The hair dyes PPD and PTD fail to induce a T_H2 immune response following repeated topical application in BALB/c mice

Abstract

1,4-Phenylenediamine (PPD) and the structurally-related 1,4-toluenediamine (PTD) are frequently used oxidative hair dye precursors that can induce a delayed-type hypersensitivity reaction known as contact allergy. Very rare cases of Type 1 (IgE-mediated) allergic responses associated with PPD or PTD have been reported among hair dye users. As part of an effort to determine if repeated dermal exposure to the dyes could induce a T-helper-2 (T_H2) response, we used a dermal exposure regimen in mice reported to identify a T_H2 response. Ear swelling was evident at post-final exposure to PPD and PTD, indicating that an immune response was observed. However, cytokine mRNA after repeated topical exposure to these two chemicals showed no shift in the expression toward the typical T_H2 cytokines interleukin (IL)-4 and IL-10 compared to the T_H1 cytokine interferon (IFN)-γ. Consistent with these cytokine profiles, no concomitant increase in total serum IgE antibody titer or in B220⁺IgE⁺ lymphocytes in lymph nodes and skin application site skin was detected. In contrast, using an identical exposure regimen, animals topically exposed to the known respiratory (Type 1) allergen toluene 2,4-diisocyanate (TDI) showed significant expression of IL-4 and IL-10 mRNA compared to IFNγ as well as an increase in total serum IgE and in B220⁺IgE⁺ cells in lymph nodes and skin application site. The data generated are consistent with the pattern of adverse reactions to hair dyes seen clinically, which overwhelmingly is of delayed rather than immediate-type hypersensitivity. Although current animal models have a limited ability to detect rare T_H2 responses to contact allergens, the present study results support the view that exposure to hair dyes is not associated with relevant T_H2 induction.

Keywords::

• Oxidative hair dyes
• type 1 allergy
• cytokine profiling

Acknowledgements

The authors like to thank Naveed Honarvar for conducting the studies and technical discussions. We thank Julie Skare and Frank Gerberick for critical review of the manuscript. We thank David Basketter for his review and assistance in the preparation of the manuscript.

Declaration of Interest

The authors report no conflicts of interest. The authors are employees of The Procter and Gamble Company.