SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
We describe the first case of paroxysmal nocturnal hemoglobinuria with Evans' syndrome. The immunohematological studies of this patient, a 27-year-old man, revealed the presence of red cell and platelet autoantibodies, related to an episode of anemia and thrombocytopenia.
BACKGROUND: Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem-cell disorder in which the affected cells are deficient in glycosylphosphatidylinositol (GPI)-anchored proteins. Paroxysmal nocturnal hemoglobinuria is frequently associated with aplastic anemia, although the basis of this relation is unknown. OBJECTIVE: To assess the PNH status of patients with diverse marrow failure syndromes. DESIGN: Correlation of cytofluorometric data with clinical features. SETTING: Hematology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland. PATIENTS: 115 patients with aplastic anemia, 39 patients with myelodysplasia, 28 patients who had recently undergone bone marrow transplantation, 18 patients with cancer that was treated with chemotherapy, 13 patients with large granular lymphocytosis, 20 controls who had received renal allografts, and 21 healthy participants. INTERVENTION: Patients with aplastic anemia, myelodysplasia, or renal allografts received antithymocyte globulin. MEASUREMENTS: Flow cytometry was used to assess expression of GPI-anchored proteins on granulocytes. RESULTS: Evidence of PNH was found in 25 of 115 (22%) patients with aplastic anemia. No patient with normal GPI-anchored protein expression at presentation developed PNH after therapy (n = 16). Nine of 39 (23%) patients with myelodysplasia had GPI-anchored protein-deficient cells. Abnormal cells were not detected in patients with constitutional or other forms of bone marrow failure or in renal allograft recipients who had received antithymocyte globulin. Aplastic anemia is known to respond to immunosuppressive therapy; in myelodysplasia, the presence of a PNH population was strongly correlated with hematologic improvement after administration of antithymocyte globulin (P = 0.0015). CONCLUSIONS: Flow cytometric analysis is superior to the Ham test and permits concomitant diagnosis of PNH in about 20% of patients with myelodysplasia (a rate similar to that seen in patients with aplastic anemia). The presence of GPI-anchored protein-deficient cells in myelodysplasia predicts responsiveness to immunosuppressive therapy. Early emergence of GPI-anchored protein-deficient hematopoiesis in a patient with marrow failure may point to an underlying immune pathogenesis.
Paroxysmal nocturnal hemoglobinuria (PNH) may present with acute anemia, thrombocytopenia and, if hemoglobin nephropathy or dehydration is present, azotemia. Thus PNH may be confused with the hemolytic uremic syndrome (HUS). Recurrent episodes, though common in PNH, are unusual in HUS. A positive acid hemolysis test can be used to differentiate between the two diseases.
Paroxysmal nocturnal hemoglobinuria (PNH) is recognized as a clonal disorder manifested as increased sensitivity of marrow cells to complement. Case reports have associated this condition with leukemia, myelodysplasia, and myeloproliferative disorders. We identified 47 patients with PNH from 1976 to 1990. In 9 of the 47 patients, PNH was associated with another clonal myelopathy. Five patients had PNH and a myelodysplastic syndrome, and four had PNH and agnogenic myeloid metaplasia. PNH preceded the development of myelodysplastic syndrome but occurred after the development of agnogenic myeloid metaplasia. This is the largest series of PNH and other clonal myelopathies. We suggest that the PNH defect may represent a second manifestation of a single stem cell disorder.
