Coquette, A., N. Berna, A. Vandenbosch and Y. Poumay. Specific Enhanced Release of Interleukin-8 and Interleukin-1a in Reconstructed Human Epidermis in Vitro After Stimulation with Different Chemical Classes of Skin Irritants and Contact Sensitisers. ATLA 1999. 27: 115.

In the present study, reconstructed human epidermis was used as an in vitro model to discriminate between skin irritants (benzalkonium chloride, benzoic acid and sodium lauryl sulphate) and the sensitizing agents (1-chloro-2,4-dinitrobenzene, nickel sulphate, oxazolone, 2,4-dinitrofluorobenzene and picrylsulphonic acid). The epidermal response was evaluated by measurement of extracellular levels of IL-1a and IL-8. Corresponding cytotoxic responses of keratinocytes were assessed by an MTT assay. Topical application of the three irritants induced different dose-dependent decreases in cell viability. IL-1a was progressively released, while conversely cell viability decreased according to the reported in vivo irritant potency of the tested agents. In contrast, topical application of five sensitisers did not induce a similar elevated release of IL-1a, although they revealed specific dose-dependent cytotoxicity. On the other hand, the sensitisers, increased IL-8 release. RT-PCR detection of IL-1a and IL-8 mRNA, and determination of intracellular levels of both proteins reveal whether irritants and sensitisers induce transcriptional responses. We found that the IL-1a release induced by an irritant (sodium lauryl sulphate) was inhibited in the presence of a sensitiser, while the specific IL-8 release induced by sensitisers was not influenced by the irritant. In conclusion, our results suggest that recognized skin allergens and irritants stimulate different patterns of epidermal release of cytokines. This stimulation also suggests interactions of the compounds with specific cellular targets. Our results show that the combination of cell viability measurements with IL-1a and IL-8 quantifications might provide enough information to discriminate, in a single assay, irritant and sensitizing agent, and consequently represents a potential alternative to classical in vivo assays.