title: Cytogenetically aberrant cells in the stem cell compartment (CD34+lin-) in acute myeloid leukemia.
abstract: Leukemia may be viewed as a clonal expansion of blast cells; however, the role of primitive cells and/or stem cells in disease etiology and progression is unclear. We investigated stem cell involvement in leukemia using fluorescence in situ hybridization (FISH), immunofluorescence labeling of hematopoietic subpopulations, and flow cytometric analysis/sorting to discriminate and quantify cytogenetically aberrant stem cells in 12 acute myeloid leukemia (AML) and three myelodysplastic (MDS) specimens. Flow cytometric analysis and sorting were used to discriminate and collect a primitive subpopulation enriched in stem cells expressing CD34+ and lacking CD33 and CD38 (CD34+lin-). A subpopulation containing progenitors and differentiating myeloid cells expressed CD34, CD33, and CD38 (CD34+lin+). Nine specimens contained less than 10% CD34+ cells and, thus, were considered to be CD34- leukemias. Mature lymphoid, myeloid, and erythroid subpopulations were sorted on the basis of antigen-linked immunofluorescence. Cytogenetically aberrant cells in sorted subpopulations were identified using FISH with enumerator probes selected on the basis of diagnosis karyotype. Cytogenetically aberrant CD34+lin- cells were present at frequencies between 9% and 99% in all specimens. CD34+lin- cytogenetically aberrant cells comprised between 0.05% and 11.9% of the marrow/blood specimens. Cytogenetically aberrant CD34+lin+ cells constituted 0.01% tp 56% of the marrow/blood population. These data demonstrate that aberrant cells are present in primitive CD34+ stem cell compartments, even in CD34- leukemias. Stem cell involvement was confirmed further by sorting lymphoid and erythroid subpopulations from eight specimens in which the predominant leukemic population lacked lymphoid/erythroid differentiation markers. In these specimens, as well as in multiple lineages, suggests involvement of a cell(s) with multilineage capabilities. The ability of aberrant CD34+lin- stem cells to contribute to clonal and compartment expansion within immunofluorescently defined subpopulations was evaluated to explore the functional phenotype of aberrant CD34+lin- cells. Analysis of compartment size and aberrant cell frequency suggests that frequency of cytogenetically aberrant stem cells is uncoupled from compartment size. These data suggest that cytogenetically aberrant cells in the primitive compartment show varying abilities to expand primitive compartments. Cytogenetically aberrant CD34+lin- cells precede the blast subpopulation in hierarchical maturation and may in some cases by considered preleukemic, requiring maturation or additional mutations before transformation (eg, compartmental expansion) occurs.
authors.affiliation: Department of Laboratory Medicine, University of California, San Francisco 94103, USA.
authors.forename: B
authors.initials: B
authors.lastname: Mehrotra
authors.forename: T I
authors.initials: TI
authors.lastname: George
authors.forename: K
authors.initials: K
authors.lastname: Kavanau
authors.forename: H
authors.initials: H
authors.lastname: Avet-Loiseau
authors.forename: D
authors.initials: D
authors.lastname: Moore
authors.forename: C L
authors.initials: CL
authors.lastname: Willman
authors.forename: M L
authors.initials: ML
authors.lastname: Slovak
authors.forename: S
authors.initials: S
authors.lastname: Atwater
authors.forename: D R
authors.initials: DR
authors.lastname: Head
authors.forename: M G
authors.initials: MG
authors.lastname: Pallavicini
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000208:Acute Disease; D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D000943:Antigens, Differentiation / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D002869:Chromosome Aberrations / Q000473:pathology*; D025063:Chromosome Disorders; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D007951:Leukemia, Myeloid / Q000473:pathology*; D008297:Male; D008562:Membrane Glycoproteins; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000473:pathology*; D009699:N-Glycosyl Hydrolases / Q000032:analysis; D014411:Neoplastic Stem Cells / Q000473:pathology*; D063268:Sialic Acid Binding Ig-like Lectin 3
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D015214:Antigens, Differentiation, Myelomonocytic; C571163:CD33 protein, human; D008562:Membrane Glycoproteins; D063268:Sialic Acid Binding Ig-like Lectin 3; D009699:N-Glycosyl Hydrolases; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1