Phosphatidylinositol-3-phosphate kinase pathway activation protects leukemic large granular lymphocytes from undergoing homeostatic apoptosis.

T-cell large granular lymphocytic leukemia (T-LGL) is characterized by chronic clonal lymphoproliferation of cytotoxic T lymphocytes (CTLs). Despite exhibiting phenotypic properties of antigen-activated cells, including expression of Fas and FasL, T-LGL cells accumulate and demonstrate resistance to apoptosis. We propose that increased activity of a prosurvival signaling pathway in T-LGL is responsible for attenuated apoptosis in T-LGL.

Brief communication: Successful treatment of pure red-cell aplasia with an anti-interleukin-2 receptor antibody (daclizumab).

Background: Pure red-cell aplasia (PRCA) is a rare hematologic disease characterized by anemia, reticulocytopenia, and absence of bone marrow erythroid precursors. Most patients respond to some form of immunosuppressive treatment, but few prospective clinical trials have been performed.

Objective: To examine the efficacy of a humanized monoclonal antibody to the interleukin-2 receptor (daclizumab) for treating PRCA.

Aplastic anemia: management of adult patients.

The primary therapeutic approach to acquired aplastic anemia (AA) in older adults differs from the primary approach used in children and younger adults because in the former group, the results of allogeneic bone marrow transplantation (BMT) are less favorable. With increasing age of the patients, immunosuppressive therapy with antithymocyte globulin (ATG) and cyclosporine (CsA) constitutes the primary treatment option and may be better than BMT. There are very few clinical clues as to the selection of patients likely to respond to immunosuppression.

Killer immunoglobulin-like receptor genotype in immune-mediated bone marrow failure syndromes.

Objective: Recent reports have shown that killer immunoglobulin-like receptors (KIR) and KIR ligand (KIR-L) genotype play a role in the pathophysiology of autoimmune disorders. Certain KIR/KIR-L combinations might convey a predisposition to immune-mediated bone marrow failure. Examining the genotypic makeup of human leukocyte antigen (HLA) class I (KIR-L) and KIR in patients with hematologic disorders could offer clues to immunogenetic risk factors for these diseases.

Dendritic cells in autologous hematopoietic stem cell transplantation for diffuse large B-cell lymphoma: graft content and post transplant recovery predict survival.

Allograft dendritic cell (DC) content has been identified as a predictor of relapse and event-free survival after allogeneic bone marrow transplantation. However, the prognostic importance of DCs has not been evaluated in the setting of autologous hematopoietic stem cell transplantation (HSCT). We prospectively determined pre-transplant and post transplant DC levels, including DC1 and DC2 subset levels, in 53 patients with diffuse large B-cell non-Hodgkin's lymphoma (DLBC NHL) undergoing autologous HSCT.

Interferon-gamma-induced gene expression in CD34 cells: identification of pathologic cytokine-specific signature profiles.

Hematopoietic effects of interferon-gamma (IFN-gamma) may be responsible for certain aspects of the pathology seen in bone marrow failure syndromes, including aplastic anemia (AA), paroxysmal nocturnal hemoglobinuria (PNH), and some forms of myelodysplasia (MDS). Overexpression of and hematopoietic inhibition by IFN-gamma has been observed in all of these conditions. In vitro, IFN-gamma exhibits strong inhibitory effects on hematopoietic progenitor and stem cells.

Characterization of an antisense transcript spanning the UL81-82 locus of human cytomegalovirus.

In this study we present the characterization of a novel transcript, UL81-82ast, UL81-82 antisense transcript, and its protein product. The transcript was initially found in a cDNA library of monocytes from a seropositive donor. mRNA was obtained from monocytes isolated from a healthy donor with a high antibody titer against human cytomegalovirus (HCMV).

Pathologic clonal cytotoxic T-cell responses: nonrandom nature of the T-cell-receptor restriction in large granular lymphocyte leukemia.

T-cell large granular lymphocyte (T-LGL) leukemia is a clonal lymphoproliferation of cytotoxic T cells (CTLs) associated with cytopenias. T-LGL proliferation seems to be triggered/sustained by antigenic drive; it is likely that hematopoietic progenitors are the targets in this process. The antigen-specific portion of the T-cell receptor (TCR), the variable beta (VB)-chain complementarity-determining region 3 (CDR3), can serve as a molecular signature (clonotype) of a T-cell clone.

Efficient identification of T-cell clones associated with graft-versus-host disease in target tissue allows for subsequent detection in peripheral blood.

