T Cell Receptor Antagonist Peptides Induce Positive Selection
University of Washington Seattle, Seattle, Washington, United States Cell
(Impact Factor: 32.24).
02/1994; 76(1):17-27. DOI: 10.1016/0092-8674(94)90169-4
We have used organ culture of fetal thymic lobes from T cell receptor (TCR) transgenic beta 2M(-/-) mice to study the role of peptides in positive selection. The TCR used was from a CD8+ T cell specific for ovalbumin 257-264 in the context of Kb. Several peptides with the ability to induce positive selection were identified. These peptide-selected thymocytes have the same phenotype as mature CD8+ T cells and can respond to antigen. Those peptides with the ability to induce positive selection were all variants of the antigenic peptide and were identified as TCR antagonist peptides for this receptor. One peptide tested, E1, induced positive selection on the beta 2M(-/-) background but negative selection on the beta 2M(+/-) background. These results show that the process of positive selection is exquisitely peptide specific and sensitive to extremely low ligand density and support the notion that low efficacy ligands mediate positive selection.
Available from: Stuart I Mannering
- "Failure to kill target cells enhances cytokine secretion by CTLs/NK cells We first generated antigen-restricted CTLs from transgenic C57BL/6.OTI (OTI) mice (Strasser et al., 1990a; Hogquist et al., 1994 "
[Show abstract] [Hide abstract]
ABSTRACT: Failure of cytotoxic T lymphocytes (CTLs) or natural killer (NK) cells to kill target cells by perforin (Prf)/granzyme (Gzm)-induced apoptosis causes severe immune dysregulation. In familial hemophagocytic lymphohistiocytosis, Prf-deficient infants suffer a fatal "cytokine storm" resulting from macrophage overactivation, but the link to failed target cell death is not understood. We show that prolonged target cell survival greatly amplifies the quanta of inflammatory cytokines secreted by CTLs/NK cells and that interferon-γ (IFN-γ) directly invokes the activation and secondary overproduction of proinflammatory IL-6 from naive macrophages. Furthermore, using live cell microscopy to visualize hundreds of synapses formed between wild-type, Prf-null, or GzmA/B-null CTLs/NK cells and their targets in real time, we show that hypersecretion of IL-2, TNF, IFN-γ, and various chemokines is linked to failed disengagement of Prf- or Gzm-deficient lymphocytes from their targets, with mean synapse time increased fivefold, from ∼8 to >40 min. Surprisingly, the signal for detachment arose from the dying target cell and was caspase dependent, as delaying target cell death with various forms of caspase blockade also prevented their disengagement from fully competent CTLs/NK cells and caused cytokine hypersecretion. Our findings provide the cellular mechanism through which failed killing by lymphocytes causes systemic inflammation involving recruitment and activation of myeloid cells.
© 2015 Jenkins et al.
Journal of Experimental Medicine 03/2015; 212(3). DOI:10.1084/jem.20140964 · 12.52 Impact Factor
Available from: Cheol-Heui Yun
- "A major role of mature DCs is antigen presentation to T cells, and subsequent T cell activation. To characterize the effect of Rv0652 on DC and T-cell interactions, we performed a syngenic mixed lymphocyte reaction assay by using OT-I T cell receptor (TCR) transgenic CD8+ T cells and OT-II TCR transgenic CD4+ T cells . Co-culture of CD4+ or CD8+ T cells (CFSE-labeled and OVA-specific) with Rv0652-DCs pulsed with OVA257–264 (Fig. 5A) or OVA323–339 (Fig. 5B) induced a significantly higher rate of proliferation than the co-culture of CD4+ or CD8+ T cells (CFSE-labeled and OVA-specific) with DCs that were pulsed with OVA257–264 or OVA323–339, but not stimulated with rRv0652. "
[Show abstract] [Hide abstract]
ABSTRACT: A key factor in dendritic cell (DC)-based tumor immunotherapy is the identification of an immunoadjuvant capable of inducing DC maturation to enhance cellular immunity. The efficacy of a 50S ribosomal protein L7/L12 (rplL) from Mycobacterium tuberculosis Rv0652, as an immunoadjuvant for DC-based tumor immunotherapy, and its capacity for inducing DC maturation was investigated. In this study, we showed that Rv0652 is recognized by Toll-like receptor 4 (TLR4) to induce DC maturation, and pro-inflammatory cytokine production (TNF-alpha, IL-1beta, and IL-6) that is partially modulated by both MyD88 and TRIF signaling pathways. Rv0652-activated DCs could activate naïve T cells, effectively polarize CD4+ and CD8+ T cells to secrete IFN-gamma, and induce T cell-mediated-cytotoxicity. Immunization of mice with Rv0652-stimulated ovalbumin (OVA)-pulsed DCs resulted in induction of a potent OVA-specific CD8+ T cell response, slowed tumor growth, and promoted long-term survival in a murine OVA-expressing E.G7 thymoma model. These findings suggest that Rv0652 enhances the polarization of T effector cells toward a Th1 phenotype through DC maturation, and that Rv0652 may be an effective adjuvant for enhancing the therapeutic response to DC-based tumor immunotherapy.
PLoS ONE 08/2014; 9(8):e104351. DOI:10.1371/journal.pone.0104351 · 3.23 Impact Factor
Available from: Cedric Louvet
- "For this line, hemizigous mice were maintained in the laboratory by breeding transgenic mice, selected by PCR genotyping, with wild-type C57BL/6 mice. OT-1 TCR-transgenic mice (C57BL/6-Tg(TcraTcrb)1100Mjb/Crl)  and Ly5.1 congenic mice (B6.SJL-Ptprca Pepcb/BoyCrl) were purshased from Charles Rivers (France). "
[Show abstract] [Hide abstract]
ABSTRACT: Therapeutic use of immunoregulatory cells represents a promising approach for the treatment of uncontrolled immunity. During the last decade, myeloid-derived suppressor cells (MDSC) have emerged as novel key regulatory players in the context of tumor growth, inflammation, transplantation or autoimmunity. Recently, MDSC have been successfully generated in vitro from naive mouse bone marrow cells or healthy human PBMCs using minimal cytokine combinations. In this study, we aimed to evaluate the potential of adoptive transfer of such cells to control auto- and allo-immunity in the mouse. Culture of bone marrow cells with GM-CSF and IL-6 consistently yielded a majority of CD11b+Gr1hi/lo cells exhibiting strong inhibition of CD8+ T cell proliferation in vitro. However, adoptive transfer of these cells failed to alter antigen-specific CD8+ T cell proliferation and cytotoxicity in vivo. Furthermore, MDSC could not prevent the development of autoimmunity in a stringent model of type 1 diabetes. Rather, loading the cells prior to injection with a pancreatic neo-antigen peptide accelerated the development of the disease. Contrastingly, in a model of skin transplantation, repeated injection of MDSC or single injection of LPS-activated MDSC resulted in a significant prolongation of allograft survival. The beneficial effect of MDSC infusions on skin graft survival was paradoxically not explained by a decrease of donor-specific T cell response but associated with a systemic over-activation of T cells and antigen presenting cells, prominently in the spleen. Taken together, our results indicate that in vitro generated MDSC bear therapeutic potential but will require additional in vitro factors or adjunct immunosuppressive treatments to achieve safe and more robust immunomodulation upon adoptive transfer.
PLoS ONE 06/2014; 9(6):e100013. DOI:10.1371/journal.pone.0100013 · 3.23 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.