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Leukemia blasts isolated from bone marrow aspirates of 44 adults with acute leukemia were incubated for 1 h with 0.008-32 microM bromodeoxyuridine (Brd-Urd). After dual labeling with monoclonal anti-BrdUrd antibodies and propidium iodide, the cells were analyzed by flow cytometry. Percent labeled cells and intensity of labeling were similar over concentrations of BrdUrd ranging from 0.8-32 microM--a 40-fold range. Therefore, despite potential interpatient variability in nucleoside pharmacokinetics, commonly used doses of BrdUrd which are intended to achieve steady-state plasma concentrations in the 8.0 microM range can be expected to provide a reliable estimate of the S-phase fraction.

The purpose of this technical report is to determine the reproducibility of flow cytometry data for ploidy and cell cycle kinetics using paraffin-embedded blocks of breast cancer tissue. One block from each of 39 tumors was studied in this report with each block having multiple sections analyzed independently. All of these sections gave ploidy analyses, while only 34 gave cell kinetic values. The standard deviation for the DNA index value in the multiple analysis study was less than 0.1 in all but three cases. The cell kinetic values gave larger variability, and the actual values were dependent on the method of analysis. Comparison of the variability for each method of analysis could not predict which procedure was superior. These results would indicate that ploidy is a reproducible value, while cell kinetic parameters should only be used as an indicator of proliferative activity that has been normalized to the mean or median of a large set of observations processed and analyzed by the same procedure.