A parathyroid-hormone-related-protein (PTH-rP)-specific cytotoxic T cell response induced by in vitro stimulation of tumour-infiltrating lymphocytes derived from prostate cancer metastases, with epitope peptide-loaded autologous dendritic cells and low-dose IL-2.

Bone metastases are one of the most common events in patients with prostate carcinoma. PTH-rP, a protein produced by prostate carcinoma and other epithelial cancers, is a key agent for the development of bone metastases. A PTH-rP-derived peptide, designated PTR-4 was identified, which is capable to bind HLA-A2.1 molecules and to generate PTH-rP-specific cytotoxic T cell (CTL) lines from healthy HLA-A2.1(+) individual peripheral-blood-mononuclear-cells (PBMC). In this model, we investigated the in vitro possibility of generating an efficient PTH-rP specific CTL response by cyclical stimulations with IL-2 and PTR-4 peptide-pulsed autologous dendritic cells (DC), of HLA-A2.1(+) tumour infiltrating lymphocytes (TIL) derived from a patient with metastatic prostate carcinoma. A T cell line generated in this way (called TM-PTR-4) had a CD3(+), CD5(+), CD4(-), CD8(+), CD45(Ro+), CD56(-) immunophenotype and a HLA-A2.1 restricted cytotoxic activity to PTR-4-peptide pulsed CIR-A2 (HLA-A2.1(+)) target cells, PTH-rP(+)/HLA-A2.1(+) CIR-A2 transfected with PTH-rP gene, prostate carcinoma LNCaP cells, and autologous metastatic prostate cancer cells (M-CaP). These lymphocytes were not cytotoxic to HLA-A2.1(+) targets not producing PTH-rP, such as peptide-unpulsed CIR-A2 and colon carcinoma SW-1463, cell lines. Our results provide evidence that PTR-4 peptide-pulsed autologous DC may break the tolerance of human TIL against the autologous tumour by inducing a PTH-rP-specific CTL immune reaction. In conclusion PTR-4 peptide-pulsed autologous DC may be a promising approach for vaccine-therapy and antigen-specific CTL adoptive immunotherapy of hormone-resistant prostrate cancer.     

HER-2/neu-derived peptide epitopes are also recognized by cytotoxic CD3(+)CD56(+) (natural killer T) lymphocytes

The human HER-2/neu gene encodes a 185 kDa transmembrane glycoprotein recognized by MHC class I-restricted CTLs. Here, we report that HER-2/neu peptide CTL epitopes can also be recognized by cytotoxic NK-T lymphocytes. Unfractionated peptides derived from HLA-A2(+), HER-2/neu(+) tumor cells acid cell extract (ACE), collected from patients with metastatic ovarian cancer, were used as antigen to generate in vitro cytotoxic effectors. ACE was able to elicit from cancer patients' PBMCs both alphabetaTCR(+)CD3(+)CD56(-) and alphaTCR(+)CD3(+)CD56(+) (NK-T) CTLs that lysed ACE-sensitized T2 cells in an HLA-A2-restricted manner. The same CTL lines also recognized T2 cells pulsed with HER-2/neu-derived CTL peptide epitopes, a HER-2/neu-transfected HLA-A2(+) cell line and autologous tumor cells. alphaTCR(+)CD3(+)CD56(+) CTL lines also exhibited NK-like cytotoxicity against autologous tumor cells. CTL clones were isolated from alphaTCR(+)CD3(+)CD56(+) bulk cultures displaying both MHC- and non-MHC-restricted cytotoxicity, thus confirming the dual cytolytic function of such cells. Our data demonstrate that ACE from metastatic ovarian tumors can be used as multiepitope vaccines for generating in vitro, besides classical CTLs, NK-T cells exerting efficient MHC- and non-MHC-restricted cytotoxicity against autologous tumor targets. Such NK-T cells expressing dual cytotoxic activity may prove advantageous in cancer immunotherapy.     

