Showing papers on "Cytotoxic T cell published in 1997"
TL;DR: Although the high-output NO pathway probably evolved to protect the host from infection, suppressive effects on lymphocyte proliferation and damage to other normal host cells confer upon NOS2 the same protective/destructive duality inherent in every other major component of the immune response.
Abstract: ▪ Abstract At the interface between the innate and adaptive immune systems lies the high-output isoform of nitric oxide synthase (NOS2 or iNOS). This remarkable molecular machine requires at least 17 binding reactions to assemble a functional dimer. Sustained catalysis results from the ability of NOS2 to attach calmodulin without dependence on elevated Ca2+. Expression of NOS2 in macrophages is controlled by cytokines and microbial products, primarily by transcriptional induction. NOS2 has been documented in macrophages from human, horse, cow, goat, sheep, rat, mouse, and chicken. Human NOS2 is most readily observed in monocytes or macrophages from patients with infectious or inflammatory diseases. Sustained production of NO endows macrophages with cytostatic or cytotoxic activity against viruses, bacteria, fungi, protozoa, helminths, and tumor cells. The antimicrobial and cytotoxic actions of NO are enhanced by other macrophage products such as acid, glutathione, cysteine, hydrogen peroxide, or superoxid...
4,027 citations
TL;DR: It is shown that chronic activation of both human and murine CD4+T cells in the presence of interleukin (IL)-10 gives rise to CD4-T-cell clones with low proliferative capacity, producing high levels ofIL-10, low levels of IL-2 and no IL-4.
Abstract: Induction and maintenance of peripheral tolerance are important mechanisms to maintain the balance of the immune system. In addition to the deletion of T cells and their failure to respond in certain circumstances, active suppression mediated by T cells or T-cell factors has been proposed as a mechanism for maintaining peripheral tolerance. However, the inability to isolate and clone regulatory T cells involved in antigen-specific inhibition of immune responses has made it difficult to understand the mechanisms underlying such active suppression. Here we show that chronic activation of both human and murine CD4+ T cells in the presence of interleukin (IL)-10 gives rise to CD4+ T-cell clones with low proliferative capacity, producing high levels of IL-10, low levels of IL-2 and no IL-4. These antigen-specific T-cell clones suppress the proliferation of CD4+ T cells in response to antigen, and prevent colitis induced in SCID mice by pathogenic CD4+CD45RB(high) splenic T cells. Thus IL-10 drives the generation of a CD4+ T-cell subset, designated T regulatory cells 1 (Tr1), which suppresses antigen-specific immune responses and actively downregulates a pathological immune response in vivo.
3,782 citations
TL;DR: In transgenic mice, elevated GATA-3 in CD4 T cells caused Th2 cytokine gene expression in developing Th1 cells, indicating that Gata-3 is necessary and sufficient for Th2inflammatory gene expression.
2,364 citations
TL;DR: In this article, two discrete primed subpopulations are found within the circulating human CD8+ T cell subset, i.e., CD45RA−CD45R0+ cells and CD27−CD27− cells.
Abstract: Human CD8+ memory- and effector-type T cells are poorly defined. We show here that, next to a naive compartment, two discrete primed subpopulations can be found within the circulating human CD8+ T cell subset. First, CD45RA−CD45R0+ cells are reminiscent of memory-type T cells in that they express elevated levels of CD95 (Fas) and the integrin family members CD11a, CD18, CD29, CD49d, and CD49e, compared to naive CD8+ T cells, and are able to secrete not only interleukin (IL) 2 but also interferon γ, tumor necrosis factor α, and IL-4. This subset does not exert cytolytic activity without prior in vitro stimulation but does contain virus-specific cytotoxic T lymphocyte (CTL) precursors. A second primed population is characterized by CD45RA expression with concomitant absence of expression of the costimulatory molecules CD27 and CD28. The CD8+CD45RA+CD27− population contains T cells expressing high levels of CD11a, CD11b, CD18, and CD49d, whereas CD62L (L-selectin) is not expressed. These T cells do not secrete IL-2 or -4 but can produce IFN-γ and TNF-α. In accordance with this finding, cells contained within this subpopulation depend for proliferation on exogenous growth factors such as IL-2 and -15. Interestingly, CD8+CD45RA+CD27− cells parallel effector CTLs, as they abundantly express Fas-ligand mRNA, contain perforin and granzyme B, and have high cytolytic activity without in vitro prestimulation. Based on both phenotypic and functional properties, we conclude that memory- and effector-type T cells can be separated as distinct entities within the human CD8+ T cell subset.
