CHANGES IN KERATINOCYTE DIFFERENTIATION FOLLOWING MILD IRRITATION BY SODIUM DODECYL-SULFATE

Although the induction of acute irritant dermatitis by detergents has been studied extensively in recent years, our understanding of the cel l biological events in the repair phase, and its relevance for the dev elopment of chronic irritant dermatitis is limited. Here we studied th e reaction pattern of human skill to short-term application of sodium dodecyl sulphate (SDS) in a model that induced a minimal acute inflamm atory reaction (absence of polymorphonuclear leucocytes, PMN) and did mot have cytopathic effects on the epidermal keratinocytes as determin ed by histological investigation. All parameters were measured up to 1 4 days after exposure to SDS. Application of SDS caused disturbances o f barrier function as measured bg transepidermal water loss and had va scular effects as judged by erythema, Several cell biological markers for epidermal growth and differentiation were examined by inmunohistoc hemistry. A rapid and strong induction of the cornified envelope precu rsor protein involucrin was seen in the stratum syinosum, with a peak at 24 h, Wit hin 24 h a strong upregulation of epidermal fatty acid bi nding protein (E-FABP) was noted, with a peak at 7 days after injury. Cellular proliferation in the basal layer was increased fivefold as as sessed by nuclear staining for the Ki-67 antigen, showing a peak at 48 h. Surprisingly no significant induction of cytokeratin 16 and SKALP/ elafin expression, two markers associated with epidermal hyperprolifer ation and inflammation, was seen, These findings suggest that the cell ular changes following exposure to detergent are distinct from those s een in other forms of skin injury. We would speculate that the epiderm al response to detergent exposure is primarily directed at restoration of barrier function.