Evaluation at single cell level of residual Philadelphia negative hemopoietic stem cells in chronic phase CML patients.
In chronic myeloid leukemia, accurate determination of Ph(-) Hemopoietic stem cells (HSC) in peripheral blood (PB), bone marrow (BM) and leukapheresis products is important for the selection of patients for whom mobilization, collection, and autografting of Ph(-) HSC are envisaged. To this effect, the BCR/ABL fusion was assessed at the single cell level in 25 sets of PB and BM samples using dual-color I-FISH in immunophenotyped CD34(+) cells and RT-PCR of individual CFU-GM colonies. In 15 cases found to be 100% Ph(+), the respective BCR/ABL gene was absent in 30% of CD34(+) cells, while the respective transcripts could not be identified in 17% of CFU-GM. The mean percentage of BCR/ABL(-) CD34(+) cells and CFU-GM cells was higher (38% and 29%, respectively) in untreated patients than in treated patients (24% and 7%, respectively). In eight cases with cytogenetic response (CgR), the percentage of Ph(-) metaphases correlated with the level of BCR/ABL(-) colonies in BM and PB and with the proportion of BCR/ABL(-) CD34(+) cells in the BM. Immunophenotyping and FISH was fast, easy, always informative, and quantitative for the BCR/ABL(-) CD34(+) cells. Our results show that (a) at early diagnosis a high frequency of BCR/ABL(-) HSC circulate in the PB and that Ph(-) hematopoiesis is not completely suppressed; (b) although normal clonogenic cells decline rapidly within a few months after diagnosis, appreciable numbers of normal CD34(+) cells survive in chronic phase, especially in patients with CgR.
Akel
S
S
First Department of Medicine, University of Athens School of Medicine, Laikon General Hospital, 17 Agiou Thoma, Athens, Greece.
Kolialexi
A
A
Mavrou
A
A
Metaxotou
C
C
Loukopoulos
D
D
Yataganas
X
X
D018952:Antigens, CD34 / Q000032:analysis; D002452:Cell Count; D016044:Fusion Proteins, bcr-abl / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D054438:Leukemia, Myeloid, Chronic, Atypical, BCR-ABL Negative / Q000235:genetics*; D015466:Leukemia, Myeloid, Chronic-Phase / Q000235:genetics* / Q000473:pathology; D008875:Middle Aged; D010677:Philadelphia Chromosome; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018952:Antigens, CD34; D012333:RNA, Messenger; D016044:Fusion Proteins, bcr-abl