ALBERT

Description: We describe a white French family in which 12 subjects presented with hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (HPP). Eight of these subjects were shown to be heterozygous for a spectrin (Sp) alpha I/74 variant, as demonstrated by analysis of partial tryptic digestion fragments of spectrin. This abnormal peptide pattern was associated with a decreased ability of Sp dimers to self-associate. In this kindred, in which four generations were available for study, the clinical expression varied from mild HE to HPP with an intermediate status of hemolytic HE. The severity of the disease appeared to be correlated both with the estimated amount of variant Sp (42% to 65%) and the excess of Sp dimers found in the membrane (30% to 51%, with a normal value of 3.7% +/- 1.6%). Reassociation studies using isolated Sp alpha and beta chains from an affected patient and an unaffected control subject showed that the Sp alpha I/74 Kd abnormal tryptic peptide resulted from a defect in the Sp alpha chain. Partial amino acid sequencing showed that the Sp alpha I/74 Kd peptide resulted from cleavage at lysine residue 42 of the Sp alpha I/80 Kd domain. Knowledge of the exon/intron organization of the human alpha Sp gene allowed us to amplify by the polymerase chain reaction the second exon of the alpha Sp gene in total cellular DNA of the HPP proposita. The amplified fragment was subcloned and sequenced. We found a G to A base substitution in the 22nd codon (CAT for CGT), which changes the normal arginine to a histidine. Hybridization of amplified DNAs with allele- specific oligonucleotides corresponding to the normal and mutant sequences confirmed the presence of the mutation in six other HE and HPP members of the family. The identification of this mutation at the DNA level confirmed the transmission of the same molecular defect in Sp through four generations but with different patterns of clinical expression.

Description: In the human erythrocyte membrane phosphatidylcholine and sphingomyelin reside mainly in the outer leaflet, whereas the aminophospholipids, phosphatidylethanolamine and phosphatidylserine, are mainly found in the inner leaflet. Maintenance of phospholipid asymmetry has been assumed to involve interactions between the aminophospholipids and the membrane skeleton, in particular spectrin. To investigate whether spectrin contributes to maintaining the phospholipid transbilayer distribution and kinetics of redistribution, we studied erythrocytes from hereditary spherocytosis patients whose spectrin levels ranged from 34% to 82% of normal. The phospholipid composition and the accessibility of membrane phospholipids to hydrolysis by phospholipases were in the normal range. Spin-labeled phosphatidylserine and phosphatidylethanolamine analogues that had been introduced into the outer leaflet were rapidly transported at 37 degrees C to the inner leaflet, whereas the redistribution of spin-labeled phosphatidylcholine was slower. The kinetics of transbilayer movement of these spin-labeled phospholipid in all samples was in the normal range and was not affected by the level of spectrin. Although these erythrocyte membranes contained as little as 34% of the normal level of spectrin and were characterized by several physical abnormalities, the composition, distribution, and transbilayer kinetics of the phospholipids were found to be normal. We therefore conclude that spectrin plays, at best, only a minor role in maintaining the distribution of erythrocyte membrane phospholipid.

Description: We studied the effect of sickling on the transmembrane reorientation and distribution of phospholipids in the red blood cells of patients homozygous for sickle cell anemia (SS). To this purpose, we followed the redistribution kinetics of trace amounts of spin-labeled analogues of natural phospholipids first introduced in the membrane outer leaflet of normal or sickle erythrocytes exposed to air or nitrogen. Deoxygenation had no effect on the lipid redistribution kinetics in normal (AA) cell membranes. At atmospheric pO2, unfractionated SS cells were not different from normal cells. However, on deoxygenation inducing sickling, phosphatidylcholine passive diffusion was accelerated and the rate of the adenosine triphosphate-dependent transport of aminophospholipids was reduced, especially for phosphatidylserine. The stationary distribution of the aminophospholipids between the two leaflets was slightly less asymmetric, a phenomenon more pronounced with phosphatidylethanolamine. These changes were rapidly reversible on reoxygenation. When SS cells were separated by density, both dense and light cells exhibited the properties cited above. However, dense cells exposed to air possessed a lower aminophospholipid transport rate. These data favor the relationship between aminophospholipid translocase activity and phospholipid transmembrane asymmetry. Sickle cell disease is the first case of aminophospholipid translocase pathology.

