Nouvelle revue francaise d'hematologie最新文献

The purpose of this study was to determine the protein composition of the vesicles released from senescent erythrocytes and its variation during their experimental conservation at +4 degrees C in citrate phosphate dextrose (CPD), over a period of 8 weeks. Techniques employed included electron microscopy, SDS-PAGE and immunoblotting. Electron microscopic observation of senescent erythrocytes showed the simultaneous release of one or several vesicles of varying size and shape, while close examination of individual vesicles revealed a slack membrane structure and the presence of band 3 protein. SDS-PAGE and immunoblotting showed the vesicles to be composed mainly of band 3 and its breakdown products and to be lacking in spectrin. Use of specific antibodies demonstrated the presence of free haemoglobin, immunoglobulin G (IgG) and fragment C3b of complement. During conservation for 8 weeks, the concentration of band 3 protein decreased, while the concentrations of IgG and C3b increased and there was no apparent variation in haemoglobin levels.

The present report describes a case of cerebral venous thrombosis occurring in a patient suffering from refractory anaemia with excess of blasts (RAEB). This unusual complication suggests that RAEB could be considered a potential prothrombotic state.

The platelet receptor for ADP has been classified as a P2 purinoceptor of the P2T type where ADP is the natural agonist and ATP a competitive antagonist. Since the P2T receptor seems to be specific to platelets, we investigated the possibility that the human megakaryoblastic cell line Meg-01 might express the platelet ADP receptor, using functional studies and the ADP analogue [33P]2MeSADP as a specific P2T radioligand. ADP and 2MeSADP were able to induce shape change and pseudopod formation in Meg-01 cells. [33P]2MeSADP binding to membrane preparations was saturable and specific, binding sites being of high affinity (Kd = 13 +/- 3 nM) and present at a concentration of 13 +/- 7 fmoles/mu g protein. In contrast to UTP and GTP, ADP and ATP were able to displace the specific [33P]2MeSADP binding. ADP, 2MeSADP, UTP and ATP induced a dose dependent increase in intracellular calcium concentration. Desensitization experiments demonstrated that UTP, and ADP share a common P2U purinoceptor and that Meg-01 cells also express a P2T purinoceptor for which ADP and 2MeSADP are agonists and ATP a competitive antagonist. It was concluded that the human megakaryoblastic cell line Meg-01 expresses two distinct types of functional P2 receptor; a P2U and a P2T purinoceptor. This cell line could therefore provide the necessary material to clone the as yet unidentified platelet P2T purinoceptor.

A 25 year old woman with chronic myelogenous leukaemia was treated for 27 months with alpha-interferon, leading to complete haematological and cytogenetic remission. One year after interruption of treatment, she became pregnant and delivered a healthy full term infant. This case provides further evidence in support of the safety of alpha-interferon with respect to the fertility of women of childbearing age.

The imputability of heparin in heparin induced thrombocytopenia (HIT) was analysed retrospectively in the chart records of 86 cases documented by the Centre Regional de Pharmacovigilance (CRPV) of Reims-Champagne Ardenne over a period of 10 years. Considerable difficulties are encountered in evaluating the degree of imputability. Chronological criteria seem to be determinant in the final imputability score, whereas semiological criteria are particularly difficult to interpret, especially as it is not yet clearly established whether biological tests should be taken into account. The method of assessment requires more precise adaptation to the specific case of HIT and could be improved by redefinition of the criteria in collaboration between pharmacologists and haematologists.

