title: Assessment of bone marrow microvessel density in chronic lymphocytic leukemia.
abstract: BACKGROUND
  Angiogenesis is a physiologic process of new blood vessels formation mediated by various cytokines called proangiogenic and antiangiogenic factors. Enhancement of angiogenesis in chronic lymphocytic leukemia (CLL) has been recognized more recently. Our study assesses CD34 and von Willebrand factor (vWf) expression and microvessel density (MVD) in the bone marrow of patients with CLL.
  
  
  OBJECTIVE
  (1) To assess bone marrow MVD in CLL using 2 different monoclonal antibodies, CD34 and vWf; and (2) To examine the possible association of marrow MVD and clinical course, pattern of marrow infiltration, Rai stage, CD38 positivity, and cytogenetic abnormalities detected by fluorescence in situ hybridization.
  
  
  METHODS
  Bone marrow specimens from 33 patients with CLL and 10 controls were studied. A single microvessel was defined as any vessel with a clear lumen. The screening of the slides was carried out by hotspot method. The slides were initially screened at low power to identify the areas with highest number of microvessel or vascularity hotspot. The count of microvessel in a sufficiently extended field (40x objective lens, 10x ocular lens) was then performed. The mean value of 10 most vascularized areas at 400x field was considered as MVD for a sample.
  
  
  RESULTS
  There was a significant difference between MVD counts according to the antibody used. MVD was higher using CD34 versus vWF (CD34: mean +/- SD, 35.91+/-15.7; 95% confidence interval of mean, 30.34-41.48 vessels/field versus vWF: 8.15+/-4.65; 95% confidence interval of mean, 4.11-12.44 vessels/field; P<0.0001]. Bone marrow MVD detected by CD34 was significantly higher in patients with CD38 expression more than 30% (P=0.006) and in patients with unfavorable cytogenetic abnormalities. However, no significant MVD differences were detected between CLL subgroups with regard to clinical course, pattern of marrow infiltration, and Rai stage. Bone marrow MVD in patients with CLL was significantly higher than that in controls (P<0.0001).
  
  
  CONCLUSIONS
  MVD assessment using anti-CD34 resulted in higher MVD counts than when using anti-vWF antibody. However, no MVD differences were detected between CLL subgroups subdivided according to the above-mentioned prognostic factors except CD38 expression and genetic abnormalities.
authors.affiliation: Clinic for Hematology, Clinical Center Serbia, Belgrade, Serbia. tweety@scnet.rs
authors.forename: Darko
authors.initials: D
authors.lastname: Antic
authors.forename: Maja Perunicic
authors.initials: MP
authors.lastname: Jovanovic
authors.forename: Marija Dencic
authors.initials: MD
authors.lastname: Fekete
authors.forename: Vladan
authors.initials: V
authors.lastname: Cokic
mesh_terms: D018952:Antigens, CD34 / Q000097:blood* / Q000276:immunology; D014408:Biomarkers, Tumor; D001853:Bone Marrow / Q000098:blood supply / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000473:pathology*; D055806:Microvessels / Q000473:pathology*; D015588:Observer Variation
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor