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Showing papers on "Antigen published in 1995"


Journal ArticleDOI
10 Mar 1995-Science
TL;DR: Fas ligand (FasL), a cell surface molecule belonging to the tumor necrosis factor family, binds to its receptor Fas, thus inducing apoptosis of Fas-bearing cells.
Abstract: Fas ligand (FasL), a cell surface molecule belonging to the tumor necrosis factor family, binds to its receptor Fas, thus inducing apoptosis of Fas-bearing cells. Various cells express Fas, whereas FasL is expressed predominantly in activated T cells. In the immune system, Fas and FasL are involved in down-regulation of immune reactions as well as in T cell-mediated cytotoxicity. Malfunction of the Fas system causes lymphoproliferative disorders and accelerates autoimmune diseases, whereas its exacerbation may cause tissue destruction.

4,190 citations


Journal ArticleDOI
TL;DR: The capacity of DCs to capture and process antigen could be modulated by exogenous stimuli was investigated and it was found that DCs respond to tumor necrosis factor alpha, CD40 ligand, IL-1, and lipopolysaccharide with a coordinate series of changes that include downregulation of macropinocytosis and Fc receptors, disappearance of the class II compartment, and upregulation of adhesion and costimulatory molecules.
Abstract: We have previously demonstrated that human peripheral blood low density mononuclear cells cultured in granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 develop into dendritic cells (DCs) that are extremely efficient in presenting soluble antigens to T cells. To identify the mechanisms responsible for efficient antigen capture, we studied the endocytic capacity of DCs using fluorescein isothiocyanate-dextran, horseradish peroxidase, and lucifer yellow. We found that DCs use two distinct mechanisms for antigen capture. The first is a high level of fluid phase uptake via macropinocytosis. In contrast to what has been found with other cell types, macropinocytosis in DCs is constitutive and allows continuous internalization of large volumes of fluid. The second mechanism of capture is mediated via the mannose receptor (MR), which is expressed at high levels on DCs. At low ligand concentrations, the MR can deliver a large number of ligands to the cell in successive rounds. Thus, while macropinocytosis endows DCs with a high capacity, nonsaturable mechanism for capture of any soluble antigen, the MR gives an extra capacity for antigen capture with some degree of selectivity for non-self molecules. In addition to their high endocytic capacity, DCs from GM-CSF + IL-4-dependent cultures are characterized by the presence of a large intracellular compartment that contains high levels of class II molecules, cathepsin D, and lysosomal-associated membrane protein-1, and is rapidly accessible to endocytic markers. We investigated whether the capacity of DCs to capture and process antigen could be modulated by exogenous stimuli. We found that DCs respond to tumor necrosis factor alpha, CD40 ligand, IL-1, and lipopolysaccharide with a coordinate series of changes that include downregulation of macropinocytosis and Fc receptors, disappearance of the class II compartment, and upregulation of adhesion and costimulatory molecules. These changes occur within 1-2 d and are irreversible, since neither pinocytosis nor the class II compartment are recovered when the maturation-inducing stimulus is removed. The specificity of the MR and the capacity to respond to inflammatory stimuli maximize the capacity of DCs to present infectious non-self antigens to T cells.

2,674 citations


Journal ArticleDOI
10 Mar 1995-Cell
TL;DR: Interaction of B 7-1 and B7-2 with shared counterreceptors CD28 and CTLA-4 results in very different outcomes in clinical disease by influencing commitment of precursors to a Th1 or Th2 lineage.

1,766 citations


Journal ArticleDOI
TL;DR: The results suggest that CB1 and CB2 can be considered as tissue-selective antigens of the central nervous system and immune system, respectively, and cannabinoids may exert specific receptor-mediated actions on the immune system through the CB2 receptor.
Abstract: Two proteins with seven transmembrane-spanning domains typical of guanosine-nucleotide-binding-protein-coupled receptors have been identified as cannabinoid receptors; the central cannabinoid receptor, CB1, and the peripheral cannabinoid receptor, CB2, initially described in rat brain and spleen, respectively. Here, we report the distribution patterns for both CB1 and CB2 transcripts in human immune cells and in several human tissues, as analysed using a highly sensitive and quantitative PCR-based method. CB1 was mainly expressed in the central nervous system and, to a lower extent, in several peripheral tissues such as adrenal gland, heart, lung, prostate, uterus, ovary, testis, bone marrow, thymus and tonsils. In contrast, the CB2 gene, which is not expressed in the brain, was particularly abundant in immune tissues, with an expression level 10-100-fold higher than that of CB1. Although CB2 mRNA was also detected in some other peripheral tissues, its level remained very low. In spleen and tonsils, the CB2 mRNA content was equivalent to that of CB1 mRNA in the central nervous system. Among the main human blood cell subpopulations, the distribution pattern of the CB2 mRNA displayed important variations. The rank order of CB2 mRNA levels in these cells was B-cells > natural killer cells >> monocytes > polymorphonuclear neutrophil cells > T8 cells > T4 cells. The same rank order was also established in human cell lines belonging to the myeloid, monocytic and lymphoid lineages. The prevailing expression of the CB2 gene in immune tissues was confirmed by Northern-blot analysis. In addition, the expression of the CB2 protein was demonstrated by an immunohistological analysis performed on tonsil sections using specific anti-(human CB2) IgG; this experiment showed that CB2 expression was restricted to B-lymphocyte-enriched areas of the mantle of secondary lymphoid follicles. These results suggest that (a) CB1 and CB2 can be considered as tissue-selective antigens of the central nervous system and immune system, respectively, and (b) cannabinoids may exert specific receptor-mediated actions on the immune system through the CB2 receptor.

