Effect of 3-aminobenzamide on chromosome damage in human blood lymphocytes adapted to bleomycin.

Human blood lymphocytes, pre-treated with very low (adaptation) concentrations of bleomycin for 48 h and then exposed to a high (challenge) dose of the same agent or X-rays, became significantly less sensitive to the induction of chromosome damage than those which did not receive the pre-treatment, indicating an induction of 'adaptive repair' process. This repair process was negated when 3-amino-benzamide, an inhibitor of poly (ADP) polymerase, was added to the cultures immediately after the challenge treatment. The magnitude of negation in the adaptation response was greater in the case of lymphocytes challenged with X-rays as compared with those challenged with bleomycin.