• Non-specific reactions were frequently observed, particularly with higher intensity tape-stripping (15X) and longer application times (48 hours).
• Specific allergic reactions to HDM allergens were identified in 29% (6/21) of patients, with a higher prevalence in those with elevated serum IgE levels (>1000 kU/l).
• Increased allergen concentration and 48-hour application duration correlated with a higher number of specific reactions, but also increased non-specific reactions.

Conclusions:

• Patch testing for HDM allergens in atopic dermatitis is prone to non-specific reactions, influenced by tape-stripping and application duration.
• Optimizing patch test parameters, such as allergen concentration and application time, is necessary for reliable results.
• Further validation with in vitro control tests is recommended to establish the definitive value and optimal methodology for HDM patch testing in AD.