Mitotic index and cell proliferation kinetics for identification of antineoplastic activity.

The mitotic index (MI) and cell proliferation kinetics (CPK) of human blood lymphocyte cultures were determined to evaluate the effects of six antineoplastic drugs with well known cytostatic activity: cisplatin, melphalan, bleomycin, methotrexate, 5-fluorouracil and 6-mercaptopurine. All six drugs showed a clear effect on the inhibition of MI. The first three drugs interact directly with DNA showing a dose-related retardation of CPK. Methotrexate, 5-fluorouracil and 6-mercaptopurine, which act on ribonucleotide biosynthesis, showed no significant effects on CPK. The results suggest that CPK and MI measurements are useful for the prescreening of drugs with potential cytostatic activity.