Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate quality of hematologic recovery in aplastic anemia (AA) patients treated with cyclosporine A (CyA), we examined polymorphonuclear leukocytes (PMNCL) from 25 AA patients for clonality and glycosyl-phosphatidylinositol (GPI)-anchored membrane protein expression. Using three different X-linked gene probes, we failed to detect clonal hematopoiesis in seven CyA-responsive female patients. Clonal hematopoiesis was detected in two of six female patients refractory to CyA therapy, although one of these two patients had shown monoclonality before therapy. Flow-cytometric analysis revealed a normal expression of GPI-linked membrane proteins, including CD55, CD59, and CD16 on PMN in all patients treated with CyA, irrespective of response, except for one patient who had a small proportion of GPI-anchored membrane protein-negative cells before therapy. The proportion remained unchanged 41 months after hematologic recovery following CyA therapy. These findings suggest that successful therapy of AA with CyA may not be associated with a significant risk of developing late clonal complications, such as paroxysmal nocturnal hemoglobinuria (PNH) and myelodysplasia.
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PMID:Quality of hematologic recovery in patients with aplastic anemia following cyclosporine therapy. 753 14

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder of hematopoiesis in which affected cells are deficient in glycosylphosphatidyl-inositol (GPI) anchored surface proteins. The authors used flow cytometry to study 10 patients with PNH. They used a comprehensive panel of monoclonal antibodies against all nine currently known GPI-linked surface proteins (CD14, CD16, CD24, CD48, CD55, CD58, CD59, CD67, CD73) on cells of various lineages. Deficient cells were identified in the granulocytic-monocytic and erythroid lineages in all patients. However, the lymphoid lineage was affected in only eight patients. The patterns of deficiency were variable, with deficient cells constituting a part to all of the cells in the lineages tested. Certain proteins, including CD16, CD58, and CD59, appeared to be preferentially expressed, despite severe deficiencies of other GPI-linked proteins. Moreover, a trimodal pattern of expression of CD16, CD48, and CD59 was observed, in which a population of cells with intermediate levels of expression were identified in addition to positive and deficient cells. The authors' findings indicated a great degree of heterogeneity in the patterns and levels of expression of the GPI-linked proteins in the various cell types, as well as a possible heterogeneity in lineage involvement. The different patterns of expression of GPI-linked proteins should be considered when using flow cytometry to diagnose PNH. Finally, the clinical progression in some of the patients suggested a possible link between PNH, aplastic anemia, and myelodysplasia.
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PMID:Flow cytometric measurement of glycosylphosphatidyl-inositol-linked surface proteins on blood cells of patients with paroxysmal nocturnal hemoglobinuria. 803 65

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia in which abnormal red blood cells with enhanced susceptibility to complement undergo intravascular hemolysis when complement is activated in vivo, resulting in hemoglobinuria. This enhancement of complement susceptibility appears to involve multipotent stem cells and, in this respect, is thought to closely resemble myelodysplastic syndrome. Recently, it has been reported that the increased susceptibility of PNH cells to complement-mediated lysis is related to a deficiency of complement regulatory membrane proteins, especially CD55 and CD59. Both proteins are glycosylphosphatidylinositol (GPI)-anchored membrane proteins. It was found that a deficiency of GPI-anchored membrane proteins in PNH cells is due to the faulty synthesis of the GPI-anchor which may occur during early synthesis. Moreover, it is suggested that an abnormality of the PIG-A (phosphatidylinositol glycan-class A) gene, which is related to the early stage of GPI-anchor synthesis, is responsible for the pathogenesis of PNH. In conclusion, the clinical expression of PNH is dependent on two factors, complement susceptibility of PNH blood cells and changes in bone marrow function. The search for the ideal treatment of this disease may be aided by resolving the relationship between the two.
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PMID:Glycosylphosphatidylinositol (GPI)-anchored membrane proteins in clinical pathophysiology of paroxysmal nocturnal hemoglobinuria (PNH). 860 38

The relationships between paroxysmal nocturnal hemoglobinuria (PNH), aplastic anemia (AA), and myelodysplastic syndrome (MDS) are not clear. Here we describe a patient, J20, who developed a reciprocal translocation of chromosome 12 and PNH during follow-up of AA. All metaphases in CD59-deficient bone marrow mononuclear cells had the translocation, whereas none of the CD59-deficient cells had it, indicating that the PNH clone coincided with a cell population bearing the chromosomal aberration. We found a somatic single-base deletion mutation in the PIG-A gene of this patient's peripheral blood cells. This is the first patient with PNH with a PNH clone containing a chromosomal translocation.
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PMID:Analysis of PIG-A gene in a patient who developed reciprocal translocation of chromosome 12 and paroxysmal nocturnal hemoglobinuria during follow-up of aplastic anemia. 861 4

