Irene Roberts

Microchimerism in female bone marrow and bone decades after fetal mesenchymal stem-cell trafficking in pregnancy

Fetal cells enter maternal blood during pregnancy and persist in women with autoimmune disease. The frequency of subsequent fetomaternal microchimerism in healthy women and its cell type is unknown. To test the hypothesis that fetal mesenchymal stem cells persist in maternal organs, we studied female bone marrow and ribs. Male cells were identified by XY fluorescence in-situ hybridisation in marrow-derived mesenchymal stem cells and in rib sections from all women with male pregnancies, but not in controls (9/9 vs 0/5, p=0.0005). We conclude that fetal stem cells transferred into maternal blood engraft in marrow, where they remain throughout life. This finding has implications for normal pregnancy, for obstetric complications that increase fetomaternal trafficking, and for graft survival after transplantation.

Bone involvement in sickle cell disease.

Bone involvement is the commonest clinical manifestation of sickle cell disease both in the acute setting such as painful vaso‐occlusive crises, and as a source of chronic, progressive disability such as avascular necrosis. Management of these problems is often difficult because of the diagnostic imprecision of most laboratory and imaging investigations and because of the lack of evidence for most surgical procedures in sickle cell disease. This review first discusses the acute problems related to bone involvement in sickle cell disease, with particular reference to differentiating infection from infarction, and then describes the long‐term effects of sickle cell disease on bone mineral density, growth, and chronic bone and joint damage.

Human CD1d-glycolipid tetramers generated by in vitro oxidative refolding chromatography.

CD1 molecules are specialized in presenting lipids to T lymphocytes, but identification and isolation of CD1-restricted lipidspecific T cells has been hampered by the lack of reliable and sensitive techniques. We here report the construction of CD1d–glycolipid tetramers from fully denatured human CD1d molecules by using the technique of oxidative refolding chromatography. We demonstrate that chaperone- and foldase-assisted refolding of denatured CD1d molecules and β2-microglobulin in the presence of synthetic lipids is a rapid method for the generation of functional and specific CD1d tetramers, which unlike previously published protocols ensures isolation of CD1d tetramers loaded with a single lipid species. The use of human CD1d–α-galactosylceramide tetramers for ex vivo staining of peripheral blood lymphocytes and intrahepatic T cells from patients with viral liver cirrhosis allowed for the first time simultaneous analysis of frequency and specificity of natural killer T cells in human clinical samples. Application of this protocol to other members of the CD1 family will provide powerful tools to investigate lipid-specific T cell immune responses in health and in disease.

Inhibition of Erythroid Progenitor Cells by Anti-Kell Antibodies in Fetal Alloimmune Anemia

BACKGROUND In alloimmune anemia of the newborn, the level of hemolysis caused by the presence of antibodies to antigens of the Kell blood-group system is less than that caused by antibodies to the D antigen of the Rh blood-group system, and the numbers of reticulocytes and normoblasts in the babys circulation are inappropriately low for the degree of anemia. These findings suggest that sensitization to Kell antigens results in suppression of fetal erythropoiesis as well as hemolysis. METHODS We compared the growth in vitro of Kell-positive and Kell-negative hematopoietic progenitor cells from cord blood in the presence of human monoclonal anti-Kell antibodies and anti-D antibodies and serum from women with anti-Kell antibodies. RESULTS The growth of Kell-positive erythroid progenitor cells (erythroid burst-forming units and colony-forming units) from cord blood was markedly inhibited by monoclonal IgG and IgM anti-Kell antibodies in a dose-dependent fashion (range of concentrations, 0.2 to 20 percent), but monoclonal anti-D antibodies had no effect. The growth of these types of cells from Kell-negative cord blood was not affected by either type of antibody. Neither monoclonal anti-Kell antibodies nor monoclonal anti-D antibodies inhibited the growth of granulocyte or megakaryocyte progenitor cells from cord blood. Serum from 22 women with anti-Kell antibodies inhibited the growth of Kell-positive erythroid burst-forming units and colony-forming units but not of Kell-negative erythroid burst-forming units and colony-forming units (P<0.001 for the difference between groups). The maternal anti-Kell antibodies had no inhibitory effects on granulocyte-macrophage or mega-karyocyte progenitor cells from cord blood. CONCLUSIONS Anti-Kell antibodies specifically inhibit the growth of Kell-positive erythroid burst-forming units and colony-forming units, a finding that supports the hypothesis that these antibodies cause fetal anemia by suppressing erythropoiesis at the progenitor-cell level.

