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      Superantigens Increase the Survival of Mice Bearing T Cell Lymphomas by Inducing Apoptosis of Neoplastic Cells

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          Superantigens bind to major histocompatibility complex class II molecules and interact with T cells expressing a particular T cell receptor Vβ inducing a strong proliferation/deletion response of the superantigen-reactive T cells. However, there have been no attempts to investigate the ability of Sags to induce apoptosis in neoplastic T cells by signaling through the Vβ region of their TCR. In the present study we show that bacterial and MMTV-encoded superantigens induce the apoptosis of AKR/J cognate lymphoma T cells both in vitro and in vivo. The Fas-Fas-L pathway was shown to be involved in the apoptosis of lymphoma T cells induced by bacterial superantigens. In vivo exposure to bacterial superantigens was able to improve the survival of lymphoma bearing mice. Moreover, the permanent expression of a retroviral encoded superantigen induced the complete remission of an aggressive lymphoma in a high percentage of mice. The possibility of a therapeutic use of superantigens in lymphoma/leukemia T cell malignancies is discussed.

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          Most cited references 46

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          Autocrine T-cell suicide mediated by APO-1/(Fas/CD95)

          The APO-1/(Fas/CD95) cell surface receptor is a member of the nerve growth factor (NGF)/tumour necrosis factor (TNF) receptor superfamily and mediates apoptosis. Peripheral activated T cells (ATC) from lymphoproliferation (lpr/lpr) mutant mice that express a reduced number of APO-1 receptors have a defect in T-cell receptor (TCR)-induced apoptosis. This suggests that TCR-induced apoptosis involves APO-1. We tested this hypothesis in various human T cells: (1) malignant Jurkat cells, (2) an alloreactive T-cell clone (S13), and (3) peripheral ATC. TCR triggering through immobilized anti-CD3 antibodies or Staphylococcus enterotoxin B (SEB) superantigen induced expression of the APO-1 ligand and apoptosis in these cells. Anti-CD3-induced apoptosis of Jurkat cells was demonstrated even in single-cell cultures. In all cases apoptosis was substantially inhibited by blocking anti-APO-1 antibody fragments and soluble APO-1 receptor decoys. The APO-1 ligand was found in the supernatant of activated Jurkat cells as a soluble cytokine. We propose that TCR-induced apoptosis in ATC can occur through an APO-1 ligand-mediated autocrine suicide. These results provide a mechanism for suppression of the immune response and for peripheral tolerance by T-cell deletion.
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            The bacterial superantigen and superantigen-like proteins.

            The bacterial superantigens are protein toxins that bind to major histocompatibility complex class II and T-cell receptor to stimulate large numbers of T cells. The majority are produced by the Gram-positive organisms Staphylococcus aureus and Streptococcus pyogenes and are the causative agents in toxic shock syndrome, an acute disease caused by the sudden and massive release of T-cell cytokines into the blood stream. The structure and function of the superantigens has revealed a common architecture that is also shared by another group of staphylococcal virulence factors called the superantigen-like proteins (SSL). Together, this family of structurally related molecules highlights how a common pathogenic organism has employed a simple but adaptable protein to generate an armamentarium of potent defense molecules designed to target of the innate and adaptive immune response.
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              Reactive oxygen species regulate activation-induced T cell apoptosis.

              Reactive oxygen species (ROS) mediate apoptosis in a number of cell types. We studied the role that ROS play in activated T cell apoptosis by activating T cells in vivo and then culturing them for a short time. Activated T cells died independently of Fas and TNF alpha. Their death was characterized by rapid loss of mitochondrial transmembrane potential (delta psi(m)), caspase-dependent DNA fragmentation, and superoxide generation. A superoxide dismutase mimetic, Mn (III) tetrakis (5, 10, 15, 20-benzoic acid) porphyrin (MnTBAP), protected T cells from superoxide generation, caspase-dependent DNA loss, loss of delta psi(m), and cell death. These results indicate that ROS can regulate signals involved in caspase activation and apoptosis and may contribute to peripheral T cell deletion.

                Author and article information

                Role: Editor
                PLoS One
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                22 December 2010
                : 5
                : 12
                [1 ]ILEX-CONICET, División Medicina Experimental, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina
                [2 ]Consejo Nacional de Investigaciones Científicas y Técnicas, Fundación Instituto Leloir, Buenos Aires, Argentina
                Health Canada, Canada
                Author notes

                Conceived and designed the experiments: IP IN. Performed the experiments: JM PMB GC DL. Analyzed the data: JM PMB GC DL IN IP. Wrote the paper: JM PMB GC IP IN.

                Mundiñano et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 11
                Research Article
                Immune Cells
                T Cells
                Model Organisms
                Animal Models
                Molecular Cell Biology
                Cell Death
                Hematologic Cancers and Related Disorders
                Basic Cancer Research



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