Altered expression of the TCR signaling related genes CD3 and FcεRIγ in patients with aplastic anemia

<p>Abstract</p> <p>Background</p> <p>Aplastic anemia (AA) is characterized by pancytopenia and bone marrow hypoplasia, which results from immune-mediated hematopoiesis suppression. Understanding the pathophysiology of the immune system, particularly T cells immunity, has led to improved AA treatment over the past decades. However, primary and secondary failure after immunosuppressive therapy is frequent. Thus, knowledge of the immune mechanisms leading to AA is crucial to fundamentally understand the disease.</p> <p>Findings</p> <p>To elucidate the T cell receptor (TCR) signal transduction features in AA, the expression levels of CD3γ, δ, ε and ζ chain and FcεRIγ genes, which are involved in TCR signal transduction, and the negative correlation of the expression levels between the CD3ζ and FcεRIγ genes in T cells from peripheral blood mononuclear cells (PBMCs) were analyzed. Real-time RT-PCR using the SYBR Green method was used to detect the expression level of these genes in PBMCs from 18 patients with AA and 14 healthy individuals. The β2microglobulin gene (β2M) was used as an endogenous reference. The expression levels of the CD3γ, CD3δ, CD3ε and CD3ζ genes in patients with AA were significantly increased compared to a healthy control group, whereas the FcεRIγ gene expression level was significantly decreased in patients with AA in comparison with the healthy control group. Moreover, the negative correlation of the expression levels between the CD3ζ and FcεRIγ genes was lost.</p> <p>Conclusions</p> <p>To our knowledge, this is the first report of the CD3γ, CD3δ, CD3ε, CD3ζ and FcεRIγ gene expression in patients with AA. The abnormally expressed TCR signaling related genes may relate to T cells dysfunction in AA.</p

Biochemical events initiated by exposure of human T lymphocyte clones to immunogenic and tolerogenic concentrations of antigen.

Interleukin 2-dependent helper T cells, cloned from human peripheral blood lymphocytes activated with strain A influenza virus hemagglutinin, proliferate in response to a 24-residue synthetic peptide (p20) of hemagglutinin, but become unresponsive to a subsequent immunogenic challenge when pretreated with a high concentration of p20. This phenomenon is associated with a loss of the T3 antigen complex, presumably in association with the T cell receptor. We have examined this phenomenon in more detail and show that in addition to changes in the expression of T3 molecules on the cell surface, high doses of p20 cause changes in the expression of certain biosynthetically and surface-labeled proteins, although total DNA and protein synthesis was unaltered. Thus, by examining these biochemical phenomena we can begin to define some of the processes which occur during antigen activation of human T lymphocytes at the clonal level

Therapy for glioblastoma: is it working?

Glioblastoma (GBM) remains one of the most intransigent of cancers, with a median overall survival of only 15 months after diagnosis. Drug treatments have largely proven ineffective, due, it is thought, to the heterogeneous nature and plasticity of GBM-initiating stem cell lineages. While many combination drug therapies are being positioned to address tumour heterogeneity, the most promising therapeutic approaches for GBM to date appear to be those targeting GBM by vaccination or antibody- and cell-based immunotherapy. We review the most recent clinical trials for GBM and discuss the role of adaptive clinical trials in developing personalised treatment strategies to address both intra- and inter-tumoral heterogeneity

Biochemical events initiated by exposure of human T lymphocyte clones to immunogenic and tolerogenic concentrations of antigen.

Interleukin 2-dependent helper T cells, cloned from human peripheral blood lymphocytes activated with strain A influenza virus hemagglutinin, proliferate in response to a 24-residue synthetic peptide (p20) of hemagglutinin, but become unresponsive to a subsequent immunogenic challenge when pretreated with a high concentration of p20. This phenomenon is associated with a loss of the T3 antigen complex, presumably in association with the T cell receptor. We have examined this phenomenon in more detail and show that in addition to changes in the expression of T3 molecules on the cell surface, high doses of p20 cause changes in the expression of certain biosynthetically and surface-labeled proteins, although total DNA and protein synthesis was unaltered. Thus, by examining these biochemical phenomena we can begin to define some of the processes which occur during antigen activation of human T lymphocytes at the clonal level

Direct evaluation of antigen binding to human T lymphocyte clones: involvement of major histocompatibility complex products in antigen binding.

