J. Vormoor et al., FLOW CYTOMETRIC IDENTIFICATION OF CANDIDATE NORMAL STEM-CELL POPULATIONS IN CD45-NEGATIVE B-CELL PRECURSOR ACUTE LYMPHOBLASTIC-LEUKEMIA, British Journal of Haematology, 100(3), 1998, pp. 501-508
CD45-negative B-cell precursor acute lymphoblastic leukaemia (ALL) pro
vides a unique model to study the stem cell compartment in ALL as leuk
aemic CD34-positive cells, unlike their normal counterparts, do not ex
press CD45. By increasing the number of events analysed to 10(6), stor
ing only the events in the region of interest (storage gate), using ap
propriate isotype controls and stringent washing procedures, a now cyt
ometric protocol was established to characterize rare CD34(+)CD19(-) e
vents. In eight of 12 patients (67%) with CD45-negative B-cell precurs
or ALL, a distinct CD34(+)CD19(-)CD45(+) candidate normal stem cell po
pulation could be detected. In one patient analysed by four-colour sta
ining, the CD34(+)CD19(-)CD45(+) cells, unlike the CD45-negative leuka
emic cells, expressed CD117 (c-kit), providing further evidence that t
hese cells represent residual nonleukaemic normal cells. By multiparam
eter analysis, this population of candidate normal stem cells could be
separated from contaminating leukaemic CD34(+)CD19(-)CD45(-) cells, w
hich were detected in 11 of the 12 patients within the CD34(+)CD19 - c
ompartment.