Blood cell diseases and thrombosis

Background and Objectives. In recent years knowledge about thrombophilia an d the mechanisms underlying the pathogenesis of thrombosis has increased gr eatly, Nevertheless the role of leukocytes and red cells in thrombogenesis is not well established and is probably underestimated. Evidence and information sources. The contribution of leukocytes and red ce lls to thrombogenesis has been reviewed. Moreover, the prevalence of thromb osis as a complication of hematologic diseases has been examined. The autho rs are involved in the investigation and management of acute and chronic he matologic diseases as well as in investigation of thrombophilia. Pub-Med wa s employed as a source of information. State of the art. Thrombosis is a major problem in myeloproliferative disor ders such as polycythemia vera and essential thrombocythemia. A clonal invo lvement of megakaryocytopoiesis resulting in elevated levels of platelet-sp ecific proteins, increased thromboxane generation, and expression of activa tion-dependent epitopes on the platelet surface is regarded as the main ori gin of thromboembolism; nevertheless, activation of leukocytes and the cons equent release of elastase and alkaline phosphatase could play an important role, determining endothelial damage. Thrombosis is a relevant problem in some hemolytic anemias such as paroxysmal nocturnal hemoglobinuria and drep anocytosis. Thrombotic events in hemolytic anemias with membrane defects ha ve been attributed, at least in part, to hypercoagulability related to the exposure of phosphatidylserine of red cell membrane activating plasma proth rombinase and supplying a procoagulant phospholipid anionic surface. A mode rate but well-established risk for thrombosis occurs in acute promyelocytic leukemia and acute lymphoblastic leukemia; this risk could be increased by antiblastic drugs affecting the procoagulant activity of cells and the pro duction of coagulation inhibitors from the liver. Perspectives. Thrombotic complications during hematologic diseases other th an thrombophilia due to plasma alteration could be decreased not only by an ticoagulant and antiaggregating agents but also by drugs inhibiting activat ion of leukocytes and red cells and their interaction with platelets, (C) 2 001, Ferrata Storti Foundation.