Platelet Function and Structure in Myeloproliferative Disease, Myelodysplastic Syndrome, and Secondary Thrombocytosis

Abstract

Platelet function and morphologic characteristics were evaluated in 43 patients with myeloproliferative disease (MPD), 5 patients with myelodysplastic syndrome (MDS), and 7 patients with secondary thrombocytosis (ST). Platelet Factor IV (PF4) and B-thromboglobulin (BTG) showed slight elevation in ST but significant elevation in all MPDs. They were either normal or slightly elevated in MDS. Defective platelet aggregation with one or more inducers was seen in 62% of all patients. An epinephrine-induced defect was the most consistent aggregation abnormality. Hyperaggregation and spontaneous aggregation were seen in 15% of patients. Of the eight patients who showed increased bleeding tendency, all eight showed defective aggregation with two or more inducers, five showed decreased surface activation response, as well as decreased or abnormal granules and dense tubular disarray in the transmission electron microscope (TEM) study. Seven patients had clinical evidence of recurrent arterial and venous thromboses. Five of these patients showed hyperaggregation response to adenosine diphosphate and collagen and abnormal Wu and Hoak platelet aggregate ratio. Four patients showed spontaneous aggregation on aggregometer. Surface activation response was significantly increased in five patients, and an increase in platelet granules by TEM study was seen in four patients. Primary thrombocythemia could be differentiated from secondary thrombocytosis (ST) by the presence of abnormal aggregation response and significantly increased PF4 and BTG in the former, and greatly elevated plasma fibrinogen and Factor VIII, as part of acute phase reactant response, in the latter.

Automated assessment of the neutrophil and platelet activation status in patients with essential thrombocythemia

“…Increased MPV and heterogeneity in platelet volume and mass were associated with decreased platelet density in this study. These findings are in agreement with those from early studies using platelet morphology in blood smears or other Hematology analyzers [21][22][23][24]. The increase in platelet volume and the decrease in platelet buoyant density that we observed could be explained by proliferation or dilation of the dense tubular and open canalicular system and reduction of the mitochondria, dense granules, and -granules, as found in ultrastructural studies of platelets from ET patients [25][26][27][28].…”

Flow cytometry demonstrates differences in platelet reactivity and microparticle formation in subjects with thrombocytopenia or thrombocytosis due to primary haematological disorders

“…In addition, functional platelet defects contributing to bleeding have been described [5][6][7][8], however it may be difficult to reliably assess platelet function using current methods in such subjects. Similarly, subjects with essential thrombocythaemia (ET) are at an increased risk of thrombosis (and in some cases bleeding), however levels of platelet activation and reactivity are not routinely assessed in these subjects.…”

Normal platelet counts mask abnormal thrombopoiesis in patients with chronic myeloid leukemia

“…In addition to marked granulocytic predominance, pathological and morphological findings show that the number of megakaryocytes in the chronic phase is frequently increased, and that these cells exhibit abnormal features (small with abnormal lobation) (2). Megakaryocytes are the source of platelet production, and dysmegakaryopoiesis implies dysregulated platelet production, involving dysmorphology (increased size, particularly giant platelets) (3,4), abnormal counts and impaired function (5)(6)(7)(8)(9)(10).…”