1,646 citations


Journal ArticleDOI
24 Feb 1995-Cell
TL;DR: It is concluded that the EBV-infected cells in vivo are B cells with a nonactivated phenotype, which represents a novel form of latency in normal B cells.

1,442 citations


Journal ArticleDOI
01 Sep 1995-Science
TL;DR: Results suggest that mutation of CDK4 can create a tumor-specific antigen and can disrupt the cell-cycle regulation exerted by the tumor suppressor p16INK4a.
Abstract: A mutated cyclin-dependent kinase 4 (CDK4) was identified as a tumor-specific antigen recognized by HLA-A2. 1-restricted autologous cytolytic T lymphocytes (CTLs) in a human melanoma. The mutated CDK4 allele was present in autologous cultured melanoma cells and metastasis tissue, but not in the patient's lymphocytes. The mutation, an arginine-to-cysteine exchange at residue 24, was part of the CDK4 peptide recognized by CTLs and prevented binding of the CDK4 inhibitor p16INK4a, but not of p21 or of p27KIP1. The same mutation was found in one additional melanoma among 28 melanomas analyzed. These results suggest that mutation of CDK4 can create a tumor-specific antigen and can disrupt the cell-cycle regulation exerted by the tumor suppressor p16INK4a.

1,182 citations


Journal ArticleDOI
TL;DR: This study has used mice deficient in immunological effector functions in combination with adoptive and passive transfer techniques to define antigen-specific cellular and humoral immune responses that underlie immunological barriers to gene therapy of cystic fibrosis.
Abstract: Recombinant adenoviruses are an attractive vehicle for gene therapy to the lung in the treatment of cystic fibrosis (CF). First-generation viruses deleted of E1a and E1b transduce genes into airway epithelial cells in vivo; however, expression of the transgene is transient and associated with substantial inflammatory responses, and gene transfer is significantly reduced following a second administration of the virus. In this study, we have used mice deficient in immunological effector functions in combination with adoptive and passive transfer techniques to define antigen-specific cellular and humoral immune responses that underlie these important limitations. Our studies indicate that major histocompatibility complex class I-restricted CD8+ cytotoxic T lymphocytes are activated in response to newly synthesized antigens, leading to destruction of virus infected cells and loss of transgene expression. Major histocompatibility complex class II-associated presentation of exogenous viral antigens activates CD4+ T-helper (TH) cells of the TH1 subset and, to a lesser extent, of the TH2 subset. CD4+ cell-mediated responses are insufficient in the absence of cytotoxic T cells to completely eliminate transgene containing cells; however, they contribute to the formation of neutralizing antibodies in the airway which block subsequent adenovirus-mediated gene transfer. Definition of immunological barriers to gene therapy of cystic fibrosis should facilitate the design of rational strategies to overcome them.

1,164 citations


Journal ArticleDOI
TL;DR: The unexpected frequency of human tumor antigens indicates that human neoplasms elicit multiple specific immune responses in the autologous host and provides diagnostic and therapeutic approaches to human cancer.
Abstract: Expression of cDNA libraries from human melanoma, renal cancer, astrocytoma, and Hodgkin disease in Escherichia coli and screening for clones reactive with high-titer IgG antibodies in autologous patient serum lead to the discovery of at least four antigens with a restricted expression pattern in each tumor. Besides antigens known to elicit T-cell responses, such as MAGE-1 and tyrosinase, numerous additional antigens that were overexpressed or specifically expressed in tumors of the same type were identified. Sequence analyses suggest that many of these molecules, besides being the target of a specific immune response, might be of relevance for tumor growth. Antibodies to a given antigen were usually confined to patients with the same tumor type. The unexpected frequency of human tumor antigens, which can be readily defined at the molecular level by the serological analysis of autologous tumor cDNA expression cloning, indicates that human neoplasms elicit multiple specific immune responses in the autologous host and provides diagnostic and therapeutic approaches to human cancer.

1,154 citations


Journal ArticleDOI
14 Jul 1995-Cell
TL;DR: The cloning of two related PfEMP1 genes from the Malayan Camp parasite strain are described and the molecular basis for antigenic variation in malaria and adherence of infected erythrocytes to host cells can now be pursued.

