ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

To bead or not to bead, that is the question posed by Ito et al. in this issue of theJournal of Immunotherapy.The generation of tumor-reactive T cells remains a major impediment to the wider application of adoptive cell transfer (ACT) therapy for the treatment of patients with cancer. Ito et al. used lymph nodes of mice draining implanted sarcomas as an enriched source of tumor antigen-specific cells. They investigated the ex vivo activation of the lymph node cells by artificial antigen presenting cells (aAPCs) for the production of therapeutic T cell cultures. The optimal aAPC consisted of magnetic beads coated with anti-CD3 and anti-CD28 antibodies. Short-term ex vivo culture with the aAPCs led to a selective expansion and/or activation of tumor antigen specific CD4+cells. These results lay a solid foundation for the clinical application of bead-based T cell activation, and promote efforts to develop the therapeutic strategy of in vivo immunization, ex vivo T cell activation, and adoptive cell transfer.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

A major obstacle limiting the efficacy of adoptive T-cell transfer (adoptive immunotherapy) to treat patients with cancer is the short survival of the transferred cells. These in vitro activated T cells depend on the growth factor, interleukin (IL)-2, and may undergo apoptosis in vivo when they are transferred. The authors previously reported that the need for an exogenous source of IL-2 could be abrogated in vitro by retrovirally transducing antitumor T lymphocytes with an exogenousIL-2gene. Here they report that this growth of IL-2 transductants depended on restimulation of the T-cell receptor complex and appeared to be regulated at the transcriptional level of the transducedIL-2gene. The transduced IL-2 transcript was barely detectable in IL-2–transductants just before they died without restimulation, and they expressed a low level of the CD25 molecule, the alpha chain of the IL-2 trimeric receptor complex. Melanoma-specific tumor-infiltrating lymphocytes (either bulk or CD8+cells alone), when transduced with an IL-2 retroviral vector, could produce IL-2 upon tumor stimulation and proliferated after the destruction of autologous tumor cells in the absence of added IL-2. Control vector–transduced tumor-infiltrating lymphocytes failed to do so under the same conditions. These findings provide a foundation for the development of clinical efforts to adoptively transfer melanoma-specific tumor-infiltrating lymphocytes transduced with an IL-2 retroviral vector for the treatment of patients with metastatic melanoma to evaluate the fate and therapeutic effect of theseIL-2gene-modified antitumor T lymphocytes in vivo.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The relative activities of interferon-&agr;2b (IFN-&agr;2b) and polyethylene glycol12000–IFN-&agr;2b (PEG–IFN-&agr;2b) were assessed in cell culture studies using WM9 melanoma or ACHN renal cell carcinoma cell lines. Interferon-&agr;2b and PEG–IFN-&agr;2b had identical antiproliferative activities when tested in cell proliferation studies conducted with equivalent antiviral units of each IFN preparation. Neither IFN formulation was effective in inducing apoptosis in WM9 melanoma cells, but both increased slightly the percentage of ACHN cells undergoing apoptosis as assessed by Annexin V staining. Interferon-&agr;2b and PEG–IFN-&agr;2b both activated signal transducer and activator of transcription complexes, and the duration of complex activation was similar for both IFN formulations. Induction of different IFN-stimulated genes was assessed by Northern blotting and the quantitative real-time reverse transcription-coupled polymerase chain reaction (RT-PCR) in WM9 melanoma, ACHN renal cell carcinoma, U937 lymphoma, and MOLT-4 and Mono Mac 6 leukemia cell lines. Interferon-&agr;2b and PEG–IFN-&agr;2b had equivalent gene-modulatory activities within each of these tumor cell lines, although cell line–specific induction patterns were observed. When compared with the antiviral 50% inhibitory concentration (IC50) values, the dose-dependent gene expression data correlated with cell sensitivity to IFN treatment. Together, the drug comparability and cell sensitivity data suggest a predictive relation between dose, time, antiviral activity, and gene transcription effects. Therefore, although the specific activity of IFN-&agr;2b is approximately three times greater than PEG–IFN-&agr;2b, the two preparations have identical in vitro biologic activities when applied to cells at equivalent antiviral units.