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Objectives Standard risk stratification for overall survival (OS) in patients with essential thrombocythemia (ET) is based on advanced age and history of thrombotic events. Recently, International Prognostic Score for ET (IPSET) incorporated also leukocytosis in prognostic model. The aim of this study was to establish additional risk factors for OS in ET patients. Methods After the median follow-up of 7 yr, in 244 consecutive ET patients, 32 deaths were documented (13.2%). The 5- and 10-yr OS was 95.9% and 79.7%, respectively. Considered additional risk factors at diagnosis of ET were the presence of arterial hypertension, diabetes, hyperlipidemia, and smoking attitude. Results The main cause of death in 75% of patients was cardiovascular (CV) comorbidity. Patients with CV risk factors had increased risk of death (HR = 2.33). Cox regression model identified age, leukocytosis, presence of CV risk factors, and previous thrombosis as unfavorable predictors of survival. Based on these parameters, four risk groups were defined, with significantly different survivals (P

We have investigated growth in vitro of bone marrow megakaryocytic progenitors (CFU-Mk) in 7 patients with paroxysmal nocturnal haemoglobinuria (PNH) to determine the sensitivity of CFU-Mk to complement. Bone marrow light density mononuclear cells were exposed to fresh or heat-inactivated AB human serum in the presence of medium or isotonic sucrose solution. We found that the proliferative activity of bone marrow CFU-Mk in PNH patients was significantly lower than in controls. In addition, the number of CFU-Mk in PNH bone marrow cells exposed to isotonic sucrose and complement was reduced to 25% of that in PNH cells exposed to isotonic sucrose without complement. In conclusion, our finding showed an increased sensitivity of CFU-Mk in PNH bone marrow cells to complement, supporting the hypothesis that the PNH defect is present at the level of CFU-Mk.

Acquired amegakaryocytic thrombocytopenia (AATP) in adults is a rare disorder characterized by severe thrombocytopenia and decreased or absent megakaryocytes in an otherwise normal bone marrow. We present a 44-yr-old man in whom the diagnosis of AATP was established in January 2001. Immunophenotyping of the peripheral blood lymphocytes showed a relative increase in the subpopulation of gamma/delta T-cell receptor (TCR) positive (gamma/delta TCR(+)) and (CD4, CD8) negative T lymphocytes, and PCR suggested a monoclonal pattern of TCR gamma chain gene rearrangement. Cytogenetic examination of his bone marrow cells showed a normal male karyotype but RT-PCR analysis revealed a BCR-ABL (p210) fusion transcript. The inhibition of CFU-Mk growth mediated by the patient's T lymphocytes indicated that the pathogenic mechanism for AATP could be an immunological attack on megakaryocyte progenitors where the gamma/delta TCR-positive T lymphocytes are directly involved. The case emphasizes the complex association of T-lymphocyte monoclonal proliferation and AATP.