1,005 citations


Journal ArticleDOI
11 May 1995-Nature
TL;DR: DEC-205 is a novel endocytic receptor that can be used by dendritic cells and thymic epithelial cells to direct captured antigens from the extracellular space to a specialized antigen-processing compartment.
Abstract: Dendritic cells and thymic epithelial cells perform important immunoregulatory functions by presenting antigens in the form of peptides bound to cell-surface major histocompatibility complex (MHC) molecules to T cells. Whereas B cells are known to present specific antigens efficiently through their surface immunoglobins, a comparable mechanism for the capture and efficient presentation of diverse antigens by dendritic cells and thymic epithelial cells has not previously been described. We show here that their antigen-presentation function is associated with the high-level expression of DEC-205, an integral membrane protein homologous to the macrophage mannose receptor and related receptors which are able to bind carbohydrates and mediate endocytosis. DEC-205 is rapidly taken up by means of coated pits and vesicles, and is delivered to a multivesicular endosomal compartment that resembles the MHC class II-containing vesicles implicated in antigen presentation. Rabbit antibodies that bind DEC-205 are presented to reactive T-cell hybridomas 100-fold more efficiently than rabbit antibodies that do not bind DEC-205. Thus DEC-205 is a novel endocytic receptor that can be used by dendritic cells and thymic epithelial cells to direct captured antigens from the extracellular space to a specialized antigen-processing compartment.

998 citations


Journal ArticleDOI
11 May 1995-Nature
TL;DR: Results provide formal evidence that, in contrast to recognition of major histocompatibility complex-bound peptide antigens by αβ T cells, human γδ T cells can recognize naturally occurring small non-peptidic antIGens.
Abstract: T lymphocytes express either alpha beta or gamma delta T-cell receptor heterodimers. Most alpha beta T cells recognize antigenic peptides bound to major histocompatibility complex molecules but the antigen recognition and biological function of gamma delta T cells is unknown. A major human gamma delta T-cell subset expressing V gamma 2 and V delta 2 germline genes, but having diverse junctional sequences, is found in human mycobacterial lesions and responds in vitro to antigens of bacteria and parasites. In addition, certain haematopoietic tumour cells are specifically recognized and lysed by these T cells. V gamma 2V delta 2-bearing T cells were shown to recognize mycobacterial antigens that are protease resistant and phosphatase sensitive. Because of the difficulty in isolating natural antigens from mycobacterial culture filtrates or extracts, we synthesized a series of monoalkyl phosphates, and found that some, particularly monoethyl phosphate, could mimic the activity of mycobacterial antigens in stimulating these gamma delta T cells. Here we report the identification of natural antigens produced by mycobacteria recognized by human V gamma 2V delta 2-bearing T cells as isopentenyl pyrophosphate and related prenyl pyrophosphate derivatives, compounds involved in the synthesis of complex polyisoprenoid compounds in microbial and mammalian cells. Substitution of phosphate for the pyrophosphate moiety, or elimination of the double bond, greatly reduced antigenic activity of these compounds. These results provide formal evidence that, in contrast to recognition of major histocompatibility complex-bound peptide antigens by alpha beta T cells, human gamma delta T cells can recognize naturally occurring small non-peptidic antigens.

Journal ArticleDOI
TL;DR: The present data suggest that the inflammatory infiltrate in the atherosclerotic plaque is involved in a T-cell-dependent, autoimmune response to oxLDL, which results in immune activation and inflammation but may not be a strong stimulus to antibody production.
Abstract: Atherosclerosis, an underlying cause of myocardial infarction, stroke, and other cardiovascular diseases, consists of focal plaques characterized by cholesterol deposition, fibrosis, and inflammation. The presence of activated T lymphocytes and macrophages and high expression of HLA class II molecules are indicative of a local immunologic activation in the atherosclerotic plaque, but the antigen(s) involved has not yet been identified. We established T-cell clones from human atherosclerotic plaques using polyclonal mitogens as stimuli and exposed the clones to potential antigens in the presence of autologous monocytes as antigen-presenting cells. Four of the 27 CD4+ clones responded to oxidized low density lipoprotein (oxLDL) by proliferation and cytokine secretion; this response was dependent on autologous antigen-presenting cells and restricted by HLA-DR. All clones that responded to oxLDL secreted interferon gamma upon activation, but only one produced interleukin 4, suggesting that the response to oxLDL results in immune activation and inflammation but may not be a strong stimulus to antibody production. No significant response to oxLDL could be detected in CD4+ T-cell clones derived from the peripheral blood of the same individuals. Together, the present data suggest that the inflammatory infiltrate in the atherosclerotic plaque is involved in a T-cell-dependent, autoimmune response to oxLDL.

