title: Leukemic burden in subpopulations of CD34+ cells isolated from the mobilized peripheral blood of alpha-interferon-resistant or -intolerant patients with chronic myeloid leukemia.
abstract: We attempted to determine the frequency of normal hematopoietic stem cells (HSC) and contaminating leukemic cells in mobilized peripheral blood (MPB) collected from chronic myeloid leukemia (CML) patients, intolerant of alpha-interferon or with interferon-resistant disease. A total of 14 MPB samples, six from patients in chronic phase (CP) and eight from patients in accelerated phase or blast crisis (AP/BC) were studied. Cytogenetic analysis of MPB collected from AP/BC patients showed that 100% of the cells were Ph+, whereas cells from four of five CP MPB were Ph-. By contrast, fluorescence in situ hybridization (FISH) analysis of CP MPB showed a mean frequency of 14.7% Ph+ cells, while AP/BC MPB contained 39.2% Ph+ cells. In an attempt to purify normal HSC, subpopulations of the MPB CD34+ cells were isolated based on expression of the Thy-1 antigen (CDw90). The mean Ph+ cell frequency as determined by FISH within the CD34+Thy-1+Lin- and CD34+Thy-1-Lin- populations from CP patients was 19.2% and 33.9%, respectively. In the AP/BC patients, levels of residual leukemic cells were significantly greater with mean Ph+ cell frequencies of 59.2% and 72.7% for the CD34+Thy-1+Lin- and CD34+Thy-1-Lin- fractions, respectively. The frequency of cobblestone area forming cells (CAFC) was used as a means of quantitating the numbers of functional HSC within these cell subpopulations. The mean CAFC frequency was 1 of 19 for the CD34+Thy-1+Lin- cells as compared with 1 of 133 for the Thy-1-fraction indicating a higher frequency of primitive progenitor cells in the Thy-1+ subpopulation. CD34+ cell subsets from two patients were also injected into SCID-hu bone assays to determine the in vivo behavior of these cell populations. After 8 weeks, multilineage donor engraftment was observed in these grafts. FISH analysis of the donor cells within the grafts showed that 55.3% and 60.0% of the cells were Ph+. We conclude that unfractionated MPB from this patient population is not leukemia-free and that the CD34+Thy-1+Lin- cell subpopulation, although predominantly enriched for normal HSC, still contains substantial numbers of residual leukemic cells.
authors.affiliation: Systemix Inc, Palo Alto, CA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Van den Berg
authors.forename: M
authors.initials: M
authors.lastname: Wessman
authors.forename: L
authors.initials: L
authors.lastname: Murray
authors.forename: J
authors.initials: J
authors.lastname: Tong
authors.forename: B
authors.initials: B
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: D
authors.initials: D
authors.lastname: Simonetti
authors.forename: J
authors.initials: J
authors.lastname: King
authors.forename: G
authors.initials: G
authors.lastname: Yamasaki
authors.forename: R
authors.initials: R
authors.lastname: DiGiusto
authors.forename: D
authors.initials: D
authors.lastname: Gearing
authors.forename: C
authors.initials: C
authors.lastname: Reading
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001752:Blast Crisis / Q000097:blood / Q000628:therapy; D001772:Blood Cell Count; D016025:Bone Transplantation; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology; D003131:Combined Modality Therapy; D004351:Drug Resistance; D005047:Etoposide / Q000008:administration & dosage / Q000494:pharmacology; D016332:Fetal Tissue Transplantation; D005434:Flow Cytometry; D006085:Graft Survival; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000737:chemistry; D006801:Humans; D007069:Ifosfamide / Q000008:administration & dosage / Q000494:pharmacology; D007155:Immunologic Factors / Q000627:therapeutic use*; D018189:Immunomagnetic Separation; D017404:In Situ Hybridization, Fluorescence; D016898:Interferon-alpha / Q000627:therapeutic use*; D007937:Leukapheresis / Q000379:methods; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood* / Q000473:pathology / Q000628:therapy; D015465:Leukemia, Myeloid, Accelerated Phase / Q000097:blood / Q000628:therapy; D015466:Leukemia, Myeloid, Chronic-Phase / Q000097:blood / Q000628:therapy; D051379:Mice; D016513:Mice, SCID; D008875:Middle Aged; D009368:Neoplasm Transplantation; D009360:Neoplastic Cells, Circulating / Q000737:chemistry; D010677:Philadelphia Chromosome; D011828:Radiation Chimera; D013047:Specific Pathogen-Free Organisms; D014183:Transplantation, Heterologous
chemical_list: D018952:Antigens, CD34; D007155:Immunologic Factors; D016898:Interferon-alpha; D016179:Granulocyte Colony-Stimulating Factor; D005047:Etoposide; D002945:Cisplatin; D007069:Ifosfamide