DNA aneuploidy in children with relapsed acute lymphoblastic leukemia as measured by flow cytometry.

An aneuploid DNA stem line has been detected by flow cytometric measurements in 17 (29%) out of 59 children entered in the BFM 83 pilot study for ALL relapse. Of 17 DNA aneuploidies, 15 were hyperdiploid. Euploidy was observed in 28 of 34 patients with an early relapse, whereas 11 of 25 children suffering a late recurrence of disease showed aneuploid DNA stem lines. In contradistinction to ALL relapse, a significantly higher frequency (38%) of pretreatment DNA aneuploidy was measured in 376 newly diagnosed patients of the BFM trials. Our findings may reflect the impact of therapy on leukemic cell clones and their relapse pattern.