Journal ArticleDOI
13 Jan 1995-Science
TL;DR: It is demonstrated that M phi s transfer Ags from phagosomes into the cytosol and that endogenous and exogenous Ags use a final common pathway for class I presentation.
Abstract: Peptides from endogenous proteins are presented by major histocompatibility complex class I molecules, but antigens (Ags) in the extracellular fluids are generally not. However, pathogens or particulate Ags that are internalized into phagosomes of macrophages (M phi s) stimulate CD8 T cells. The presentation of these Ags is resistant to chloroquine but is blocked by inhibitors of the proteasome, a mutation in the TAP1-TAP2 transporter, and brefeldin A. Moreover, phagocytosis of a ribosomal-inactivating protein inhibited M phi protein synthesis. These results demonstrate that M phi s transfer Ags from phagosomes into the cytosol and that endogenous and exogenous Ags use a final common pathway for class I presentation.

Journal ArticleDOI
22 Jun 1995-Nature
TL;DR: The results highlight a previously unknown mechanism of viral escape from CTL surveillance, and support the view that the resistance of cells expressing EBNA1 to rejection mediated by CTL is a critical requirement for EBV persistence and pathogenesis.
Abstract: The Epstein-Barr virus (EBV)-encoded nuclear antigen (EBNA1) is expressed in latently EBV-infected B lymphocytes that persist for life in healthy virus carriers, and is the only viral protein regularly detected in all malignancies associated with EBV. Major histocompatibility complex (MHC) class I-restricted, EBNA1-specific cytotoxic T lymphocyte (CTL) responses have not been demonstrated. Using recombinant vaccinia viruses encoding chimaeric proteins containing an immunodominant human leukocyte antigen A11-restricted CTL epitope, amino acids 416-424 of the EBNA4 protein, inserted within the intact EBNA1, or within an EBNA1 deletion mutant devoid of the internal Gly-Ala repetitive sequence, we demonstrate that the Gly-Ala repeats generate a cis-acting inhibitory signal that interferes with antigen processing and MHC class I-restricted presentation. Insertion of the Gly-Ala repeats downstream of the 416-424 epitope inhibited CTL recognition of a chimaeric EBNA4 protein. The results highlight a previously unknown mechanism of viral escape from CTL surveillance, and support the view that the resistance of cells expressing EBNA1 to rejection mediated by CTL is a critical requirement for EBV persistence and pathogenesis.

Journal ArticleDOI
TL;DR: Evidence demonstrating that B cell activation via TI stimuli does not play merely a permissive role in allowing for cell cycle entry and enhanced responsiveness to other stimuli is presented, rather, the nature of the B cell activating signal is critical in determining the quantitative and qualitative profile of Ig isotype production.
Abstract: In this review we have attempted to define the characteristics of TI-2 antigens that enable them to stimulate antibody production in the absence of T cell help. One of the most critical properties of this group of antigens is their ability to deliver prolonged and persistent signaling to the B cell. This by itself is not however sufficient to stimulate Ig synthesis, and they must therefore stimulate non-T cells to interact with the B cells either directly or indirectly via cytokine production. There is evidence implicating the NK cell and T cell as playing this important role in response to TI antigens. Furthermore, we discuss the importance of cytokines such as IL-3, GMCSF, and IFN-gamma, which significantly enhance antibody production by these antigens. Finally, we present evidence demonstrating that B cell activation via TI stimuli does not play merely a permissive role in allowing for cell cycle entry and enhanced responsiveness to other stimuli. Rather, the nature of the B cell activating signal is critical in determining the quantitative and qualitative profile of Ig isotype production.

Journal ArticleDOI
13 Jul 1995-Nature
TL;DR: It is reported that oral antigen can delete antigen-reactive T cells in Peyer's patches, in mice transgenic for the ovalbumin-specific T-cell receptor genes, and was dependent on dosage and frequency of feeding.
Abstract: ORAL administration of antigen is used to induce antigen-specific peripheral immune tolerance1,2. As well as preventing systemic immune responses to ingested proteins3, oral tolerance to autoanti-gens has also been used to suppress autoimmune diseases in animals4-10and humans11,12. Both active suppression and clonal anergy are suggested to be mechanisms of oral tolerance, depending on the dose of antigen fed13,14. Here we report that oral antigen can delete antigen-reactive T cells in Peyer's patches, in mice transgenic for the ovalbumin-specific T-cell receptor genes. The deletion was mediated by apoptosis, and was dependent on dosage and frequency of feeding. At lower doses deletion was not observed; instead there was induction of antigen-specific cells that produced transforming growth factor (TGF)-β and interleukin (IL)-4 and IL-10 cytokines. At higher doses, both Thl and Th2 cells were deleted following their initial activation, whereas cells which secrete TGF-β were resistant to deletion. These findings demonstrate that orally administered antigen can induce tolerance not only by active suppression and clonal anergy but by extrathymic deletion of antigen-reactive Th1 and Th2 cells.