1,439 citations
TL;DR: The specificity and function of mouse NK1 T cells are reviewed, the relationship of this lineage to mainstream T cells and NK cells is discussed, and the novel regulatory pathway, which straddles the innate and the adaptive immune systems, is discussed.
Abstract: NK1 T cells are a specialized population of alpha/beta T cells that coexpress receptors of the NK lineage and have the unique potential to very rapidly secrete large amounts of cytokines, providing early help for effector cells and regulating the Th1 or Th2 differentiation of some immune responses. NK1 T cells express a restricted TCR repertoire made of an invariant TCR alpha chain, V alpha 14-J alpha 281, associated with polyclonal V beta 8, V beta 7, and V beta 2 TCR beta chains. NK1 T cells recognize the products of the conserved family of MHC class I-like CD1 genes, apparently in the absence of foreign antigens. Thus, this novel regulatory pathway, which straddles the innate and the adaptive immune systems, is unique in that its activation may not require associative recognition of antigen. Here, we review the specificity and function of mouse NK1 T cells, and we discuss the relationship of this lineage to mainstream T cells and NK cells.
1,311 citations
TL;DR: R reverse transcription-PCR analysis showed NY-ESO-1 mRNA expression in a variable proportion of a wide array of human cancers, including melanoma, breast cancer, bladder cancer, prostate cancer, and hepatocellular carcinoma, which indicates that it belongs to an expanding family of immunogenic testicular antigens.
Abstract: Serological analysis of recombinant cDNA expression libraries (SEREX) using tumor mRNA and autologous patient serum provides a powerful approach to identify immunogenic tumor antigens. We have applied this methodology to a case of esophageal squamous cell carcinoma and identified several candidate tumor targets. One of these, NY-ESO-1, showed restricted mRNA expression in normal tissues, with high-level mRNA expression found only in testis and ovary tissues. Reverse transcription–PCR analysis showed NY-ESO-1 mRNA expression in a variable proportion of a wide array of human cancers, including melanoma, breast cancer, bladder cancer, prostate cancer, and hepatocellular carcinoma. NY-ESO-1 encodes a putative protein of Mr 17,995 having no homology with any known protein. The pattern of NY-ESO-1 expression indicates that it belongs to an expanding family of immunogenic testicular antigens that are aberrantly expressed in human cancers in a lineage-nonspecific fashion. These antigens, initially detected by either cytotoxic T cells (MAGE, BAGE, GAGE-1) or antibodies [HOM-MEL-40(SSX2), NY-ESO-1], represent a pool of antigenic targets for cancer vaccination.
1,270 citations
TL;DR: It is shown that in a patient whose early CTL response was focused on a highly immunodominant epitope in gp160, there was rapid elimination of the transmitted virus strain and selection for a virus population bearing amino acid changes at a single residue within this epitope, which conferred escape from recognition by epitope-specific CTL.
Abstract: The HIV-1-specific cytotoxic T lymphocyte (CTL) response is temporally associated with the decline in viremia during primary HIV-1 infection, but definitive evidence that it is of importance in virus containment has been lacking. Here we show that in a patient whose early CTL response was focused on a highly immunodominant epitope in gp160, there was rapid elimination of the transmitted virus strain and selection for a virus population bearing amino acid changes at a single residue within this epitope, which conferred escape from recognition by epitope-specific CTL. The magnitude (> 100-fold), kinetics (30–72 days from onset of symptoms) and genetic pathways of virus escape from CTL pressure were comparable to virus escape from antiretroviral therapy, indicating the biological significance of the CTL response in vivo. One aim of HIV-1 vaccines should thus be to elicit strong CTL responses against multiple codominant viral epitopes.
1,254 citations
TL;DR: The largely reciprocal expression of CXCR4 and CCR5 among peripheral blood T cells implies distinct susceptibility of T cell subsets to viral entry by T cell line- Tropic versus macrophage-tropic strains during the course of HIV infection.