Graft-versus-host disease (GVHD) causes severe morbidity and mortality in allogeneic haematopoietic stem cell transplantation (HSCT) because of destruction of recipient tissues by donor alloreactive T cells. We hypothesized that GVHD-specific T-cell clones are expanded within affected tissue of HSCT patients and can also be detected in blood at the time of active disease. A multiplex polymerase chain reaction (PCR) was used to amplify T-cell receptor (TCR) variable beta (VB) chain rearrangements in skin biopsies from eight allogeneic HSCT patients.

Differential gene expression in hematopoietic progenitors from paroxysmal nocturnal hemoglobinuria patients reveals an apoptosis/immune response in 'normal' phenotype cells.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired stem cell disorder characterized clinically by intravascular hemolysis, venous thrombosis, and bone marrow failure. Despite elucidation of the biochemical and molecular defects in PNH, the pathophysiology of clonal expansion of glycosylphosphatidylinositol-anchored protein (GPI-AP)-deficient cells remains unexplained. In pursuit of evidence of differences between GPI-AP-normal and -deficient CD34 cells, we determined gene expression profiles of isolated marrow CD34 cells of each phenotype from PNH patients and healthy donors, using DNA microarrays.

Large granular lymphocyte (LGL)-like clonal expansions in paroxysmal nocturnal hemoglobinuria (PNH) patients.

In paroxysmal nocturnal hemoglobinuria (PNH), clonal expansion of glycosylphosphatidylinositol-anchored proteins (GPI-AP)-deficient cells leads to a syndrome characterized by hemolytic anemia, marrow failure, and venous thrombosis. PNH is closely related to aplastic anemia and may share its immune pathophysiology. In vivo expansion of dominant T-cell clones can reflect an antigen-driven immune response but may also represent autonomous proliferation, such as in large granular lymphocytic (LGL)-leukemia.

Molecular TCR diagnostics can be used to identify shared clonotypes after allogeneic hematopoietic stem cell transplantation.

Objective: In allogeneic hematopoietic stem cell (HSCT) transplantation, recovery of the T cell receptor (TCR) repertoire depends upon the composition of the graft and is modulated by peri-transplant immunosuppression, viral infections, and graft-vs-host disease (GVHD). We hypothesized that after allogeneic HSCT, molecular analysis of the TCR repertoire can be used to identify and quantitate immunodominant T cell clones that may play a role in GVHD or other clinical events.

Methods: We utilized a rational strategy for the analysis of the expanded CTL clones.

Distinctive gene expression profiles of CD34 cells from patients with myelodysplastic syndrome characterized by specific chromosomal abnormalities.

Aneuploidy, especially monosomy 7 and trisomy 8, is a frequent cytogenetic abnormality in the myelodysplastic syndromes (MDSs). Patients with monosomy 7 and trisomy 8 have distinctly different clinical courses, responses to therapy, and survival probabilities. To determine disease-specific molecular characteristics, we analyzed the gene expression pattern in purified CD34 hematopoietic progenitor cells obtained from MDS patients with monosomy 7 and trisomy 8 using Affymetrix GeneChips.

Transfer of glycosylphosphatidylinositol-anchored proteins to deficient cells after erythrocyte transfusion in paroxysmal nocturnal hemoglobinuria.

In paroxysmal nocturnal hemoglobinuria (PNH), an acquired mutation of the PIGA gene results in the absence of glycosylphosphatidylinositol (GPI)-anchored cell surface membrane proteins in affected hematopoietic cells. Absence of GPI-anchored proteins on erythrocytes is responsible for their increased sensitivity to complement-mediated lysis, resulting in hemolytic anemia. Cell-to-cell transfer of CD55 and CD59, 2 GPI-anchored proteins, by red cell microvesicles has been demonstrated in vitro, with retention of their function.

CDR3 spectratyping identifies clonal expansion within T-cell subpopulations that demonstrate therapeutic antitumor activity.

Background: Antigen-specific T cells undergoing clonal expansion share common rearrangements of the variable complementary determining region 3 (CDR3) of the T-cell receptor (TCR), which can be identified using polymerase chain reaction-based V beta (VB) spectratyping. The purpose of this study was to determine whether CDR3 spectratyping identifies clonal expansion within tumor-draining lymph node (TDLN) subpopulations with antitumor therapeutic activity.

Methods: Recently sensitized T cells from 4T1 murine mammary carcinoma TDLN were fractionated based on CD62L (L-selectin) surface expression before RNA isolation and culture.

