Induction and persistence of SCE-inducing damage in human lymphocytes exposed to vinyl acetate and acetaldehyde in vitro.

The frequency of sister-chromatid exchange (SCE) was studied in cultures of human lymphocytes exposed to vinyl acetate (VA) or acetaldehyde (AA) for various time periods and in different phases of the cell cycle. Equimolar concentrations (0.1-2.4 mM) of VA and AA were found to induce very similar, dose-dependent increases of SCE. The SCE frequency in cells treated with VA was found to increase linearly with exposure times up to 24 h. Cells exposed to VA or AA in the late G1-phase of the cell cycle showed a 2-fold higher SCE frequency than cells exposed in early G1. Cultures treated with VA in the first G1-phase showed a significant increase of SCE during 3 subsequent cell cycles. These results indicate that (1) AA is likely to be responsible for the SCE induction observed in VA-treated cells, (2) the SCE-inducing activity of AA persists for several cell cycles in vitro, and (3) removal of SCE-inducing AA-damage occurs during G1. Taken together, the data suggest that AA has a slow turn-over in human lymphocytes in vitro, and may accumulate in the cells, possibly by forming reversible Schiff bases, and when released gives rise to SCE-inducing DNA cross-links.