Search PubMed⌕ Search

Biomedical subjects

F Ronchese

Publications and source records attributed to F Ronchese.

At least 19 recordsLinked to original sources
PubMed2004

B-Lymphocytes activated by CD40 ligand induce an antigen-specific anti-tumour immune response by direct and indirect activation of CD8(+) T-cells.

In this report, we describe the ability of CD40-ligand (CD40L)-activated, antigen-loaded B-cells to initiate antigen-specific anti-tumour immune responses in vivo. Mice immunized by means of intravenous administration of CD40L-activated B-cells loaded with an MHC class-I-binding peptide, and challenged with a tumour cell line expressing the same class-I epitope, showed a marked delay in tumour growth, compared to non-immunized controls or to mice receiving either freshly isolated B-cells or B-cells activated with lipopolysaccharide or interleukin-4. The ability of CD40L-activated B-cells to induce antigen-specific T-cell activation appeared to be through a combination of cross-presentation of antigen from activated B-cells to resident antigen-presenting cells and direct T-cell activation by the administered B-cells themselves. Immunization with CD40L-activated B-cells may, therefore, represent a means by which to stimulate anti-tumour CD8(+) T-cell responses in vivo.

Animals↗
PubMed2001

Tumor-specific Tc1, but not Tc2, cells deliver protective antitumor immunity.

We investigated whether secretion of multiple cytokines by CD8+ T cells is associated with improved protection against tumor challenge. We show that antitumor immunity induced by immunization with dendritic cells and a MHC class I-binding tumor peptide are dependent on secretion of IFN-gamma but not IL-4 or IL-5 by host cells. To further address the role of IL-4 and IL-5 in antitumor immunity, tumor-specific TCR-transgenic CD8+ T cells were activated in vitro to generate cytotoxic T (Tc) 1 cells that secrete high IFN-gamma and no IL-4 or IL-5 or Tc2 cells that secrete IL-4, IL-5, and some IFN-gamma. Both cell types killed target cells in vitro. Tc1 and Tc2 cells were adoptively transferred into syngeneic hosts, and their ability to protect against tumor challenge was compared. Tc1 cells were able to significantly delay tumor growth, whereas Tc2 cells or Tc2 cells from IFN-gamma(-/-) donors had no effect. This was due to neither the inability of Tc2 cells to survive in vivo or to migrate to the tumor site nor their inability to secrete IL-4 and/or IL-5 in the presence of limiting amounts of anti-CD3. However, IFN-gamma secretion by Tc2 cells was triggered inefficiently by restimulation with Ag compared with anti-CD3. We conclude that the ability to secrete "type 2" cytokines, and cytotoxic ability, have a limited role in antitumor immune responses mediated by CD8+ T cells, whereas the capacity to secrete high amounts of IFN-gamma remains the most critical antitumor effector mechanism in vivo.

Animals↗
PubMed2001

Gene microarrays reveal extensive differential gene expression in both CD4(+) and CD8(+) type 1 and type 2 T cells.

An important subdivision of effector T cells can be made based on patterns of cytokine production and functional programs. Type 1 T cells produce IFN-gamma and protect against viral pathogens, whereas type 2 cells produce cytokines such as IL-4 and IL-5 and protect against large extracellular parasites. Both CD4(+) and CD8(+) T cells can be polarized into type 1 or type 2 cytokine-secreting cells, suggesting that both populations play a regulatory role in immune responses. In this study, we used high-density oligonucleotide arrays to produce a comprehensive picture of gene expression in murine CD4(+) Th1 and Th2 cells, as well as CD8(+) type 1 and type 2 T cells. Polarized type 1 and 2 cells transcribed mRNA for an unexpectedly large number of genes, most of which were expressed in a similar fashion between type 1 and type 2 cells. However, >100 differentially expressed genes were identified for both the CD4(+) and CD8(+) type 1 and 2 subsets, many of which have not been associated with T cell polarization. These genes included cytokines, transcription factors, molecules involved in cell migration, as well as genes with unknown function. The program for type 1 or type 2 polarization was similar for CD4(+) and CD8(+) cells, since gene expression patterns were roughly the same. The expression of select genes was confirmed using real-time PCR. The identification of genes associated with T cell polarization may give important insights into functional and phenotypic differences between effector T cell subsets and their role in normal responses and inflammatory disease.

Animals↗
PubMed2001

CD80 costimulation is required for Th2 cell cytokine production but not for antigen-specific accumulation and migration into the lung.

