An acquired form of Bernard Soulier syndrome associated with acute myeloid leukemia.
ABSTRACT To investigate glycoprotein-1b (GP-1b) expression on platelets from patients with acute myeloid leukemia (AML).
Purified platelets, obtained from AML-patients and normal control subjects, were examined for surface membrane GP1b-expression by flow cytometry and GP1b-mediated aggregation responses by aggregometry. The level of elastase in plasma from patients and controls was measured by enzymed-linked immunosorbent assay. The whole of this work was carried out at the University of Liverpool, Liverpool, United Kingdom during the period of 1994-2001.
Platelets from the majority of AML-patients showed reduced GP1b-expression and reduced GP1b-mediated aggregation responses. Reduction in platelet GP1b-expression was associated with increased plasma elastase levels.
The present study suggests that elastase, released from leukemic blasts, degrades platelet GP1b, resulting in dysfunctional circulating platelets in AML-patients. These results could explain the bleeding disorders observed in these patients.
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ABSTRACT: Multiparameter flow cytometric analysis of bone marrow and peripheral blood cells has proven to be of help in the diagnostic workup of myelodysplastic syndromes. However, the usefulness of flow cytometry for the detection of megakaryocytic and platelet dysplasia has not yet been investigated. The aim of this pilot study was to evaluate by flow cytometry the diagnostic and prognostic value of platelet dysplasia in myelodysplastic syndromes. We investigated the pattern of expression of distinct surface glycoproteins on peripheral blood platelets from a series of 44 myelodysplastic syndrome patients, 20 healthy subjects and 19 patients with platelet alterations associated to disease conditions other than myelodysplastic syndromes. Quantitative expression of CD31, CD34, CD36, CD41a, CD41b, CD42a, CD42b and CD61 glycoproteins together with the PAC-1, CD62-P, fibrinogen and CD63 platelet activation-associated markers and platelet light scatter properties were systematically evaluated. Overall, flow cytometry identified multiple immunophenotypic abnormalities on platelets of myelodysplastic syndrome patients, including altered light scatter characteristics, over-and under expression of specific platelet glycoproteins and asynchronous expression of CD34; decreased expression of CD36 (n = 5), CD42a (n = 1) and CD61 (n = 2), together with reactivity for CD34 (n = 1) were only observed among myelodysplastic syndrome cases, while other alterations were also found in other platelet disorders. Based on the overall platelet alterations detected for each patient, an immunophenotypic score was built which identified a subgroup of myelodysplastic syndrome patients with a high rate of moderate to severe alterations (score>1.5; n = 16) who more frequently showed thrombocytopenia, megakaryocytic dysplasia and high-risk disease, together with a shorter overall survival. Our results show the presence of altered phenotypes by flow cytometry on platelets from around half of the myelodysplastic syndrome patients studied. If confirmed in larger series of patients, these findings may help refine the diagnostic and prognostic assessment of this group of disorders.Haematologica 01/2012; 97(6):895-902. DOI:10.3324/haematol.2011.057158 · 5.87 Impact Factor