IL-1alpha and IL-1ra secretion from epidermal equivalents and the prediction of the irritation potential of mild soap and surfactant-based consumer products.

We have previously evaluated the measurement of viability and cytokine release from skin equivalents, for predicting the skin irritation potential of topically applied surfactants and demonstrated that IL-1alpha and interleukin-1 receptor antagonist (IL-1ra) release from epidermal skin equivalents correlates with skin irritation potential. In this study, the utility of the model was confirmed by the evaluation of cleansing bars and cleansing lotions that exhibited varying degrees of irritation potential as determined by exaggerated arm wash human clinical studies. Epidermal equivalents were exposed to increasing concentrations of the cleansing bars and cleansing liquids and viability and release of IL-1alpha and IL-1ra were measured. Loss of viability was used to identify the stronger irritants of the products tested. A linear correlation was demonstrated between IL-1alpha and IL-1ra secretion and human irritation data, demonstrating that the model can correctly predict the irritation potential of soap and surfactant products. These results show that this in vitro model is useful for rank ordering the irritation potential of mild consumer products and for demonstrating enhanced mildness in products with minor differences.