Sister chromatid exchange and growth kinetics in untreated acute leukemia.

Sister chromatid exchange (SCE) frequency has been analyses after short-term culture of leukemic bone marrow cells of eight untreated patients with acute leukemia. Compared to normal bone marrow, results show a statistically significant decrease of SCE (p less than 0.001) in euploid as well as in aneuploid leukemias, ranging from 2.11 to 2.97 SCE per metaphase. The different SCE values were not related to contraction status of chromosomes and could not be explained by the age of patients. Therefore, low SCE may be a typical feature of leukemic cells. An examination of growth rates by the SCE technique revealed a high turnover of normal bone marrow cells. About 80% of the cells did not need more than 50 h to run two or three cell cycles. Leukemic cells, however, apparently divided more slowly, which is in good agreement with data obtained by autoradiographic methods.