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Franca Ronchese

Publications and source records attributed to Franca Ronchese.

16 recordsLinked to original sources
PubMed2006

Long-term deposition of inhaled antigen in lung resident CD11b-CD11c+ cells.

In this study we report the characterization of a population of lung resident CD11b(-)CD11c(+) cells that are able to take up inhaled antigen and retain it for extended periods of time. Ovalbumin conjugated to fluorescein-isothiocyanate (FITC-OVA) administered intranasally to mice was taken up by two main populations of cells in the lung, a migratory CD11c(+)CD11b(+) population consisting of dendritic cells (DC), which rapidly transported antigen to the draining lymph node (LN), and a resident CD11b(-)CD11c(+) population that retained engulfed antigen without apparently degrading it for up to 8 wk after administration. The FITC(+)CD11b(-)CD11c(+) cells did not migrate to draining LN at a detectable rate, and did not up-regulate expression of costimulatory molecules in response to LPS treatment. FITC(+)CD11b(-)CD11c(+) cells were found in the lung and bronchoalveolar lavage fluid, and their distribution was compatible with macrophages. Although FITC(+)CD11b(-)CD11c(+) cells expressed the DC marker DEC205 and other molecules associated with antigen-presenting cell function, they did not induce proliferation of antigen-specific CD4(+) T cells in vitro or acute cytokine production by activated CD4(+) T cells in vivo. Thus, FITC(+)CD11b(-)CD11c(+) cells appear to represent an intermediate cell type sharing properties with DC and macrophages. These cells may have a role in modulating the responses of lung resident T cells to inhaled antigens.

Administration, Intranasal↗
PubMed2006

A2A adenosine receptor protects tumors from antitumor T cells.

The A2A adenosine receptor (A2AR) has been shown to be a critical and nonredundant negative regulator of immune cells in protecting normal tissues from inflammatory damage. We hypothesized that A2AR also protects cancerous tissues by inhibiting incoming antitumor T lymphocytes. Here we confirm this hypothesis by showing that genetic deletion of A2AR in the host resulted in rejection of established immunogenic tumors in approximately 60% of A2AR-deficient mice with no rejection observed in control WT mice. The use of antagonists, including caffeine, or targeting the A2 receptors by siRNA pretreatment of T cells improved the inhibition of tumor growth, destruction of metastases, and prevention of neovascularization by antitumor T cells. The data suggest that effects of A2AR are T cell autonomous. The inhibition of antitumor T cells via their A2AR in the adenosine-rich tumor microenvironment may explain the paradoxical coexistence of tumors and antitumor immune cells in some cancer patients (the "Hellstrom paradox"). We propose to target the hypoxia-->adenosine-->A2AR pathway as a cancer immunotherapy strategy to prevent the inhibition of antitumor T cells in the tumor microenvironment. The same strategy may prevent the premature termination of immune response and improve the vaccine-induced development of antitumor and antiviral T cells. The observations of autoimmunity during melanoma rejection in A2AR-deficient mice suggest that A2AR in T cells is also important in preventing autoimmunity. Thus, although using the hypoxia-->adenosine-->A2AR pathway inhibitors may improve antitumor immunity, the recruitment of this pathway by selective drugs is expected to attenuate the autoimmune tissue damage.

Adenosine↗
PubMed2006

Langerhans cells cross-present antigen derived from skin.

Dendritic cells (DC) efficiently cross-present exogenous antigen on MHC class I molecules to CD8+ T cells. However, little is known about cross-presentation by Langerhans cells (LC), the DCs of the epidermis. Therefore, we investigated this issue in detail. Isolated murine LCs were able to cross-present soluble ovalbumin protein on MHC-class I molecules to antigen-specific CD8+ T cells, albeit less potently than the CD8+ DC subsets from spleen. Furthermore, LCs cross-presented cell-associated ovalbumin peptide and protein expressed by neighboring keratinocytes. Use of transporter associated with antigen processing (TAP-1)-deficient mice suggested a TAP-dependent pathway. Similar observations were made with migratory LC. Antigen expressed in the epidermis was ingested by LCs during migration from the epidermis and presented to antigen-specific T cells in vitro. Cross-presentation of ovalbumin protein by LCs induced IFN-gamma production and cytotoxicity in antigen-specific CD8+ T cells. Additionally, epicutaneous application of ovalbumin protein induced in vivo proliferation of OT-I T cells in the draining lymph nodes; this was markedly enhanced when antigen was applied to inflamed, barrier-disrupted skin. Thus, LCs cross-present exogenous antigen to CD8+ T cells and induce effector functions, like cytokine production and cytotoxicity, and may thereby critically contribute in epicutaneous vaccination approaches.

Animals↗
PubMed2006

Autologous dendritic cells pulsed with eluted peptide as immunotherapy for advanced B-cell malignancies.

