Biomedical subjects

Sophie Paczesny

Publications and source records attributed to Sophie Paczesny.

10 recordsLinked to original sources

PubMed2007

Efficient generation of CD34+ progenitor-derived dendritic cells from G-CSF-mobilized peripheral mononuclear cells does not require hematopoietic stem cell enrichment.

As a result of their potent antigen-presentation function, dendritic cells (DC) are important tools for cell therapy programs. In vitro-generated DC from enriched CD34+ hematopoietic stem cells (HSC; enriched CD34 DC) have already proven their efficiency in Phase I/II clinical trials. Here, we investigated whether enrichment of CD34+ HSC before the onset of culture was absolutely required for their differentiation into DC. With this aim, we developed a new two-step culture method. PBMC harvested from G-CSF-mobilized, healthy patients were expanded for 7 days during the first step, with early acting cytokines, such as stem cell factor, fetal liver tyrosine kinase 3 ligand (Flt-3L), and thrombopoietin. During the second step, expanded cells were then induced to differentiate into mature DC in the presence of GM-CSF, Flt-3L, and TNF-alpha for 8 days, followed by LPS exposure for 2 additional days. Our results showed that the rate of CD34+/CD38+/lineageneg cells increased 19.5+/-10-fold (mean+/-sd) during the first step, and the expression of CD14, CD1a, CD86, CD80, and CD83 molecules was up-regulated markedly following the second step. When compared with DC generated from enriched CD34+ cells, which were expanded for 7 days before differentiation, DC derived from nonenriched peripheral blood stem cells showed a similar phenotye but higher yields of production. Accordingly, the allogeneic stimulatory capacity of the two-step-cultured DC was as at least as efficient as that of enriched CD34 DC. In conclusion, we report herein a new two-step culture method that leads to high yields of mature DC without any need of CD34+ HSC enrichment.

Antigens, CD34↗

PubMed2005

Long-term outcomes in patients with metastatic melanoma vaccinated with melanoma peptide-pulsed CD34(+) progenitor-derived dendritic cells.

Between March 1999 and May 2000, 18 HLA-A*0201(+) patients with metastatic melanoma were enrolled in a phase I trial using a dendritic cell (DC) vaccine generated by culturing CD34(+) hematopoietic progenitors. This vaccine includes Langerhans cells. The DC vaccine was loaded with four melanoma peptides (MART-1/MelanA, tyrosinase, MAGE-3, and gp100), Influenza matrix peptide (Flu-MP), and keyhole limpet hemocyanin (KLH). Ten patients received eight vaccinations, one patient received six vaccinations, one patient received five vaccinations, and six patients received four vaccinations. Peptide-specific immunity was measured by IFN-gamma production and tetramer staining in blood mononuclear cells. The estimated median overall survival was 20 months (range: 2-83), and the median event-free survival was 7 months (range: 2-83). As of August 2005, four patients are alive (three patients had M1a disease and one patient had M1c disease). Three of them have had no additional therapy since trial completion; two of them had solitary lymph node metastasis, and one patient had liver metastasis. Patients who survived longer were those who mounted melanoma peptide-specific immunity to at least two melanoma peptides. The present results therefore justify the design of larger follow-up studies to assess the immunological and clinical outcomes in patients with metastatic melanoma vaccinated with peptide-pulsed CD34-derived DCs.

Adult↗

PubMed2005

Immunotherapy via dendritic cells.

The immune system evolved to protect us from microbes. The antigen (Ag)-nonspecific innate immunity and Ag-specific adaptive immunity synergize to eradicate the invading pathogen through cells, such as dendritic cells (DCZ7) and lymphocytes, and through their effector proteins including antimicrobial peptides, complement, and antibodies. Its intrinsic complexity renders the immune system prone to dysfunction including cancer, autoimmunity, chronic inflammation and allergy. DCs are unique in their capacity to induce and regulate immune responses and are therefore attractive candidates for immunotherapy. However, DCs consist of distinct subsets with common as well as unique functions that lead to distinct types of immune responses. Therefore, understanding DC heterogeneity and their role in immunopathology is critical to design better strategies for immunotherapy. Indeed, what we learn from studying autoimmunity will help us induce strong vaccine specific immunity, either protective, as in the case of microbes, or therapeutic, as in the case of tumors.