An analysis of autologous T-cell anti-tumour responses in colon-carcinoma patients following active specific immunization (ASI).

As part of a phase-II clinical trial of post-operative active specific immunization (ASI) with virus-modified autologous tumour cells (AuTu) in colorectal carcinoma patients, we have analyzed in vitro anti-AuTu immune responses with lymphocytes isolated from the peripheral blood (PBL) of 5 treated patients. The PBL of 3 "responder patients", those who developed a positive DTH reaction to AuTu, when stimulated in standard in vitro autologous lymphocyte tumour-cell cultures (ALTC), showed cytotoxic anti-AuTu reactivity only in association with natural-killer-cell(NK)-like activity. We removed nonspecific cytotoxic cells (CD56-positive) from PBL of colon carcinoma or melanoma patients and positively selected T cells with strong CD8 staining (CD8hi) using FACS. Following in vitro stimulation, specific cytotoxic T cells (CTL) directed against either autologous EBV-transformed B cells (AuEBV-B) or autologous melanoma cells were identified in the CD8hi T-cell population. However, even using this novel technique, no specific CTL against autologous colon carcinoma cell lines were detected in PBL from ASI-treated patients (2 DTH responders and 2 DTH non-responders). If AuTu-specific CTL precursors existed in these blood samples, their frequency must have been very low (less than 1 in 8 x 10(4) CD8 positive T cells). Sorted CD4 T cells from these patients, in the presence of autologous antigen-presenting cells, showed no specific anti-tumour proliferative response, and in one instance we observed inhibition of proliferation in the presence of tumour cells.     

Tumor lysate and IL-18 loaded dendritic cells elicits Th1 response,tumor-specific CD8+ cytotoxic T cells in patients with malignant glioma

In this study, we demonstrate that tumor lysate-loaded dendritic cells can elicit a specific CD8+ cytotoxic T lymphocyte response against autologous tumor cells in patients with malignant glioma. CTL from three of five patients expressed strong cytolytic activity against autologous glioma cells, did not lyse autologous lymphoblasts and were variably cytotoxic against the LAK-sensitive cell line Daudi. Also, DCs pulsed normal brain lysate failed to induce cytolytic activity against autologous glioma cells, suggesting the lack of autoimmune response. Two of five patients CD8+ T cells expressed a modest cytotoxicity against autologous glioma cells. CD8+ T cells isolated during these ineffective primings secreted large amounts of IL-10, less amounts of IFN-γ as detected by ELISA, Type 2 bias in the CD8+ T cell response accounts for the lack of cytotoxic effector function from these patients. Cytotoxicity against autologous glioma cells could be significantly inhibited by anti-HLA class I antibody. These data demonstrate that tumor lysate-loaded DC can be an effective tool in inducing glioma-specific CD8+ CTL able to kill autologous glioma cells in vitro. However, high levels of tumor specific tolerance in some patients may account for a significant barrier to therapeutic vaccination. Moreover, cytotoxic responses were augmented by transfecting DC with the gene for IL-18. For all five patients, CD8+T cells treated with IL18 transfected DC produced Th1 response. These results may have important implications for the treatment of malignant glioma patients with immunotherapy. DCs loaded with total tumor lysate and IL-18 may represent a method for inducing Th1 immunoresponses against the entire repertoire of glioma antigens.     

Recognition of breast cancer cells by CD8+ cytotoxic T-cell clones specific for NY-BR-1

