title: Circulating autoantibodies to endothelial progenitor cells: binding characteristics and association with risk factors for atherosclerosis.
abstract: OBJECTIVE
  Endothelial progenitor cells (EPC) are committed to transform into EC promoting vasculogenic ischemic repair. Anti-endothelial cells (AECA) have been described in various disorders with an associated vascular damage. Herein, we explored a novel circulating population of IgG reactive with EPC, in patients with differential risk profile for atherosclerotic vascular disease.
  
  
  RESULTS
  A novel cyto-ELISA system was established where the coated cells were late outgrowth EPC. Levels of anti-EPC antibodies were determined in 100 subjects and differential risk score for atherosclerosis, as well as to circulating EPC levels and the inflammatory markers IL-6 and C-reactive protein. To study endothelial cell (EC) activating properties, sera were tested for their ability to induce VCAM-1 expression in a cell ELISA system. Detectable levels of anti-EPC antibodies, that correlated with age, Framingham risk score and CRP concentrations but did not associate with levels of LDL, HDL, hypertension or diabetes, were detected. Anti-EPC antibodies were distinct from EC binding antibodies as shown by competitive inhibition studies, and have been positively correlated with the extent of EC activation manifested by in vitro VCAM-1 expression.
  
  
  CONCLUSIONS
  This is the first study showing a newly defined subgroup of self-antibodies binding EPC and associating positively with the Framingham risk score. Further studies are required to characterize and test this interesting subset of EPC binding autoantibodies and their potential significance.
authors.affiliation: Heart Center, Kaplan Medical Center, Rehovot, Affiliated to the Hebrew University, Jerusalem, Israel.
authors.forename: Jacob
authors.initials: J
authors.lastname: George
authors.affiliation: Department of Experimental and Clinical Medicine, Division of Rheumatology AOUC, University of Florence, Florence, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Matucci-Cerinic
authors.affiliation: Heart Center, Kaplan Medical Center, Rehovot, Affiliated to the Hebrew University, Jerusalem, Israel.
authors.forename: Iris
authors.initials: I
authors.lastname: Bar
authors.affiliation: Heart Center, Kaplan Medical Center, Rehovot, Affiliated to the Hebrew University, Jerusalem, Israel.
authors.forename: Sara
authors.initials: S
authors.lastname: Shimoni
mesh_terms: D050197:Atherosclerosis / Q000097:blood* / Q000276:immunology / Q000473:pathology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology / Q000302:isolation & purification; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D002452:Cell Count; D066026:Endothelial Progenitor Cells / Q000276:immunology*; D004730:Endothelium, Vascular / Q000276:immunology* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D002097:C-Reactive Protein