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Platelet spherocytosis: a new bleeding disorder.
James G White1, Pedro A de Alarcon
1Departments of Laboratory Medicine & Pathology, University of Minnesota Medical School, 420 Delaware Street SE, Mayo Mail Code 490, Minneapolis, MN 55455, USA. white003@tc.umn.edu
American Journal of Hematology
|July 12, 2002
Summary
This study investigated a child with a rare bleeding disorder and spherical platelets lacking microtubules. Platelet shape, microtubule formation, and aggregation were analyzed, revealing shape may cause bleeding symptoms.
Area of Science:
- Hematology
- Cell Biology
- Congenital Disorders
Background:
- Thrombocytopenia and congenital bleeding disorders can be associated with platelet abnormalities.
- Platelet shape is crucial for normal function, with discoid morphology supported by microtubules.
Purpose of the Study:
- To evaluate a child with thrombocytopenia and a rare congenital bleeding disorder characterized by platelet spherocytosis.
- To investigate the structural and functional defects in the patient's spherical platelets.
Main Methods:
- Differential interference phase contrast microscopy (DIC) and electron microscopy were used to examine platelet morphology.
- Immunofluorescence staining with anti-tubulin antibody assessed microtubule presence.
- Platelet aggregation studies were performed using standard agonists.
- Taxol was used to assess the potential for microtubule formation.
Main Results:
- Patient platelets were spherical and nearly devoid of microtubules (MT) and microtubule coils (MTC).
- Exposure to Taxol induced MT formation and disc conversion in 82% of patient platelets.
- Platelets adhered and spread normally but failed to aggregate irreversibly, associated with a lack of shape change and filopodia extension.
Conclusions:
- The patient's spherical platelet shape, due to a lack of microtubules, likely contributes to thrombocytopenia and bleeding symptoms.
- Microtubule formation is essential for normal platelet aggregation and function.
- Congenital platelet spherocytosis represents a distinct defect affecting platelet structure and hemostasis.