Platelets release thrombopoietin (Tpo) upon activation: another regulatory loop in thrombocytopoiesis?
Thromb Haemost
; 83(6): 923-30, 2000 Jun.
Article
en En
| MEDLINE
| ID: mdl-10896250
ABSTRACT
Thrombopoietin is produced at a constant rate by the liver and kidney and is removed from the circulation upon binding and subsequent uptake via the Tpo receptor, c-Mpl, expressed by platelets and mega-karyocytes. Apart from uptake, this study shows that platelets can also function as a storage pool for Tpo. Upon stimulation with various platelet agonists, full-length biologically active Tpo was released by platelets. Platelet fractionation experiments indicated that this Tpo most likely is contained in the granules. When platelets were preincubated with Tpo-peptide mimetic or truncated Tpo prior to maximal activation, a three- to fivefold increment in Tpo release was seen. whereas, the release of other granule proteins such as vWF-propeptide or serotonin remained unchanged. Therefore, the Mpl agonists might compete with Mpl-bound Tpo, thereby releasing Tpo into the platelet supernatant. Intravascular release of Tpo by platelets might occur in patients with massive platelet activation, as occurs in patients with disseminated intravascular coagulation. The Tpo concentration in these patients is elevated (p <0.01) and correlates with markers for thrombin generation, TAT complexes and F1+2(r(p)= 0.8 and 0.9; p <0.01). This suggests that the increment in Tpo concentration was attributed to Tpo release by activated platelets in vivo, which might be instrumental in subsequent stimulation of thrombocytopoiesis.
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Bases de datos:
MEDLINE
Asunto principal:
Trombopoyetina
/
Plaquetas
/
Activación Plaquetaria
/
Receptores de Citocinas
/
Proteínas de Neoplasias
Límite:
Adult
/
Aged
/
Aged80
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Female
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Humans
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Male
/
Middle aged
Idioma:
En
Revista:
Thromb Haemost
Año:
2000
Tipo del documento:
Article
País de afiliación:
Países Bajos