ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

MUC1 mucin peptides stimulated cytotoxic T lymphocytes (CTL) from humans with adenocarcinomas. Peripheral blood mononuclear cells, tumor-draining lymph node cells, or tumor-infiltrating lymphocytes were stimulated using mononuclear cells from humans with adenocarcinomas of breast or ovary, respectively, using (a) a native MUC1 mucin tandem repeat peptide of 20 amino acids (MUC1-mtr1) plus recombinant human interleukin-2 (IL-2), (b) the mutated (T3N) MUC1-mtr1plus IL-2, or (c) immobilized anti-CD3 plus IL-2, or (d) IL-2 alone. The CTL stimulated by each of these four conditions were predominately CD4+. However, the CTL stimulated by either the native MUC1-mtr1or (T3N) MUC1-mtr1showed 5–10 times greater cytotoxicity of a breast cancer cell line that expresses MUC1 compared to CTL stimulated by either anti-CD3 + IL-2 or IL-2 alone. Each incubation condition generated CTL with different variable beta gene families of T-cell receptors, implying an oligoclonal expansion of a limited CTL repertoire for each. Thus, peptide-stimulated T cells showed expression of cytotoxic cells, which was not induced by nonspecific (anti-CD3 or IL-2) stimulation.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Previously the authors showed that interleukin-4 (IL-4), used in combination with IL-2, increases the reduced proliferation rate of T cells of glioblastoma-bearing patients after in vitro autologous immunization. In this report, they sought to determine whether this effect is caused by a direct mitogenic effect of IL-4, or rather by an indirect effect through an increased expression of the IL-2 receptor subunits or an enhanced recruitment of responsive cells. Flow cytometric analysis confirmed that the IL-2 receptor subunits are less expressed on circulating T cells from patients with glioblastoma than on those from healthy donors. Because no significant modification of the expression of the p55 and p75 subunits of the IL-2 receptor is observed in cultures treated with both IL-2 and IL-4, the reported enhanced proliferation rate cannot be attributed to an increased level of IL-2 receptor expression. Limiting dilution assays, using autologous target cell immunization, show that treatment with both cytokines (IL-2 plus IL-4) significantly increases the number of recruitable precursor cells without affecting their proliferation rate. These results indicate that IL-4 facilitates an immune response against the autologous tumor cells in glioblastoma-bearing patients by increasing the recruitable precursor T-cell frequency.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

