Decrease in toxic potential of tensides when used in association: in vitro study on normal human keratinocytes

Sodium lauryl sulphate (SLS) is an anionic tenside that is widely utilised as a model for studying acute and cumulative irritation. When used in culture, SLS induces an inhibition of DNA synthesis and a decrease in cellular viability. It has previously been reported that the barrier damage caused by SLS in vivo is lower when SLS is applied to the skin in combination with other tensides. The aim of our study was to evaluate if the cytotoxic effect of SLS is reduced by the association with different tensides also in vitro. Normal human keratinocytes from plastic surgery were grown in serum free medium. At subconfluency cells were treated with SLS at a dose corresponding to the IC 50 in combination with cocamidopropylbetaine, Tween 20 and Tween 80 at the minimum toxic dose. Following tenside treatment, the culture medium was changed and after 24 hours the cells were collected for thymidine incorporation, MTT assay and neutral red uptake. The cytotoxic effect on normal human keratinocytes as evaluated by thymidine incorporation, MTT assay and neutral red uptake was significantly decreased by combination with all the tested tensides