X-ray microanalysis of cultured keratinocytes: methodological aspects and effects of the irritant sodium lauryl sulphate on elemental composition

Irritant substances have been shown to induce elemental changes in human an d animal epidermal cells in situ. However, skin biopsies are a complicated experimental system and artefacts can be introduced by the anaesthesia nece ssary to take the biopsy. We therefore attempted to set up an experimental system for X-ray microanalysis (XRMA) consisting of cultured human keratino cytes. A number of methodological aspects were studied: different cell type s, washing methods and different culture periods for the keratinocytes. It was also investigated whether the keratinocytes responded to exposure to so dium lauryl sulphate (SLS) with changes in their elemental composition. The concentrations of biologically important elements such as Na, Mg, P and K were different in HaCaT cells (a spontaneously immortalized non-tumorigenic cell line derived from adult human keratinocytes) compared to natural huma n epidermal keratinocytes. The washing procedure and time of culture influe nced the intracellular elemental content, and rinsing with distilled water was preferred for further experiments. Changes in the elemental content in the HaCaT cells compatible with a pattern of cell injury followed by repair by cell proliferation were seen after treatment with 3.33 mu m and 33 mu m SLS. We conclude that XRMA is a useful tool for the study of functional ch anges in cultured keratinocytes, even though the preparation methods have t o be strictly controlled. The method can conceivably be used for predicting effects of different chemicals on human skin.