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Epstein-Barr virus nuclear antigen type 1 (EBNA1), the only viral protein that is unequivocally expressed in all Epstein-Barr virus (EBV)–associated malignant diseases, is essential for viral DNA replication and maintenance of the viral episome in infected cells. A glycine-alanine repeat domain inhibits antigen processing through the ubiquitin–proteasome pathway for presentation on human leukocyte antigen (HLA) class I molecules. EBNA1 is not protected from the HLA class II processing pathway, and CD4+HLA class II–restricted T cells recognize the antigen. CD4+T-helper (Th) cells play critical roles in initiating, regulating, and maintaining immune responses against viral infections and tumors, so that inclusion of EBNA1 as a target antigen may improve immunotherapy for EBV-associated cancers. In this study, the authors used the TEPITOPE software program to predict promiscuous class II epitope candidates. After several HLA-DR–restricted peptides were identified by in vitro analysis of the T-cell response to synthetic peptides, a T-cell clone was established that was specific for one of the peptides. Functional studies were performed with this clone. The CD4+T helper cells specific for the HLA-DR15–restricted peptide EBNA1482(AEGLRALLARSHVER) recognized naturally processed EBNA1 protein. This epitope was presented by several HLA-DR alleles, including DR4, DR7, and DR11. The inclusion of the promiscuous, naturally processed EBNA1482epitope in vaccine constructs could enhance immune responses against EBV-positive cancers.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Ligation of TCR and CD28 expressed on T cells via mAbs results in activation of T cells capable of tumor destruction in adoptive immunotherapy. In a murine model, the authors examined in vitro activation conditions utilizing plate-immobilized and bead-conjugated mAbs that bind to CD3 and CD28. Bead-activated tumor-draining lymph node (TDLN) cells demonstrated superior cytokine (IFN-&ggr;, GM-CSF, IL-2, and IL-10) secretion and mediated tumor regression more efficiently compared with plate-activated cells. The bead-activated TDLN cells had a significantly higher percentage of CD4+cells compared with plate-activated cells. On a per-cell basis, positively selected CD4+cells activated with bead-coupled or plate immobilized mAbs mediated tumor-specific regression equally. Bead-activated CD4+TDLN cells demonstrated significantly higher levels of tumor specific IL-2 secretion compared with plate-activated CD4+cells that may provide helper function to CD8+effector cells. The antitumor reactivity of bead-activated lymphoid cells depended upon their source. TDLN cells after bead activation were more potent than splenocytes from tumor-bearing hosts in mediating tumor regression in vivo. Bead-activated LN cells and splenocytes from nontumor-bearing hosts demonstrated nonspecific cytokine secretion and minimal efficacy in adoptive immunotherapy. At minimal doses of IL-2, the antitumor reactivity of bead-activated TDLN cells was significantly enhanced. Anti-CD3/anti-CD28 bead activation of tumor-primed T cells represents an efficient method to generate effector cells for immunotherapy.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Among cytokines applied for immunotherapy of cancer, one of the most successful approaches to date involves systemic delivery of high-dose interleukin (IL)-2. However, the clinical utility of high-dose IL-2 has been limited by significant adverse effects, including vascular leak syndrome. Given this limitation, many attempts to decrease the dosage of IL-2 while maintaining its antitumor therapeutic effects are being made. In this study, the authors observed that combined use of IL-18 and low-dose IL-2 synergistically promoted in vitro proliferation of natural killer cells with up-regulation of IL-2 receptor-&agr; and also synergistically stimulated cytolytic activity and interferon-&ggr; production by these cells. Furthermore, intratumoral injections of these two cytokines completely eradicated day-12 established subcutaneous tumor and induced CD4+-dependent memory in a MCA205 murine tumor model. Observed primary antitumor responses depended largely on natural killer cells and partly on CD8+T cells. Fas-L pathway and interferon-&ggr; production were critical in tumor eradication. These results indicate that combined administration of IL-18 and low-dose IL-2 could be a new model for cancer immunotherapy, which probably engages the activation of natural killer cells through interferon-&ggr;– and Fas-L–dependent pathways.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Dendritic cells (DCs) have been shown to activate cytotoxic T-lymphocytes (CTLs) for many tumor and virus-associated antigens in vitro. In this study, the authors tested the feasibility of using DCs to expand polyclonal, cytomegalovirus (CMV)-specific CTL lines for adoptive immunotherapy. Two stimulations with DCs expressing pp65, the immunodominant antigen of CMV, effectively activated and expanded MHC-class I restricted, CMV-specific CTLs from peripheral blood mononuclear cells. However, limiting monocyte-derived DC numbers precluded the authors from expanding the CTLs to the numbers required for adoptive transfer protocols. Nonspecific stimulation methods failed to expand CTL lines specifically. However, the authors found that lymphoblastoid cell lines (LCLs) expressing pp65 expanded pp65-specific CTL lines without competition from EBV-specific CTLs. An unlimited source of antigen presenting cells that could present antigen in the appropriate MHC context emerged as a critical point for expansion of polyclonal, antigen-specific CTL lines.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

