Atopy patch test with house dust mite allergen--an IgE-mediated reaction?

Area of Science:

• Immunodermatology
• Allergy Research
• Atopic Dermatitis Pathogenesis

Background:

• The atopy patch test (APT) reaction is hypothesized to be immunoglobulin E (IgE) mediated.
• However, APT reactions can occur in individuals lacking detectable allergen-specific IgE in their serum.
• The precise role of allergen-specific IgE in the APT reaction requires further elucidation.

Purpose of the Study:

• To evaluate the significance of allergen-specific serum IgE in mediating the APT reaction.
• To investigate the cellular and molecular mechanisms underlying the APT response in relation to IgE levels.

Main Methods:

• Ten patients with positive APT to Dermatophagoides pteronyssinus extract were divided into two groups: five with detectable serum IgE (Group A) and five without (Group B).
• Patients underwent APT with D. pteronyssinus extract for 6, 24, 48, and 72 hours.
• Skin biopsies were analyzed for various cellular markers including IgE, FcepsilonRI, eosinophils (EG2), CD4, CD8, and matrix metalloproteinase 9 (MMP9).

Main Results:

• In Group A, there was a time-dependent increase in IgE+, CD4+, EG2+, and MMP9+ cells.
• FcepsilonRI+ and CD8+ cells increased over time in both groups.
• A positive correlation was observed between serum IgE levels and the severity of dermal cell infiltrates at 72 hours, with patients having higher IgE levels showing greater EG2+ cell expression and higher APT scores.

Conclusions:

• The study provides evidence supporting the hypothesis that IgE plays a crucial role in the APT reaction.
• IgE may act as an amplifier of the APT response.
• These findings contribute to understanding the immunological mechanisms of allergic skin reactions.