The CD28 ligands CD80 and CD86 are expressed on APC, and both provide costimulatory function. However, the reason for the expression of two separate CD28 ligands remains unclear. We have previously shown that blockade of CD80 costimulation by Y100F-Ig, a CTL-associated Ag-4 (CTLA4)-Ig mutant that does not bind CD86, inhibits the development of lung inflammatory immune responses, but does not affect blood eosinophilia or Ab production. Each of those responses was inhibited by treatment with CTLA4-Ig, which binds both CD80 and CD86. To clarify the mechanism underlying these observations we have developed a model of lung inflammation using adoptively transferred CD4(+) T cells expressing a Valpha11(+)Vbeta3(+) transgenic TCR specific for I-E(k) and moth cytochrome c. Treatment with Y100F-Ig inhibited the induction of lung eosinophilia in adoptively transferred mice. However, Y100F-Ig did not detectably affect the accumulation of Ag-specific T cells at the site of peptide deposit or in the draining lymphoid tissues. Acquisition of an activated phenotype and expression of adhesion molecules required for migration into the lung were modestly affected. Importantly, treatment with Y100F-Ig diminished the ability of T cells to produce the cytokines IL-4 and IL-5 following intranasal challenge with Ag. All the responses examined were severely inhibited by treatment with CTLA4-Ig. We conclude that T cells require CD80 costimulation for the optimal production of IL-5 following intranasal administration of Ag. Decreased IL-5 production is the most likely explanation for the diminished airway eosinophilia observed.

Abatacept↗
PubMed2000

Dendritic cell elimination as an assay of cytotoxic T lymphocyte activity in vivo.

We show in this paper that the survival of antigen-loaded dendritic cells in vivo may be used as a sensitive readout of CTL activity. We have previously shown that dendritic cells labeled with the fluorescent dye CFSE and injected sub-cutaneously into mice migrate spontaneously to the draining lymph node where they persist for several days. In the presence of effector CTL responses, dendritic cells loaded with specific antigen rapidly disappear from the draining lymph node. In this paper we extend the above observations and set up a simple and sensitive method to reveal CTL activity in individual mice in vivo. Dendritic cells were labeled with two different fluorochromes, loaded with antigen or left untreated, and mixed together before injection into mice. We show that only the dendritic cells loaded with specific antigen were cleared from the draining lymph node, while dendritic cells not loaded with antigen remained unaffected. Cytotoxic responses generated by immunization with peptide-loaded dendritic cells, or by infection with influenza virus, could be revealed using this method. Comparison of the differential survival of dendritic cells populations mixed together also allowed us to accurately evaluate the disappearance of dendritic cells, irrespective of variability in the injection site and other parameters. Given the ability of dendritic cells to efficiently take up and present complex antigens, nucleic acids and apoptotic bodies, this method may also allow the evaluation of cytotoxic activity against antigens that are not characterized in terms of peptide epitopes.

Animals↗
PubMed2000

Immunotherapy with dendritic cells and tumor major histocompatibility complex class I-derived peptides requires a high density of antigen on tumor cells.

Immunization with dendritic cells and unfractionated MHC class I-binding peptides derived from autologous tumor cells has been shown to induce effective antitumor immunity. However, the importance of the relative abundance of tumor peptides on the surface of tumor cells is not known. We have addressed this question using peptides isolated from three tumor cell lines transfected with a minigene encoding amino acids 33-41 of the lymphocytic choriomeningitis virus glycoprotein (LCMV(33-41)). The three cell lines expressed different levels of MHC class I molecules and had different abilities to stimulate proliferation of LCMV(33-41)-specific T cells in vitro. We found that antitumor immune responses were best elicited by immunizing mice with dendritic cells and synthetic LCMV(33-41) peptide. Peptide preparations from a given tumor cell line conferred protection against challenge with the same tumor cell line. However, protective immunity to a different tumor could be induced only if the cell line used for peptide preparation presented a high relative proportion of LCMV(33-41) in association with MHC class I. Our results suggest that multiple peptide epitopes are required for the induction of an effective antitumor immune response using MHC class I-binding peptides from tumor cells. Also, the ability to induce an antitumor immune response appears to correlate with the proportion, rather than the absolute amount, of tumor-specific peptide in the mixture used for immunization.

Animals↗
PubMed2000

CD8+ T cell-dependent elimination of dendritic cells in vivo limits the induction of antitumor immunity.