A total of 123 tumor-infiltrating T lymphocyte (TIL) cultures established from patients with HLA-A1, -A2, -A3, -A24, or -A31 metastatic melanoma in the Surgery Branch, National Cancer Institute, were screened for recognition of shared melanoma antigens including five melanosomal proteins (tyrosinase, MART-1/melan-A, gp100, TRP1, TRP2) as well as peptides derived from MAGE-1 and MAGE-3. Examination of the specificity of these T cells indicated that 16% of HLA-A1 TIL, 57% of HLA-A2 TIL, 7% of HLA-A3 TIL, 13% of HLA-A24 TIL, and 27% of HLA-A31 TIL recognized shared melanoma antigens restricted by major histocompatibility complex class I. Melanosomal proteins were frequently recognized by these TIL, and MART-127-35, gp100154-162, gp100209-217, and gp100280-288represent highly immunogenic epitopes that were recognized by a high percentage of HLA-A2 restricted melanoma reactive TIL. Recognition of gp100 by HLA-A2 restricted TIL significantly correlated with clinical response to adoptive immunotherapy with TIL in 21 HLA-A2 melanoma patients (p = 0.024). Four HLA-A1, two HLA-A2, two HLA-A3, one HLA-A24, and two HLA-A31 restricted shared antigen-specific TIL did not recognize the previously identified antigens tested in this study, and may be useful for the identification of new melanoma antigens. The observation that TILs isolated from patients with metastatic melanoma recognized melanosomal proteins in the context of predominant HLA-A alleles implies that it may be possible to develop immunotherapies for patients with melanoma expressing diverse HLA types.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Class I expression in context with T-cell receptor expression is crucial for peptide presentation and induction of CD8+ cytotoxic T lymphocytes (CTL). Presentation of class I bound peptides is dependent on transporter-associated proteins (TAP) expression and function. Tumor infiltrating lymphocytes from a patient with melanoma were isolated, expanded in vitro in the presence of interleukin-2, and tested for cytotoxicity against HLA-A2 positive, MART-1 positive autologous tumor cells, an HLA-A2-positive, MART-1 positive melanoma cell line (Mel-501), and HLA-A2-negative melanoma cells. Significant killing occurred against both A2-positive cell lines (63% and 65%, respectively), but not against the A2-negative line (18%) or A2-positive autologous tumor (1.5%). These CTL preferentially recognized the MART-1 peptide F119, 27–35, and gp100 peptide F125, 280–288, resulting in a 30% to 60% enhancement of lysis when autologous tumor or major histocompatibility complex class I “empty” T2 cells were pulsed with either peptide. To address whether the deficiency in autologous tumor recognition might be related to a deficiency in Ag presentation, we screened for the presence of TAP1 and TAP2 transcripts by polymerase chain reaction, Southern blotting, and scanning densitometry using sequence-specific primers and probes. Both TAP1 and TAP2 expression levels in the autologous tumor were minimal, yet were upregulated 7-to 18-fold, respectively, by interferon-&ggr;. Despite this increase, a similar increase in cytotoxicity did not occur. In short, deficiencies in TAP presentation may have functional significance for tumor escape from immunosurveillance and with respect to impending vaccine trials.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The significance of CD4+lymphocytes and major histocompatibility complex (MHC) class II-restricted antigens in antitumor immunity has been demonstrated in several animal models as well as in some human tumors. However, because of the lack of known class II-restricted antigens, the participation of CD4+cells in antitumor responses has not been well characterized. Recent reports showed that class II proteins covalently linked to an antigenic peptide could be constructed and cells expressing these fusion proteins were recognized by specific THcells. The aim of this study was to determine the effect of the expression of a class II-peptide construct on the tumorigenicity and immunogenicity of transfected murine tumor cells. We have constructed a gene for I-Ed&bgr; chain covalently coupled to the I-Ed-restricted THcell determinant of sperm whale myoglobin (SWM132-145). This class II fusion protein was recognized by a specific THcell line on the surface of COS-7 cells or BALB/c sarcoma cells. The sarcoma cells expressing the MHC–peptide complex were rejected by immunocompetent BALB/c mice, and in vivo T-cell subset depletion experiments suggested the importance of CD4+cells in the rejection. Moreover, splenocytes from mice immunized with tumor cells expressing the I-Ed–SWM complex showed specific peptide recognition in vitro. Such covalent MHC–peptide complexes could prove useful in studies on the role of CD4+lymphocytes in antitumor immune responses, and also in designing new, more effective vaccine approaches to the immunotherapy of cancer, as class II-restricted tumor-associated antigens are identified for human cancers.