The effects of skin integrity on para-phenylenediamine hypersensitivity in BALB/c mice

Abstract

Rationale Para-Phenylenediamine (PPD) is a common contact allergen found in dyes including non-permanent (henna) tattoos. In addition, several reports have demonstrated urticaria and anaphylaxis following PPD exposure. These studies were conducted to evaluate whether skin integrity modulates the Th1 versus Th2 response to PPD in murine models of hypersensitivity. Methods For the local lymph node assay (LLNA), female BALB/c mice were dosed for 3 days with vehicle (acetone) or increasing concentrations of PPD (0.05-1.0%) on the dorsal ear pinnae. Following injection of [3H]-thymidine, draining lymph nodes were radioassayed on day 6. In a phenotypic analysis assay, mice were similarly exposed to 0.05 − 6.0% PPD through intact or abraded skin for 4 days. On day 10 post-exposure, lymph nodes were excised to evaluate B220+ and IgE+B220+ cell populations. In a 3-week time course study, mice were exposed to PPD through intact or abraded skin and tail bled for serum IgE analysis at 2 and 3 weeks post initial exposure. Results A significant response was observed in the LLNA and phenotypic analysis assays at concentrations as low as 0.5 and 2.0%, respectively. Following 3 weeks of PPD exposure, IgE levels reached statistical significance ( p<0.05) in the high dose abraded skin group, however only a modest increase in IgE was observed. Conclusions These studies revealed that PPD is a potent contact sensitizer in BALB/c mice while demonstrating only weak IgE inducing potential even when exposure is through abraded skin.