Animals↗

PubMed2005

Spontaneous proliferation and type 2 cytokine secretion by CD4+T cells in patients with metastatic melanoma vaccinated with antigen-pulsed dendritic cells.

We observed the induction of spontaneous, i.e., without adding exogenous antigen, in vitro proliferation of PBMCs from patients with stage IV melanoma who underwent repeated vaccinations with antigen-loaded dendritic cells (DCs) derived from CD34(+) hematopoietic progenitors (CD34-DCs). Proliferating cells are CD4(+)T cells. Their proliferation is dependent on (1) CD11c(+) myeloid DCs, since their depletion from PBMCs abolishes it; and (2) IL-2, as it can be blocked by neutralizing anti-IL-2 antibodies. Spontaneous proliferation is associated to the secretion of type 2 cytokines. To analyze the frequency of spontaneous proliferation induction in the cohort of 18 vaccinated patients, an index of spontaneous proliferation was defined as a ratio of PBMCs proliferation from post- vs pre-DC vaccination blood samples. Ten out of sixteen analyzed patients showed an index > 2. The index of spontaneous proliferation correlates with antigen-specific PBMC proliferation to the vaccine antigen KLH. Furthermore, both spontaneous- and antigen-specific proliferation in PBMC cultures are dependent on blood myeloid DCs.

Antigen Presentation↗

PubMed2004

Expansion of melanoma-specific cytolytic CD8+ T cell precursors in patients with metastatic melanoma vaccinated with CD34+ progenitor-derived dendritic cells.

Cancer vaccines aim at inducing (a) tumor-specific effector T cells able to reduce/eliminate the tumor mass, and (b) long-lasting tumor-specific memory T cells able to control tumor relapse. We have shown earlier, in 18 human histocompatibility leukocyte antigen (HLA)-A*0201 patients with metastatic melanoma, that vaccination with peptide-loaded CD34-dendritic cells (DCs) leads to expansion of melanoma-specific interferon gamma-producing CD8+ T cells in the blood. Here, we show in 9 out of 12 analyzed patients the expansion of cytolytic CD8+ T cell precursors specific for melanoma differentiation antigens. These precursors yield, upon single restimulation with melanoma peptide-pulsed DCs, cytotoxic T lymphocytes (CTLs) able to kill melanoma cells. Melanoma-specific CTLs can be grown in vitro and can be detected in three assays: (a) melanoma tetramer binding, (b) killing of melanoma peptide-pulsed T2 cells, and (c) killing of HLA-A*0201 melanoma cells. The cytolytic activity of expanded CTLs correlates with the frequency of melanoma tetramer binding CD8+ T cells. Thus, CD34-DC vaccines can expand melanoma-specific CTL precursors that can kill melanoma antigen-expressing targets. These results justify the design of larger follow-up studies to assess the immunological and clinical response to peptide-pulsed CD34-DC vaccines.

Antigens, CD34↗

PubMed2003

Dendritic cells as vectors for immunotherapy of cancer.

Dendritic cells (DCs) initiate and regulate immune responses. Numerous studies in mice showed that tumor antigens-loaded DCs are able to induce therapeutic and protective anti-tumor immunity. The immunogenicity of antigens delivered on DCs has now been demonstrated in cancer patients and some clinical responses without any significant toxicity have been observed. Nevertheless, many parameters of DC vaccination need to be established including: (1) the type of DCs, their maturation stage and stimuli; (2) the quality and the breadth of induced immune responses; (3) host-related factors, such as the extent of metastatic disease and myeloablation; and (4) efficacy as measured by the clinical outcome.

Animals↗

PubMed2003

Dendritic cells: controllers of the immune system and a new promise for immunotherapy.

