RELEASE OF INFLAMMATORY MEDIATORS IN HUMAN KERATINOCYTE CULTURES FOLLOWING EXPOSURE TO A SKIN IRRITANT

The most common pathological response of the skin, associated with chemical-induced primary irritation, is inflammation. Release of inflammatory mediators occurs in primary irritant dermatitis in both laboratory animals and humans. Inflammatory mediators (prostaglandin E2, leukotrienes C4, D4, E4 and 15-hydroxyeicosatetranoic acid) were determined by radioimmunoassay, and leukotriene B4 and the cytokine, interleukin 1alpha, were measured by enzyme-linked immunosorbent assay, in cultures of normal adult human keratinocytes. Release of inflammatory mediators into the culture medium was assessed at various time points following treatment of the cultures with the anionic surfactant sodium dodecyl sulphate (SDS), a known human skin irritant. A cytotoxic response was confirmed by the neutral red uptake assay after a 24-hr exposure to SDS. A dose-related release of inflammatory mediators was observed. The magnitude of the response varied between different mediators and as a function of time. The results show that release of inflammatory mediators occurs in human epidermal keratinocyte cultures, following chemical insult. Large inter-experimental variations in release of the various mediators probably preclude their use in a routine assay to determine irritation potential. In the case of SDS, release of inflammatory mediators is not a sensitive indicator of cytotoxicity. However, such techniques may provide important mechanistic data on the role of inflammatory mediators in the irritative response to certain chemicals, or on the possible role and interaction of certain mediators in the irritative process.