Cytokinetic studies in acute leukemia during early induction therapy

The proliferative activity of bone marrow blasts was determined in 19 patients with acute leukemia during early induction therapy using in vitro tritiated thymidine (3H-TdR) cytoautoradiography and propidium iodide DNA flow cytofluorometry. Following 1-3 courses of treatment, the aliquot of bone marrow blasts in 9 patients, who later achieved remission or marrow aplasia, was reduced to a greater extent than that of the remaining 10 patients who failed to respond. In the first group of patients, the 3H-TdR labelling index was increased by 259-653% over the pretreatment value, whereas it was lower than 104% of the pretreatment value in all but one unresponsive patient. Leukemic blast recruitment is conceivable. It might have facilitated remission by increasing the effectiveness of the antileukemic agents administered later.