Haema 2010; 1(2): 112-120
by Michael Spanoudakis, Christina Kalpadakis, Helen A. Papadaki
Haematology Department, University of Crete School of Medicine, Heraklion, Greece
Abstract
Idiopathic thrombocytopenic purpura (ITP) or primary immune thrombocytopenia (primary ITP) is a benign haematologic disorder characterized by thrombocytopenia mainly due to increased platelet destruction by humoral (autoantibodies) or cellular (cytotoxic T-lymphocytes) immune mechanisms. In vivo data showing development of thrombocytopenia in healthy subjects following infusion of plasma from ITP patients, amelioration of thrombocytopenia in ITP patients following therapy that blockade the macrophage system or after splenectomy, have long demonstrated that peripheral removal of platelets represents the most common pathogenetic mechanism in ITP. However, morphological studies showing (para)apoptotic characteristics of bone marrow megakaryocytes in ITP in association with in vitro data demonstrating suppression of normal megakaryopoiesis by plasma from ITP patients, and platelet kinetic studies showing reduced platelet turnover in more than 80% of ITP patients strongly suggest inappropriate platelet production as an additional pathogenetic mechanism in ITP. In favour of this aspect are the relatively low serum/plasma thrombopoietin levels in patients with ITP compared to patients with the same degree thrombocytopenia due to marrow failure such as aplastic anaemia as well as the marked improvement of thrompbocytopenia in patients with chronic, resistant ITP following treatment with the novel thrombopoietin receptor agonists. The current review summarizes the available data showing that ITP, in contrast to the traditional concept, should be considered as a disease of increased platelet destruction and decreased platelet production.