The fate of dendritic cells (DC) after they have initiated a T cell immune response is still undefined. We have monitored the migration of DC labeled with a fluorescent tracer and injected s.c. into naive mice or into mice with an ongoing immune response. DC not loaded with Ag were detected in the draining lymph node in excess of 7 days after injection with maximum numbers detectable approximately 40 h after transfer. In contrast, DC that had been loaded with an MHC class I-binding peptide disappeared from the lymph node with kinetics that parallel the known kinetics of activation of CD8+ T cells to effector function. In the presence of high numbers of specific CTL precursors, as in TCR transgenic mice, DC numbers were significantly decreased by 72 h after injection. The rate of DC disappearance was extremely rapid and efficient in recently immunized mice and was slower in "memory" mice in which memory CD8+ cells needed to reacquire effector function before mediating DC elimination. We also show that CTL-mediated clearance of Ag-loaded DC has a notable effect on immune responses in vivo. Ag-specific CD8+ T cells failed to divide in response to Ag presented on a DC if the DC were targets of a pre-existing CTL response. The induction of antitumor immunity by tumor Ag-loaded DC was also impaired. Therefore, CTL-mediated clearance of Ag-loaded DC may serve as a negative feedback mechanism to limit the activity of DC within the lymph node.

Animals↗
PubMed2000

Differential requirement for CD80 and CD80/CD86-dependent costimulation in the lung immune response to an influenza virus infection.

The CD28 costimulatory pathway is critical to T cell activation. Blockade of the interaction of CD28 with its ligands CD80 and CD86 using CTLA4-Ig has been proposed as a therapy for a number of immune-based disorders. We have used a murine model of influenza virus infection to study the role of CD28-dependent costimulation in the development of antiviral immune responses. In vivo treatment with CTLA4-Ig to block the interaction of CD28 with CD80 and CD86 reduced virus-specific cytotoxicity and IFN-gamma production by bronchoalveolar lavage fluid CD8+ T lymphocytes in vitro. It also resulted in decreased numbers of virus-specific CD8+ T lymphocytes in the bronchoalveolar lavage fluid, lung, and spleen and lowered virus-specific Ab titers. Mice treated with CTLA4-Ig were able to control and clear the virus infection, but this was delayed compared with controls. Treatment with Y100F-Ig, a mutant form of CTLA4-Ig which selectively binds to CD80 and blocks the CD28-CD80 interaction leaving CD28-CD86 binding intact, did not affect Ab production, spleen cytotoxic precursors, or clearance of virus. However, Y100F-Ig treatment had a clear effect on lung effector cell function. Secretion of IFN-gamma by bronchoalveolar lavage fluid CD8+ T lymphocytes in vitro was decreased, and the number of virus-specific CD8+ T lymphocytes in the bronchoalveolar lavage fluid and lungs of infected mice was reduced. These results indicate that CD28-dependent costimulation is important in the antiviral immune response to an influenza virus infection. The individual CD28 ligand, CD80, is important for some lung immune responses and cannot always be compensated for by CD86.

Abatacept↗
PubMed1999

Impaired ability of MHC class II-/- dendritic cells to provide tumor protection is rescued by CD40 ligation.

The contribution of CD4+ T cells to dendritic cell (DC) activation and to the induction of CD8+ T cell responses in vivo was investigated using a model of antitumor immune responses. Immunization with peptide-loaded MHC class II-deficient (MHC class II-/-) DC induced the activation of Ag-specific CD8+ T cells and their accumulation in the lymph nodes and spleens of immunized mice. The accumulation induced by MHC class II-/- DC immunization was lower than the accumulation observed after immunization with MHC class II+/+ DC. Similarly, immunization with peptide-loaded, MHC class II-/- DC induced some degree of protection against tumor challenge, but this protection was lower than the protection achieved after immunization with MHC class II+/+ DC. Incubation with a membrane-associated form of CD40 ligand resulted in the up-regulation of costimulatory molecules on MHC class II-/- DC and fully rescued their ability to induce antitumor immunity. We conclude that CD4+ T cells play a critical role in the generation of antitumor immune responses through their capacity to induce the activation of DC via CD40/CD40 ligand interaction, and thus maximize CD8+ T cell responses.

Animals↗
PubMed1999

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) can regulate dendritic cell-induced activation and cytotoxicity of CD8(+) T cells independently of CD4(+) T cell help.

