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1.  Dendritic Cell-Derived Exosomes Promote Natural Killer Cell Activation and Proliferation: A Role for NKG2D Ligands and IL-15Rα 
PLoS ONE  2009;4(3):e4942.
Dendritic cell (DC) derived-exosomes (Dex) are nanomeric vesicles harboring functional MHC/peptide complexes promoting T cell-dependent tumor rejection. In the first Phase I trial using peptide-pulsed Dex, the observation of clinical regressions in the absence of T cell responses prompted the search for alternate effector mechanisms. Mouse studies unraveled the bioactivity of Dex on NK cells. Indeed, Dex promoted an IL-15Rα- and NKG2D-dependent NK cell proliferation and activation respectively, resulting in anti-metastatic effects mediated by NK1.1+ cells. In humans, Dex express functional IL-15Rα which allow proliferation and IFNγ secretion by NK cells. In contrast to immature DC, human Dex harbor NKG2D ligands on their surface leading to a direct engagement of NKG2D and NK cell activation ex vivo. In our phase I clinical trial, we highlight the capacity of Dex based-vaccines to restore the number and NKG2D-dependent function of NK cells in 7/14 patients. Altogether, these data provide a mechanistic explanation on how Dex may stimulate non MHC restricted-anti-tumor effectors and induce tumor regression in vivo.
PMCID: PMC2657211  PMID: 19319200
2.  CD4+CD25+ regulatory T cells inhibit natural killer cell functions in a transforming growth factor–β–dependent manner 
The Journal of Experimental Medicine  2005;202(8):1075-1085.
Tumor growth promotes the expansion of CD4+CD25+ regulatory T (T reg) cells that counteract T cell–mediated immune responses. An inverse correlation between natural killer (NK) cell activation and T reg cell expansion in tumor-bearing patients, shown here, prompted us to address the role of T reg cells in controlling innate antitumor immunity. Our experiments indicate that human T reg cells expressed membrane-bound transforming growth factor (TGF)–β, which directly inhibited NK cell effector functions and down-regulated NKG2D receptors on the NK cell surface. Adoptive transfer of wild-type T reg cells but not TGF-β−/− T reg cells into nude mice suppressed NK cell–mediated cytotoxicity, reduced NKG2D receptor expression, and accelerated the growth of tumors that are normally controlled by NK cells. Conversely, the depletion of mouse T reg cells exacerbated NK cell proliferation and cytotoxicity in vivo. Human NK cell–mediated tumor recognition could also be restored by depletion of T reg cells from tumor-infiltrating lymphocytes. These findings support a role for T reg cells in blunting the NK cell arm of the innate immune system.
PMCID: PMC2213209  PMID: 16230475
3.  Vaccination of metastatic melanoma patients with autologous dendritic cell (DC) derived-exosomes: results of thefirst phase I clinical trial 
DC derived-exosomes are nanomeric vesicles harboring functional MHC/peptide complexes capable of promoting T cell immune responses and tumor rejection. Here we report the feasability and safety of the first Phase I clinical trial using autologous exosomes pulsed with MAGE 3 peptides for the immunization of stage III/IV melanoma patients. Secondary endpoints were the monitoring of T cell responses and the clinical outcome.
Patients and methods
Exosomes were purified from day 7 autologous monocyte derived-DC cultures. Fifteen patients fullfilling the inclusion criteria (stage IIIB and IV, HLA-A1+, or -B35+ and HLA-DPO4+ leukocyte phenotype, tumor expressing MAGE3 antigen) were enrolled from 2000 to 2002 and received four exosome vaccinations. Two dose levels of either MHC class II molecules (0.13 versus 0.40 × 1014 molecules) or peptides (10 versus 100 μg/ml) were tested. Evaluations were performed before and 2 weeks after immunization. A continuation treatment was performed in 4 cases of non progression.
The GMP process allowed to harvest about 5 × 1014 exosomal MHC class II molecules allowing inclusion of all 15 patients. There was no grade II toxicity and the maximal tolerated dose was not achieved. One patient exhibited a partial response according to the RECIST criteria. This HLA-B35+/A2+ patient vaccinated with A1/B35 defined CTL epitopes developed halo of depigmentation around naevi, a MART1-specific HLA-A2 restricted T cell response in the tumor bed associated with progressive loss of HLA-A2 and HLA-BC molecules on tumor cells during therapy with exosomes. In addition, one minor, two stable and one mixed responses were observed in skin and lymph node sites. MAGE3 specific CD4+ and CD8+ T cell responses could not be detected in peripheral blood.
The first exosome Phase I trial highlighted the feasibility of large scale exosome production and the safety of exosome administration.
PMCID: PMC554765  PMID: 15740633
exosomes; dendritic cells; phase I trial; cancer vaccine; immunotherapy
4.  Novel mode of action of c-kit tyrosine kinase inhibitors leading to NK cell–dependent antitumor effects 
Journal of Clinical Investigation  2004;114(3):379-388.