Clinical, immunological, and pathological consequences of Fas-deficient conditions

BACKGROUND The surface molecule named Fas/CD95, which is expressed on activated lymphocytes, can trigger cell death following interaction with its ligand (Fas L). This Fas-Fas-L interaction is thought to be a major regulatory mechanism for controlling the life span of peripheral lymphocytes, and therefore autoimmunity. METHODS We assessed clinical, immunological and pathological features in three children who inherited mutations of the Fas-encoding gene. One infant had a genomic homozygous deletion, while two siblings had a heterozygous mutation in the fas gene. FINDINGS The patient with a complete lack of Fas protein expression had prenatal onset of massive lymphoproliferation, which involved the spleen, the liver, and the intrathoracic and abdominal lymph nodes. Lymphoproliferation mainly involved T cells negative for the CD4 and CD8 receptors. These cells, which had a high mitotic index, were essentially found in the T cell zones of lymphoid organs. Active cell division was indicated by a rapid rise in the lymphocyte count following a chemotherapy-induced reduction in the lymphocyte burden. Despite the total Fas protein deficiency, limited autoimmunity was found in this child at age 1 year. A lymphoproliferative syndrome with similar characteristics--but less intense than in the patient with complete Fas deficiency--also occurred from a young age in the siblings with a fas gene mutation on one allele only. One sibling developed neutropoenia, autoimmune haemolytic anaemia, and severe recurrent thrombocytopoenia. INTERPRETATION Fas-deficiency causes a non-malignant syndrome characterised by the accumulation of dividing lymphocytes. Severity of disease is probably related to the degree of functional Fas deficiency. Heterozygous fas gene mutations, like homozygous deletions, can also be expressed in various cells and tissues and may predispose towards autoimmune disorders. Fas deficiency should be considered in children with enlarged peripheral lymphoid organs and hyperimmunoglobulinaemia, and sometimes the occurrence of autoimmune manifestations towards blood cells.

Hypomorphic promoter mutation in PIGM causes inherited glycosylphosphatidylinositol deficiency.

Attachment to the plasma membrane by linkage to a glycosylphosphatidylinositol (GPI) anchor is a mode of protein expression highly conserved from protozoa to mammals. As a clinical entity, deficiency of GPI has been recognized as paroxysmal nocturnal hemoglobinuria, an acquired clonal disorder associated with somatic mutations of the X-linked PIGA gene in hematopoietic cells. We have identified a novel disease characterized by a propensity to venous thrombosis and seizures in which deficiency of GPI is inherited in an autosomal recessive manner. In two unrelated kindreds, a point mutation (c → g) at position −270 from the start codon of PIGM, a mannosyltransferase-encoding gene, disrupts binding of the transcription factor Sp1 to its cognate promoter motif. This mutation substantially reduces transcription of PIGM and blocks mannosylation of GPI, leading to partial but severe deficiency of GPI. These findings indicate that biosynthesis of GPI is essential to maintain homeostasis of blood coagulation and neurological function.

Management of Evans syndrome

Evans syndrome is an uncommon condition defined by the combination (either simultaneously or sequentially) of immune thrombocytopenia (ITP) and autoimmune haemolytic anaemia (AIHA) with a positive direct antiglobulin test (DAT) in the absence of known underlying aetiology. This condition generally runs a chronic course and is characterised by frequent exacerbations and remissions. First‐line therapy is usually corticosteroids and/or intravenous immunoglobulin, to which most patients respond; however, relapse is frequent. Options for second‐line therapy include immunosuppressive drugs, especially ciclosporin or mycophenolate mofetil; vincristine; danazol or a combination of these agents. More recently a small number of patients have been treated with rituximab, which induces remission in the majority although such responses are often sustained for <12 months and the long‐term effects in children are unclear. Splenectomy may also be considered although long‐term remissions are less frequent than in uncomplicated ITP. For very severe and refractory cases stem cell transplantation (SCT) offers the only chance of long‐term cure. The limited data available suggest that allogeneic SCT may be superior to autologous SCT but both carry risks of severe morbidity and of transplant‐related mortality. Cure following reduced‐intensity conditioning has now been reported and should be considered for younger patients in the context of controlled clinical trials.

