Rivka Yona

Molecular alterations in the TP53 gene of peripheral blood cells of patients with chronic myeloid leukemia

The TP53 gene has been extensively studied in patients with chronic myeloid leukemia (CML), both in chronic phase and in blast crisis. Mutations in the gene were found in up to 30% of the patients, especially among those in blast crisis. We report the results of an analysis of 29 blood samples from CML patients: 8 samples from chronic phase patients, 8 from patients in the accelerated phase, and 13 from patients in blast crisis. By using genomic DNA, we sequenced PCR products of the coding exons and most introns of the TP53 gene, finding genetic changes in 30% of the blast crisis samples and 12% in chronic phase. All mutations were found in introns and were previously unreported. Immunocytochemical studies revealed accumulation of TP53 in blood cells of samples both from chronic phase and blast crisis patients. Since these samples had no TP53 mutations, we believe that wild type TP53 accumulates in blood cells of CML patients. Our results, therefore, indicate that molecular changes in coding regions of the TP53 gene are rare. The significance of the abundance of intronic changes should be investigated further. Accumulation of wild type TP53 in CML cells may indicate an additional mechanism involving this gene in the pathogenesis of this disease. Genes Chromosomes Cancer 21:2–7, 1998.

Enhanced generation of monocyte tissue factor and increased plasma prothrombin fragment1+2 levels in patients with polycythemia vera: Mechanism of activation of blood coagulation

Polycythemia vera (PV) is associated with a high incidence of thrombosis. The association of apparent and secondary polycythemia with thrombosis is not clear. It was suggested that activation of the coagulation system contributes to thrombus formation in PV. However, the mechanism of activation is unknown. Monocytes generate a potent tissue factor (TF) upon stimulation with various substances, which is involved in thrombus formation in various disorders. Therefore, we studied the possibility that the factor is involved in the activation of coagulation and thrombus formation also in PV. Unstimulated peripheral blood mononuclear cells (PBMC) from each of the different types of polycythemia expressed weak TF activity (2 U) and antigen (41.4 to 52.9 pg/ml), which were similar to normal controls. Following stimulation with endotoxin, PBMC from normal controls and from apparent and secondary polycythemia showed a 3.9‐ to 4.5‐fold increase in TF, while cells from PV showed a 21‐fold increase (P < 0.001). Similar levels were generated by PBMC after treatment of PV and at the spent phase. TF was generated by monocytes but not by lymphocytes. Plasma prothrombin fragment1+2 (F1+2) levels, assayed at the same time, were significantly higher in PV (2.46 nm) compared to normals and apparent and secondary polycythemia (0.22 to 0.32 nm), and were in a significant correlation with monocyte TF activity and antigen levels (r = 0.77, 0.87). The high levels of F1+2 confirm that the coagulation system is activated in PV. The increased capacity of monocytes to generate TF may be responsible for the activation of the coagulation system and thrombus formation. The hypercoagulability state that is induced by this mechanism suggests that long‐life oral anticoagulation should be considered once thrombosis has been developed in PV. Am. J. Hematol. 56:5–11, 1997

The onset of p53-dependent apoptosis plays a role in terminal differentiation of human normoblasts

The p53 tumor suppressor gene was found to play a role in the differentiation of several tissue types. We report here that p53-dependent apoptosis plays a role in the final stages of physiological differentiation of normoblasts, resulting in nuclear condensation and expulsion without cell death. Blood samples of healthy newborns, cord blood as well as bone marrow, were analysed for apoptosis by TUNEL and p53 expression by immunostaining. While some samples exhibited simultaneously several distinct patterns of apoptosis, such as perinuclear, diffused nuclear or nuclear apoptotic bodies, others presented a single defined pattern. Overexpression of p53 protein was detected in normoblasts exhibiting either perinuclear or diffused nuclear p53, corresponding to the nuclear apoptotic pattern in the same sample. Similar results were also evident with colonies cultivated for 12–14 days in culture. Differentiated erythroid colonies exhibited overexpression of p53 and positive TUNEL staining only in the normoblasts. We further examined the state of caspase 3/7 and observed a decrease of this activated enzyme during erythroid differentiation in culture. This study suggests a novel role for apoptosis in normoblast differentiation where nuclear degradation occurs with a delay in the actual cell death. A pivotal role for the p53-dependent apoptosis in the erythroid lineage development is implied. However, this apoptotic process is not fully executed because of the exhaustion in caspase 3/7 and thus cells are diverted towards final stages of differentiation.

Clinical manifestations and laboratory findings in patients with lupus anticoagulants

Clinical and laboratory features were evaluated in 48 patients with lupus anticoagulants and the efficiency of three different assays in the detection of lupus anticoagulants was compared. The diagnosis of lupus anticoagulants was based on a prolonged activated partial thromboplastin test not corrected in a mixture of 1:1 with normal plasma and lack of specific inhibitors against coagulation factors. Platelet neutralization procedure was positive for lupus anticoagulants in 98% of the patients, tissue thromboplastin inhibition ratio in 79%, and kaolin clotting time index in 77%. At least one of the assays was positive in 100% of the cases. The largest minority of the patients (31%) suffered from systemic lupus erythematosus. The others had a variety of non‐immunological disorders. In the 13 patients who had been operated on, only 1 with renal failure developed hemorrhagic complications after renal biopsy due to thrombocytopathy. The incidence of recurrent spontaneous miscarriage, immune thrombocytopenia and positive direct antiglobulin test, anti‐nuclear and anti‐DNA antibodies and VDRL was significantly higher in patients with lupus anticoagulants and systemic lupus erythematosus compared to patients with lupus anticoagulants but without systemic lupus erythematosus.

Functions of polymorphonuclear (PMN) leukocytes of patients with lymphoproliferative diseases

PMN leukocytes from untreated patients with multiple myeloma (MM), Hodgkins disease (HD) and non-Hodgkin lymphoma (NHL) were studied in vitro for their phagocytic and chemotactic function. Alkaline phosphatase score and the reduction of nitroblue tetrazolium (NBT) in these leukocytes were also determined. Most of the functions of PMN leukocytes from untreated patients with MM were impaired, compared to control leukocytes, while those from patients with HD and NHL were impaired only in their chemotactic response to casein and endotoxin-activated serum (EAS).

Danazol and Myelodysplasic Syndromes

Excerpt To the editor: The successful treatment with danazol of three patients with myelodysplastic syndromes and severe thrombocytopenia was described recently by Cines and coworkers (1). After ad...