We have studied the feasibility, safety and efficacy of vaccination with autologous dendritic cells pulsed with eluted peptide in patients with advanced low-grade B-cell malignancies. This study demonstrates that autologous dendritic cell vaccines can be successfully produced from patients with advanced disease and be delivered without significant toxicity. Furthermore, we have demonstrated immunological and clinical responses in two of ten patients treated. These results provide further evidence for the use of immunotherapy in the management of B-cell malignancies, but also suggest that sustained responses may only be possible in patients with low bulk disease early in the disease course.

Adult↗
PubMed2006

5,6-Dimethylxanthenone-4-acetic acid treatment of a non-immunogenic tumour does not synergize with active or passive CD8+ T-cell immunotherapy.

The chemotherapeutic drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA) inhibits intratumoural blood flow, causing hypoxia, haemorrhagic necrosis, vascular collapse and tumour cell death. Production of TNF-alpha and IFN is also induced, causing local inflammation and activation of immune cells including CD8+ T cells. We used the tumour cell line LL-LCMV, which expresses the gp33 epitope of lymphocytic choriomeningitis virus in a non-immunogenic form, to investigate whether tumour cell death caused by treatment with DMXAA may improve the success of tumour immunotherapy mediated by CD8+ T cells. Treatment with DMXAA was effective at reducing the size of LL-LCMV tumours. However, compared to normal mice, tumour reduction was no more marked or sustained in mice carrying high numbers of naive, tumour-specific CD8+ T cells. The antitumour effect of activated CD8+ T cells was also not affected by DMXAA treatment. Tumour-specific CD8+ T cells activated in vivo by immunization with dendritic cells and specific tumour peptide antigen, or generated in vitro and adoptively transferred into tumour-bearing mice by i.v. injection, did not improve or sustain the reduction in tumour size induced by DMXAA treatment. We conclude that the presence of high numbers of naive CD8+ T cells, or immunotherapies leading to CD8+ T-cell activation, do not synergize with the tumour cell death and local inflammation induced by DMXAA treatment. It is possible that this lack of synergism may result from both treatments inducing activation of CD8+ T cells and that treatments that activate different populations of immune cells may achieve better success.

Animals↗
PubMed2005

Perforin-dependent elimination of dendritic cells regulates the expansion of antigen-specific CD8+ T cells in vivo.

The lifespan and survival of dendritic cells (DC) in vivo are potentially critical to the expansion of T cell immune responses. We have previously reported that DC loaded with specific antigen are rapidly eliminated by cytotoxic T lymphocytes (CTL) in vivo, but the site, mechanism, and consequences of DC elimination were not defined. In this article we show that DC elimination in vivo occurs in a perforin-dependent manner and does not require IFN-gamma or the presence of CD4(+)CD25(+) regulatory T cells. Most importantly, failure to eliminate DC had profound consequences on the CTL immune response. Perforin-deficient mice showed a progressive increase in the numbers of antigen-specific CD8(+) T cells after repeated immunizations with DC. In contrast, in control mice the number of antigen-specific CD8(+) T cells did not notably increase with repeated immunizations. Lastly, we also show that CTL-mediated elimination of DC occurs in peripheral tissues but not in the lymph node. Our data suggest that CTL act as "gatekeepers" that control access of antigen-loaded DC into the lymph node, thereby preventing continued expansion of antigen-specific T cells.

Adoptive Transfer↗
PubMed2005

Dendritic cells loaded with stressed tumor cells elicit long-lasting protective tumor immunity in mice depleted of CD4+CD25+ regulatory T cells.

Dendritic cell (DC)-based vaccination represents a promising approach to harness the specificity and potency of the immune system to combat cancer. Finding optimal strategies for tumor Ag preparation and subsequent pulsing of DC, as well as improving the immunogenicity of weak tumor Ags remain among the first challenges of this approach. In this report, we use a prophylactic vaccine consisting of DC loaded with whole, nonmanipulated B16-F10 melanoma cells that had been stressed by heat shock and gamma irradiation. Stressed B16-F10 cells underwent apoptosis and were internalized by bone marrow-derived DC during coculture. Surprisingly, coculture of DC with stressed B16-F10 undergoing apoptosis and necrosis did not induce DC maturation. However, a marked retardation in tumor growth was observed in C57BL/6 mice immunized using DC loaded with stressed B16-F10 cells and subsequently challenged with B16-F10 cells. Growth retardation was further increased by treating DC with LPS before in vivo administration. In vivo depletion studies revealed that both CD8(+) and CD4(+) T cells played a critical role in retarding tumor growth. In addition, treatment with anti-CD25 Ab to deplete CD4(+)CD25(+) regulatory T cells before DC vaccination considerably improved the effect of the vaccine and allowed the development of long-lived immune responses that were tumor protective. Our results demonstrate that depletion of regulatory T cells is an effective approach to improving the success of DC-based vaccination against weakly immunogenic tumors. Such a strategy can be readily applied to other tumor models and extended to therapeutic vaccination settings.

