Chromosome damage and polyploidization induced in human peripheral leukocytes in vivo and in vitro with nitrogen mustard, 6-mercaptopurine, and A-649.

Chromosomal analysLs of peripheral leukocytes in patients being treated with nitrogen mustard, 6-mercaptopurine, and A649 demonstrated an increase in i>olyploidy, including cells show ing endoreduplication. With nitrogen mustard, up to 15% of cells cultured were polyploids; with 6-mercaptopurine, 9% polyploidy was evident; anrl when A-649 was used, up to 14% polyploidy was seen. Chromosomal damage was evident with an increase in chmmatid breaks and fragmentation. Dicentric chromosomes were the most common rearrangement found. These findings were not present in pretreatment cultures. When leukocytes from normal donors were incubated in vitro with these 3 agents, similar changes of jjolyploidization and structural ab normalities were produced. Care must be taken in the evaluation of chromosomal changes in patients undergoing active treatment.