Immunotherapy for breast cancer using cytotoxic T cells (CTL) is hindered by the lack of well-characterized breast cancer antigens that are expressed in most breast tumor cells and recognized by CD8+ CTL. A recently described breast tissue differentiation antigen, NY-BR-1, is expressed in >80% breast tumors and elicits a humoral response in a subset of breast cancer patients. To identify potential NY-BR-1 epitopes that are recognized by CTL, CD8+ T cells were stimulated in vitro with autologous dendritic cells pulsed with NY-BR-1 peptides that were predicted to bind to HLA-A2. In multiple normal female donors and breast cancer patients, specific CD8+ CTL responses were detected by enzyme-linked immunospot assay against several NY-BR-1 peptides after two cycles of stimulation. CD8+ CTL clones against three NY-BR-1 epitopes were isolated and recognized peptide-pulsed target cells with high avidity. T-cell clones specific for one of the NY-BR-1 epitopes (p904) also recognized breast tumor cells expressing NY-BR-1, NY-BR-1(-) cells transfected with a cDNA encoding the NY-BR-1 protein, and autologous dendritic cells pulsed with opsonized NY-BR-1+ breast tumor cells. Taken together, these results show that the p904 epitope derived from NY-BR-1 is efficiently processed and presented endogenously and identify NY-BR-1 as a promising target for T-cell-based immunotherapy for breast cancer.     

Generation of autologous tumor-specific T cell clones from a patient with adenosquamous carcinoma of the lung

BACKGROUND: Adenosquamous carcinoma of the lung is not a common cancer, but its prognosis is worse than that of adenocarcinoma or squamous cell carcinoma. Therefore, new therapeutic strategies need to be developed to treat this type of lung cancer. Recently, vaccination using tumor antigens which are recognized by cytotoxic T lymphocytes (CTL) has been applied mainly to melanoma patients. We therefore attempted to establish T cell clones specific for autologous tumor cells (AT) from a patient with adenosquamous carcinoma in order to analyze the specific immune responses against AT. METHODS: A lung adenosquamous carcinoma cell line was established from a resected tumor obtained from a 72-year-old patient. Regional lymph node lymphocytes were stimulated weekly with CD80-transfected AT to induce CTL. The CTL activities were assessed by a standard (51)Cr release assay and by cytokine release. RESULTS: We succeeded in inducing an AT-specific CTL line. Using a limiting dilution method, eight T cell clones were established. AT-specific activity was observed in three CD8(+) T cell clones and one CD4(+) T cell clone out of the eight clones tested. Anti-HLA class I and anti-HLA-B/C mAbs inhibited IFN-gamma production from the AT-specific CD8(+) clones co-cultured with AT, thus indicating the restriction element to be HLA-B*5201 or HLA-Cw*1202. In contrast, the CD4(+) T cell clone recognized AT in an HLA class II-restricted manner. CONCLUSIONS: These results are the first demonstration of a successful induction of AT-specific T cell clones from a patient with lung adenosquamous carcinoma. It may therefore supply a possible way to apply specific immunotherapy to this type of lung cancer.     

The Wilms' tumor antigen is a novel target for human CD4+ regulatory T cells: implications for immunotherapy

Compelling evidences indicate a key role for regulatory T cells (T(reg)) on the host response to cancer. The Wilms' tumor antigen (WT1) is overexpressed in several human leukemias and thus considered as promising target for development of leukemia vaccine. However, recent studies indicated that the generation of effective WT1-specific cytotoxic T cells can be largely affected by the presence of T(regs). We have generated T-cell lines and clones that specifically recognized a WT1-84 (RYFKLSHLQMHSRKH) peptide in an HLA-DRB1*0402-restricted manner. Importantly, they recognized HLA-DRB1*04-matched fresh leukemic cells expressing the WT1 antigen. These clones exerted a T helper 2 cytokine profile, had a CD4(+)CD25(+)Foxp3(+)GITR(+)CD127(-) T(reg) phenotype, and significantly inhibited the proliferative activity of allogeneic T cells independently of cell contact. Priming of alloreactive T cells in the presence of T(regs) strongly inhibited the expansion of natural killer (NK), NK T, and CD8(+) T cells and had an inhibitory effect on NK/NK T cytotoxic activity but not on CD8(+) T cells. Furthermore, priming of T cells with the WT1-126 HLA-A0201-restricted peptide in the presence of T(regs) strongly inhibited the induction of anti-WT1-126 CD8(+) CTL responses as evidenced by both very low cytotoxic activity and IFN-gamma production. Moreover, these T(reg) clones specifically produced granzyme B and selectively induced apoptosis in WT1-84-pulsed autologous antigen-presenting cells but not in apoptotic-resistant DR4-matched leukemic cells. Importantly, we have also detected anti-WT1-84 interleukin-5(+)/granzyme B(+)/Foxp3(+) CD4(+) T(regs) in five of eight HLA-DR4(+) acute myeloid leukemia patients. Collectively, our in vitro and in vivo findings strongly suggest important implications for the clinical manipulation of T(regs) in cancer patients.     

