title: Platelet ultrastructural and functional studies in myelodysplasia.
abstract: We studied the platelets of 8 patients with myelodysplasia aged 49-77 years, using both ultrastructural and functional techniques. Five of the 8 patients were classified as having refractory anaemia, and 3 as refractory anaemia with excess of blasts (RAEB). Electron microscopically, the myelodysplastic patients had in addition to normal ones, platelets containing significantly less alpha-granules. In part of these hypogranular platelets, the dense tubular system was abundant, but in contrast with normal platelets, it was not dispersed between the other organelles, nor did it form a membrane complex with the open cannalicular system. From a functional point of view, collagen-induced shape change was the most frequently disturbed parameter: there was a total loss of collagen-induced shape change in 5 patients. In 2 patients, there was a complete lack of response to collagen in platelet-rich plasma (both shape change and aggregation); in one of them, there was also a total loss of adenosine triphosphate secretion in response to all inducers tested. After 4 years of follow-up, 5 patients had died, of whom 3 were RAEB patients. An initial complete absence of collagen-induced shape change was found in these 5 patients, while in the 3 patients who were still alive at the end of the follow-up period, collagen-induced shape change was normal in 2 and slightly diminished in one.
authors.affiliation: Department of Internal Medicine, University of Leuven, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Blockmans
authors.forename: M J
authors.initials: MJ
authors.lastname: Heynen
authors.forename: G E
authors.initials: GE
authors.lastname: Verhoef
authors.forename: J
authors.initials: J
authors.lastname: Vermylen
mesh_terms: D000368:Aged; D000753:Anemia, Refractory / Q000097:blood* / Q000235:genetics / Q000401:mortality; D000754:Anemia, Refractory, with Excess of Blasts / Q000097:blood* / Q000235:genetics / Q000401:mortality; D001792:Blood Platelets / Q000187:drug effects / Q000648:ultrastructure*; D048429:Cell Size; D003094:Collagen / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007425:Intracellular Membranes / Q000648:ultrastructure; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000648:ultrastructure; D010974:Platelet Aggregation / Q000187:drug effects; D010978:Platelet Factor 4 / Q000032:analysis; D010979:Platelet Function Tests; D011379:Prognosis; D001620:beta-Thromboglobulin / Q000032:analysis
chemical_list: D001620:beta-Thromboglobulin; D010978:Platelet Factor 4; D003094:Collagen