Thromb Haemost 2000; 83(01): 35-41
DOI: 10.1055/s-0037-1613753
Commentary
Schattauer GmbH

Inherited Macrothrombocytopenia with Distinctive Platelet Ultrastructural and Functional Features

Bianca Rocca
Department of From the Research Center for Pathophysiology of Haemostasis, Department of Internal Medicine
,
Franco O. Ranelletti
1   Department of Histology, Catholic University School of Medicine, Rome, Italy
,
Nicola Maggiano
2   Department of Pathology, Catholic University School of Medicine, Rome, Italy
,
Giovanni Ciabattoni
3   Department of Pharmacology, Catholic University School of Medicine, Rome, Italy
,
Raimondo De Cristofaro
Department of From the Research Center for Pathophysiology of Haemostasis, Department of Internal Medicine
,
Raffaele Landolfi
Department of From the Research Center for Pathophysiology of Haemostasis, Department of Internal Medicine
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Publikationsverlauf

Received 31. März 1999

Accepted after resubmission 02. September 1999

Publikationsdatum:
06. Dezember 2017 (online)

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Summary

We report a family with inherited macrothrombocytopenia and characteristic large membrane complexes in the platelets. Two affected subjects had platelet counts of 40 and 65X109/L respectively as assessed by contrast phase microscopy. Ultrastructural studies revealed giant spheroid platelets with characteristic large membrane complexes and/or giant vacuoles containing platelet organelles. Immunohistochemical studies of actin and tubulin showed a disorganization of the microtubule and actin systems. These abnormalities were absent in leukocytes, indicating a platelet-specific cytoskeleton disorder.

Platelet autoantibodies were repeatedly absent. Nevertheless, in the peripheral blood we observed several figures of platelet phagocytosis by macrophages and neutrophils. The in vitro aggregometric response of platelets to ADP, collagen, thrombin, ristocetin was present, but shape change was absent. The urinary excretion of thromboxane A2 metabolites of the affected subjects were approximately 2 standard deviations above control values, in spite of a reduced maximal biosynthetic capacity of thromboxane from giant platelets assessed in vitro during whole blood clotting.

This inherited platelet disorder shows structural and functional features which allow to distinguish it from other syndromes associated with giant platelets. We also propose to include ultrastructural and cytoskeletal studies in the diagnosis as well as in the classification of inherited giant platelet disorders.