Abstract: The chemokine receptors CXCR4 and CCR5 function as coreceptors for HIV-1 entry into CD4+ cells. During the early stages of HIV infection, viral isolates tend to use CCR5 for viral entry, while later isolates tend to use CXCR4. The pattern of expression of these chemokine receptors on T cell subsets and their regulation has important implications for AIDS pathogenesis and lymphocyte recirculation. A mAb to CXCR4, 12G5, showed partial inhibition of chemotaxis and calcium influx induced by SDF-1, the natural ligand of CXCR4. 12G5 stained predominantly the naive, unactivated CD26low CD45RA+ CD45R0− T lymphocyte subset of peripheral blood lymphocytes. In contrast, a mAb specific for CCR5, 5C7, stained CD26high CD45RAlow CD45R0+ T lymphocytes, a subset thought to represent previously activated/memory cells. CXCR4 expression was rapidly up-regulated on peripheral blood mononuclear cells during phytohemagglutinin stimulation and interleukin 2 priming, and responsiveness to SDF-1 increased simultaneously. CCR5 expression, however, showed only a gradual increase over 12 days of culture with interleukin 2, while T cell activation with phytohemagglutinin was ineffective. Taken together, the data suggest distinct functions for the two receptors and their ligands in the migration of lymphocyte subsets through lymphoid and nonlymphoid tissues. Furthermore, the largely reciprocal expression of CXCR4 and CCR5 among peripheral blood T cells implies distinct susceptibility of T cell subsets to viral entry by T cell line-tropic versus macrophage-tropic strains during the course of HIV infection.
1,073 citations
TL;DR: The attraction of TH2 cells by eotaxin could represent a key mechanism in allergic reactions, because it promotes the allergen-driven production of interleukin-4 and interleucin-5 necessary to activate basophils and eosinophils.
Abstract: There is growing evidence that T helper cell subsets (T H 1 and T H 2) can be differentially recruited to promote different types of inflammatory reactions. Murine T H 1 but not T H 2 cells are recruited through P- and E-selectin into inflamed tissues, where they induce delayed-type hypersensitivity reactions. The human eotaxin-receptor CCR3, originally described on eosinophils and basophils, was also found to be expressed by T H 2 cells. An antibody to CCR3 was used to isolate T cells from peripheral blood that give rise to T H 2-polarized cell lines and to identify T H 2 cells derived from naive T cells in vitro. Eotaxin stimulated increases in intracellular calcium and chemotaxis of CCR3 + T cells. The attraction of T H 2 cells by eotaxin could represent a key mechanism in allergic reactions, because it promotes the allergen-driven production of interleukin-4 and interleukin-5 necessary to activate basophils and eosinophils.
1,057 citations
TL;DR: IFN-γ may prevent early Th cells from premature commitment to the Th2 pathway by controlling the expression of the IL-12R β2 subunit, which could be an important therapeutic target for the redirection of ongoing Th cell responses.
Abstract: The developmental commitment to a T helper 1 (Th1)- or Th2-type response can significantly influence host immunity to pathogens. Extinction of the IL-12 signaling pathway during early Th2 development provides a mechanism that allows stable phenotype commitment. In this report we demonstrate that extinction of IL-12 signaling in early Th2 cells results from a selective loss of IL-12 receptor (IL-12R) β2 subunit expression. To determine the basis for this selective loss, we examined IL-12R β2 subunit expression during Th cell development in response to T cell treatment with different cytokines. IL-12R β2 is not expressed by naive resting CD4+ T cells, but is induced upon antigen activation through the T cell receptor. Importantly, IL-4 and IFN-γ were found to significantly modify IL-12 receptor β2 expression after T cell activation. IL-4 inhibited IL-12R β2 expression leading to the loss of IL-12 signaling, providing an important point of regulation to promote commitment to the Th2 pathway. IFN-γ treatment of early developing Th2 cells maintained IL-12R β2 expression and restored the ability of these cells to functionally respond to IL-12, but did not directly inhibit IL-4 or induce IFN-γ production. Thus, IFN-γ may prevent early Th cells from premature commitment to the Th2 pathway. Controlling the expression of the IL-12R β2 subunit could be an important therapeutic target for the redirection of ongoing Th cell responses.
965 citations
TL;DR: Maintenance of CD8 T cell memory still required TCR-MHC class I interactions, but memory T cells may have a lower functional activation threshold that facilitates secondary responses.