Red blood cells from patients with paroxysmal nocturnal hemoglobinuria (PNH) were found to be liable to vesiculate, as demonstrated by both DMPC liposome- and CaCl2-induced vesiculation and measured in terms of acetylcholinesterase activity and 3H-inositol radioactivity in the supernatant. Membrane proteins released from the cells during vesiculation included several constituents with molecular weights identical to those of some complement regulating factors (e.g. DAF) which play an essential role in complement-mediated hemolysis. Red blood cells from both normal and PNH patients showed decreased deformability after vesiculation. Liability to vesiculate and the consequential loss of certain essential membrane proteins and decreased deformability might be a factor contributing to the mechanism of hemolysis in PNH.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired genetic disorder of the bone marrow that produces intravascular hemolysis, proclivity to venous thrombosis, and hematopoietic failure. Mutation in the PIG-A gene in a stem cell aborts synthesis of glycosyl-phosphoinositol (GPI) anchors and therefore expression of all GPI-anchored proteins on the surface of progeny erythrocytes, leukocytes, and platelets. The hemolytic anemia of PNH is well understood, and erythrocyte susceptibility to complement may be treated with anti-C5a monoclonal antibody. The pathophysiology of PNH cell clonal expansion and its association with immune-mediated marrow failure are not understood, but PNH/aplasia responds to immunosuppressive regimens such as antithymocyte globulin and cyclosporine. The mechanism of thrombosis in PNH is also obscure, but frequently fatal clotting episodes may be prevented by Coumadin (Bristol-Myers Squibb Pharma Co., Wilmington, DE) prophylaxis.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal blood disorder characterized by chronic hemolysis with hemoglobinuria and venous thrombosis. PNH clones arise through somatic mutations in the X-linked PIG-A gene that occur in early hematopoietic stem cells. Here we report 28 previously undescribed mutations; we confirm that somatic mutations are spread throughout the entire coding region of the PIG-A gene and that the majority are frameshift mutations producing a non-functional PIG-A protein (PIG-A(o)). In addition, we found 1 total deletion of the PIG-A gene, and 2 short nucleotide duplications. Although mutations are spread throughout the entire coding region, we observe more missense mutations in exon 2 than in the other exons. The increasing number of identified missense PIG-A mutations should help elucidate structure-function relationships in the PIG-A protein.
In paroxysmal nocturnal hemoglobinuria (PNH), little is known about the molecular events leading to the clinical manifestations except for the hemolysis. To unfold the complex pathophysiology, it is necessary to elucidate the nature of the PNH clone. PNH exhibits an acquired stem cell disorder, a clonal expansion of affected cells, concomitant depression of normal hematopoiesis in bone marrow (BM), and, although infrequently, the development of leukemia. The PNH clone is thus expected to exhibit some neoplastic features. We report here that CD34+ hematopoietic progenitor cells of PNH-BM yielded blood cells of three lineages with PNH phenotype alone when transplanted into sublethally irradiated severe combined immunedeficient mice. The hematopoiesis persisted for more than 10 months and did not always need human cytokines. In contrast, the hematopoiesis by control grafts obtained from healthy volunteers required an intense cytokine treatment. This in vivo model defines the preferential hematopoiesis of pluripotent PNH progenitor cells, indicating the intrinsic growth abnormality of PNH clone.
Erythrocytes from six cases of paroxysmal nocturnal hemoglobinuria (PNH) were analysed by the H*1 hematology analyser using laser inspection for each individual red cell. The computer program categorized the red cells into 9 groups based on the data of red cell volume and intracellular hemoglobin concentration. The only 46.3 +/- 10.9 per cent (Mean +/- SD) of PNH red cells were normochromic normocytic. Hypochromia (hemoglobin concentration less than 28 g/dL) with normal red cell volume (between 60 to 120 fL) were found in 22.8 +/- 19.7 per cent and with large cell volume (greater than 120 fL) = 14.9 +/- 4.5 per cent of total red cells. Large cells with normal hemoglobin concentration were found in 12.9 +/- 13.2 per cent. The red cells had increased heterogeneity in red cell volume measured as red cell distribution width (RDW), Mean +/- SD = 23.6 +/- 2.3 per cent and increased heterogeneity in their hemoglobin concentration distribution with (HDW) (3.4 +/- 0.5 g/dL). The high RDW was resulted from increased number of varying size of macrocytes and the high HDW was caused by the increased number of hypochromic red cells. Heterogeneity in PNH red cell population described in this study has been postulated to relate with the clonal abnormality of the PNH red cells.
