Multilineage glycosylphosphatidylinositol anchor-deficient haematopoiesis in untreated aplastic anaemia.

Aplastic anaemia and paroxysmal nocturnal haemoglobinuria (PNH) are closely related disorders. In PNH, haematopoietic stem cells that harbour PIGA mutations give rise to blood elements that are unable to synthesize glycosylphosphatidylinositol (GPI) anchors. Because the GPI anchor is the receptor for the channel-forming protein aerolysin, PNH cells do not bind the toxin and are unaffected by concentrations that lyse normal cells.

Durable treatment-free remission after high-dose cyclophosphamide therapy for previously untreated severe aplastic anemia.

Background: Severe aplastic anemia is a life-threatening bone marrow failure disorder. High-dose cyclophosphamide therapy followed by allogeneic bone marrow transplantation cures the disease. However, it requires a suitable donor and carries the risk for graft-versus-host disease.

Elimination of alloantibodies by immunoablative high-dose cyclophosphamide.

Background: Alloimmunization is a major problem for patients being considered for solid organ transplantation and in patients who require blood transfusion support. We previously demonstrated that high-dose cyclophosphamide (200 mg/kg) without hematopoietic stem cell transplantation leads to durable complete remissions in aplastic anemia and other autoimmune disorders. We now examine the ability of high-dose cyclophosphamide to eliminate alloreactivity.

Glycophosphatidylinositol-anchored protein deficiency as a marker of mutator phenotypes in cancer.

Phosphatidylinositol glycan-A (PIGA) is a gene that encodes an element required for the first step in glycosylphosphatidylinositol (GPI) anchor assembly. Because PIGA is X-located, a single mutation is sufficient to abolish cell surface GPI-anchored protein expression. In this study, we investigated whether mutation of the PIGA gene could be exploited to identify mutator (Mut) phenotypes in cancer.

Channels formed by subnanomolar concentrations of the toxin aerolysin trigger apoptosis of T lymphomas.

Aerolysin is a channel-forming toxin that binds to glycosylphosphatidylinositol (GPI)-anchored proteins, such as Thy-1, on target cells. Here, we show that subnanomolar concentrations of aerolysin trigger apoptosis of T lymphomas. Using inactive aerolysin variants, we determined that apoptosis was not directly triggered by binding to GPI-anchored receptors, nor was it caused by receptor clustering induced by toxin oligomerization.

Improved detection and characterization of paroxysmal nocturnal hemoglobinuria using fluorescent aerolysin.

Paroxysmal nocturnal hemoglobinuria (PNH) is caused by a somatic mutation in the gene PIGA, which encodes an enzyme essential for the synthesis of glycosylphosphatidylinositol (GPI) anchors. The PIGA mutation results in absence or marked deficiency of more than a dozen proteins on PNH blood cells. Current flow cytometric assays for PNH rely on the use of labeled antibodies to detect deficiencies of specific GPI anchor proteins, such as CD59.

Hematopoietic stem cell transplantation for systemic lupus erythematosus.

Many institutions worldwide are conducting clinical studies using immunoablative therapy followed by hematopoietic stem cell transplantation for the treatment of SLE. Interpretation of these studies will be complicated by the differences in patient selection, conditioning regimens, and the method of stem cell collection. A major concern with this approach is that autoreactive effector cells will be re-infused with the autologous graft.

Philadelphia chromosome-negative engraftment after autologous transplantation with granulocyte-macrophage colony-stimulating factor for chronic myeloid leukemia.

Autologous bone marrow transplantation (BMT) has not been curative in chronic myeloid leukemia (CML), because of the inability to purge CML from the autograft and the absence of the allogeneic T cell-mediated antileukemic activity. However, recent advances demonstrate that normal progenitors can be selected from CML marrows by a variety of techniques, including isolation by their small size. Furthermore, we found that myeloid growth factors have a potent antileukemic effect against CML progenitors in vitro by inducing their terminal differentiation.

Immunoablative high-dose cyclophosphamide without stem cell rescue in paraneoplastic pemphigus: report of a case and review of this new therapy for severe autoimmune disease.

Paraneoplastic pemphigus (PNP) is a refractory and life-threatening autoimmune mucocutaneous disease. We have recently reported the effectiveness and safety of ablative intravenous cyclophosphamide (200 mg/kg daily over 4 days) without stem cell rescue in patients with refractory autoimmune diseases including systemic lupus erythematosus, autoimmune cytopenias, chronic inflammatory demyelinating polyneuropathy, and aplastic anemia. We report chronic lymphocytic leukemia-associated PNP in a patient who presented with extensive and debilitating painful oral ulcerations and received ablative therapy.

Bone marrow transplantation for autoimmune diseases.

Autoimmune diseases afflict approximately 2% of the US population and span virtually every medical specialty. Most patients with autoimmune diseases have a normal life expectancy and are managed conservatively; however, a subset of patients have a progressive disease course associated with significant morbidity and mortality. High-dose cytotoxic therapy followed by autologous stem cell transplantation has been proposed as a novel treatment for severe autoimmune diseases.

Resistance of paroxysmal nocturnal hemoglobinuria cells to the glycosylphosphatidylinositol-binding toxin aerolysin.

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disorder caused by a somatic mutation of the PIGA gene. The product of this gene is required for the biosynthesis of glycosylphosphatidylinositol (GPI) anchors; therefore, the phenotypic hallmark of PNH cells is an absence or marked deficiency of all GPI-anchored proteins. Aerolysin is a toxin secreted by the bacterial pathogen Aeromonas hydrophila and is capable of killing target cells by forming channels in their membranes after binding to GPI-anchored receptors.

