Effect of intracellular calcium modulation on sulfur mustard cytotoxicity in cultured human neonatal keratinocytes

Previous studies in human skin keratinocyte cultures have shown that sulfur mustard (HD) induces an immediate and irreversible increase in internal fr ee calcium levels that was independent of external calcium concentrations. These findings suggested a role for calcium in the aetiology of HD-induced cell death and that modulation of intracellular calcium concentrations may assist in providing protection against this agent, In the current work, act ively proliferating and confluent cultures of first passage neonatal human skin keratinocytes were used to assess the effect of altered intra- and ext racellular calcium Levels on HD toxicity. Treatment of cultures with the en doplasmic reticulum calcium ATPase inhibitor thapsigargin, or the calcium c helator BAPTA-AM, which reduce HD-induced elevation of intracellular free c alcium, did not modulate the toxicity of HD, Furthermore, alteration of ext ernal calcium concentrations during these same experiments failed to elicit any change in the viability of HD-exposed cells. Treatment of confluent cu ltures with ionomycin at either low (100 mu M) or high (1.2 mM) external ca lcium concentrations also failed to modulate the toxicity of HD in any way. It appears that in neonatal human skin keratinocytes in culture, HD-induce d intracellular calcium perturbation does not play a major role in HD-induc ed cytotoxicity. Crown Copyright (C) 2000 Published by Elsevier Science Ltd . All rights reserved.