Affected erythrocytes in patients with paroxysmal nocturnal hemoglobinuria (PNH) have been detected as complement-sensitive cells by the complement sensitivity assay. Decay-accelerating factor (DAF), a molecular mass of 70 kDa complement-regulatory membrane glycoprotein, has been reported to be deficient on affected PNH blood cells. In the present study, DAF on erythrocytes from 12 patients with PNH were stained by an immunocytochemical method and the ratio of DAF+ erythrocytes was compared with their laboratory data concerning hemolysis, almost all normal human erythrocytes stained positively for DAF. In contrast, various percentages of DAF+ erythrocytes were found in the patients with PNH. The percentages of DAF+ erythrocytes correlated positively with the total amounts of DAF on erythrocytes measured by an enzyme-linked immunosorbent assay (ELISA), negatively with % hemolysis in Ham's test and in sucrose hemolysis assay and with percentages of PNH type III (PNH-III) erythrocytes. In some patients with PNH, subpopulations of erythrocytes weakly-positive for DAF were demonstrated in addition to DAF- erythrocytes. The immunocytochemical method for staining DAF on erythrocytes developed in the present study is useful for the detection of affected PNH erythrocytes and applicable to further studies on membrane defects in PNH.
BACKGROUND: The mechanism by which the paroxysmal nocturnal hemoglobinuria (PNH) clone progressively takes over normal hematopoietic cells remains unknown. The respective in vivo differentiation of normal and PNH erythroid progenitors was investigated through the expression of two fetal erythroid markers (i antigen and fetal hemoglobin [HbF]) whose expression in adult red cells is associated with altered erythropoiesis. STUDY DESIGN AND METHODS: Murine monoclonal antibodies directed against HbF and i and CD59 antigens were used to phenotype red cells of 10 PNH patients. A multiparametric flow cytometry assay of red cells and reticulocytes was designed to assess a possible association of i and HbF with PNH or normal red cells. RESULTS: Most patients exhibited greater expression of i and HbF than did normal controls. In each case, the percentages of i-positive or HbF-positive cells within CD59-deficient and CD59-positive red cells were very close, clearly showing a lack of preferential association of these markers with normal or PNH cells. CONCLUSION: In PNH patients, normal and PNH erythroid progenitors have the same ability to promote HbF and i antigen expression, which suggests that normal and PNH erythroid progenitors (burst-forming units-erythroid, colony-forming units-erythroid, erythroblasts) behave similarly in response to bone marrow stress.
A 26-year-old man with the diagnosis of paroxysmal nocturnal hemoglobinuria presented with papilledema due to increased intracranial pressure without localizing neurological signs. It is concluded that papilledema and benign intracranial hypertension could result from a cerebral vein thrombosis which can complicate the course of paroxysmal nocturnal hemoglobinuria. This has not been a well-recognized feature of the disease.
Paroxysmal nocturnal hemoglobinuria (PNH), a hematopoietic stem cell disorder, is caused by the loss of glycosylphosphatidylinositol (GPI)-anchored proteins on the cell membrane. PNH can be simply diagnosed by flow cytometry using monoclonal antibodies against GPI-anchored proteins or fluorescent-tagged aerolysin, a bacterial toxin that binds GPI anchored proteins. Clostridium septicum alpha toxin is homologous to aerolysin and specifically binds GPI-anchored proteins. Previously, we found that an alpha toxin m45 mutant with two amino acid changes, S189C/S238C, lost cytotoxicity but still possessed binding activity for GPI-anchored proteins. To use this mutant toxin as a diagnostic probe in flow cytometry, we constructed the EGFP-AT(m45) expression vector, comprising a S189C/S238C alpha toxin mutant with EGFP and His tags at the N and C termini, respectively. The recombinant EGFP-AT(m45) was easily purified using single-step affinity chromatography against His tag from Escherichia coli. EGFP-AT(m45) bound to CHO and HeLa cells in a similar manner to monoclonal antibodies against GPI-anchored proteins or aerolysin. In whole blood from a PNH patient, GPI-deficient granulocytes could be differentiated by EGFP-AT(m45) using the same procedure as that employed with commercially available monoclonal antibodies. Therefore, nontoxic EGFP-conjugated C. septicum alpha toxin could be used clinically for PNH diagnosis.