STUDIES OF THE PLATELET DENSITY ABNORMALITY IN MYELOPROLIFERATIVE DISEASE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 103  (3) , 373-383
Abstract
The extinction (optical density) of normal fresh platelets correlates closely with their apparent volume as determined with the Coulter counter and that platelets from patients with myeloproliferative disorders (MPD) have a decrease in extinction relative to their apparent volume. The reduction in extinction of MPD platelets correlates with a decrease in platelet density and with a decrease in the refractive index of the platelet hyaloplasm. To explore the abnormality of the hyaloplasm, normal and MPD platelets were incubated in plasma from blood anticoagulated with EDTA. Normal platelets responded with marked swelling, as shown by an increase in apparent Coulter volume and by corresponding decreases in density, extinction and refractive index of hyaloplasm. The magnitude of these changes was markedly less with MPD platelets. Ultrastructural studies by others have indicated that the swelling effect of EDTA results from dialation of intracellular channels such as the surface-connected canalicular system and that these structures occupy more of the interior of MPD platelets than in the case of normal platelets. MPD platelets apparently circulate with dilated internal channels that are unable to dilate further with EDTA. MPD platelets display an increased dispersion (geometric SD) of their apparent Coulter volumes. The dispersion abnormally correlates with the density abnormality and the increase in dispersion apparently is not confined to a subpopulation of abnormal light platelets; rather, it is present in all density subpopulations. The abnormalities in density and dispersion originate at the time of shedding from the megakaryocyte.