Description: Six individuals with hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (HPP) from three unrelated families were evaluated. Defects in the ability of spectrin (Sp) to undergo self-association were present, and associated with increased recovery of the Sp alpha I 74-kD fragment after limited tryptic digestion (Sp alpha I/74 variant). Because mutations associated with the Sp alpha I/74 variant described to date have been localized to the 5′ coding region of the alpha-Sp gene (exon 2) or at the 3′ coding end of the beta-Sp gene (exon 30), the polymerase chain reaction (PCR)-based single-strand conformation polymorphism (SSCP) method was used to detect mutations in these two regions. In one family with HE, an abnormal pattern of migration of PCR- amplified fragments containing exon 2 was observed, and led to the detection of a new mutation (Ile24Ser) in helix 3 of repeating segment alpha 1. In the two other families, an abnormal pattern of migration of PCR-amplified fragments containing exon 30 was observed in affected individuals, and sequencing led to the identification of two new mutations (Ala2023Val and Trp2024Arg) in helix 1 of repeating segment beta 17. The elliptogenic potential of these mutations emphasizes the importance of the conformational integrity of each of the three helices involved in the formation of the Sp heterodimer contact site, and will help identify critical amino acids involved in this interaction.

Description: The CXCR4 chemokine receptor is a Gi protein–coupled receptor that triggers multiple intracellular signals in response to stromal cell-derived factor 1 (SDF-1), including calcium mobilization and p44/42 extracellular signal-regulated kinases (ERK1/2). Transduced signals lead to cell chemotaxis and are terminated through receptor internalization depending on phosphorylation of the C terminus part of CXCR4. Receptor endocytosis is also required for some receptors to stimulate ERK1/2 and to migrate through a chemokine gradient. In this study, we explored the role played by the 3 intracellular loops (ICL1-3) and the C terminus domain of CXCR4 in SDF-1–mediated signaling by using human embryonic kidney (HEK)–293 cells stably expressing wild-type or mutated forms of CXCR4. ICL3 of CXCR4 is specifically involved in Gi-dependent signals such as calcium mobilization and ERK activation, but does not trigger CXCR4 internalization after SDF-1 binding, indicating that ERK phosphorylation is independent of CXCR4 endocytosis. Surprisingly, ICL2, with or without the aspartic acid, arginine, and tyrosine (DRY) motif, is dispensable for Gi signaling. However, ICL2 and ICL3, as well as the C terminus part of CXCR4, are needed to transduce SDF-1–mediated chemotaxis, suggesting that this event involves multiple activation pathways and/or cooperation of several cytoplasmic domains of CXCR4.

Description: Limited tryptic digestion of spectrin (Sp) from seven related individuals manifesting hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (HPP) phenotypes revealed the presence of a novel peptide with a molecular weight of 78 Kd and a concomitant decrease in the alpha I domain (80-Kd peptide), which is the domain involved in the dimer self-association process. Sp from the normal members of this white family exhibited a normal peptide pattern, as compared with controls. The abnormal peptide pattern was associated with a decreased ability of Sp dimer to self-associate. In this kindred in which three generations were available for study, the clinical manifestations were quite variable and ranged from the asymptomatic HE carrier state to hemolytic HE or to severe anemia requiring splenectomy. The severity of the disease appeared to be correlated both with the amount of mutant spectrin (31% to 69%) and with the excess of the Sp dimer found in the membrane (26% to 60%, compared with a normal value of 5.6% +/- 2.2%). Partial amino acid sequencing showed that the alpha I/78-Kd peptide resulted from cleavage at lysine residue 10 of the alpha I/80-Kd domain. Knowledge of the exon/intron structure of cloned genomic DNA encoding the alpha I domain allowed us to amplify in vitro a DNA fragment containing the third exon of the alpha-spectrin gene. The amplified fragment was subcloned and sequenced. A G to T transversion was found in the 39th codon (AGT for AGG), which changed the normal arginine to a serine. Hybridization of amplified DNAs with allele- specific oligonucleotides corresponding to the normal and mutant sequences confirmed the presence of the mutation in three other HE members of the family (the propositus mother, brother, and sister).

Description: Six individuals with hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (HPP) from three unrelated families were evaluated. Defects in the ability of spectrin (Sp) to undergo self-association were present, and associated with increased recovery of the Sp alpha I 74-kD fragment after limited tryptic digestion (Sp alpha I/74 variant). Because mutations associated with the Sp alpha I/74 variant described to date have been localized to the 5′ coding region of the alpha-Sp gene (exon 2) or at the 3′ coding end of the beta-Sp gene (exon 30), the polymerase chain reaction (PCR)-based single-strand conformation polymorphism (SSCP) method was used to detect mutations in these two regions. In one family with HE, an abnormal pattern of migration of PCR- amplified fragments containing exon 2 was observed, and led to the detection of a new mutation (Ile24Ser) in helix 3 of repeating segment alpha 1. In the two other families, an abnormal pattern of migration of PCR-amplified fragments containing exon 30 was observed in affected individuals, and sequencing led to the identification of two new mutations (Ala2023Val and Trp2024Arg) in helix 1 of repeating segment beta 17. The elliptogenic potential of these mutations emphasizes the importance of the conformational integrity of each of the three helices involved in the formation of the Sp heterodimer contact site, and will help identify critical amino acids involved in this interaction.