Cloned human helper T lymphocytes reactive with a defined peptide (p20; residues 306-329) of the HA-1 molecule of influenza virus hemagglutinin were analyzed for their capacity to specifically bind peptide antigen. Three different methods of analyzing antigen binding to T cell receptors were compared. One method involved the binding of radiolabeled T cells to antigen-pulsed populations of sheep erythrocyte rosette-negative (E-) cells (B cells and monocytes). The binding was antigen specific, in that only E- cells pulsed with the appropriate antigen bound the treated T cells, and was inhibitable by free peptide. Furthermore, antigen binding was major histocompatibility complex-restricted in that only E- cells histocompatible at the HLA-D region locus bound the T cells, and monoclonal antibody of the relevant specificity was able to inhibit the binding. Secondly, it was demonstrated that tritiated T cells could bind to insolubilized antigen (p20) in the absence of E- cells. The binding was inhibited by anti-class II antibody suggesting that the interaction of antigen with the T cells involves recognition of T cell major histocompatibility complex class II determinants. Finally, radiolabeled peptides were also used to detect binding to the appropriate clones in the absence of presenting cells. This binding was specific, inhibitable by the appropriate unlabeled peptide and temperature dependent. These studies demonstrate that the process of antigen binding to receptors is analyzable and should in turn facilitate the analysis of the mechanism of T cell activation

Antigen-specific and non-specific helper activities derived from supernatants of human influenza virus-specific T-cell lines.

A T-cell line (H3) was established by culturing human peripheral blood mononuclear cells with influenza virus A/X31 and maintained in long term culture with Interleukin-2 (TCGF). Supernatants were prepared by culturing these cells overnight in the absence of Interleukin-2 but with A/X31 and irradiated autologous E rosette negative cells as a source of antigen presenting cells, and harvesting by centrifugation. The supernatants were shown to replace T cells in helping E- (B) cells to produce antibody specific to A/X31 which was measured by enzyme immunoassay (EIA). Although maximal help was obtained with autologous or semi allogeneic B cells (in the latter case bearing HLA-DR 3 loci) there was still significant antibody production with allogeneic combinations. The supernatants were subsequently fractionated into specific and non-specific helper activities by gel filtration, giving an approximate mol. wt of 50-70,000 and 10-30,000 for each respectively. The specific HF was shown to be genetically restricted in its action upon B cells and also to generate antibody to A/X31 only. The lower molecular weight material acted on any responding B cell regardless of HLA-DR type and produced antibody non-specifically in culture with E- cells even in the absence of antigen. The apparent lack of restriction was therefore due to the masking effect of non-specific and non-restricted HF(s) on the genetically restricted specific HF produced by this line

Antigen-specific T cell unresponsiveness in cloned helper T cells mediated via the CD2 or CD3/Ti receptor pathways.

We have investigated the role of the CD2 protein in the negative regulation of immune function and report that similar to antigen and anti-CD3, the monoclonal anti-CD2 antibodies (T112 and T113) can induce specific unresponsiveness. Antigen and anti-CD2 tolerogenic signals both down-regulated the phenotypic expression of CD3-Ti. In contrast CD2 surface expression was up-regulated after exposure to peptide and down-regulated after anti-T112 and T113 preincubation. However, in both instances interleukin 2 receptor surface levels were increased. These phenotypic changes could only be partly explained by variations in the levels of the transcripts encoding the CD3-Ti and CD2 molecules

Production of human monoclonal antibody to X31 influenza virus nucleoprotein.

In vitro stimulation of human peripheral blood mononuclear cells with X31 influenza virus antigen has been used to enrich for specific anti-X31 antibody-producing cells. Following Epstein-Barr virus transformation of these stimulated cells, a cell line which produces human antibody to X31 virus was derived and subsequently cloned. The cloned cells secrete and IgGl kappa antibody which is directed against the nucleoprotein of A type influenza virus. Culture supernatants contain 10 to 20 micrograms/ml of specific antibody which is now used as a standard for the ELISA assay used in our laboratory to detect antibodies to influenza virus