Cytogenetic effects of cis-platinum(II)diamminedichloride on human lymphocyte cultures.

Human lymphocytes were treated with the antitumor agent cis-platinum)II)diamminedichloride (PDD) during either the last 24 h or 48 h of incubation. A dose-dependent effect was observed for both inhibition of mitotic activity and increased frequency of metaphases with chromosomal aberrations. The aberrations observed consisted primarily of chromatid breaks. Statistical analysis of 3244 PDD-induced breakpoints demonstrated a significantly nonrandom distribution of breakpoints between chromosomes. The pattern of distribution varied with the type of aberration. Only chromosome number 9 had a significant increase of breakpoints for each type of aberration analyzed. The breakpoints were located predominantly in lightly staining G-gands. Certain individual bands had relatively high frequencies of breakpoints, indicating a specific interaciton occurs between PDD and the DNA of human lymphocytes in vitro.