Abstract: The requisite molecular interactions for CD8 T cell memory were determined by comparison of monoclonal naive and memory CD8+ T cells bearing the T cell receptor (TCR) for the HY antigen. Naive T cells required only the right major histocompatibility complex (MHC) class I–restricting molecule to survive; to expand, they also needed antigen. In contrast, for survival, memory cells did not require the restricting MHC allele, but needed only a nonspecific class I; for expansion the correct class I, but not antigen, was required. Thus, maintenance of CD8 T cell memory still required TCR–MHC class I interactions, but memory T cells may have a lower functional activation threshold that facilitates secondary responses.
TL;DR: It is shown that antibody-secreting plasma cells from bone marrow are as long-lived as memory B cells.
Abstract: Immune protection is based on long-lived memory cells and effector cells, which are either cytotoxic or secrete antibodies. The lifespan of these effector cells has not so far been determined. Here we show that antibody-secreting plasma cells from bone marrow are as long-lived as memory B cells.
TL;DR: It is shown that IL-6, probably secreted by antigen-presenting cells, is able to polarize naive CD4+ T cells to effector Th2 cells by inducing the initial production of IL-4 in CD4+, a key factor in determining the nature of the immune response.
Abstract: Interleukin (IL)-4 is the most potent factor that causes naive CD4+ T cells to differentiate to the T helper cell (Th) 2 phenotype, while IL-12 and interferon γ trigger the differentiation of Th1 cells. However, the source of the initial polarizing IL-4 remains unclear. Here, we show that IL-6, probably secreted by antigen-presenting cells, is able to polarize naive CD4+ T cells to effector Th2 cells by inducing the initial production of IL-4 in CD4+ T cells. These results show that the nature of the cytokine (IL-12 or IL-6), which is produced by antigen-presenting cells in response to a particular pathogen, is a key factor in determining the nature of the immune response.
TL;DR: It is demonstrated that CD8+ T cells when compared with CD4+ T Cells are preferentially responsive to both early activation events and proliferative signals provided via the TCR and 4-1BB.
Abstract: The 4-1BB receptor is an inducible type I membrane protein and member of the tumor necrosis factor receptor (TNFR) superfamily that is rapidly expressed on the surface of CD4+ and CD8+ T cells after antigen- or mitogen-induced activation. Cross-linking of 4-1BB and the T cell receptor (TCR) on activated T cells has been shown to deliver a costimulatory signal to T cells. Here, we expand upon previously published studies by demonstrating that CD8+ T cells when compared with CD4+ T cells are preferentially responsive to both early activation events and proliferative signals provided via the TCR and 4-1BB. In comparison, CD28-mediated costimulatory signals appear to function in a reciprocal manner to those induced through 4-1BB costimulation. In vivo examination of the effects of anti-4-1BB monoclonal antibodies (mAbs) on antigen-induced T cell activation have shown that the administration of epitope-specific anti-4-1BB mAbs amplified the generation of H-2d–specific cytotoxic T cells in a murine model of acute graft versus host disease (GVHD) and enhanced the rapidity of cardiac allograft or skin transplant rejection in mice. Cytokine analysis of in vitro activated CD4+ and CD8+ T cells revealed that anti-4-1BB costimulation markedly enhanced interferon-γ production by CD8+ T cells and that anti-4-1BB mediated proliferation of CD8+ T cells appears to be IL-2 independent. The results of these studies suggest that regulatory signals delivered by the 4-1BB receptor play an important role in the regulation of cytotoxic T cells in cellular immune responses to antigen.
TL;DR: The dramatic reversal of EBV-driven lymphoproliferations in bone marrow transplant patients following CTL infusion demonstrates the potential of this approach, and prospects for its extension to otherEBV-positive tumors in which the immunodominant EBNA3A, 3B, 3C proteins are not expressed are discussed.
Abstract: ▪ Abstract Epstein-Barr virus (EBV) provides one of the most informative systems with which to study cytotoxic T lymphocyte (CTL) responses in humans. The virus establishes a highly immunogenic growth-transforming infection of B lymphocytes, associated with the coordinate expression of six virus-coded nuclear antigens (EBNAs 1, 2, 3A, 3B, 3C, -LP) and two latent membrane proteins (LMPs 1 and 2). This elicits both primary and memory CT8+ CTL responses that are markedly skewed toward HLA allele-specific epitopes drawn from the EBNA3A, 3B, 3C subset of latent proteins, with reactivities to other antigens being generally much less frequent. This heirarchy of immunodominance among the different latent proteins may at least partly reflect their differential accessibility to the HLA class I–processing pathway. Furthermore, CTLs to some of the immunodominant epitopes involve highly conserved T cell receptor (TCR) usage, a level of focusing which evidence suggests could have immunopathological consequences from cr...
