Para-Phenylenediamine Sensitization and Polysensitization: TNF-α, CXCL11, and Immune-Regulatory Gene Polymorphisms

Area of Science:

• Dermatology
• Allergology
• Immunogenetics

Background:

• Para-phenylenediamine (PPD) is a common hair dye allergen.
• PPD sensitization is linked to increased risk of broader allergic contact dermatitis.
• The interplay between PPD sensitization, polysensitization (PS), and host genetics is not well understood.

Purpose of the Study:

• To determine the association between PPD sensitization and PS in Korean patients.
• To investigate if genetic variations in immunoregulatory genes modify the PPD sensitization-PS relationship.

Main Methods:

• Retrospective analysis of 647 Korean patients undergoing patch testing.
• Polysensitization (PS) defined as reactivity to ≥3 unrelated allergens.
• Multivariable logistic regression identified PPD sensitization predictors; heatmaps visualized allergen networks.
• Exploratory genotyping of 17 patients for SNPs in key immune genes.

Main Results:

• PPD sensitization occurred in 5.9% of patients and was independently associated with PS (aOR 2.72).
• Mercury ammonium chloride and fragrance mix I were also significant predictors of PPD sensitization.
• Allergen heatmaps showed clustering of preservatives and rubber allergens in PPD and PS positive groups.
• Preliminary genetic analysis suggested altered CXCL11 variant frequencies in PPD+/PS+ patients.

Conclusions:

• PPD sensitization is a significant risk factor for polysensitization.
• Patients sensitized to PPD may also react to mercury compounds and fragrances.
• Further research with larger sample sizes is needed to confirm potential immunogenetic influences.