Antigenic characterization of endothelial cell-derived microparticles and their detection ex vivo

J Thromb Haemost. 2003 Nov;1(11):2434-43. doi: 10.1046/j.1538-7836.2003.00455.x.


Background: Endothelial activation and dysfunction are associated with several diseases. However, hardly any specific markers are available. Microparticles (MP) from endothelial cells (EC; EMP) were reported in patient groups and healthy individuals. The antibodies used to detect EMP, however, were mainly directed against antigens without EC specificity.

Objectives: We evaluated the antigens on EC and EMP to establish proper markers for EMP detection.

Methods: EMP were isolated from supernatants of resting and interleukin (IL)-1alpha activated human umbilical vein EC (HUVEC; n=3; 0-72 h), stained with annexin V and monoclonal antibodies, and analyzed by flow cytometry. Human platelet-MP (PMP), the main MP population in plasma, were prepared in vitro. EMP and PMP were studied in plasma from systemic lupus erythematosus (SLE) patients (n=11) and healthy individuals (n=10).

Results: Platelet-endothelial cell adhesion molecule-1 (PECAM-1), alphanu and beta3 were constitutively exposed on HUVEC, but (almost) absent on EMP (<15% positive for alphanu and beta3), or only exposed on a subpopulation (PECAM-1; 30-60%). Activated HUVEC (>80%) and (subpopulations of) EMP exposed E-selectin and tissue factor. PMP strongly exposed PECAM-1, beta3, and glycoprotein (GP)Ib (CD42b), but not alphanu or E-selectin. GPIb and P-selectin (CD62P) were absent on EMP. Plasma samples contained 0.5% MP staining for E-selectin and/or alphanu. Plasma from one SLE patient contained E-selectin exposing MP (21%), but little alphanu-positive MP.

Conclusions: EC release EMP in vitro. The antigenic phenotype of EMP released from resting and IL-1alpha-stimulated EC differs among each other as well as from resting and stimulated EC, respectively. E-selectin exposed on IL-1alpha-stimulated EC is a valid marker for EMP detection ex vivo to establish endothelial cell activation.

MeSH terms

  • Adult
  • Antigens / analysis*
  • Biomarkers / analysis
  • Case-Control Studies
  • E-Selectin / analysis*
  • E-Selectin / immunology
  • Endothelial Cells / immunology
  • Endothelial Cells / metabolism*
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / pathology*
  • Exocytosis
  • Female
  • Flow Cytometry
  • Humans
  • Interleukin-1 / pharmacology
  • Lupus Erythematosus, Systemic / pathology
  • Middle Aged
  • Particle Size
  • Umbilical Veins


  • Antigens
  • Biomarkers
  • E-Selectin
  • Interleukin-1