TL;DR: The data suggest that apoptosis induced by bleomycin is mediated, at least in part, by p53-dependent stimulation of the CD95 receptor/ligand system, the same applies to other anti-cancer drugs such as cisplatin and methotrexate.
Abstract: Chemotherapeutic drugs are cytotoxic by induction of apoptosis in drug-sensitive cells. We investigated the mechanism of bleomycin-induced cytotoxicity in hepatoma cells. At concentrations present in the sera of patients during therapy, bleomycin induced transient accumulation of nuclear wild-type (wt) p53 and upregulated expression of cell surface CD95 (APO-1/Fas) receptor in hepatoma cells carrying wt p53 (HepG2). Bleomycin did not increase CD95 in hepatoma cells with mutated p53 (Huh7) or in hepatoma cells which were p53-/- (Hep3B). In addition, sensitivity towards CD95-mediated apoptosis was also increased in wt p53 positive HepG2 cells. Microinjection of wt p53 cDNA into HepG2 cells had the same effect. In contrast, bleomycin did not enhance susceptibility towards CD95-mediated apoptosis in Huh7 and in Hep3B cells. Furthermore, bleomycin treatment of HepG2 cells increased CD95 ligand (CD95L) mRNA expression. Most notably, bleomycin-induced apoptosis in HepG2 cells was almost completely inhibited by antibodies which interfere with CD95 receptor/ligand interaction. These data suggest that apoptosis induced by bleomycin is mediated, at least in part, by p53-dependent stimulation of the CD95 receptor/ligand system. The same applies to other anti-cancer drugs such as cisplatin and methotrexate. These data may have major consequences for drug treatment of cancer and the explanation of drug sensitivity and resistance.
TL;DR: It is shown that the induction of T cell anergy in vivo is due to an abortive T cell response that requires recognition of B7 molecules, since blocking B7 maintains T cells in an unactivated but functionally competent state.
TL;DR: It is shown that CTL induction by cross-priming with cell-associated ovalbumin requires the active involvement of CD4+ helper T cells, and it is argued that the cognitive nature of this event suggests that theCD4+ T cell actively modifies the APC, converting it into an effective stimulator for the successful priming of the CTL precursor.
Abstract: Class I-restricted presentation is usually associated with cytoplasmic degradation of cellular proteins and is often considered inaccessible to exogenous antigens. Nonetheless, certain exogenous elements can gain entry into this so-called endogenous pathway by a mechanism termed cross-presentation. This is known to be effective for class I-restricted cytotoxic T lymphocyte (CTL) cross-priming directed against a variety of exogenous tumor, viral, and minor transplantation antigens. The related effect of cross-tolerance can also effectively eliminate responses to selected self components. In both cases, this presentation appears to require the active involvement of a bone marrow-derived antigen presenting cell (APC). Here, we show that CTL induction by cross-priming with cell-associated ovalbumin requires the active involvement of CD4+ helper T cells. Importantly, this CD4+ population is only effective when both the helper and CTL determinants are recognized on the same APC. Moreover, we would argue that the cognitive nature of this event suggests that the CD4+ T cell actively modifies the APC, converting it into an effective stimulator for the successful priming of the CTL precursor.
TL;DR: Positive selection of HIV-1 proviral sequences encoding variants within a CTL epitope in Nef, a gene product critical for viral pathogenicity, is demonstrated during and after seroconversion.
Abstract: Cytotoxic T lymphocytes (CTLs) are thought to play a crucial role in the termination of the acute primary HIV-1 syndrome, but clear evidence for this presumption has been lacking. Here we demonstrate positive selection of HIV-1 proviral sequences encoding variants within a CTL epitope in Nef, a gene product critical for viral pathogenicity, during and after seroconversion. These positively selected HIV-1 variants carried epitope sequence changes that either diminished or escaped CTL recognition. Other proviruses had mutations that abolished the Nef epitope altogether. These results provide clear evidence that CTLs exert selection pressure on the viral population in acute HIV-1 infection.
TL;DR: The key to the onset of immune dysregulation and aberrant increase in the number of autoreactive T cells in the periphery may be that the activation threshold required for TCR-stimulation is markedly increased in T cells from NOD mice and humans with IDDM.