Journal ArticleDOI
TL;DR: It is shown that the antigen dose used in primary cultures could directly affect Th phenotype development from naive DO11.10 TCR-alpha beta-transgenic CD4+ T cells when dendritic cells or activated B cells were used as the antigen- presenting cells.
Abstract: The dose of foreign antigen can influence whether a cell-mediated or humoral class of immune response is elicited, and this may be largely accounted for by the development of CD4+ T helper cells (Th) producing distinct sets of cytokines. The ability of antigen dose to direct the development of a Th1 or Th2 phenotype from naive CD4+ T cells, however, has not been demonstrated. In this report, we show that the antigen dose used in primary cultures could directly affect Th phenotype development from naive DO11.10 TCR-alpha beta-transgenic CD4+ T cells when dendritic cells or activated B cells were used as the antigen-presenting cells. Consistent with our previous findings, midrange peptide doses (0.3-0.6 microM) directed the development of Th0/Th1-like cells, which produced moderate amounts of interferon gamma (IFN-gamma). As the peptide dose was increased, development of Th1-like cells producing increased amounts of IFN-gamma was initially observed. At very high (> 10 microM) and very low (< 0.05 microM) doses of antigenic peptide, however, a dramatic switch to development of Th2-like cells that produced increasing amounts of interleukin 4 (IL-4) and diminishing levels of IFN-gamma was observed. This was true even when highly purified naive, high buoyant density CD4+ LECAM-1hi T cells were used, ruling out a possible contribution from contaminating "memory" phenotype CD4+ T cells. Neutralizing anti-IL-4 antibodies completely inhibited the development of this Th2-like phenotype at both high and low antigen doses, demonstrating a requirement for endogenous IL-4. Our findings suggest that the antigen dose may affect the levels of endogenous cytokines such as IL-4 in primary cultures, resulting in the development of distinct Th cell phenotypes.

Journal Article
TL;DR: Results indicate that P can favor the development of Th cells producing Th2-type cytokines and is an inducer of both transient IL-4 production and CD30 expression in established Th1 cells.
Abstract: The effect of progesterone (P) on the cytokine production profile of Ag-specific human CD4+ T cell lines and clones was investigated. T cell lines specific for purified protein derivative or streptokinase (SK) derived in the presence of P exhibited significant increased ability to produce IL-5 in comparison with T cell lines derived in the absence of P. Moreover, IL-4 was significantly increased in SK-specific T cell lines derived in the presence of P in comparison with SK-specific T cell lines derived in the absence of this hormone. In addition, SK-specific T cell lines generated in the presence of P developed into T cell clones showing a Th0-, instead of Th1-like, cytokine profile. Furthermore, SK-specific T cell clones with an established Th1 profile of cytokine secretion did express mRNA for, and produced detectable amounts of, IL-4 when stimulated with P in combination with insoluble anti-CD3 mAb. Combined stimulation with P and insoluble anti-CD3 mAb also enabled Th1 clones to express CD30 on their surface membrane. These results indicate that P can favor the development of Th cells producing Th2-type cytokines and is an inducer of both transient IL-4 production and CD30 expression in established Th1 cells. Thus, P production at the placental level may be responsible, at least in part, for increased production of Th2-type cytokines which have been implied in fetal allograft survival and maintenance of successful pregnancy.

Journal ArticleDOI
TL;DR: A critical signal response domain in I kappa B alpha is defined that coordinately controls the biologic activities of I k Kappa B alpha and NF-kappa B in response to viral and immune stimuli and is consistent with a causal linkage between the phosphorylation status and proteolytic stability of this cytoplasmic inhibitor.
Abstract: The eukaryotic transcription factor NF-kappa B plays a central role in the induced expression of human immunodeficiency virus type 1 and in many aspects of the genetic program mediating normal T-cell activation and growth. The nuclear activity of NF-kappa B is tightly regulated from the cytoplasmic compartment by an inhibitory subunit called I kappa B alpha. This cytoplasmic inhibitor is rapidly phosphorylated and degraded in response to a diverse set of NF-kappa B-inducing agents, including T-cell mitogens, proinflammatory cytokines, and viral transactivators such as the Tax protein of human T-cell leukemia virus type 1. To explore these I kappa B alpha-dependent mechanisms for NF-kappa B induction, we identified novel mutants of I kappa B alpha that uncouple its inhibitory and signal-transducing functions in human T lymphocytes. Specifically, removal of the N-terminal 36 amino acids of I kappa B alpha failed to disrupt its ability to form latent complexes with NF-kappa B in the cytoplasm. However, this deletion mutation prevented the induced phosphorylation, degradative loss, and functional release of I kappa B alpha from NF-kappa B in Tax-expressing cells. Alanine substitutions introduced at two serine residues positioned within this N-terminal regulatory region of I kappa B alpha also yielded constitutive repressors that escaped from Tax-induced turnover and that potently inhibited immune activation pathways for NF-kappa B induction, including those initiated from antigen and cytokine receptors. In contrast, introduction of a phosphoserine mimetic at these sites rectified this functional defect, a finding consistent with a causal linkage between the phosphorylation status and proteolytic stability of this cytoplasmic inhibitor. Together, these in vivo studies define a critical signal response domain in I kappa B alpha that coordinately controls the biologic activities of I kappa B alpha and NF-kappa B in response to viral and immune stimuli.

