Diagnosis: Weibel-Palade Bodies
• Weibel-Palade bodies are secretory organelles found in endothelial cells.
• They appear as oval or elongated organelles with a whorled or “fingerprint”-like appearance on electron microscopy.
• Weibel-Palade bodies store von Willebrand factor (vWF) and P-selectin. vWF participates in primary hemostasis by binding platelets to the subendothelium and also stabilizes factor VIII in the plasma. P-Selectin participates in leukocyte adhesion.
• Qualitative or qualitative disorders of vWF can lead to a mild to severe bleeding disorder known as von Willebrand disease.
• Other proteins contained in Weibel-Palade bodies include interleukin-8, endothelin, and tissue plasminogen activator.
• Desmopressin-induced increase in vWF is most likely due to the direct release of multimeric vWF from Weibel Palade bodies.