Carcinogen-induced repair and binding in the DNA of chronic lymphocytic leukemic lymphocytes

Unscheduled DNA synthesis (repair) of carcinogen induced damage of the DNA of lymphocytes from 16 normal and 16 chronic lymphocytic leukemic (CLL) subjects was determined quantitatively for a standard dose of 10 micronM N-acetoxy-2-acetylaminofluorene (NA-AAF). Essentially all the CLL cases (15 of 16) had lower NA-AAF induced repair synthesis values than the normal subjects. Concurrent measurements for the levels of 3H-labeled 7,12-dimethyl-benz(a)anthracene (DMBA) to the DNAs of the normal and CLL lymphocytes after 18 h of culturing in 5 micronM DMBA have shown that 14 of 16 CLL cases had reduced levels of DNA bound carcinogen when compared to the normal individuals. Together these results suggest that CLL lymphocytes have a reduced repair synthesis because there is disproportionately less initial carcinogen-induced damage, and thereby, less substrate stimulation of repair enzymatic activity.