Animals↗
PubMed2005

Effector lymphoid tissue and its crucial role in protective immunity.

It is often argued that T cell-mediated immunity to secondary infection is dependent on the 'accelerated' responses of memory T cells in lymph nodes. However, new evidence points to a crucial role for effector memory T cells, which are resident in peripheral tissues, in immune protection. These T cells, which reside in peripheral tissues, are not necessarily bound by an anatomical structure and can be present at many sites. Collectively, they represent a third functional tissue of the immune system, uniquely specialized to mediate protective immunity. We propose that the paradigm 'effector lymphoid tissue' needs to be articulated and developed as a focus of new research to describe and understand the unique role this tissue has in protective immunity.

Animals↗
PubMed2005

The phenotype of type 1 and type 2 CD8+ T cells activated in vitro is affected by culture conditions and correlates with effector activity.

We used various culture conditions to generate type 1 (Tc1) or type 2 (Tc2) cytotoxic T cells in vitro. T-cell receptor (TCR) transgenic T cells were cultured with antigen and spleen cells, or antigen and dendritic cells (DC), or anti-CD3 and anti-CD28. Tc1 cultures contained interleukin (IL)-2 and IL-6, and Tc2 cultures contained IL-2, IL-6 and IL-4. Tc2 cells generated in each culture condition acquired a CD62L(low) CD44(high) phenotype, had high cytotoxic activity, and secreted IL-4, IL-5 and moderate amounts of interferon-gamma (IFN-gamma). In contrast, the phenotype and function of Tc1 cells varied depending on culture conditions. Tc1 cells from anti-CD3 and anti-CD28 cultures had high cytotoxic activity and were CD62L(low) CD44(high), while Tc1 cells from antigen and spleen cell cultures had low cytotoxic activity and were CD62L(high) CD44(low). Tc1 cells from antigen and DC cultures had an intermediate phenotype. All Tc1 cells secreted high amounts of IFN-gamma, but only Tc1 from anti-CD3 and anti-CD28 cultures had antitumour activity in vivo. Differences were not caused by suboptimal culture conditions, as Tc1 cells divided at a similar rate whether cultured with antigen and spleen cells or with anti-CD3 and anti-CD28. We conclude that IL-4 not only induces 'type 2' cytokine secretion in CD8(+) T cells, but also affects their expression of surface markers and cytotoxic activity.

Animals↗
PubMed2005

Tissue localization and frequency of antigen-specific effector CD4 T cells determines the development of allergic airway inflammation.

Previous activation of effector Th2 cells is central to the development of allergic inflammatory responses. We have observed that priming of allergen-specific Th2 cells in C57BL/6 or B10.A mice with allergen delivered via the i.p. or s.c. routes results in very different outcomes following subsequent airway exposure to the same allergen. Systemic allergen immunization (via the i.p. route) resulted in the formation of a lung-resident population of allergen-specific T cells, and mice developed severe allergic airway inflammation in response to inhaled allergen. The localization of cells to the lung did not require the presence of antigen at this site, but reflected a large pool of circulating activated allergen-specific T cells. In contrast, localized immunization (via the s.c. route) resulted in a small T-cell response restricted to the draining lymph node, and mice were not responsive to inhaled allergen. These data indicate that prior sensitization to an allergen alone was not sufficient for the induction of allergic inflammation; rather, responsiveness was largely determined by precursor frequency and tissue localization of the allergen-specific effector Th2 cells.

Amino Acid Sequence↗
PubMed2004

IL-4 deficiency does not impair the ability of dendritic cells to initiate CD4+ and CD8+ T cell responses in vivo.

Several reports have described a role of IL-4 in dendritic cell function. We have examined the number and phenotype of dendritic cells from C57Bl/6 wild-type and IL-4-/- mice, and compared their ability to induce T cell immune responses in vivo and in vitro. We observed that the number of dendritic cells in the spleens and lymph nodes of IL-4-/- mice is comparable to the number found in wild-type mice. In addition, the expression of maturation markers such as MHC II, CD40, CD80 and CD86, and of differentiation markers such as CD4, CD8 and CD11b, was also comparable in the two populations. Splenic wild-type and IL-4-/- dendritic cells were both able to present antigen to T cell receptor transgenic CD4+ or CD8+ T cells in culture. When pulsed with antigen in vitro and then injected subcutaneously into C57BL/6 host mice, both populations of dendritic cells were able to induce the division of T cell receptor transgenic CD4+ or CD8+ T cells in vivo. This was the case regardless of whether the antigen used in these experiments was a low or a high affinity T cell receptor ligand. Similarly, both populations of dendritic cells were able to activate antigen-specific cytotoxic T cell responses and initiate tumor-protective immune responses in vivo. We conclude that IL-4-/- and wild-type dendritic cells have a comparable ability to initiate T cell immune responses when in an IL-4-sufficient environment.