The mechanisms that regulate the strength and duration of CD8(+) cytotoxic T cell activity determine the effectiveness of an antitumor immune response. To better understand the antitumor effects of anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibody treatment, we analyzed the effect of CTLA-4 signaling on CD8(+) T cells in vitro and in vivo. In vitro, cross-linking of CTLA-4 on purified CD8(+) T cells caused decreased proliferative responses to anti-CD3 stimulation and rapid loss of activation marker expression. In vivo, blockade of CTLA-4 by neutralizing anti-CTLA-4 mAb greatly enhanced the accumulation, activation, and cytotoxic activity of CD8(+) T cells induced by immunization with Ag on dendritic cells (DC). This enhanced response did not require the expression of MHC class II molecules on DC or the presence of CD4(+) T cells. These results demonstrate that CTLA-4 blockade is able to directly enhance the proliferation and activation of specific CD8(+) T cells, indicating its potential for tumor immunotherapy even in situations in which CD4(+) T cell help is limited or absent.

Abatacept↗
PubMed1999

CTLA4-Ig inhibits optimal T helper 2 cell development but not protective immunity or memory response to Nippostrongylus brasiliensis.

The B7 co-stimulatory pathway is critical to T cell activation, however its role in the generation of Th2 cells in vivo remains controversial. We have studied the role of B7 co-stimulation in the development of a Th2 immune response to the nematode parasite Nippostrongylus brasiliensis. Blockade of B7 co-stimulation with murine CTLA4-Ig (mCTLA4-Ig) resulted in decreased Th2 cell development as determined by IL-4 and IL-5 cytokine production in vitro. It also resulted in lowered Th2 cell effector function in vivo, with marked reductions in IgE production. Blood eosinophilia was variably affected by mCTLA4-Ig treatment, which resulted in both slight and very severe inhibition in different experiments. However, an effective immune response was still evident as demonstrated by the further reduction of cytokine production, IgE titers, and blood eosinophilia in mice treated with a combination of mCTLA4-Ig and anti-CD4 mAb, and by the ability of mCTLA4-Ig-treated mice to expel adult worms. In addition, mCTLA4-Ig treatment did not alter the development of a memory response following secondary infection with N. brasiliensis, with the exception of IgE production. We conclude from these results that B7 co-stimulation is required in this experimental model for optimal Th2 cell development and effector function in vivo but is not necessary for protective immunity.

Abatacept↗
PubMed1999

The role of B7 costimulation in T-cell immunity.

CD4+ T cells are considered to be the major controlling element of the adaptive immune response. They recognize foreign peptides by interaction of the T cell receptor (TCR) with peptide complexed to major histocompatibility complex (MHC) class II molecules on the surface of antigen presenting cells (APC). Once activated, CD4+ T cells orchestrate the various phases of the immune response. They are responsible for the production of numerous cytokines, which activate specific immune effector cell populations including B cells, eosinophils, mast cells and macrophages. Not surprisingly, the activation of CD4+ T cells needs to be tightly regulated and is subject to finely tuned control mechanisms. The requirement for a second or 'costimulatory' signal, in addition to the antigenic signal, provides a key element for the exquisite control of T cell activation. One of the major signalling pathways responsible for delivery of this costimulatory signal is induced by interaction of CD28 on T cells with B7 molecules found only on APC. The present review outlines our current understanding of the physiological role of B7 costimulatory signals in regulating CD4+ T cell responses.

Abatacept↗
PubMed1998

Antigen expressed on tumor cells fails to elicit an immune response, even in the presence of increased numbers of tumor-specific cytotoxic T lymphocyte precursors.

We have used T-cell receptor (TCR) transgenic mice to analyze the interaction of tumors with the immune system. We show that the tumor cell line Lewis lung-lymphocytic choriomeningitis virus (LL-LCMV), genetically manipulated to express an H-2 Db-restricted epitope of the lymphocytic choriomeningitis virus glycoprotein (LCMV33-41), can grow progressively in TCR transgenic mice, where approximately 50% of CD8+ T cells are specific for LCMV33-41. TCR transgenic T cells were not deleted in tumor-bearing mice, and their surface phenotype and cytokine secretion patterns remained typical of naive T cells. Also, TCR transgenic T cells from tumor-bearing mice had undiminished capacity to proliferate to antigen in vitro. Tumor-protective immune responses could be elicited in TCR transgenic mice by immunization with LCMV33-41 peptide-loaded dendritic cells. Tumor resistance correlated with the switch of TCR transgenic T cells from a CD44low to a CD44high phenotype and increased capacity to produce IFNgamma in vitro. Results similar to those obtained in TCR transgenic mice were also obtained using an adoptive transfer system, where small numbers of TCR transgenic T cells were injected into normal C57BL/6 hosts. These data indicate that even large tumors may not induce specific immunization, tolerance, or anergy to tumor antigens, and that high numbers of tumor-specific CTL precursors are not sufficient to provide tumor resistance.