Journal ArticleDOI
TL;DR: The lymphoid and respiratory systems have the most remarkable lesions and appear to be the major site of replication of these viruses.
Abstract: One hundred 4-week-old cesarean-derived colostrum-deprived pigs were inoculated with one of two different US porcine reproductive and respiratory syndrome virus (PRRSV) isolates (VR2385, VR2431) or the European Lelystad virus to detect and compare the location and amount of virus antigen. Interstitial pneumonia, myocarditis, lymphadenopathy, and encephalitis were consistently seen in all three groups; however, disease and lesions were more severe in the VR2385 group. Immunohistochemical evaluation of formalin-fixed tissues revealed virus antigen in alveolar macrophages in lungs of 22/25, 14/25, 14/25, and 0/25 of the VR2385, VR2431, Lelystad, and control pigs, respectively. Follicular macrophages and dendritic cells in the lymph nodes of 14/25, 10/25, 10/25, and 0/25 pigs from the VR2385, VR2431, Lelystad, and control groups, respectively, stained positive for virus antigen. Similar cells in the tonsils from 25/25, 21/25, 23/25, and 0/25 pigs from the VR2385, VR2431, Lelystad, and control groups, respectively, stained positive for virus antigen. Other tissues and cells in which virus antigen was detected included macrophages and endothelial cells in the heart, macrophages, and interdigitating cells in the thymus, macrophages and dendritic cells in the spleen and Peyer's patches, and macrophages in hepatic sinusoids, renal medullary interstitium, and adrenal gland. PRRSV persisted in macrophages in the lung, tonsil, lymph node, and spleen for at least 28 days. Significantly more PRRSV antigen was detected in the lung (P < 0.01), lymph nodes (P < or = 0.05), and tonsils (P < 0.05) of the VR2385 pigs than was detected in the same tissues of the VR2431 and Lelystad pigs. The cell types in which PRRSV antigen was detected and the distribution of PRRSV antigen-positive cells within particular tissues and organs were generally similar for the different virus inoculation groups despite differences in virulence of the isolates.

Journal ArticleDOI
27 Jul 1995-Nature
TL;DR: CD 19 is crucial for both initial B-cell activation by T-cell-dependent antigens and the maturation and/or selection of the activated cells into the memory compartment, and an impairment in ligand-driven selection may also be responsible for the observation of a striking reduction in the B-l B- cell subset.
Abstract: CD19 is the hallmark differentiation antigen of the B lineage. Its early expression has implicated a role for CD19 during the antigen-independent phases of B-cell development, whereas in mature B cells CD19 can act synergistically with surface immunoglobulin to induce activation. We have generated CD19-deficient mice and found that development of conventional B cells is unperturbed. However, mature CD19-/- B cells show a profound deficiency in responding to protein antigens that require T-cell help. This is accompanied by a lack of germinal centre formation and affinity maturation of serum antibodies. Thus CD19 is crucial for both initial B-cell activation by T-cell-dependent antigens and the maturation and/or selection of the activated cells into the memory compartment. An impairment in ligand-driven selection may also be responsible for the observation of a striking reduction in the B-1 (formerly Ly-1) B-cell subset, thought to develop under the control of self-antigens and bacterial antigens (reviewed in ref. 2).

Journal ArticleDOI
19 Jan 1995-Nature
TL;DR: In this article, the authors used flow cytometry to identify the presence of intracellular cytokines (cytoflow) and analyse T-cell production of IFN-gamma and IL-4 from mice infected with Listeria monocytogenes or Nippostrongylus brasiliensis.
Abstract: Exposure to various pathogens can stimulate at least two patterns of cytokine production by CD4-positive T cells. Responses that result in secretion of interferon-gamma (IFN-gamma), lymphotoxin and interleukin-2 (IL-2) are classified as T-helper-1 (Th1); CD4+ T-cell production of IL-4, IL-5, IL-9, IL-10 and IL-13 is called a T-helper-2 response (Th2). Differentiation of CD4+ T cells into either Th1 or Th2 cells is influenced by the cytokine milieu in which the initial antigen priming occurs. Here we use flow cytometry to identify the presence of intracellular cytokines (cytoflow) and analyse T-cell production of IFN-gamma and IL-4 from mice infected with Listeria monocytogenes or Nippostrongylus brasiliensis. We show that T cells bearing gamma delta receptors discriminate early in infection between these two pathogens by producing cytokines associated with the appropriate T-helper response. Our results demonstrate that gamma delta T cells are involved in establishing primary immune responses.

