Proliferative characteristics of acute nonlymphocytic leukemia in vivo

The proliferative characteristics of myeloid leukemias were defined in vivo following intravenous bromodeoxyuridine (BrdU). Fifteen patients received a 2-hour infusion of BrdU. A monoclonal anti-BrdU antibody was used to detect the in vivo incorporation of BrdU by S-phase cells. The percentage of S-phase cells obtained from the biopsies (mean 17.3%) was significantly higher (p = 0.00001) than the percentage determined from the aspirates (7.8%). It is concluded that the true estimate of S-phase cells can only be obtained from biopsies following in vivo labeling of cells synthesizing DNA. The persistence of BrdU-labeled cells in follow-up studies can be used to recognize 'residual leukemia', and the subsequent fate of these cells can be defined in vivo.