ABSTRACT

Cross-reactivity was commonly found among individuals sensitized to PPD or TDA, and was strongly related to the strength of the patch test reaction. Regarding co-sensitizations, a frequently appearing or common exposure source could not be determined. However, modification of the allergen by, for example, the skin microbiota may have caused the formation of molecules that are, for the human immune system, indistinguishable from PPD.

The prevalence rates in the patch tested and general population of The Netherlands are comparable with the prevalence rates of other mid-European centres. PPD sensitization is often attributed to hair dye. However, this study shows that subjects sensitized by black henna tattoos present with very severe elicitation reactions, emphasizing the need for more strict policing the prohibition.