Increased procoagulant cell-derived microparticles (C-MP) in splenectomized patients with ITP.
BACKGROUND
Splenectomy is frequently employed for therapeutic and diagnostic purposes in various clinical disorders. However its long-term safety is not well elucidated. Although risk of infection by encapsulated organisms is widely recognized, less well-known are risks of thrombosis and cardiovascular disease.


METHODS
We investigated levels of cell-derived microparticles (C-MP) in 23 splenectomized ITP (ITP-S) and 53 unsplenectomized ITP patients (ITP-nS). Assay of C-MP derived from platelets (PMP), leukocytes (LMP), red cells (RMP) and endothelial cells (EMP) were performed by flow cytometry. Coagulation parameters included PT, aPTT and activities of FVIII, IX and XI. Results of all measures were compared between the two groups, ITP-S vs ITP-nS.


RESULTS
Levels of all C-MP were higher in ITP-S than ITP-nS but only RMP and LMP reached statistical significance (p = 0.0035 and p < 0.0001, respectively). The aPTT was significantly shorter in ITP-S (p = 0.029). Interestingly, correlation analysis revealed that RMP, but not other C-MP, were associated with shortening of aPTT (p = 0.024) as well as with increased activities of factors VIII (p = 0.023), IX (p = 0.021) and XI (p = 0.0089).


CONCLUSIONS
RMP and LMP were significantly elevated in splenectomized compared to non-splenectomized ITP patients. This suggests that the spleen functions to clear procoagulant C-MP, and that elevation of C-MP might contribute to increased risk of thrombosis, progression of atherosclerosis and cardiovascular disease following splenectomy.
Fontana
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Wallace H Coulter Platelet Laboratory, Division of Hematology/Oncology, University of Miami, Miller School of Medicine, 1600 NW 10th Ave, Room 7109A, Miami, FL 33136, USA.
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Ahn
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Dudkiewicz
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Horstman
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Duncan
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Ahn
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D001779:Blood Coagulation Factors / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000209:etiology; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000473:pathology; D004912:Erythrocytes / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood* / Q000150:complications / Q000601:surgery*; D012307:Risk Factors; D013156:Splenectomy / Q000009:adverse effects*; D013927:Thrombosis / Q000209:etiology
D001779:Blood Coagulation Factors