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Dendritic cells (DCs) are powerful antigen-presenting cells. Because DCs are rare cells, methods to produce them in vitro are valuable ways to study their biologic properties and to generate cells for immunotherapy. This study defines the antigen-presenting properties of DCs generated in vitro from CD34+cells of patients with breast cancer. The combination of cytokines flt3 ligand + c-kit ligand + granulocyte-macrophage colony-stimulating factor (GM-CSF) + interleukin-4 (IL-4) + tumor necrosis factor-&agr; (TNF-&agr;) was used to maximize the output of mature DCs in the culture of CD34+cells while minimizing the production of monocytes. Cells grew and differentiated into DCs as measured by a time-dependent upregulation of cell surface antigens major histocompatibility complex class II, CD1a, CD80, CD86, CD40, and CD4, so that 40% ± 9% (n = 6) of cells in culture at day 15 were CD1a+CD14−. Markers were acquired in the same sequence as on monocytes induced to differentiate with GM-CSF + IL-4. Differentiation was marked by a time-dependent increase in allostimulatory function, which, at its peak, was more potent than in cultures of DCs generated from monocytes with GM-CSF + IL-4, but was comparable on a cell-to-cell basis to that of mature monocytes cultured in flt3-ligand + c-kit-ligand + GM-CSF + IL-4 + TNF-&agr;. Both CD34+cell-derived and monocyte-derived DCs were able to process and to present tetanus toxoid and keyhole limpet hemocyanin to autologous T cells and to present major histocompatibility class I–binding peptides to CD8+cytotoxic T lymphocytes inducing interferon-&ggr; production. Altogether, these results suggest that DCs generated from CD34+cells of patients with breast cancer with flt3 ligand, c-kit ligand, GM-CSF, IL-4, and TNF-&agr; are competent antigen-presenting cells, particularly for CD8+cytotoxic T lymphocytes, and resemble mature monocyte-derived DCs in the assays described here.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The murine melanoma B16 expresses the murine counterpart of the human MART-1/Melan-A (MART-1) antigen, sharing a 68.6% amino acid sequence identity. In this study, mice were vaccinated with bone marrow–derived murine dendritic cells genetically modified with a replication-incompetent adenoviral vector to express the humanMART-1gene (AdVMART1). This treatment generated a protective response to a lethal tumor challenge of unmodified murine B16 melanoma cells. The response was mediated by major histocompatibility complex class I–restricted cytotoxic T lymphocytes specific for MART-1 antigen, which produced high levels of interferon-&ggr; when reexposed to MART-1 in vitro and lysed targets in a calcium-dependent mechanism suggestive of perforin/granzyme B lysis. MART-1 was presented by the dendritic cells used for vaccination and not by epitopes cross-presented by host antigen-presenting cells. In conclusion, dendritic cells genetically modified to express the human MART-1 antigen generate potent murine MART-1–specific protective responses to B16 melanoma.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The goal of immunotherapy is to eliminate tumors by generating tumor-specific cytotoxic T lymphocytes (CTLs) in patients or by adoptively transferring ex vivo–activated CTLs into patients. Clinical trials have shown that tumor-specific CTLs often disappear before tumors are completely eliminated. In this study, the authors show that CTLs specific for cervical tumor cells undergo apoptosis after they are co-cultured with cervical tumor cells. The established cervical tumor cell lines and cervical cancer tissues express CD95 (Fas/Apo-1) ligand. The tumor cell–induced T-cell apoptosis can be blocked by an inhibitory anti-CD95 (APO-1/Fas) antibody, indicating that tumor cells induce apoptosis of CTLs through CD95–CD95 ligand interaction. Addition of interleukin-2 (IL-2) and IL-7 into the culture rescues the CTL from tumor cell–induced apoptosis. The rescued T cells retain their full antitumor cytotoxicity. These data suggest that human cervical tumor cells might actively downregulate a cellular immune response by inducing apoptosis of specific T cells during immunotherapy. Local use of IL-2 and IL-7 as adjuvants may promote survival of the CTL and, thus, enhance the efficacy of immunotherapy.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Genetic education of dendritic cells (DCs) with tumor-associated antigens is an encouraging development in DC-mediated tumor immunotherapy. In this study, to increase the transgene expression by DCs using nonviral vectors, a cytoplasmic T7 vector (T7T7/T7Luc) was used to transfect bone marrow–derived DCs with the firefly luciferase gene as a reporter and as a model tumor antigen. As a result, the luciferase activity of T7T7/T7Luc-transfected DCs was more than four times greater than that of DCs transfected with pCMVLuc, a commonly used nonviral vector. Furthermore, the luciferase activity was increased three times more when dendritic progenitor cells rather than mature DCs were transfected. In vivo tumor studies showed that T7T7/T7Luc-transfected DCs, which express high levels of luciferase (model tumor antigen), stimulated a stronger immune response than did pCMVLuc-transfected DCs, which express relatively low levels of luciferase, as indicated by the cytotoxic T lymphocyte assay. T7T7/T7Luc transfected DCs, when injected into recipient mice, evoked an antigen-specific immune response that can effectively eradicate implanted metastasis and prevent new tumor development by murine melanoma cells genetically modified to express luciferase. Therefore, the T7 system is a powerful nonviral vector that can be used to genetically educate DCs with tumor-associated antigens for tumor immunotherapy.

ISSN:1524-9557    

出版商:OVID    

年代:2000

数据来源: OVID