Arachidonic acid metabolism in primary irritant dermatitis produced by patch testing of human skin with surfactants

A clinical study was performed to determine the effects of patch testing hu man skin with four industrially used surfactants on erythema formation, tra nsepidermal water loss, and the contents in suction blister fluids of prima ry proinflammatory mediators including arachidonic acid, eicosanoids, and I L-1 alpha, which were analyzed by quantitative gas chromatography/negative ion chemical ionization mass spectrometry and by an enzyme-immunoassay, res pectively. Benzalkonium chloride (BKCl) and sodium lauryl sulfate (SLS) eli cited erythema and caused increased transepidermal water loss, indicating a disturbance of the epidermal barrier. Triethanolamine (TEA) and Tween 80 d id not evoke these gross symptoms of inflammation. Suction blister fluids c ollected after a 24-h application of BKCl, SLS, and Tween 80 contained sign ificantly increased amounts of individual eicosanoids whereas TEA induced n o response. The induced eicosanoid profile was characteristic for each comp ound, pointing to different cell types of skin to be involved in their prod uction. The elevation of prostaglandin and LTB4 contents correlated with th e induction of erythema and the impairment of the epidermal barrier as show n for BKCl and SLS and preceded the maximum of erythema formation. IL-1 alp ha contents did not correlate with these gross symptoms of inflammation. Th e results of this in vivo study support those of a previous study using hum an keratinocytes in culture indicating the release of arachidonic acid and prostaglandins to be an early event involved in the interaction of keratino cytes with surfactants. Moreover, the in vivo data with human skin undersco re the mechanistic relationship to the in vitro model and support the conce pt that arachidonic acid and eicosanoid release from keratinocytes can be u sed as a marker of primary Skin irritation. (C) 1998 Academic Press.