Platelet prothrombinase activity and aggregation were studied in parallel in the same platelet suspensions with the aim of determining the relationship between these two responses. Stimulation of platelets with thrombin (0.12 U/ml) plus collagen (20 mu g/ml) led to maximum thrombin generation when the aggregation intensity was still only 30%. Since the rate of thrombin formation then remained constant as aggregation intensity was still only 30%. Since the rate of thrombin formation then remained constant as aggregation increased up to its maximum intensity, the aggregation processes did not appear to result in partial masking of any procoagulant surface. This was confirmed by the fact that thrombin generation was the same on aggregated platelets as on activated platelets prevented from aggregating by addition of RGDS. Finally, maximum 5-hydroxy-tryptamine release could be obtained in the absence of thrombin generation. Thus platelet procoagulant activity did not appear to be related to aggregation or secretion and thrombin formation on the surface of activated platelets was in fact two to three times more important in the absence of stirring than under the conditions of continuous stirring required for aggregation. In conclusion, these results suggest procoagulant activity and aggregation to be two independent platelet responses which occur in different physiological situations.

We studied the feasibility of in vitro expansion of CD34+ cells from patients with multiple myeloma (MM) or follicular non Hodgkin lymphoma (NHL). CD34+ cells were selected from peripheral blood (PB) using avidinbiotin immunoadsorption columns: purified CD34+ cells from three MM and five NHL patients were expanded. First, CD34+ cells (2 MM, 4 NHL) were grown for 14 days in 5 ml of IMDM plus 12.5% horse serum (HS), 12.5% fetal calf serum (FCS) and a commonly used combination of cytokines: IL1alpha, IL3, IL6, SCF, GM-CSF, G-CSF (10 ng/ml each) and EP (4 UI/ml). In these conditions, at day 14, average increase in CD34+, CFU-GM and total cell numbers were, respectively: x 6.0 x 23 and x 2,113 fold with 20 to 35% of granulocytic cells. In terms of CD34+ cell, CFU-GM and total cell outputs, MM cultures were comparable to NHL cultures, but MM cultures seemed to produce less granulocytic cells than NHL cultures. Next, in vitro expansion of PB CD34+ cells was tested in culture media suitable for clinical use. Two cultures (1 MM, 1 NHL) were carried out for 14 days in 20 ml of X-Vivo 10 medium, 2% human serum, IL1alpha, IL3, IL6, SCF, GM-CSF, G-CSF (6 ng/ml each) and EP (2 UI/ml). Increase in CD34+, CFU-GM and total cell numbers in these conditions were, respectively: x 5.7 and x 19.7, x 11.9 and x 40.9, x 424 and x 408 fold, with at least 75% of granulocytic cells in both cultures. We conclude that, although further improvements are necessary, in vitro expansion of PB CD34+ cells can presumably be carried out successfully for MM patients as well as for NHL patients, including in conditions suitable for clinical use.

Peripheral blood stem cells (PBSC) are used increasingly for autotransplantation in the treatment of acute leukemia, lymphoma, multiple myeloma, solid tumors such as ovarian and breast carcinoma. They are collected by leukaphereses during rapid hematopoietic recovery, following cytotoxic chemotherapy with or without administration of hematopoietic growth factors. We studied the clonogenic and cytokine-mediated expansion potential of CD34+ cells from mobilized PBSC. Low density mononuclear cells were processed using the CEPRATE LC CD34 KIT (CellPro). CD34+ purified cells, were cultured in suspension with 6 combined hematopoietic growth factors (IL1beta, IL3, IL6 at 100 U/ml and G-CSF, GM-CSF and stem cell factor at 10 ng/ml of each) for up to four weeks. Every week, cells were counted and CFU-GM assay was performed in a methylcellulose based medium. We have analysed the percentage of cells bearing CD34, CD33, CD38, HLA-DR, CD45RA, CD45RO antigens. Our results showed, that CD34+ cells were obtained with a purity of 92 +/- 2.3% and a yield of 71 +/- 10.7%. The majority co-expressed CD33 (57.76 +/- 34.16%) and CD38 (62.2 +/- 34%) antigens. These culture conditions, are necessary to obtain a fold increase of nucleated cells (377 fold at week 4), of CFU-GM progenitors (41.2 fold at week 3) and of CD34+ cell absolute number (10 fold at week 1) with an important differentiation of progenitors in particular myeloid progenitors.