Determination of cellularly processed HLA-A2402-restricted novel CTL epitopes derived from two cancer germ line genes, MAGE-A4 and SAGE.

PURPOSE: For identification of CTL epitopes useful for cancer vaccines, it is crucial to determine whether cognate epitopes are presented on the cell surface of target cancer cells through natural processing of endogenous proteins. For this purpose, we tried to use the cellular machinery of both mice and human to define naturally processed CTL epitopes derived from two "cancer germ line" genes, MAGE-A4 and SAGE. EXPERIMENTAL DESIGN: We vaccinated newly produced HLA-A2402 transgenic mice with DNA plasmids encoding target antigens. Following screening of synthesized peptides by splenic CD8(+) T cells of vaccinated mice, we selected candidate epitopes bound to HLA-A2402. We then examined whether human CD8(+) T cells sensitized with autologous CD4(+) PHA blasts transduced by mRNA for the cognate antigens could react with these selected peptides in an HLA-A2402-restricted manner. RESULTS: After DNA vaccination, murine CD8(+) T cells recognizing MAGE-A4(143-151) or SAGE(715-723) in an HLA-A2402-restricted manner became detectable. Human CTLs specific for these two peptides were generated after sensitization of HLA-A2402-positive CD8(+) T cells with autologous CD4(+) PHA blasts transduced with respective mRNA. CTL clones were cytotoxic toward tumor cell lines expressing HLA-A2402 and cognate genes. Taken together, these CTL epitopes defined in HLA-A24 transgenic mice are also processed and expressed with HLA-A2402 in human cells. The presence of SAGE(715-723)-specific precursors was observed in HLA-A2402-positive healthy individuals. CONCLUSIONS: Two novel HLA-A2402-restricted CTL epitopes, MAGE-A4(143-151) and SAGE(715-723), were identified. Our approach assisted by cellular machinery of both mice and human could be widely applicable to identify naturally processed CTL epitopes.     

Direct Activation of Human CD8+ Cytotoxic T Lymphocytes by Interleukin-18

Direct activation of human cytotoxic T lymphocytes (CTL) by interleukin (IL)-18 was observed in a system in which CTL effective against autologous tumor cells were generated. Peripheral blood mononuclear cells (PBMC) from tumor-bearing patients, after removal of natural killer (NK) cells, were cultured in a medium containing IL-1, -2, -4, and -6, with or without IL-18, and stimulated with autologous tumor cells. IL-18 increased the activity of the CTL and the proportion of autologous CD8⁺ T cells present after 28 days in the induction culture. When purified CD8⁺ T cells were cultured in the presence of IL-18 and IL-2 for 7 days, the CTL showed enhanced cytotoxic activity against autologous tumor cells. Moreover, a purified CD8⁺ T cell population, which did not exhibit any apparent cytotoxic activity against autologous tumor cells, displayed cytotoxic activity after 7-day incubation with IL-18. These results suggest that IL-18 may be useful to generate autologous CTL in humans and may thereby contribute to adoptive immunotherapy for tumors.     

