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 :W e 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, aPTTand 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 pb0.0001, 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).