Interaction of nickel with UV-light in the induction of cytogenetic effects in human peripheral lymphocytes

Chemical interaction is of major concern in the assessment of risk by regulatory agencies. In the present study, treatment of human lymphocytes with NiSO4 (1-100 microM) or UV-light (200, 1000 ergs/mm2) induced micronuclei (MN) in a dose-dependent fashion. Statistical analysis of the interaction factor (IF), showed that combined treatments of Ni(II) (1-100 microM) with UV-light (200, or 1000 ergs/mm2) interacted antagonistically for the induction of MN. Recently we reported that Ni(II) (0.5-10 microM) with UV-light (200 or 1000 ergs/mm2) or Cr(VI) or X-rays interacted antagonistically for the induction of sister chromatid exchanges (SCE), in peripheral human lymphocytes. These observations suggest that nickel present in complex mixtures may reduce the response, even in the presence of strong MN or SCE inducers, and may lead, therefore, to an underestimate of chemical exposure as assessed by these assays. Furthermore, metals affecting certain microsteps in the process of DNA replication or repair (e.g., histones, polymerases, ligases) may have similar antagonistic effects. Further studies are therefore recommended.