In vivo uptake of daunorubicin by acute myeloid leukemia (AML) cells measured by flow cytometry.

Monitoring of daunorubicin (DNR) concentrations in leukemic cells in blood and bone marrow in vivo of patients with acute myeloid leukemia may yield insight into the interindividual variations of the clinical response to treatment. We evaluated the applicability of flow cytometry for measuring DNR uptake in direct comparison with high performance liquid chromatography (HPLC). In vitro studies revealed good correlations between the mean cellular fluorescence measured by flow cytometry and the cellular DNR concentrations determined with HPLC. In vivo cell measurements were then obtained in 17 evaluable patients during their first remission induction treatment with DNR and cytosine arabinoside. The results indicate that: (a) DNR fluorescence of leukemic blast cells is intermediate between the smaller lymphocytes and the approximately equally large granulocytes; (b) DNR fluorescence of peripheral blast cells and bone marrow blast cells correlate well (p less than 0.001); and (c) patients reaching complete remission show a tendency of higher DNR fluorescence of leukemic blast cells than do partial responders.