Elevated peripheral allergen-specific T cell response is crucial for a positive atopy patch test reaction

Area of Science:

• Immunology
• Dermatology
• Allergy Research

Background:

• Atopic eczema is a chronic inflammatory skin condition with diverse patient subgroups.
• Atopy patch testing (APT) identifies allergen sensitization in atopic eczema patients lacking detectable allergen-specific IgE.
• This suggests non-IgE mediated factors are crucial in the allergic reaction.

Purpose of the Study:

• To investigate the relationship between APT reactions and allergen-specific peripheral IgE and T cell reactivity in atopic eczema patients.
• To clarify the role of T cell responses in atopic eczema pathogenesis.

Main Methods:

• Adult atopic eczema patients (n=64) and healthy controls (n=24) underwent APT for Malassezia sympodialis.
• Specific plasma IgE levels were measured.
• ELISpot assay determined the frequency of interleukin-4 and interleukin-5 producing allergen-reactive peripheral blood mononuclear cells.

Main Results:

• M. sympodialis reactivity detected in 69% of atopic eczema patients, while controls were negative.
• T cell reactivity (IL-4, IL-5 production) strongly correlated with and predicted positive APT reactions.
• Allergen-specific IgE levels did not predict APT outcomes or correlate with APT scores.

Conclusions:

• Peripheral allergen-specific T helper 2 cell responses are essential for positive APT reactions to M. sympodialis.
• Measuring peripheral allergen-specific T cell responses holds diagnostic potential for atopic eczema.