Among acquired stem cell disorders, pathological links between myelodysplastic syndromes (MDS) and aplastic anaemia (AA), and paroxysmal nocturnal haemoglobinuria (PNH) and AA, have been often described, whereas the relationship between MDS and PNH is still unclear. We analysed blood cells of patients with MDS to determine the incidence of the PNH clone, and analysed the PIG-A gene to find mutations characteristic of the PNH clone in MDS. In four (10%) of 40 patients with MDS, flow cytometry showed affected erythrocytes and granulocytes negative for decay-accelerating factor (DAF) and CD59. The population of affected erythrocytes was smaller in MDS patients with PNH clone (MDS/PNH) than in patients with de novo PNH, and haemolysis was milder in the MDS/PNH patients. PIG-A mutations were found in granulocytes of all patients with MDS/PNH. In type and site, the PIG-A mutations were heterogeneous, similar to that observed in de novo PNH; i.e. no mutation specific to MDS/PNH was identified. Of note, three of four patients with MDS/PNH each had two PNH clones with different PIG-A mutations, suggesting that PIG-A is mutable in patients with MDS/PNH. In a MDS/PNH patient with trisomy 8, FISH detected a distinct karyotype in a portion of granulocytes with PNH phenotype, indicating that PNH and MDS partly shared affected cells. Thus, MDS predisposes to PNH by creating conditions favourable to the genesis of PNH clone. Considering the increasing prevalence and incidence of MDS, these disorders could be useful for investigating the mechanism by which PIG-A mutation is induced.
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PMID:Paroxysmal nocturnal haemoglobinuria clones in patients with myelodysplastic syndromes. 1155 7

A 25-year-old man was admitted for evaluation of pancytopenia on May 2, 1997. On admission, he had pancytopenia with a normal reticulocyte count. Bone marrow aspirate specimens displayed a normal karyotype and hypocellularity without myelodysplasia. Although total bilirubin and lactate dehydrogenase levels were within their normal ranges, the haptoglobin level was low; additionally, two-color flow cytometric analysis determined that 3.3% of erythrocytes were double-negative for CD55 and CD59 expression. Atypical paroxysmal nocturnal hemoglobinuria with bone marrow hypoplasia was diagnosed. Because initial treatment with cyclosporin A was not effective, the patient was subsequently given a combination of antithymocyte globulin, cyclosporin A, and granulocyte colony-stimulating factor. Although the pancytopenia subsided, the percentage of double-negative erythrocytes in the patient's blood remained almost unchanged compared to findings obtained on admission.
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PMID:[Effective treatment combining antithymocyte globulin, cyclosporin A, and granulocyte colony-stimulating factor for atypical paroxysmal nocturnal hemoglobinuria accompanied by bone marrow hypoplasia]. 1022 33