Description: Abstract 5166 Rationale: In Ph1 myeloproliferative neoplasms (MPN), the blood stream carries a variety of microparticles and exosomes released by cells from myeloid lineages and endothelium; we had already demonstrated an excess of platelet microparticles (PMP) in ET and PV patients (ASH Annual Meeting 2009, Abstr. 1906). A further step has been to characterize five categories of MP depending on their origin. Then we used this method to compare the sub-populations found in Polycythemia vera (PV) and secondary erythrocytosis (SE). Patients and methods: We analyzed plasma samples from 20 PV diagnosed in accordance to WHO classification and 20 SE patients. SE was defined by elevated hematocrit, normal or increased serum EPO, Jak2V617F negative and a presumable cause, mainly respiratory. The 2 groups were comparable for age and sex-ratio. Mean Hb level was 18.0g/dl in the PV group and 18.1g/dl in the SE group. The concentration of MP was measured by flow cytometry using a FC500 cytometer (BeckmanCoulter™). All the MP subtypes express Annexin V thus defining the total MP. Additional co-expression of either CD41, CD144, CD14, CD11b or GPA identify MP populations originating respectively from platelets (PMP), endothelial cells (EMP), monocytes (MoMP), granulocytes (GrMP) and red cells (EryMP). Pre-analytical and testing procedures complied with the recommendations of the ISTH Standardization Sub-committee. Results: MP from endothelial cells (EMP) and leukocytes (GrMP and MoMP) are minor populations whose proportions are similar in both groups of patients (7%, 4% and 2% respectively). Conversely, EryMP and PMP are significantly different (p

Description: Intensive sequential chemotherapy with mitoxantrone, 12 mg/m2/d on days 1 through 3, etoposide, 200 mg/m2/d as a continuous infusion on days 8 through 10, and cytarabine, 500 mg/m2/d as a continuous infusion on days 1 through 3 and 8 through 10 was administered to 72 patients aged less than 60 years with previously treated acute myelogenous leukemia (AML). Forty patients had refractory AML (nonresponse to prior therapy, early first relapse, or multiple relapse) and 32 had late first relapse. Sixty-one percent of patients, with a 95% confidence interval (CI) ranging from 49% to 72%, achieved complete remission (CR), including 45% (CI: 30% to 62%) of refractory patients and 81% (CI: 64% to 93%) of late first relapse patients. Twenty-nine percent of patients (CI: 19% to 41%) did not respond to therapy and 10% (CI: 4% to 19%) died from therapy-related toxicity. Median duration of aplasia was 30 days. Nonhematologic WHO grade 3 or more toxicity included sepsis (57% of patients), vomiting (10%), mucositis (35%), diarrhea (7%), skin rash (6%), and hyperbilirubinemia (11%). Postinduction therapy was attempted in 36 of 44 CR patients: 16 of them received a second course of the same regimen, 7 received maintenance chemotherapy, 4 underwent autologous bone marrow transplantation (BMT), and 9 allogeneic BMT. At a median follow-up of 20 months, 23 of the 44 complete remitters have relapsed, 1 to 14 months after achievement of CR, including 19 of 31 patients not undergoing BMT. Median survival is 7 months with 16% (CI: 4% to 28%) projected survival at 47 months. Median disease-free survival is 6 months with 21% (CI: 3% to 39%) of CR patients projected to remain disease-free at 46 months. Twenty-six percent (CI: 13% to 43%) of the evaluable patients who did not receive transplantation had inversion of CR duration. Among patients younger than 50 years, there was no significant difference in disease-free survival between patients receiving postinduction chemotherapy and those receiving BMT. We conclude that this chemotherapy regimen is highly efficient and could be used as first-line therapy in young patients with AML.

Description: In vitro RBC production from stem cells could represent an alternative to classic transfusion products. Until now the clinical feasibility of this concept has not been demonstrated. We addressed the question of the capacity of cultured RBCs (cRBCs) to survive in humans. By using a culture protocol permitting erythroid differentiation from peripheral CD34+ HSC, we generated a homogeneous population of cRBC functional in terms of their deformability, enzyme content, capacity of their hemoglobin to fix/release oxygen, and expression of blood group antigens. We then demonstrated in the nonobese diabetes/severe combined immunodeficiency mouse that cRBC encountered in vivo the conditions necessary for their complete maturation. These data provided the rationale for injecting into one human a homogeneous sample of 1010 cRBCs generated under good manufacturing practice conditions and labeled with 51Cr. The level of these cells in the circulation 26 days after injection was between 41% and 63%, which compares favorably with the reported half-life of 28 ± 2 days for native RBCs. Their survival in vivo testifies globally to their quality and functionality. These data establish the proof of principle for transfusion of in vitro–generated RBCs and path the way toward new developments in transfusion medicine. This study is registered at http://www.clinicaltrials.gov as NCT0929266.