Mutant isoforms of the KIT or PDGF receptors expressed by gastrointestinal stromal tumors (GISTs) are considered the therapeutic targets for STI571 (imatinib mesylate; Gleevec), a specific inhibitor of these tyrosine kinase receptors. Case reports of clinical efficacy of Gleevec in GISTs lacking the typical receptor mutations prompted a search for an alternate mode of action. Here we show that Gleevec can act on host DCs to promote NK cell activation. DC-mediated NK cell activation was triggered in vitro and in vivo by treatment of DCs with Gleevec as well as by a loss-of-function mutation of KIT. Therefore, tumors that are refractory to the antiproliferative effects of Gleevec in vitro responded to Gleevec in vivo in an NK cell–dependent manner. Longitudinal studies of Gleevec-treated GIST patients revealed a therapy-induced increase in IFN-γ production by NK cells, correlating with an enhanced antitumor response. These data point to a novel mode of antitumor action for Gleevec.
PMCID: PMC489961  PMID: 15286804
5.  Dendritic Cell Maturation Overrules H-2d–Mediated Natural Killer T (Nkt) Cell Inhibition 
The Journal of Experimental Medicine  2001;194(8):1179-1186.
Given the broad expression of H-2 class Ib molecules on hematopoietic cells, antigen presentation pathways among CD1d expressing cells might tightly regulate CD1d-restricted natural killer T (NKT) cells. Bone marrow–derived dendritic cells (BM-DCs) and not adherent splenocytes become capable of triggering NK1.1+/T cell receptor (TCR)int hepatic NKT cell activation when (a) immature BM-DCs lack H-2Db−/− molecules or (b) BM-DCs undergo a stress signal of activation. In such conditions, BM-DCs promote T helper type 1 predominant CD1d-restricted NKT cell stimulation. H-2 class Ia–mediated inhibition involves more the direct H-2Db presentation than the indirect Qa-1b pathway. Such inhibition can be overruled by B7/CD28 interactions and marginally by CD40/CD40L or interleukin 12. These data point to a unique regulatory role of DCs in NKT cell innate immune responses and suggest that H-2 class Ia and Ib pathways differentially control NKT cell recognition of DC antigens.
PMCID: PMC2193518  PMID: 11602646
inhibitory receptors; IFN-γ; costimulation; CD1d; NKT cells
6.  Immune Response to Recombinant Adenovirus in Humans: Capsid Components from Viral Input Are Targets for Vector-Specific Cytotoxic T Lymphocytes 
Journal of Virology  2000;74(16):7678-7682.
We previously demonstrated that a single injection of 109 PFU of recombinant adenovirus into patients induces strong vector-specific immune responses (H. Gahéry-Ségard, V. Molinier-Frenkel, C. Le Boulaire, P. Saulnier, P. Opolon, R. Lengagne, E. Gautier, A. Le Cesne, L. Zitvogel, A. Venet, C. Schatz, M. Courtney, T. Le Chevalier, T. Tursz, J.-G. Guillet, and F. Farace, J. Clin. Investig. 100:2218–2226, 1997). In the present study we analyzed the mechanism of vector recognition by cytotoxic T lymphocytes (CTL). CD8+ CTL lines were derived from two patients and maintained in long-term cultures. Target cell infections with E1-deleted and E1-plus E2-deleted adenoviruses, as well as transcription-blocking experiments with actinomycin D, revealed that host T-cell recognition did not require viral gene transcription. Target cells treated with brefeldin A were not lysed, indicating that viral input protein-derived peptides are associated with HLA class I molecules. Using recombinant capsid component-loaded targets, we observed that the three major proteins could be recognized. These results raise the question of the use of multideleted adenoviruses for gene therapy in the quest to diminish antivector CTL responses.
PMCID: PMC112292  PMID: 10906225
7.  Immune Response to Recombinant Capsid Proteins of Adenovirus in Humans: Antifiber and Anti-Penton Base Antibodies Have a Synergistic Effect on Neutralizing Activity 
Journal of Virology  1998;72(3):2388-2397.
Replication-deficient adenovirus used in humans for gene therapy induces a strong immune response to the vector, resulting in transient recombinant protein expression and the blocking of gene transfer upon a second administration. Therefore, in this study we examined in detail the capsid-specific humoral immune response in sera of patients with lung cancer who had been given one dose of a replication-defective adenovirus. We analyzed the immune response to the three major components of the viral capsid, hexon (Hx), penton base (Pb), and fiber (Fi). A longitudinal study of the humoral response assayed on adenovirus particle-coated enzyme-linked immunosorbent assay plates showed that patients had preexisting immunity to adenovirus prior to the administration of adenovirus–β-gal. The level of the response increased in three patients after adenovirus administration and remained at a maximum after three months. One patient had a strong immune response to adenovirus prior to treatment, and this response was unaffected by adenovirus administration. Sera collected from the patients were assayed for recognition of each individual viral capsid protein to determine more precisely the molecular basis of the humoral immune response. Clear differences existed in the humoral response to the three major components of the viral capsid in serum from humans. Sequential appearance of these antibodies was observed: anti-Fi antibodies appeared first, followed by anti-Pb antibodies and then by anti-Hx antibodies. Moreover, anti-Fi antibodies preferentially recognized the native trimeric form of Fi protein, suggesting that they recognized conformational epitopes. Our results showed that sera with no neutralizing activity contained only anti-Fi antibodies. In contrast, neutralizing activity was only obtained with sera containing anti-Fi and anti-Pb antibodies. More importantly, we showed that anti-native Fi and anti-Pb antibodies had a synergistic effect on neutralization. The application of these conclusions to human gene therapy with recombinant adenovirus should lead to the development of strategies to overcome the formation of such neutralization antibodies, which have been shown to limit the efficacy of gene transfer in humans.