WHAT IS HYPOPLASTIC ANEMIA? Aplastic anemia is a hematological disease characterized by pancytopenia and bone marrow hypoplasia. Acquired cases of aplastic anemia are almost all idiopathic and arise from unknown causes. Other cases of aplastic anemia are secondary and are caused by radiation, chemicals or viruses. PATHOPHYSIOLOGY: Aplastic anemia is manifested as a marked reduction in the number of pluripotent hematopoietic stem cells, but why this occurs is still uncertain. Some of the proposed causes include abnormalities of the hematopoietic stem cells, abnormalities in the hematopoietic microenvironment, and immunologically mediated damage to the hematopoietic stem cells (Figure 1). ABNORMALTIES OF THE HEMATOPOIETIC STEM CELLS: Patients with aplastic anemia, and long-term survivors in particular, are at increased risk of developing paroxysmal nocturnal hemoglobinuria (PNH), myelodysplastic syndrome (MDS), or acute myelocytic leukemia. This suggests that, in at least some of these patients, the hematopoietic stem cells themselves are abnormal. It also suggests that in some of these patients the blood cells are clonal (that is, all the blood cells are derived from a single pluripotent stem cell). In short, what these findings imply is that aplastic anemia may be caused by the emergence of an abnormal clone. Clonal hematopoiesis, however, can also be considered nothing more than a consequence. In other words, it is possible that hematopoiesis in this kind of patient is performed by a lone pluripotent stem cell that somehow managed to survive eradication. No definitive interpretation of clonal hematopoiesis has been agreed upon, and it is still a topic for future research. ABNORMAL HEMATOPOIETIC MICROENVIRONMENT: The presence of stromal cells, which form the microenvironment of bone marrow, is very important in hematopoiesis. Hematopoietic stem cells proliferate and differentiate either by adhering to stromal cells or by being stimulated by the various hematopoietic factors that stromal cells produce. Therefore, it is quite possible that aplastic anemia is caused by abnormalities in the hematopoietic microenvironment. However, many separate studies have demonstrated that the hematopoietic microenvironment in the vast majority of aplastic anemia cases is normal. IMMUNE MECHANISMS: Immunosuppressive agents are often effective in treating aplastic anemia, and therefore it is believed that immunological mechanisms contribute to the disease in more than half the cases. The following mechanisms have been proposed as causes for the onset of immunologically mediated aplastic anemia: * Decreases in Hematopoietic Factors Produced by Monocytes and Lymphocytes. Some patients with aplastic anemia show decreased production of interleukin 1 (IL-1) by peripheral blood monocytes, and it is possible that a drop in the concentration of this factor is linked to the onset of the disease [1]. It is also possible, however, that decreased IL-1 production by monocytes is not a cause of the disease, but merely a consequence. Moreover, no cases have been reported that exhibit reduced production of hematopoietic factors produced by lymphocytes such as GM-CSF, IL-3, or IL-6. * Damage by Cytokines that Suppress Hematopoiesis. It has been reported that increased levels of interferon &ggr; (IFN-&ggr;), which is produced by lymphocytes, and tumor necrosis factor &agr; (TNF-&agr;), which is produced by monocytes and macrophages, are found in the bone marrow and peripheral blood of aplastic anemia patients [2, 3]. These two factors act as suppressors of hematopoiesis, and it is possible that they contribute to the disease. The increase of these inflammatory cytokines in the bone marrow strongly suggests the presence of either specific or non-specific destruction of the hematopoietic stem cells by immunoregulatory cells. * Suppression of Hematopoiesis by Cytotoxic T Cells (Killer T Cells). Cases have been reported in which cytotoxic T cell clones that damage the autologous hematopoietic precursor cells are present [4]. Therefore, we can easily conceive of a mechanism in which these cytotoxic T cells specifically destroy the hematopoietic stem cells and cause aplastic anemia. * Suppression of Hematopoiesis by Natural Killer (NK) Cells. NK activity of aplastic anemia patients is depressed, and, generally speaking, it is highly unlikely that NK cells contribute to this condition. However, it has been reported that clonal NK cells are thought to cause the disease in patients exhibiting pancytopenia and bone marrow hypoplasia. Therefore, when this disease is diagnosed, a peripheral blood granular lymphocyte count and NK cell surface marker analysis should always be performed. DIAGNOSIS: A necessary condition for the diagnosis of aplastic anemia is the presence of pancytopenia. Moreover, it is necessary to rule out all other causes of pancytopenia. It is especially important in differential diagnosis to look for PNH and MDS. In cases of aplastic anemia there are patients that exhibit PNH during the course of the disease, and this condition is called aplastic anemia-PNH syndrome. It has recently been shown that bone marrow and peripheral blood cells in some patients diagnosed with aplastic anemia are partially lacking GPI anchor proteins (CD16, CD55, and CD59) [5]. Whether such patients become to exhibit aplastic anemia-PNH syndrome in the future remains to be elucidated. In MDS the bone marrow generally exhibits normoplasia or hyperplasia, and only in rare cases does it exhibit hypoplasia. This condition is referred to as hypoplastic MDS. Hypoplastic MDS can be differentiated from aplastic anemia by the presence of abnormal cell morphology that is sometimes accompanied by chromosomal abnormalities. TREATMENT:Aplastic anemia is treated with androgens, high-dose methylprednisolone, cyclosporin A (CyA), antithymocyte globulin (ATG), antilymphocyte globulin (ALG), hematopoietic growth factors such as G-CSF, and bone marrow transplantation. Interestingly, patients who require continuous CyA administration to maintain stable hematopoiesis have a specific HLA class II haplotype (DRB1*1501-DQA1*0102-DQB1*0602) [6]. Recent reports from EBMT SAA Working Party showed the excellent therapeutic result (response rate 82%) when severe cases were treated with ALG, CyA and G-CSF in combination [7].
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PMID:Special Education: Aplastic Anemia. 1038 86