Animals↗
PubMed2004

The VITAL assay: a versatile fluorometric technique for assessing CTL- and NKT-mediated cytotoxicity against multiple targets in vitro and in vivo.

Assessment of cell-mediated toxicity has traditionally been achieved by measuring the specific activity of enriched effector cell populations against antigen-loaded target cells labeled with radioactive isotopes in vitro. Fluorometric techniques are viewed as a promising alternative to the use of radioactive isotopes for these analyses. Direct assessment of cytotoxicity in vivo can be achieved by monitoring survival of injected fluorescent targets relative to a differentially labeled internal control population without specific antigen. We have developed this approach, incorporating the use of multiple target cell populations labeled with different dyes so that cytotoxicity can be assessed against titrated doses of a given antigen, or against a range of different antigens, simultaneously. We show that this assay, referred to as the VITAL assay, can be used to assess cytotoxic activity of CTL and iNKT cells in vivo and in vitro. CTL responses measured in vivo could be correlated with antigen doses used in immunization strategies, and also with the size of specific CTL populations enumerated in the blood with fluorescent MHC/peptide tetramers. The VITAL assay is, therefore, a sensitive technique allowing analysis of complex multi-epitope responses.

Animals↗
PubMed2004

The MBP-reactive repertoire is shaped by recognition of minor histocompatibility antigens.

While it is known that the degeneracy of T-cell antigen recognition is involved in many aspects of T cell-immunology, its importance in the selection of the T cell repertoire remains an aspect to be better investigated. Here we examined if an intrathymic degenerate T cell recognition mechanism shapes the myelin basic protein (MBP)-reactive repertoire inducing resistance to experimental autoimmune encephalomyelitis (EAE) in some MHC and/or minor histocompatibility antigens (MiHAs) heterozygous F1 mice bearing the H-2(s) susceptibility allele. We found a considerable degree of cross-reactivity between MBP and MiHAs encoded in various EAE resistant mouse strains: (1) MBP-specific T cells can be re-stimulated in vitro by cells expressing these MiHAs and maintain their encephalitogenic activity, and (2) lymphoid cells from parental strains that generate EAE resistant F1 hybrids can induce disease relapse when injected into EAE-susceptible hosts. The results suggest that heterozygosity, through the degeneracy of T cell antigen recognition mechanism, may provide further means to constrain the potential autoreactive repertoire.

Animals↗
PubMed2003

The effects of B7-dependent costimulation on T cell division and survival in vivo and in vitro are dependent on antigen concentration.

We used 5-(and 6-) carboxyfluorescein diacetate succinimidyl ester labeled TCR-transgenic CD4(+) T cells to investigate the contribution of B7 costimulation to T cell activation and clonal expansion. B7 costimulation was blocked with the fusion protein cytotoxic T lymphocyte-associated antigen-4 (CTLA-4)-Ig, which prevents the interaction of B7 with its receptor CD28 on T cells. CTLA4-Ig had different effects depending on the density of antigen (Ag)/MHC ligands available by T cells. In the presence of CTLA4-Ig, tenfold higher concentrations of Ag were required for T cells to undergo cell division in vitro. At high Ag concentrations, T cell division occurred at comparable rates whether in the presence or absence of CTLA4-Ig; however, T cell survival and clonal expansion were strongly inhibited. Addition of IL-2 restored T cell survival but not responsiveness to low doses of Ag. In vivo, B7 costimulation was similarly required for the survival of Ag-specific T cells but not for cell division in response to high amounts of Ag. Thus, B7 costimulation regulates CD4(+) T cell responses by promoting cell division in the presence of limiting amounts of Ag, and by protecting T cells from the onset of apoptosis.

Abatacept↗
PubMed2002

Differential T cell function and fate in lymph node and nonlymphoid tissues.

The functions and fate of antigen-experienced T cells isolated from lymph node or nonlymphoid tissues were analyzed in a system involving adoptive transfer of in vitro-activated T cells into mice. Activated T cells present in the lymph nodes could be stimulated by antigen to divide, produce effector cytokines, and migrate to peripheral tissues. By contrast, activated T cells that had migrated into nonlymphoid tissues (lung and airway) produced substantial effector cytokines upon antigen challenge, but were completely unable to divide or migrate back to the lymph nodes. Therefore, activated T cells can undergo clonal expansion in the lymph node, but are recruited and retained as nondividing cells in nonlymphoid tissues. These distinct regulatory events in lymph node and nonlymphoid tissues reveal simple key mechanisms for both inducing and limiting T cell immunity.

Adoptive Transfer↗