01 Jan 1997
TL;DR: In this article, the authors showed that cross-presentation of self-antigens can lead to the peripheral deletion of autoreactive CD8 1 T cells (OT-I cells).
Abstract: Summary In this report, we show that cross-presentation of self-antigens can lead to the peripheral deletion of autoreactive CD8 1 T cells. We had previously shown that transfer of ovalbumin (OVA)-specific CD8 1 T cells (OT-I cells) into rat insulin promoter‐membrane-bound form of OVA transgenic mice, which express the model autoantigen OVA in the proximal tubular cells of the kidneys, the b cells of the pancreas, the thymus, and the testis of male mice, led to the activation of OT-I cells in the draining lymph nodes. This was due to class I‐restricted cross-presentation of exogenous OVA on a bone marrow‐derived antigen presenting cell (APC) population. Here, we show that adoptively transferred or thymically derived OT-I cells activated by cross-presentation are deleted from the peripheral pool of recirculating lymphocytes. Such deletion only required antigen recognition on a bone marrow‐derived population, suggesting that cells of the professional APC class may be tolerogenic under these circumstances. Our results provide a mechanism by which the immune system can induce CD8 1 T cell tolerance to autoantigens that are expressed outside the recirculation pathway of naive T cells.
TL;DR: The phenotype of CD8+ T cells, which persist at a low frequency long after recovery from an acute viral infection, suggests that they play a role in protective immunological memory.
Abstract: The nature of the CD8+ T cells that underlie antiviral protective immunological memory in vivo is unclear. We have characterized peptide-specific CD8+ T lymphocytes directly ex vivo from peripheral blood in humans with past exposure to influenza virus, using single cell interferon γ (IFN-γ) release as a measure of effector function. In individuals in the memory state with respect to influenza virus infection, unrestimulated antigen-specific CD8+ T cells displayed IFN-γ release within 6 h of antigen contact, identifying a population of memory CD8+ T cells that exhibit effector function without needing to divide and differentiate over several days. We have quantified circulating CD8+ effector T cells specific for six different MHC class I–restricted influenza virus epitopes. Enumeration of these CD8+ T cells gives frequencies of peptide-specific T cells that correlate with, but are in general severalfold higher than, CTL precursor frequencies derived from limiting dilution analysis, indicating that this novel population of memory CD8+ T cells has hitherto been undetected by standard means. The phenotype of these cells, which persist at a low frequency long after recovery from an acute viral infection, suggests that they play a role in protective immunological memory.
TL;DR: It is demonstrated that GATA-3 is critical for expression of the IL-5 gene in bona fide Th2 cells and has therapeutic potential in the treatment of asthma and other hypereosinophilic diseases.
TL;DR: It is shown that adoptively transferred or thymically derived OT-I cells activated by cross-presentation are deleted from the peripheral pool of recirculating lymphocytes, suggesting that cells of the professional APC class may be tolerogenic under these circumstances.
Abstract: In this report, we show that cross-presentation of self-antigens can lead to the peripheral deletion of autoreactive CD8+ T cells. We had previously shown that transfer of ovalbumin (OVA)-specific CD8+ T cells (OT-I cells) into rat insulin promoter–membrane-bound form of OVA transgenic mice, which express the model autoantigen OVA in the proximal tubular cells of the kidneys, the β cells of the pancreas, the thymus, and the testis of male mice, led to the activation of OT-I cells in the draining lymph nodes. This was due to class I–restricted cross-presentation of exogenous OVA on a bone marrow–derived antigen presenting cell (APC) population. Here, we show that adoptively transferred or thymically derived OT-I cells activated by cross-presentation are deleted from the peripheral pool of recirculating lymphocytes. Such deletion only required antigen recognition on a bone marrow–derived population, suggesting that cells of the professional APC class may be tolerogenic under these circumstances. Our results provide a mechanism by which the immune system can induce CD8+ T cell tolerance to autoantigens that are expressed outside the recirculation pathway of naive T cells.
Journal Article•
TL;DR: In this paper, minimal enhancer/promoter constructs derived from the 5' flank of the human PSA gene (prostate-specific enhancer) were inserted into adenovirus type 5 DNA so as to drive the E1A gene.