Adoptive Transfer↗
PubMed1998

The emerging role of the dendritic cell in novel cancer therapies.

Research over the last two years has explored a number of possible approaches to applying dendritic cell immunotherapy to the treatment of human cancers. The chosen strategy in clinical situations will vary for individual patients and will depend on the type of tumour, availability of tissue samples and potential source of dendritic cells. We believe that the isolation of fractionated tumour peptide from individual patients' tumours for use with autologous stem cell-derived dendritic cells may provide, in at least some cases, an effective and practical approach to cancer immunotherapy. This approach will provide a 'closed' system of tumour immunotherapy with all components (dendritic cells, antigen and cytotoxic T lymphocytes) being provided by the patient and applied in a tailor-made fashion to individual patients as an adjuvant to current anti-tumour therapies.

Antigens, Neoplasm↗
PubMed1998

Immunoregulatory networks in asthma.

It is now well established that a subset of T-cell-derived cytokines (termed Th2 cytokines) programme the timing and characteristics of atopic airway disease including mast-cell sensitization, eosinophil and lymphocyte infiltration and recently mucus secretion. To date, attempts to devise ways to selectively limit the activities of Th2 cytokine-producing cells have been frustrated. However, the recent identification of the molecules which direct the activation and maturation of T cells has led to some successful attempts to block the activities of Th2 cells in models of atopic airway inflammation. Some of the agents with the most potential include antagonists of the T-cell costimulatory molecule CD28, local stimulators of the Thl subset of cytokines such as the BCG vaccine and potentially, antagonists of the eotaxin chemokine receptor and agonists of the T-cell costimulatory molecule CTLA-4. Not only do such agonists and antagonists represent potential new therapies, they could represent a rich hunting ground for those who aim to determine the ways in which atopic airway disease can be diagnosed and understood.

Abatacept↗
PubMed1997

CD80 costimulation is essential for the induction of airway eosinophilia.

CD80 and CD86 (B7-1 and B7-2) are the ligands on antigen-presenting cells (APCs) which bind CD28 and deliver the costimulatory signals necessary for T cell activation. The reasons for the existence of two CD28 binding molecules are not well understood. We created a mutant version of CTLA4-Ig that could selectively bind CD80 and block CD28-CD80 interaction but leave CD28-CD86 binding intact. CD80 blockade prevented antigen-induced accumulation of eosinophils and lymphocytes in the lung of immunized mice, but did not block antigen induced systemic blood eosinophilia or IgE antibody production. No preferential expression of CD80 could be demonstrated on a population of lung APC consisting mainly of macrophages. These results indicate that CD80 costimulation is not necessary for the induction of Th2 immune responses but rather for the maintenance or amplification of lung inflammatory responses.

Abatacept↗
PubMed1997

Blockade of CD28/B7 co-stimulation by mCTLA4-Hgamma1 inhibits antigen-induced lung eosinophilia but not Th2 cell development or recruitment in the lung.

We have studied the role of the CD28/B7 co-stimulatory pathway in the development of a Th2-type lung immune response. Mice injected two or three times intraperitoneally with ovalbumin in alum adjuvant and then re-exposed to the same antigen by intranasal (i.n.) inoculation show infiltration of the lung tissue and appearance in the broncho-alveolar lavage (BAL) fluid of significant numbers of eosinophils and lymphocytes, in a pattern which is reminiscent of asthmatic inflammation. The accumulation of eosinophils in the airways is completely dependent on interleukin (IL)-5 secretion by CD4+ T cells. We have used mice transgenic for a soluble form of murine CTLA-4 (mCTLA4-Hgamma1) which binds to B7 molecules on antigen-presenting cells, thereby preventing their interaction with T cell-expressed CD28. mCTLA4-Hgamma1-transgenic mice immunized intraperitoneally and challenged i.n. with ovalbumin failed to generate any eosinophil infiltration, suggesting that little or no IL-5 was secreted in the lungs of these mice. In contrast with the complete lack of eosinophils, the numbers and phenotypes of infiltrating lymphocytes were comparable in the lungs of mCTLA4-Hgamma1-transgenic and normal mice. Also, lung lymphocytes from immunized mCTLA4-Hgamma1-transgenic and normal mice could be shown to secrete comparable amounts of IL-4 and IL-5 when stimulated in culture in the absence of mCTLA4-Hgamma1. We conclude that mCTLA4-Hgamma1 can efficiently block the production of IL-5 during in vivo responses and inhibit eosinophil recruitment, but that it does not block the development of CD4+ T cells into Th2 cells with the potential to secrete IL-5.

Abatacept↗