To exploit alloreactive T-cell responses known as the graft-versus-tumor effect, allogeneic hematopoietic stem cell transplantation is being explored as experimental therapy in selected solid tumors, including metastatic melanoma. However, donor T-cell responses are often delayed and associated with severe graft-versus-host disease. Posttransplant adoptive immunotherapy using tumor-specific cytotoxic T lymphocytes (CTL) of donor origin might provide immediate graft-versus-tumor effects but not graft-versus-host disease. Therefore, the aim of the current study was to define in vitro conditions for the expansion of allogeneic major histocompatibility complex–matched CTLs targeting melanoma-associated antigens (MAA). The CTLs were generated from peripheral blood mononuclear cells (PBMCs) of HLA-A*0201+ healthy donors by repetitive stimulations with HLA-A*0201–restricted MAA-derived peptides. Melanoma reactivity, as determined by lysis of peptide-pulsed T2 cells and HLA-A2+/Ag+ melanoma cells, was detected using in vitro expanded CTL targeting MAA peptides AAGIGILTV(MT27–35), IMDQVPFSV(G209–2M), and YMDGTMSQV(T368–376). In contrast, FLWGPRALV(MAGE3271–279) and VLPDVFIRCV(GnT-Vnt38–67) induced peptide-specific recognition of T2 target cells only, whereas ITDQVPFSV(G209–217), KTWGQYWQV(G9154), MLLAVLYCL(T1–9), and tumor lysate could not induce specific CTLs. Specific cytolytic activity was accompanied by interferon-&ggr; secretion. Peptide-pulsed dendritic cells were required only for the initial stimulation of CTLs and could be substituted by PBMCs during restimulations. The median expansion rate of CTL was five to six times, regardless of whether dendritic cells or PBMCs were used after the initial stimulation. The results delineate the conditions for effective ex vivo expansion of melanoma-specific CTLs from PBMCs of healthy donors to be used as an adjunct in allogeneic cell therapy of metastatic melanoma.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Activated monocytes–macrophages may be associated with antitumor activity, and activation of these cells by certain cytokines, primarily interferon gamma (IFN-&ggr;), can be indicated by alterations in the concentrations of neopterin, nitrate, or tryptophan. Specimens of peritoneal fluid were obtained from patients with intra-abdominal neoplasia who were undergoing treatment in a phase I trial of weekly intraperitoneal recombinant interleukin-12 (rhIL-12), an inducer of IFN-&ggr;. Concentrations of neopterin, nitrate, tryptophan, IFN-&ggr;, and tumor necrosis factor alpha (TNF-&agr;) were determined at various times during the first 48 hours in 11 patients who received intraperitoneal rhIL-12 in doses ranging from 100 to 1,500 ng/kg. An increase in peritoneal fluid nitrate concentrations was observed in nine of these patients. Increased concentrations of TNF-&agr; and IFN-&ggr; were detected in 3 of 9 and 8 of 11 patients, respectively. Increased peritoneal fluid neopterin concentrations were detected by 24 hours after the injection in all patients studied. A significant increase in the ascitic fluid neopterin level could still be detected after 1 or 2 weeks of treatment (mean ± standard error, 7.8 ± 1.5 nM vs. 4.6 ± 0.3 nM; Wilcoxon test, p = 0.0019), which is consistent with monocyte–macrophage activation. In contrast, the tryptophan concentration was lower (4.7 ± 1.1 &mgr;M vs. 6.1 ± 1.2 &mgr;M; p = 0.0428) after 1 or 2 weeks of treatment. There was a significant correlation between the dose of rhIL-12 and posttreatment neopterin concentrations (rs= 0.559, p = 0.0102). The intraperitoneal delivery of rhIL-12 appears to be associated with an immediate, sustained, and dose-dependent increase in peritoneal fluid neopterin, associated in most patients by an increase in IFN-&ggr; and in certain patients by an increase in nitrate and a decrease in tryptophan concentrations.

ISSN:1524-9557    

出版商:OVID    

年代:2003

数据来源: OVID