1. This in vitro study was undertaken as a preliminary approach before assessing whether the alkaline elution assay can be applied to peripheral blood lymphocytes (PBL) for the monitoring of humans exposed to genotoxic agents such as
polycyclic aromatic hydrocarbons (PAH). We have compared in vitro, with the aid of the alkaline elution assay, the formation and the repair of
DNA single-strand breaks (ssb) induced by different genotoxic agents [gamma-irradiation,
ethyl methanesulfonate (EMS),
benzo<a>pyrene diol
epoxide (
BPDE)] on quiescent and PHA-stimulated human lymphocytes and on a fibroblast cell line. 2. Gamma-irradiation (4 Gy) induced an equivalent amount of
DNA ssb in the three cell types. On the other hand,
after treatment with EMS (10 mM) and
BPDE (50 microM), a higher production of
DNA ssb was observed in replicating cells (PHA-stimulated lymphocytes and fibroblasts) when compared with quiescent lymphocytes. 3. After gamma-irradiation, all cell types repaired more than 65% of ssb within 1 h.
After treatment with EMS, we noted a
deficient DNA repair capacity in quiescent lymphocytes in comparison with replicating cells. In all cell types treated with
BPDE, more breaks were observed after a 2 h repair period than immediately
after treatment, demonstrating the involvement of a slow repair mechanism after
BPDE treatment.(ABSTRACT TRUNCATED AT 250 WORDS)