The immune system is controlled by dendritic cells (DCs). Just as lymphocytes comprise different subsets, DCs comprise several subsets that differentially control lymphocyte function. In humans, the myeloid pathway includes Langerhans cells (LCs) and interstitial DCs (intDCs). While both subsets produce IL-12, only intDCs make IL-10 and induce B cell differentiation. Another pathway includes plasmacytoid DCs, which promptly secrete large amounts of IFN-alpha/beta viral encounter. Thus, insights into in vivo DC functions are important to understand the launching and modulation of immunity.

Dendritic Cells↗

PubMedDate not supplied

Single injection of CD34+ progenitor-derived dendritic cell vaccine can lead to induction of T-cell immunity in patients with stage IV melanoma.

There is evidence that dendritic cell (DC) vaccines induce tumor-specific immune responses that correlate with clinical responses. Little is known, however, about the kinetics of T-cell responses to antigens presented on DC vaccines. The authors vaccinated 18 HLA A*0201+ patients with stage IV melanoma with CD34 HPC-derived DCs pulsed with six antigens: influenza matrix peptide (Flu-MP), KLH, and peptides derived from the four melanoma antigens: MART-1/Melan A, gp100, tyrosinase, and MAGE-3. A single DC vaccination was sufficient for induction of KLH-specific CD4 T-cell responses in five patients and Flu-MP-specific CD8 T-cell responses in eight patients. A single DC vaccine was sufficient for induction of tumor-specific effectors to at least one melanoma antigen in five patients. Thus, a single injection of CD34 HPC-derived DCs can lead to rapid immune response to CD4 epitopes or to melanoma antigens.

Adolescent↗

PubMedDate not supplied

Measuring melanoma-specific cytotoxic T lymphocytes elicited by dendritic cell vaccines with a tumor inhibition assay in vitro.

Improving cancer vaccines depends on assays measuring elicited tumor-specific T-cell immunity. Cytotoxic effector cells are essential for tumor clearance and are commonly evaluated using 51Cr release from labeled target cells after a short (4 hours) incubation with T cells. The authors used a tumor inhibition assay (TIA) that assesses the capacity of cytotoxic T lymphocytes (CTLs) to control the survival/growth of EGFP-labeled tumor cell lines. TIA was validated using CD8+ T cells primed in vitro against melanoma and breast cancer cells. TIA was then used to assess the CTL function of cultured CD8+ T cells isolated from patients with metastatic melanoma who underwent vaccination with peptide-pulsed CD34+ HPCs-derived DCs. After the DC vaccination, T cells from six of eight patients yielded CTLs that could inhibit the survival/growth of melanoma cells. The results of TIA correlated with killing of tumor cells in a standard 4-hour 51Cr release assay, yet TIA allowed detection of CTL activities that appeared marginal in the 51Cr release assay. Thus, TIA might prove valuable for measuring spontaneous and induced antigen-specific cytotoxic T cells.

Antigens, CD34↗

PubMedDate not supplied

Boosting vaccinations with peptide-pulsed CD34+ progenitor-derived dendritic cells can expand long-lived melanoma peptide-specific CD8+ T cells in patients with metastatic melanoma.

The immunogenicity of dendritic cell (DC)-based vaccines has been shown in patients with advanced cancer, but it has not yet been established whether the elicited cancer-specific immunity is durable and whether it can be maintained by boosting vaccinations. The authors showed earlier, in 18 HLA-A*0201 metastatic melanoma patients, that four vaccinations over 6 weeks with peptide-loaded CD34-DCs (the induction phase) expand in the blood melanoma-specific CD8+ T cells, as documented by melanoma peptide-specific IFN-gamma ELISPOT and cytotoxic T-lymphocyte (CTL) activity against melanoma cell lines. The authors show here that the melanoma peptide-specific CD8+ T-cell immunity is short-lived, but it could be reactivated in 7 of 11 patients who received four boosting vaccinations with peptide-loaded CD34-DCs. Expansion of recall memory CD8+ T cells was confirmed by tetramer binding and CTL activity against melanoma peptide-pulsed T2 cells. In two patients boosted over 15 months, induced melanoma peptide-specific recall memory CD8+ T cells lasted at least 6 months. Thus, boosting vaccination with peptide-loaded CD34-DCs can expand long-lived tumor peptide-specific immunity.

Antigens, CD34↗