Human Fetal Mesenchymal Stem Cells as Vehicles for Gene Delivery

First‐trimester fetal blood contains a readily expandable population of stem cells, human fetal mesenchymal stem cells (hfMSCs), which might be exploited for autologous intrauterine gene therapy. We investigated the self‐renewal and differentiation of hfMSCs after transduction with onco‐retroviral and lentiviral vectors. After transduction with either a MoMuLV retrovirus or an HIV‐1‐based lentiviral vector carrying the β‐galactosidase and green fluorescent reporter gene, respectively, transgene expression, self‐renewal, and differentiation capabilities were assessed 2 and 14 weeks later. Transduction with the lentiviral vector resulted in higher efficiencies than with the MoMuLV‐based vector (mean, 97.7 ± 1.4% versus 80.2 ± 5.4%; p = .02). Transgene expression was maintained with lentiviral‐transduced cells (94.6 ± 2.6%) but decreased over 14 weeks in culture with onco‐retroviral‐transduced cells (48.3 ± 3.9%). The self‐renewal capability of these cells and their ability to undergo osteogenic, adipogenic, and myogenic differentiation was unimpaired after transduction with either vector. Finally, clonal expansion of lentivirally modified cells was expanded over 20 population doublings with maintenance of multiline age differentiation capacity. These results suggest that hfMSCs may be suitable targets for ex vivo genetic manipulation with onco‐retroviral or lentiviral vectors without affecting their stem cell properties.

Matched-related donor transplantation for sickle cell disease: report from the Center for International Blood and Transplant Research

We report outcomes after myeloablative haematopoietic cell transplantation (HCT) from human leucocyte antigen (HLA)‐matched sibling donors in 67 patients with sickle cell disease transplanted between 1989 and 2002. The most common indications for transplantation were stroke and recurrent vaso‐occlusive crisis in 38% and 37% of patients respectively. The median age at transplantation was 10 years and 67% of patients had received >10 red blood cell transfusions before HCT. Twenty‐seven percent of patients had a poor performance score at transplantation. Ninety‐four percent received busulfan and cyclophosphamide‐containing conditioning regimens and bone marrow was the predominant source of donor cells. Most patients achieved haematopoietic recovery and no deaths occurred during the early post‐transplant period. Rates of acute and chronic graft‐versus‐host disease were 10% and 22% respectively. Sixty‐four of 67 patients are alive with 5‐year probabilities of disease‐free and overall survival of 85% and 97% respectively. Nine patients had graft failure with recovery of sickle erythropoiesis, eight of who had recurrent sickle‐related events. This report confirms and extends earlier reports that HCT from HLA‐matched related donors offers a very high survival rate, with few transplant‐related complications and the elimination of sickle‐related complications in the majority of patients who undergo this therapy.

Outcome of patients with hemoglobinopathies given either cord blood or bone marrow transplantation from an HLA-identical sibling

We analyzed the outcomes of 485 patients with thalassemia major (TM) or sickle cell disease (SCD) receiving HLA-identical sibling cord blood transplantation (CBT, n = 96) or bone marrow transplantation (BMT, n = 389). Compared with patients given BMT, CBT recipients were significantly younger (median age 6 vs 8 years, P = .02), and were treated more recently (median year 2001 vs 1999, P < .01). A higher proportion of patients with TM belonging to classes II-III of the Pesaro classification received BMT (44%) compared with CBT (39%, P < .01). In comparison with patients receiving BMT (n = 259, TM; n = 130, SCD), those given CBT (n = 66, TM; n = 30, SCD) had slower neutrophil recovery, less acute graft-versus-host disease (GVHD) and none had extensive chronic GVHD. With a median follow-up of 70 months, the 6-year overall survival was 95% and 97% after BMT and CBT, respectively (P = .92). The 6-year disease-free survival (DFS) was 86% and 80% in TM patients after BMT and CBT, respectively, whereas DFS in SCD patients was 92% and 90%, respectively. The cell dose infused did not influence outcome of patients given CBT. In multivariate analysis, DFS did not differ between CBT and BMT recipients. Patients with TM or SCD have excellent outcomes after both HLA-identical sibling CBT and BMT.