Abstract: Prostate-specific antigen (PSA) is a widely used marker for the diagnosis and management of prostate cancer Minimal enhancer/promoter constructs derived from the 5' flank of the human PSA gene (prostate-specific enhancer) were inserted into adenovirus type 5 DNA so as to drive the E1A gene, thereby creating a prostate-specific enhancer-containing virus, CN706 E1A was expressed at high levels in CN706-infected human PSA-producing LNCaP cells but not in CN706-infected DU145 cells, which are human prostate cells that do not express PSA The titer of CN706 was significantly higher in LNCaP cells compared to several human cell lines that do not produce PSA (HBL100, PANC-1, MCF-7, DU145, and OVCAR3) Furthermore, in LNCaP cells, the yield of CN706 was dependent on exogenous androgen (R1881) CN706 destroyed large LNCaP tumors (1 x 10(9) cells) and abolished PSA production in nu/nu mouse xenograft models with a single intratumoral injection
TL;DR: It is demonstrated that HSPs are CD8+ T cell response–eliciting adjuvants that are immunologically active, as tested by their ability to elicit antitumor immunity and specificCD8+ cytolytic T lymphocyte response.
Abstract: Heat shock protein (HSP) preparations derived from cancer cells and virus-infected cells have been shown previously to elicit cancer-specific or virus-specific immunity. The immunogenicity of HSP preparations has been attributed to peptides associated with the HSPs. The studies reported here demonstrate that immunogenic HSP-peptide complexes can also be reconstituted in vitro. The studies show that (a) complexes of hsp70 or gp96 HSP molecules with a variety of synthetic peptides can be generated in vitro; (b) the binding of HSPs with peptides is specific in that a number of other proteins tested do not bind synthetic peptides under the conditions in which gp96 molecules do; (c) HSP-peptide complexes reconstituted in vitro are immunologically active, as tested by their ability to elicit antitumor immunity and specific CD8+ cytolytic T lymphocyte response; and (d) synthetic peptides reconstituted in vitro with gp96 are capable of being taken up and re-presented by macrophage in the same manner as gp96- peptides complexes generated in vivo. These observations demonstrate that HSPs are CD8+ T cell response-eliciting adjuvants.
TL;DR: The results show that the fusion cells stimulate naive T cells in the primary mixed lymphocyte reaction (MLR) and induce MC38 tumor-specific CTLs in vivo and induces rejection of established metastases.
Abstract: Dendritic cells (DCs) are potent antigen-presenting cells that prime naive cytotoxic T-cells (CTLs). In this study, we have fused DCs with MC38 carcinoma cells. The fusion cells were positive for major histocompatibility (MHC) class I and II, costimulating molecules and intercellular cell adhesion molecule-1 (ICAM-1). The results show that the fusion cells stimulate naive T cells in the primary mixed lymphocyte reaction (MLR) and induce MC38 tumor-specific CTLs in vivo. Antibody-mediated depletion experiments demonstrate that induction of CD4+ and CD8+ CTLs protects against challenge with tumor cells. We also show that immunization with the fusion cells induces rejection of established metastases. These findings represent the first demonstration that fusions of DCs and tumor cells can be used in the treatment of cancer.
TL;DR: It is shown that enforced expression of the bcl-2 gene in T-lymphoid cells (by crossing in the Emu-bcl- 2 transgene) in IL-7R alpha-deficient mice results in a significant restoration of thymic positive selection and T cell numbers and function.
TL;DR: A critical role for CD1 is demonstrated in the positive selection and function of natural T cells that coexpress the T cell receptor (TCR) and the natural killer cell receptor NK1.1.
TL;DR: Lymphocyte-specific interferon regulatory factor (LSIRF) (now called IRF4) is a transcription factor expressed only in lymphocytes that is essential for the function and homeostasis of both mature B and mature T lymphocytes.
Abstract: Lymphocyte-specific interferon regulatory factor (LSIRF) (now called IRF4) is a transcription factor expressed only in lymphocytes. Mice deficient in IRF4 showed normal distribution of B and T lymphocyes at 4 to 5 weeks of age but developed progressive generalized lymphadenopathy. IRF4-deficient mice exhibited a profound reduction in serum immunoglobulin concentrations and did not mount detectable antibody responses. T lymphocyte function was also impaired in vivo; these mice could not generate cytotoxic or antitumor responses. Thus, IRF4 is essential for the function and homeostasis of both mature B and mature T lymphocytes.