To detect a small population of blood cells with a deficiency of glycosyl phosphatidylinositol (GPI)-anchored protein, we evaluated the expression of CD59 by flow cytometry on one million erythrocytes, which is about 100 times more than the number of erythrocytes tested by our standard immunoassay. Blood samples from healthy volunteers, patients with aplastic anemia (AA), and patients with myelodysplastic syndrome (MDS), who all showed no detectable GPI deficiency by the standard assay, were investigated. The numbers of CD59-deficient erythrocytes were 5 to 145/10(6) erythrocytes in the healthy volunteers (mean 29.2), and one of the volunteers had an increase in the deficient cells exceeding the mean + 3 SD (141.7), a normal limit. A CD59-deficient population was detected in 6 of the 21 (28.6%) patients with AA and 5 of the 18 (27.8%) patients with MDS. The new assay was performed again in 5 of these 11 patients and the normal individual who had the CD59-deficient populations at 6 and 12 months after the initial study. The number of deficient cells gradually increased in 1 patient with MDS (from 511 to 2892/10(6) erythrocytes), while the numbers of the other 4 patients showed a tendency to decline, although the deficient populations were repeatedly detected on most of the occasions. Changes in the number of the deficient cells were also seen in the healthy volunteer, but they were rather rapid; the numbers changed from 145 to 5661 and then to 18/10(6) erythrocytes within 3 months. The CD59 assay used in this study is easy to perform and enabled us to detect less than 1% GPI-deficient cells.
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PMID:Detection of small populations of CD59-deficient erythrocytes in patients with aplastic anemia or myelodysplastic syndrome and normal individuals. 1095 Sep 45

Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired clonal stem cell disorder characterized by intravascular haemolysis, venous thrombosis, marrow hypoplasia, frequent episodes of infection, and rarely leukaemic conversion. At the cellular level, PNH is characterized by the decrease or absence of glycosylphosphatidylinositol (GPI)-anchored molecules, such as CD55 and CD59, from the cell surface. PNH-like clones have been described in various haematological disorders. The link between PNH and aplastic anaemia (AA) has been established but the relationship of PNH with myelodysplastic syndromes (MDS) or myeloproliferative disorders (MPD) remains unclear. In this study, the presence of CD55 and/or CD59 defective (PNH-like) red cell populations was evaluated in 21 patients with AA, 133 with MDS, 197 with MPD, 7 with PNH and in 121 healthy blood donors using the Sephacryl Gel Test microtyping system. Red cell populations deficient in both molecules CD55 and CD59 were detected in 33.3% of AA patients, in 16.5% of MDS patients (50% with hypoplastic bone marrow), in 14.2% of MPD patients (more often in essential thrombocythemia, 21.2%) and in all PNH patients. CD55 deficient red cell populations were found in 14.2% of patients with AA, 12.7% of patients with MDS and 21.3% of patients with MPD. CD59 deficient populations were found in 9.5% of AA patients, 2.2% of MDS patients and 2% of MPD patients. These results indicate an association between PNH, AA and MDS or even between PNH and MPD. Further investigation is necessary to work out the mechanisms of this association, and to define classification criteria for borderline cases, where diagnosis is difficult.
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PMID:Detection of CD55 and/or CD59 deficient red cell populations in patients with aplastic anaemia, myelodysplastic syndromes and myeloproliferative disorders. 1134 8

PNH is a disorder of the pluripotent stem cells resulting in a deficient expression of membrane-bound GPI-anchored proteins in different cell types. Several flow cytometric approaches are designed to detect this antigen deficiency. But they all require drawing and testing of normal samples as control. Therefore, in the present study two flow cytometric assays for the detection of CD55 and CD59 deficiency in erythrocytes (REDQUANT CD55/CD59) and granulocytes (CELLQUANT CD55/CD59) are proposed. Precalibrated beads are used to define the cut off between normal and deficient cell populations. The specificity of the tests has been evaluated in healthy blood donors (n=52) resulting in a clear and reproducible cut off (3%) for the normal percentage of GPI-deficient cells. This cut off has been confirmed in leukaemia and lymphoma patients not suspected for developing PNH. The sensitivity has been tested in patients suffering from known PNH (n=23). Both tests performed in combination allowed a reliable detection of PNH in all patients showing antigen deficiencies in both cell types in most patients (20/23). In contrast, the PNH clones in the investigated patients with MDS (4/19) or AA (4/22) were present in granulocytes or erythrocytes, only. This underlines the necessity of analysing erythrocytes as well as granulocytes. Preliminary data regarding a possible correlation between disease activity and percentage of antigen-deficient cells lead to the assumption that haemolytic crises can only be determined on granulocytes whereas deficient erythrocytes disappeared due to complement-mediated lysis of the PNH clone. In conclusion, the combination of the test kits enables the differential diagnosis of PNH clones in a standardized, simple and rapid approach which may have therapeutic consequences.
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PMID:A standardized flow cytometric method for screening paroxysmal nocturnal haemoglobinuria (PNH) measuring CD55 and CD59 expression on erythrocytes and granulocytes. 1148 46


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