Basophils in allergen-induced patch test sites in atopic dermatitis

Area of Science:

• Dermatology
• Allergology
• Immunology

Background:

• Atopic dermatitis is frequently associated with elevated immunoglobulin E (IgE) and positive immediate skin reactions to common allergens.
• The precise role of allergens in the pathogenesis of atopic dermatitis remains a subject of debate.

Purpose of the Study:

• To investigate the capacity of specific allergens to induce eczematous lesions in patients with atopic dermatitis.
• To determine if a positive immediate skin reaction to an allergen is a prerequisite for allergen-induced lesion development.

Main Methods:

• Patch testing was performed on superficially abraded skin sites for 48 hours.
• Patients with atopic dermatitis underwent patch testing with common allergens.
• Skin reactions were assessed, and induced lesions were analyzed for cellular infiltrate. Specific serum IgE and leukocyte histamine release were measured.

Main Results:

• Allergens induced eczematous lesions in atopic dermatitis patients exclusively when they exhibited a positive immediate skin reaction to the same allergen.
• Lesions induced by house dust mite antigen P1 contained a mixed inflammatory infiltrate, including mononuclear cells, basophils, eosinophils, and neutrophils.
• Patients demonstrated elevated specific serum IgE against antigen P1, and their leukocytes released histamine upon exposure to this antigen.

Conclusions:

• Inhalant allergens can acutely induce eczematous lesions in the skin of atopic dermatitis patients.
• The findings support a direct role for specific allergens in triggering skin inflammation in susceptible individuals with atopic dermatitis.