Journal ArticleDOI
TL;DR: Results suggest that blockade of costimulatory signals by CTLA4Ig or anti-B7-2 acts early in disease development, after insulitis but before the onset of frank diabetes, and that different members of the B7 family have distinct regulatory functions during the development of autoimmune diabetes.
Abstract: Insulin-dependent diabetes mellitus (IDDM) is thought to be an immunologically mediated disease resulting in the complete destruction of the insulin-producing islets of Langerhans. It has become increasingly clear that autoreactive T cells play a major role in the development and progression of this disease. In this study, we examined the role of the CD28/B7 costimulation pathway in the development and progression of autoimmune diabetes in the nonobese diabetic (NOD) mouse model. Female NOD mice treated at the onset of insulitis (2-4 wk of age) with CTLA4Ig immunoglobulin (Ig) (a soluble CD28 antagonist) or a monoclonal antibody (mAb) specific for B7-2 (a CD28 ligand) did not develop diabetes. However, neither of these treatments altered the disease process when administered late, at > 10 wk of age. Histological examination of islets from the various treatment groups showed that while CTLA4Ig and anti-B7-2 mAb treatment blocked the development of diabetes, these reagents had little effect on the development or severity of insulitis. Together these results suggest that blockade of costimulatory signals by CTLA4Ig or anti-B7-2 acts early in disease development, after insulitis but before the onset of frank diabetes. NOD mice were also treated with mAbs to another CD28 ligand, B7-1. In contrast to the previous results, the anti-B7-1 treatment significantly accelerated the development of disease in female mice and, most interestingly, induced diabetes in normally resistant male mice. A combination of anti-B7-1 and anti-B7-2 mAbs also resulted in an accelerated onset of diabetes, similar to that observed with anti-B7-1 mAb treatment alone, suggesting that anti-B7-1 mAb's effect was dominant. Furthermore, treatment with anti-B7-1 mAbs resulted in a more rapid and severe infiltrate. Finally, T cells isolated from the pancreas of these anti-B7-1-treated animals exhibited a more activated phenotype than T cells isolated from any of the other treatment groups. These studies demonstrate that costimulatory signals play an important role in the autoimmune process, and that different members of the B7 family have distinct regulatory functions during the development of autoimmune diabetes.

Journal ArticleDOI
TL;DR: It is concluded that currently available adenoviral vectors have serious limitations for use for long-term gene therapy.
Abstract: Recombinant adenoviruses containing the canine factor IX (FIX) cDNA were directly introduced in the hind leg muscle of mice. We show that (i) in nude mice, high expression (1-5 micrograms/ml in plasma) of FIX protein can be detected for > 300 days; (ii) in contrast, expression of FIX protein was transient (7-10 days) in normal mice; (iii) CD8+ lymphocytes could be detected within 3 days in the infected muscle tissue; (iv) use of beta 2-microglobulin and immunoglobulin M heavy chain "knockout" mice showed that lack of sustained expression of FIX protein is due to cell-mediated and humoral immune responses; (v) normal mice, once infected with recombinant adenovirus, could not be reinfected efficiently for at least 30 days due to neutralizing viral antibodies; and, finally, (vi) using immunosuppressive drugs, some normal mice can be tolerized to produce and secrete FIX protein for > 5 months. We conclude that currently available adenoviral vectors have serious limitations for use for long-term gene therapy.

Journal ArticleDOI
01 Feb 1995-Immunity
TL;DR: The identification of a new gene that codes for a putative protein of 43 aa and seems to belong to a family of several genes, which may prove useful for cancer immunotherapy.

Journal ArticleDOI
TL;DR: It is reported here the identification of the gene coding for MZ2-F, another antigen recognized by autologous CTL on Mz2-MEL cells.
Abstract: Human melanoma MZ2-MEL expresses several distinct antigens that are recognized by autologous cytolytic T lymphocytes (CTL). Some of these antigens are encoded by genes MAGE-1, MAGE-3, and BAGE, which are expressed in a large fraction of tumors of various histological types but are silent in normal adult tissues with the exception of testis. We report here the identification of the gene coding for MZ2-F, another antigen recognized by autologous CTL on MZ2-MEL cells. This gene, which was named GAGE-1, is not related to any presently known gene. It belongs to a family of genes that are expressed in a variety of tumors but not in normal tissues, except for the testis. Antigenic peptide YRPRPRRY, which is encoded by GAGE-1, is recognized by anti-MZ2-F CTL on class I molecule HLA-Cw6. The two genes of the GAGE family that code for this peptide, namely GAGE-1 and GAGE-2, are expressed in a significant proportion of melanomas (24%), sarcomas (25%), non-small cell lung cancers (19%), head and neck tumors (19%), and bladder tumors (12%). About 50% of melanoma patients carry on their tumor at least one of the presently defined antigens encoded by the MAGE, BAGE, and GAGE genes.

