Abstract
Conceptually, irritant contact dermatitis (irritation) and allergic contact dermatitis (ACD) in man should provide the ideal platforms to launch in vitro toxicology into the pantheon of in vitro testing assays. In theory, irritant dermatitis has been considered by most a simple area of cutaneous biology, whereas ACD is a complex area of biology. However, both result in responses that are reasonably stereotypical and well characterized. The biology of the underlying mechanisms is becoming characterized and will thus allow development of mechanistically based in vitro assays that will be scientifically validated and thus acceptable to regulatory agencies.