RAPID COMMUNICATION Concentrations of Thrombopoietin in Bone Marrow in Normal Subjects and in Patients With Idiopathic Thrombocytopenic Purpura, Aplastic Anemia, and Essential Thrombocythemia Correlate With Its mRNA Expression

The function of bone marrow (BM) stromal thrombopoietin (TPO) in megakaryopoiesis remains unknown. In the present study we attempted to clarify the pathophysiological impli-cations of stromal TPO in normal subjects (NS) and in patients with idiopathic thrombocytopenic purpura (ITP), aplastic anemia (AA), and essential thrombocythemia (ET) by measuring TPO concentrations in BM and peripheral blood (PB) and by estimating the levels of stromal TPO mRNA with TaqMan fluorescence-based post–reverse tran-scription-polymerase chain reaction product detection sys-tem. The results showed that TPO concentrations in PB were significantly elevated in patients with ITP (34.9 6 11.7 pg/mL) and AA (364.1 6 153.5 pg/mL) but within normal range in patients with ET (each 20.0 and 22.1; NS, 22.1 6 8.2 pg/mL). In all subjects, the TPO concentrations in BM corre