Journal ArticleDOI
TL;DR: Synthetic peptide analogues of sequences in the HER-2 protooncogene (HER-2) were selected based on the presence of HLA-A2.1 anchor motifs to identify the epitopes on Her-2 recognized by ovarian tumor-reactive CTL.
Abstract: Synthetic peptide analogues of sequences in the HER-2 protooncogene (HER-2) were selected based on the presence of HLA-A2.1 anchor motifs to identify the epitopes on HER-2 recognized by ovarian tumor-reactive CTL. 19 synthetic peptides were evaluated for recognition by four HLA-A2 ovarian-specific cytotoxic T lymphocyte (CTL) lines obtained from leukocytes associated with ovarian tumors. The nonapeptide E75 (HER-2, 369-377:KIFGSLAFL) was efficient in sensitizing T2 cells for lysis by all four CTL lines. This peptide was specifically recognized by cloned CD8+ CTL isolated from one of the ovarian-specific CTL lines. E75-pulsed T2 cells inhibited lysis by the same CTL clone of both an HLA-A2+ HER-2high ovarian tumor and a HER-2high cloned ovarian tumor line transfected with HLA-A2, suggesting that this or a structurally similar epitope may be specifically recognized by these CTL on ovarian tumors. Several other HER-2 peptides were recognized preferentially by one or two CTL lines, suggesting that both common and private HER-2 epitopes may be immunogenic in patients with ovarian tumors. Since HER-2 is a self-antigen, these peptides may be useful for understanding mechanisms of tumor recognition by T cells, immunological tolerance to tumor, and structural characterization of tumor antigens.

Journal Article
TL;DR: Four of ten HLA-A2-restricted melanoma specific CTL that were derived from tumor-infiltrating lymphocytes (TIL) and administered to patients recognized the gp100 melanoma Ag and nine of ten recognized the MART-1 Ag.
Abstract: Four of ten HLA-A2-restricted melanoma specific CTL that were derived from tumor-infiltrating lymphocytes (TIL) and administered to patients recognized the gp100 melanoma Ag and nine of ten recognized the MART-1 Ag. Adoptive transfer of the four gp100-reactive CTL, but not the other TIL, resulted in tumor regression when infused into autologous patients along with IL-2. Tumor regression was thus correlated with the recognition of gp100 by the administered T cells (p = 0.0048). To identify the epitopes recognized by these four gp100-reactive CTL, 169 peptides containing HLA-A2.1 binding motifs were synthesized and screened for their recognition by TIL using cytotoxicity and IFN-gamma release assays. Five gp100 epitopes (two for TIL620, three for TIL660, one for TIL1143, and two for TIL1200) were recognized by CTL derived from different patients. Five of eight HLA-A2 binding melanoma epitopes (five gp100, one MART-1/Melan-A, two tyrosinase) had intermediate binding affinity to HLA-A2.1. These gp100 epitopes may be responsible for mediating tumor rejection in vivo and thus may be useful for the development of immunotherapies for patients with melanoma.

Journal ArticleDOI
TL;DR: Recent work suggests that the peptide/MHC ligand for positive selection may bind with low avidity to the TCR, which could have implications for the nature of T cell recognition during positive selection.
Abstract: Differentiation of alpha beta T cell receptor (TCR)-expressing T cells involves an obligatory interaction with self-major histocompatibility complex (MHC) molecules in the thymus This process, called positive selection, both rescues thymocytes from programmed cell death and induces their differentiation into mature T cells Another critical event in thymic development is to prevent maturation of hazardous autoreactive T cells; thus, mechanisms exist to eliminate T cells with self-reactive receptors (negative selection) How can these two pathways be distinguished? This question, which has long taxed immunologists, is more opposite because many features of the interactions in positive and negative selection are shared: Both processes are exquisitely MHC-allele specific, they involve MHC-bound peptide recognition, and employ at least some overlapping signal transduction pathways However, resolution of this paradox has become much more feasible with the advent of powerful systems for withdrawing and reconstituting individual components involved in positive selection This review describes recent advances in our understanding of the cells, receptors, ligands, and signaling pathways involved in this process A pivotal part of this puzzle is the basis for discrimination between TCR ligands that induce positive vs negative selection Recent work suggests that the peptide/MHC ligand for positive selection may bind with low avidity to the TCR The implications of these data for the nature of T cell recognition during positive selection are discussed below

Journal ArticleDOI
30 Nov 1995-Nature
TL;DR: The structure shows that the CLIP fragment binds to DR3 in a way almost identical to that in which antigenic peptides bind class II histocompatibility gly cop rote ins.
Abstract: A complex between HLA-DR3 and a fragment of invariant chain called CLIP was isolated from a human cell line defective in antigen presentation and its X-ray crystal structure determined. Previous data indicate that this complex is an intermediate in class II histocompatibility maturation, occurring between invariant chain-DR3 and antigenic peptide-DR3 complexes. The structure shows that the CLIP fragment binds to DR3 in a way almost identical to that in which antigenic peptides bind class II histocompatibility glycoproteins. The structure is the substrate for the loading of antigenic peptides by an exchange process catalysed by DM.