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal disorder in which intravascular hemolysis results from the somatic mutation of the totipotent stem cells causing an intrinsic defect in red cell membrane. PNH cells lack glycosylphosphatidylinositol (GPI) anchored membrane proteins. Of these proteins absence of CD 59 (MIRL--membrane inhibitor of reactive lysis, protectin) and CD 55 (DAF--decay accelerating factor) makes the PNH cells abnormally sensitive to the lytic action of complement. The defect appears to be in the somatic mutation of the X-linked PIG-A (phosphatidylinositolglycan A class) gene which participate in an early step of GPI-anchor synthesis. PNH is characterized by recurrent life threatening venous thromboses and an intimate association with aplastic anemia (AA). It seems that PNH always coexists with bone marrow failure (BMF) (37). The possible explanation may be that some GPI-anchored proteins may be a critical target recognized by immune effector cells. PNH clones not possessing these critical GPI-anchored proteins will survive because they are selectively resistant to the autoimmune assault that eliminates most normal clones. The flow cytometry of erythrocytes using anti-CD 59 and anti-CD 59 and anti-CD 55 of granulocytes has been now introduced as a very sensitive and quantitative method of PNH diagnosis able to detect PNH cells even in normal individuals (1,54). Thus it seems now clear that we must make distinction between the detection of very occasional PNH cells in patients with BMF and PNH as a clinicohematological entity. Unfortunately, we do not know the minimal content of PNH cells required to produce clinical signs of PNH (38).
A long-term study of 17 patients with paroxysmal nocturnal hemoglobinuria revealed an unexpectedly high incidence of functional and anatomic renal abormalities. All patients demonstrated varying degrees of hematuria and proteinuria distinct from hemoglobinuria. All patients also had granular casts in multiple urinalyses. Evaluation of renal function revealed hyposthenuria, abnormal tubular function and declining creatinine clearance. Radiologically, one or more of these demonstrated enlarged kidneys, renal cortical infarcts and thinning, papillary necrosis, acute renal atrophy, retroperitoneal hematoma and ureteral infarction, which were confirmed by autopsy studies. Hypertension developed in 7 patients. Urinary tract infection was uncommon and no patient had a clinical history compatible with chronic or acute pyelonephritis. Contrary to usual opinion our compatible clearly showed evidence of frequent and widespread renal pathology in paroxysmal nocturnal hemoglobinuria most likely due to repeated microvascular thromboses similar to the venous trombosis involving other organs in this disorder. Since most of these patients present initially to urologists knowledge of this entity is mandatory.
The chromosomes of 14 patients (9 males, 5 females) suffering from paroxysmal nocturnal hemoglobinuria in Merida, Mexico between April 1989 and July 1992 were analyzed. Four of the patients were children (range, 3-15 years old) and 9 were adults (range, 19-62 years old). None of the patients had any evidence of leukemic transformation and 9 of them had antecedent insecticide exposure. In 50%, the clinical presentation was anemia plus hemorrhagic syndrome. Only 1 case had thrombosis. The lapse between the beginning of the disease and the karyotypic analysis was 14.5 months on average (range, 1-172 months). In all cases we found a normal chromosomic complement. In addition, 5 patients had an acentric fragment in only 1 metaphase and one of these had a mar and Cq chromatid break in another metaphase, but neither could be considered as specific chromosomal abnormality for paroxysmal nocturnal hemoglobinuria.
A patient with pulmonary embolism caused by paroxysmal nocturnal hemoglobinuria (PNH) is described. PNH sometimes causes venous thrombosis in the extremities, hepatic vein, or cerebral vein, but pulmonary embolism rarely occurs.
Circulating immune complexes were investigated in sera of 13 patients with paroxysmal nocturnal hemoglobinuria. A significant inhibition was observed in the complement-dependent rosette formation (EAC) in 6 cases; 2 patients presented an increased anticomplementary activity; antilymphocyte antibodies were demonstrated in 2 patients. The levels of C3d and immunoconglutinins were also increased; there were no differences in the total hemolytic complement between patients and normal controls. There was a significant correlation between C3d and immunoconglutinins with the inhibition of the EAC rosette formation test. These results provide evidence for the presence of circulating immune complexes in paroxysmal nocturnal hemoglobinuria.