title: Immunophenotypic analysis of myelodysplastic syndromes.
abstract: OBJECTIVE
  In contrast with hematologic malignancies in which the value of immunophenotypic studies is well established, information on the immunophenotypic characteristics of myelodysplastic syndromes (MDS) is scanty. The main goal of the present study was to explore the immunophenotypic differences between patients with MDS and normal individuals, including changes in distribution of cell lineages as well as phenotypic aberrations and blockades in cell maturation pathways.
  
  
  METHODS
  In MDS the proportion of bone marrow CD34+ cells was higher than in normal patients but the most immature progenitors (CD34+CD38-) were less represented. By contrast the proportion of myelomonocytic CD34+ cells was greater than in normal individuals, translating into an increased myeloid/non-myeloid CD34+ hematopoietic progenitor cell ratio.
  
  
  RESULTS
  This suggests that in MDS, the majority of CD34+ cells are already committed to the myeloid lineage. Upon analyzing the granulo-monocytic differentiation pathway, MDS patients showed an increased proportion of monocytic cells with a decreased percentage of cells of neutrophil lineage, leading to a lower neutrophil/monocytic cell ratio. Maturational arrests in the monocytic but not in the neutrophil differentiation pathway were observed. In refractory anemia with excess blasts in transformation (RAEB-t) such blockades mainly occurred during the earliest stages of differentiation but in the other MDS subtypes they occurred in later stages.
  
  
  CONCLUSIONS
  Phenotypic aberrations occurred in 90% of patients and a high proportion of cases showed >=2 aberrations. In summary, our results show that, in addition to an abnormal distribution of the bone marrow cell compartment, MDS patients frequently show aberrant phenotypes and maturational arrests. Some of these features may help in cases in which the diagnosis of MDS is questionable.
authors.affiliation: Servicio de Hematología, Hospital Universitario de Salamanca, Paseo San Vicente 58-182, 3700 Salamanca, Spain. concarol@usal.es
authors.forename: M Consuelo
authors.initials: MC
authors.lastname: Del Cañizo
authors.forename: M Eugenia
authors.initials: ME
authors.lastname: Fernández
authors.forename: Antonio
authors.initials: A
authors.lastname: López
authors.forename: Belén
authors.initials: B
authors.lastname: Vidriales
authors.forename: Eva
authors.initials: E
authors.lastname: Villarón
authors.forename: José L
authors.initials: JL
authors.lastname: Arroyo
authors.forename: Francisco
authors.initials: F
authors.lastname: Ortuño
authors.forename: Alberto
authors.initials: A
authors.lastname: Orfao
authors.forename: Jesus F
authors.initials: JF
authors.lastname: San Miguel
mesh_terms: D001854:Bone Marrow Cells; D001856:Bone Marrow Examination; D016022:Case-Control Studies; D002454:Cell Differentiation; D019070:Cell Lineage; D006801:Humans; D016130:Immunophenotyping; D009190:Myelodysplastic Syndromes / Q000473:pathology*