Skin eosinophilia in atopic patients

Area of Science:

• Immunology
• Dermatology
• Allergy Research

Background:

• Atopic individuals display heightened skin reactivity to allergens.
• Platelet-activating factor (PAF) acether and f-methionyl-leucyl-phenylalanine (FMLP) are known inflammatory mediators.
• Understanding cellular responses in atopic skin is crucial for allergy research.

Purpose of the Study:

• To investigate the immediate and late-phase skin reactions to allergens, PAF acether, and FMLP in atopic and non-atopic individuals.
• To analyze the cellular infiltrate in skin following exposure to these agents using the Rebuck skin window technique.
• To determine if atopic patients exhibit specific cellular responses, particularly eosinophil accumulation.

Main Methods:

• Intracutaneous administration of allergens, PAF acether, and FMLP in six atopic and six control patients.
• Assessment of immediate wheal-and-flare skin reactions.
• Evaluation of cellular responses at 24 hours via the Rebuck skin window technique.

Main Results:

• Atopic patients showed similar immediate skin reactions to allergens and PAF acether compared to controls.
• No macroscopic late-phase reactions were observed for any agent in either group.
• A significant late (24-hour) eosinophilic response, with degranulated eosinophils, was observed in atopic skin but not in non-atopic skin, which showed predominantly neutrophils.
• PAF acether and FMLP induced potent eosinophil accumulation in atopic skin.

Conclusions:

• Atopic human skin demonstrates a potent eosinophil-attracting activity specifically in allergic patients.
• This eosinophil accumulation mirrors findings in allergic lung responses and severe asthma.
• The chemoattractant activity of FMLP on eosinophils requires further investigation beyond histamine release.