Immunoablative high-dose cyclophosphamide without stem-cell rescue for refractory, severe autoimmune disease.

Background: Immunoablative high-dose cyclophosphamide without stem-cell rescue induces durable, complete remission in most patients with aplastic anemia.

Objective: To determine the efficacy of high-dose cyclophosphamide in various refractory, severe autoimmune diseases.

Design: Prospective phase II study.

Inhibited apoptosis and drug resistance in acute myeloid leukaemia.

Despite extensive investigation into mechanisms of drug resistance in acute myeloid leukaemia (AML), the aetiology of therapeutic resistance is unclear. We found that five leukaemia cell lines (K562, HL-60, CEM. CEM induced to overexpress bcl-2, and REH) displayed parallel sensitivity to four antileukaemia drugs with different mechanisms of action, with K562 generally being the least sensitive and REH being the most sensitive.

Biology and management of acquired severe aplastic anemia.

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure disorder characterized by pancytopenia and a hypocellular marrow. Drugs, chemical exposure, radiation, and viruses are implicated as etiologic agents, although the majority of community-acquired SAA is idiopathic. Regardless of the inciting event, most cases of SAA result from immune-mediated destruction of bone marrow progenitor cells, which spares pluripotent hematopoietic stem cells.

Resistance to apoptosis caused by PIG-A gene mutations in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder resulting from mutations in an X-linked gene, PIG-A, that encodes an enzyme required for the first step in the biosynthesis of glycosylphosphatidylinositol (GPI) anchors. PIG-A mutations result in absent or decreased cell surface expression of all GPI-anchored proteins. Although many of the clinical manifestations (e.

Complete remission in severe aplastic anemia after high-dose cyclophosphamide without bone marrow transplantation.

Severe aplastic anemia (SAA) can be successfully treated with allogeneic bone marrow transplantation (BMT) or immunosuppressive therapy. However, the majority of patients with SAA are not eligible for BMT because they lack an HLA-identical sibling. Conventional immunosuppressive therapy also has major limitations; many of its remissions are incomplete and relapse or secondary clonal disease is common.

Diffuse neuroendocrine system: structural and functional effects of radiation injury to amine precursor uptake and decarboxylation (APUD) cells.

The paper presents a review of the results obtained by the authors on the study of external (gamma) and internal (I-131) radiation effects on the functional morphology and linkage of the diffuse neuroendocrine system (DNES) and amine precursor uptake and decarboxylation (APUD) cells of the stomach and duodenum. The investigations performed enabled us to determine that the morphological changes noted in APUD cells had a dose and time dependency. The present study supports the point of view that the radiation initiates serotonin release from APUD cells, which appears to initiate the mechanism of early postirradiation dysfunctions of the gastrointestinal tract and the subsequent adaptive response of DNES.

Are growth factors leukemogenic?

The National Cancer Institute (NCI) recently alerted clinicians to the possibility that patients, entered on a NCI-sponsored cooperative group trial of doxorubicin and cyclophosphamide adjuvant therapy for breast cancer, may be at high risk of developing secondary acute myeloid leukemia (AML). Secondary AML following standard doses of doxorubicin and cyclophosphamide is uncommon, suggesting that the high risk on this trial may result from its higher-than-standard doses of chemotherapy. However, the cases of secondary AML were characteristic of the type that follows treatment with topoisomerase II-active agents, especially etoposide, and this type of secondary AML is rare after treatment with either cyclophosphamide or doxorubicin at any dose.

Genetic defects underlying paroxysmal nocturnal hemoglobinuria that arises out of aplastic anemia.

Treatment of severe aplastic anemia with antithymocyte globulin (ATG) and cyclosporin leads to clinical remission in a large proportion of patients. As many as 10% to 57% of these patients, however, develop paroxysmal nocturnal hemoglobinuria (PNH). We and others have observed that this secondary PNH appears to be more indolent than classical PNH, which results from an acquired mutation in the PIG-A gene.

Low-dose caudal morphine for postoperative analgesia in infants and children: a report of 500 cases.

Study Objective: To determine the effectiveness of morphine 0.03 mg/kg or 0.04 mg/kg administered caudally to children for postoperative pain relief.

Peripheral blood harvest of unaffected CD34+ CD38- hematopoietic precursors in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) arises from somatic mutation of a bone marrow progenitor that disrupts glycosylinositol phospholipid (GPI) anchoring of cell surface proteins. We recently characterized the expression of GPI-anchored decay acclerating factor (DAF) and CD59 during hematopoietic development in PNH marrow. We found that, although a subset of early hematopoietic precursors identified by the CD34+CD38- phenotype exhibits normal DAF and CD59 expression, DAF and CD59 are absent on the majority of CD34+CD38- cells.

Purified GPI-anchored CD4DAF as a receptor for HIV-mediated gene transfer.

CD4 is the major cellular receptor for the human immunodeficiency virus (HIV). A hybrid gene encoding the extracellular domains of CD4, linked to the sequence encoding the membrane attachment region of the glycosylphosphatidylinositol (GPI)-anchored protein decay accelerating factor (DAF) was stably transfected into HeLa cells. The resultant cell line (T4HD) expressed GPI-anchored CD4DAF at high levels and was susceptible to gene transfer with a recombinant HIV vector.

Acquired sideroblastic anaemia following progesterone therapy.

We report a case of acquired sideroblastic anaemia precipitated by progesterone. On two separate occasions, over 15 years apart, the patient developed sideroblastic anaemia with iron overload shortly after the administration of progesterone. No other cause for sideroblastic anaemia was found, and treatment with folic acid, pyridoxine or androgens corrected the anaemia.