Flow cytometric determination of the S-phase compartment in adult acute leukemia

Flow-cytometric analysis of bone marrow aspirates and blood samples was performed in 106 adult patients with acute leukemia in order to assess the size and the prognostic significance of the percentage of S-phase cells in the bone marrow (%Sbm). A correction procedure was applied for the fraction of contaminating peripheral nucleated cells in bone marrow aspirates (%Fpb). In 82 out of 106 patients studied, the %Sbm could be reliably determined, and was compared to the %Sbm in 25 healthy controls. The %Sbm in these healthy controls ranged from 8.4 to 14.6%. The median %Sbm in 31 patients with acute nonlymphocytic leukemia (ANLL) at diagnosis (11.3%) and in 14 patients with ANLL at relapse (11.8%) did not differ significantly from the median %Sbm in normal bone marrow (11.7%). On the other hand, in 12 out of 23 patients with acute lymphocytic leukemia (ALL) at diagnosis and in 6 out of 11 patients with ALL at relapse the %Sbm was much higher and ranged from 17.8 to 44.0%. The prognosis of patients with ALL with a high %Sbm (greater than 15%) was significantly worse. Blast cells with an abnormal DNA content (aneuploid cells) were noticed in 7.7% of the patients with acute leukemia at diagnosis. This incidence, however, was significantly higher in ALL patients at relapse (i.e. 42.1%).