PMCID: PMC109538  PMID: 9499099
8.  EORTC Group Phase II Study of Oral Etoposide for Pretreated Soft Tissue Sarcoma 
Sarcoma  1997;1(2):99-101.
Purpose. This study investigates the efficacy and toxicity of daily oral etoposide in chemotherapy for non-heavily pretreated advanced and metastatic soft tissue sarcoma (STS).
Subjects. Twenty-seven patients with progressive and measurable disease were treated. Median age was 53 years (range 20–71 years) and performance status WHO 0 or 1. Histologies included mainly leiomyosarcoma (8), malignant fibrous histiocytoma (4), rhabdomyosarcoma (4), liposarcoma (2) and synovial sarcoma (2). Fifteen patients had received prior radiotherapy, of whom three included sites with haematopoiesis. All patients had received prior chemotherapy, including adjuvant therapy (7) and mostly consisted of one two-drug schedule (ifosfamide and doxorubicin) or two single-drug regimens.
Methods. Chemotherapy consisted of etoposide (VP16-213), 50 mg m-2 day-1 × 21 q 4 weeks. Blood cell counts were done weekly. Dose reductions and a maximum delay of 2 weeks was allowed depending on cell counts during treatment and at the start of a new 4-week treatment cycle.
Results. No objective response was observed. Progressive disease was observed after two treatment cycles in 17/27 patients (68%) and after three cycles in 22/27 patients (81%). The other patients received three to five cycles. Twenty-four patients went off study due to progressive disease. Grade 3 and 4 neutropenia was observed in eight and one patients, respectively. Thrombocytopenia grade 3 was seen in two patients. Non-haematological toxicity grade 3 (nausea, diarrhoea or alopecia) was observed in three patients, and grade 4 (dyspnea, hypotension or haemorrhage) in three patients.
Discussion. No objective response was obtained. Oral etoposide at a dose of 50 mg m-2 day-1 × 21 q 4 weeks is inactive in chemotherapy of pretreated STS. Disease progression occurred within three cycles in the majority (81%) of patients. Toxicity of this regimen in non-heavily pretreated patients is low.
PMCID: PMC2395351  PMID: 18521209
9.  Autoantibodies to B Lymphocytes in a Patient with Hypoimmunoglobulinemia 
Journal of Clinical Investigation  1977;60(2):405-410.
In a young woman with ulcerative colitis, hypoimmunoglobulinemia, and humoral immunodeficiency, lymphocyte counts vary between 600 and 1,000 per mm3 with 0.5-1.5% bone marrow-derived (B) cells and 98-99% thymus-derived (T) cells. Anti-lymphocyte antibodies were detected by immunofluorescence and by microlymphocytotoxicity with increased reactivity at +4°C. They belonged to the IgM class and were polyclonal. Studies performed with various normal lymphocyte subpopulations, several lymphoblastoid cell lines and lymphocytes from immunodeficiency patients showed that these antibodies reacted with B cells. The corresponding antigen(s) is distinct from membrane-bound immunoglobulins, is not an alloantigen, and is probably unrelated to the la-like molecules. Pokeweed mitogen stimulated B cells appear to lose this antigen. Cells from various lymphoproliferative disorders were tested. T-derived and “non T-non-B” leukemic cells did not react with the antibody. Malignant cells from B-derived lymphomas and prolymphocytic leukemias were reactive. The incidence of positivity of the leukemic cells among patients with common B chronic lymphocytic leukemia was surprisingly low (one-third of the patients).
The autoantibody nature of the anti-B-cell antibodies and their pathogenic role in the genesis of the patient's hypoimmunoglobulinemia was demonstrated by the effect of removal of antibodies by massive plasmaphereses which were followed by a dramatic and transitory increase of B-cell figures. Whereas most primary immunodeficiency syndromes appear to result from an arrest in the differentiation capabilities of immunologically competent cells, autoantibodies to circulating B lymphocytes may be incriminated in the pathogenesis of some cases of hypogammaglobulinemia.
PMCID: PMC372381  PMID: 301527
10.  Simultaneous Occurrence of Acute Myeloblastic Leukaemia and Multiple Myeloma without Previous Chemotherapy 
British Medical Journal  1974;2(5920):642-643.
The simultaneous detection of multiple myeloma and acute myeloblastic leukaemia is reported in two patients who had not undergone chemotherapy. Histological examinations confirmed the infiltration by both myeloblasts and plasma cells. Only the latter contained monoclonal immunoglobulin chains at immunofluorescent studies. The possible relation between the two distinct proliferative processes is briefly discussed.
PMCID: PMC1613074  PMID: 4600910

Results 1-10 (10)