Differential susceptibility to a mutagen among human individuals: synergistic effect on chromosome damage between bleomycin and aphidicolin.

Lymphocytes of standard human blood cultures were treated with bleomycin, aphidicolin and a combination of these two agents. A synergistic effect on chromosome damage was obvious when the two agents were used simultaneously. Various experiments showed that Aphidicolin induces chromosome breakage only in cells in the S-phase; Despite the quantitative differences in response to bleomycin among individuals, the frequency of chromatid breakages becomes high when the two agents are used together. The data suggest a differential DNA repair capacity among human subjects, since aphidicolin is known to inhibit DNA polymerase alpha, which is necessary for DNA replication and DNA repair.