Concentration- and time-related effects of sulphur mustard on human epidermal keratinocyte function

The concentration- and time-dependent effects of sulphur mustard on cultured human epidermal keratinocyte function were investigated with respect to cell proliferation, DNA and protein synthesis, the level of NAD(+) and ATP, and the intracellular activity of lactate dehydrogenase. If human epidermal keratinocytes were stimulated to proliferate by replating following exposure to sulphur mustard, inhibition of cell growth was observed after treatment of cells with 0.5 mum-sulphur mustard or more. Similarly, DNA synthesis was reduced in a concentration-dependent manner following exposures to 0.5 mum-sulphur mustard or higher. Inhibition of protein synthesis was observed only on exposure to concentrations higher than 10 mum. These effects could be detected immediately after exposure and were constant for at least 24 hr. In contrast, parameters for cellular energy decreased with time following exposure. At 24 hr post-exposure a concentration-dependent depletion of NAD(+) and ATP was observed, starting at exposure levels of 50 mum-sulphur mustard. Decrease of intracellular lactate dehydrogenase activity also occurred with exposures to 50 mum-sulphur mustard or more, although it was not possible to cause a reduction of more than 50% of control values. Furthermore, the results showed that sulphur mustard induces either persistent damage or damage that develops within 24 hr following treatment. The concurrent inhibition of DNA and protein synthesis combined with a decreased energy supply may have an important role in sulphur mustard-induced blister formation in skin.