Extended-term cultures of human T-lymphocytes and the comet assay: a useful combination when testing for genotoxicity in vitro?

Extended-term cultures of human lymphocytes provide a source of uniform human cells that can be used for several experiments performed over a long time, avoiding the variability arising from taking blood samples for individual experiments. The use of extended-term cultures of human T-lymphocytes in the alkaline single-cell gel electrophoresis assay (comet assay) was evaluated as a test for the potential genotoxicity of chemicals. The DNA-damaging effects of five DNA-reactive mutagens and clastogens (benzo[a]pyrene, cyclophosphamide, formaldehyde, 4-nitroquinoline-N-oxide (4NQO) and N-nitrosopiperidine) was determined and compared with the effects of one non-DNA-reactive mutagen (5-hydroxyurea), and one non-mutagenic agent (ethanol).