Relationships between eosinophil-associated parameters and disease severity in atopic dermatitis

Area of Science:

• Immunology
• Dermatology
• Allergology

Background:

• Atopic dermatitis (AD) is a chronic inflammatory skin disease often linked to house dust mite (HDM) allergy.
• Eosinophils play a key role in allergic inflammation, but their precise activation mechanisms in AD remain under investigation.

Purpose of the Study:

• To investigate the presence of HDM-specific antibodies and eosinophil activation markers in patients with atopic dermatitis.
• To explore the relationship between eosinophil activation, serum eosinophil cationic protein (ECP) levels, and disease severity in AD.

Main Methods:

• Sera from 27 AD patients were analyzed for HDM-specific IgE and IgG antibodies.
• Serum and plasma ECP levels were measured.
• Eosinophil surface markers (CD32, EG2) and gamma globulin expression were assessed.
• In vitro eosinophil activation by immune complexes was examined.

Main Results:

• AD patients showed HDM-specific IgE and IgG, elevated serum ECP, and low plasma ECP, indicating ECP release.
• Increased numbers of CD32+ and EG2+ eosinophils were found in AD patients, correlating with serum ECP levels.
• AD eosinophils exhibited enhanced sensitivity to IgG-immune complexes via CD32, but HDM or IgE/HDM complexes did not induce activation.
• Serum ECP levels correlated with EG2+ eosinophil numbers, not CD32-mediated degranulation.

Conclusions:

• HDM-specific immune responses and eosinophil activation are present in AD patients.
• EG2+ eosinophils, indicative of activation, are significantly associated with elevated serum ECP levels in AD.
• HDM-initiated dermatitis events likely regulate eosinophil generation and function in lesional skin, potentially creating a feedback loop in AD progression.