Nickel-keratinocyte interaction: a possible role in sensitization

Normal human keratinocytes and the keratinocyte-derived cell lines NCTC 2544 and A 431, were exposed for different periods (1-5 days) to various concentrations (0.023-46.6 micrograms/ml) of nickel (Ni2+). A dose- and time-dependent inhibition of cell growth and viability was observed. Cultures exposed to 2.3 micrograms Ni2+/ml showed approximately 50% cell survival at 5 days. An increase in release of interleukin 1 by keratinocytes was detected following culture for 24 h with a Ni2+ concentration of 2.3-11.5 micrograms/ml. Short periods of incubation (30 min) with these concentrations induced an activation of lipoxygenase in leucocytes from healthy subjects, without modifying cell viability. The results suggest that the percutaneous penetration of small amounts of Ni2+ can result in damage to keratinocytes and can initiate sensitization.