Detection of benzo(a)pyrene diol epoxide-DNA adducts in sperm of men exposed to cigarette smoke

To determine whether the adducts formed when benzo(a)pyrene, a diol epoxide derivative, binds covalently to DNA (BPDE-DNA adducts) are detectable in the sperm of men who smoke cigarettes.

Prospective study.

The Toronto Hospital IVF-ET program.

Twenty-three patients with normal seminal parameters: 11 smokers (20.6 +/- 0.7 cigarettes per day) and 12 nonsmokers.

Semen samples obtained by masturbation.

Seminal plasma samples were assessed for cotinine by RIA. Sperm were treated with dithiothreitol to release disulfide bonds and allow for DNA binding, then exposed to an anti-BPDE monoclonal antibody, a biotinylated antibody, and streptavidin-conjugated peroxidase. Staining intensity scores, determined in 100 cells per individual, were correlated with seminal plasma cotinine levels, a marker of smoking.

Cotinine levels correlated highly with the number of cigarettes smoked per day. Mean cotinine levels and mean staining intensity scores were higher in smokers than in nonsmokers. Staining intensity correlated highly with cotinine levels.

We demonstrated, for the first time, that BPDE-DNA adducts in sperm cells are increased by smoking; we also detected comparatively high levels in nonsmokers, which indicates that environmental exposure also is substantial. The formation of adducts in spermatozoa is a potential source of transmissible prezygotic DNA damage.