Cytogenetic effect of bleomycin on human leukocytes in vitro

Human leukocytes treated with bleomycin (BLM) for clinical use, at concentrations of 0.1, 0.5, 1.0, 10 and 50 mug/ml were studied. Both chromosome- and chromatid-type aberrations were observed. The groups of larger chromosomes were more affected at every concentration. At dosages from 0.1 to 10 mug/ml no significant difference of effects on chromosomes was observed. However, a dose-difference of about 500 times showed significant differences in effect both on the degree of chromosomal aberration and on mitotic indices.