Cytotoxic and genotoxic effects of extracellular generated singlet oxygen in human lymphocytes in vitro.

The induction of sister-chromatid exchanges (SCE) together with the proliferation rate index (PRI) were studied in human lymphocytes in vitro after treatment with singlet oxygen. When produced outside the cells, singlet oxygen can increase the duration of the cellular cycle as measured by an enhancement of the differences between the proliferation rate indexes of the control and the treated cells. A dose-dependent increase in the SCE rate per chromosome was also detected after contact between the singlet oxygen and lymphocytes.