Regulation of cellular gene expression in endothelial cells by sin nombre and prospect hill viruses.

Mechanisms of hantavirus-induced vascular leakage remain unknown. This study was initiated to determine whether hantavirus-induced changes in endothelial cell gene expression may provide insight into disease mechanisms. Additionally, by using pathogenic Sin Nombre virus (SNV) and non-pathogenic Prospect Hill virus (PHV), we wanted to identify cellular responses that are likely to differentiate pathogenic from nonpathogenic hantaviruses.

In-vivo dominant immune responses in aplastic anaemia: molecular tracking of putatively pathogenetic T-cell clones by TCR beta-CDR3 sequencing.

Background: Aplastic anaemia is a bone-marrow-failure syndrome characterised by low blood-cell counts and fatty bone marrow. In most cases, no obvious aetiological factor can be identified. However, clinical responses to immunosuppression strongly suggest an immune pathophysiology.

Human cytomegalovirus persists in myeloid progenitors and is passed to the myeloid progeny in a latent form.

CD34+ progenitor cells can harbour latent human cytomegalovirus (HCMV); however, the mechanisms of HCMV latency remain unclear. We have investigated the effects of the haematopoietic lineage restriction on the establishment and spread of the latent HCMV to progeny cells. In vitro-infected and latently-infected haematopoietic progenitor cells derived from HCMV seropositive donors were studied.

Genomic instability in bone marrow failure syndromes.

Aneuploidy is frequently seen in leukemia and myelodysplasia (MDS) but was thought to be uncommon in aplastic anemia (AA). We examined marrow cells from 96 unselected patients with bone marrow failure syndromes to assess the frequency of undetected aneuploidy for chromosomes 7 and 8 by fluorescence in situ hybridization (FISH) as compared to routine cytogenetic analysis. Twenty-eight percent (27/96) of patients had an abnormal karyotype.

Clinical implications of T cell receptor repertoire analysis after allogeneic stem cell transplantation.

Stem cell transplantation (SCT) constitutes a major challenge to the immune system. Long-term impairment of immunity against various common infectious stimuli leads to increased susceptibility to infectious diseases; in contrast, an immune response against the recipient may cause the devastating graft-versus-host disease (GvHD). Recovery of the immune system (both qualitative and quantitative) after SCT is perhaps the most important factor in determining the clinical outcome.

Is there a direct effect of antithymocyte globulin on hematopoiesis?

The efficacy of immunosuppressive therapy in aplastic anemia (AA) provides the strongest argument to support its immune-mediated pathophysiology. While several immunosuppressive effects of antithymocyte globulin (ATG) can be demonstrated in vitro, some reports have implied that the activity of ATG in AA may be rather due to a variety of positive hematopoietic effects. We studied the effects of horse (h) and rabbit (r) ATG on marrow progenitors in vitro.

Evolution of clonal cytogenetic abnormalities in aplastic anemia.

Prior to the introduction of effective therapies, the high mortality rates of severe aplastic anemia (AA) precluded recognition of late complications of this disease. Once the survival of AA improved, observation of clonal evolution raised questions as to whether the development of secondary myelodysplastic syndrome (MDS) is a part of the extended natural history of the disease or is related to the therapies applied. Clinical features of myelodysplasia and AA can overlap, and typical MDS may evolve as a complication of AA.

The prognostic value of glomerular immaturity in the nephrotic syndrome in children.

The study group consisted of 16 children (9 boys and 7 girls) aged 6-52 months (mean age 27 months) with a first episode of nephrotic syndrome. Histological diagnosis (diffuse mesangial proliferation with signs of glomerular immaturity) was established by renal biopsy. The control group consisted of 47 children (26 boys and 21 girls) aged 7-58 months (mean 29 months) hospitalized with a first episode of nephrotic syndrome with diffuse mesangial proliferation, documented exclusively by histological examination.

Shared and individual specificities of immunodominant cytotoxic T-cell clones in paroxysmal nocturnal hemoglobinuria as determined by molecular analysis.

Objective: Similar immune mechanisms have been suggested to operate in aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH), and the presence of PNH clones in AA may indicate that an immune reaction directed against hematopoietic stem cells may be responsible for the immune selection pressure leading to PNH evolution. We previously described expansions of selective cytotoxic T-lymphocyte (CTL) clones in AA patients.

Materials And Methods: We applied a molecular analysis of the T-cell receptor repertoire to study the characteristics of CTL response in patients with various forms of PNH.