Altered CD94/NKG2A and perforin expression reduce the cytotoxic activity in malignant pleural effusions

CD94/NKG2A is an inhibitory receptor expressed by NK cells and cytotoxic lymphocytes and, upon activation by HLA-E, downregulates the cytolytic activities of these cells thus representing a tumour immune escape mechanism.This study was aimed at assessing whether cytotoxic lymphocytes (CD8+) and NK cells from malignant pleural effusions have a deregulated expression of CD94/NKG2A.The expression of membrane CD94/NKG2A and perforin was evaluated by flow-cytometry in CD8+ and NK cells from pleural effusions and autologous peripheral blood of cancer (n = 19) and congestive heart failure (CHF) (n = 11) patients. Intracellular CD94/NKG2A expression was evaluated by flow-cytometry in pleural effusion CD8+ and NK cells from cancer patients (n = 10). Cytotoxic activity against cancer cells exerted by pleural and autologous peripheral blood T lymphocytes from cancer patients was assessed by flow-cytometry assay.Pleural CD8+ from cancer patients showed a reduced expression of membrane CD94/NKG2A and perforin when compared to autologous peripheral blood and CHF pleural effusions. Reduced numbers of NK cells were present in pleural effusions from both cancer and CHF patients. Pleural NK from cancer patients showed a reduced expression of membrane CD94/NKG2A and perforin when compared to autologous peripheral blood. Pleural T lymphocytes from cancer patients exhibited a reduced cytotoxic activity against cancer cells when compared to autologous peripheral blood T lymphocytes. The intracellular expression of CD94/NKG2A in CD8+ and NK cells from cancer patients was higher than membrane expression.In conclusion, this study provides compelling evidences of new mechanisms underlying the reduced host defence against cancer within the pleural space.     

Superior antitumor in vitro responses of allogeneic matched sibling compared with autologous patient CD8+ T cells

Allogeneic cell therapy as a means to break immunotolerance to solid tumors is increasingly used for cancer treatment. To investigate cellular alloimmune responses in a human tumor model, primary cultures were established from renal cell carcinoma (RCC) tissues of 56 patients. In three patients with stable RCC line and human leukocyte antigen (HLA)-identical sibling donor available, allogeneic and autologous RCC reactivities were compared using mixed lymphocyte/tumor cell cultures (MLTC). Responding lymphocytes were exclusively CD8(+) T cells, whereas CD4(+) T cells or natural killer cells were never observed. Sibling MLTC populations showed higher proliferative and cytolytic antitumor responses compared with their autologous counterparts. The allo-MLTC responders originated from the CD8(+) CD62L(high)(+) peripheral blood subpopulation containing naive precursor and central memory T cells. Limiting dilution cloning failed to establish CTL clones from autologous MLTCs or tumor-infiltrating lymphocytes. In contrast, a broad panel of RCC-reactive CTL clones was expanded from each allogeneic MLTC. These sibling CTL clones either recognized exclusively the original RCC tumor line or cross-reacted with nonmalignant kidney cells of patient origin. A minority of CTL clones also recognized patient-derived hematopoietic cells or other allogeneic tumor targets. The MHC-restricting alleles for RCC-reactive sibling CTL clones included HLA-A2, HLA-A3, HLA-A11, HLA-A24, and HLA-B7. In one sibling donor-RCC pair, strongly proliferative CD3(+)CD16(+)CD57(+) CTL clones with non-HLA-restricted antitumor reactivity were established. Our results show superior tumor-reactive CD8 responses of matched allogeneic compared with autologous T cells. These data encourage the generation of antitumor T-cell products from HLA-identical siblings and their potential use in adoptive immunotherapy of metastatic RCC patients.     

Dendritic cells fused with allogeneic colorectal cancer cell line present multiple colorectal cancer-specific antigens and induce antitumor immunity against autologous tumor cells.

The aim of antitumor immunotherapy is to induce CTL responses against autologous tumors. Previous work has shown that fusion of human dendritic cells and autologous tumor cells induce CTL responses against autologous tumor cells in vitro. However, in the clinical setting of patients with colorectal carcinoma, a major difficulty is the preparation of sufficient amounts of autologous tumor cells. In the present study, autologous dendritic cells from patients with colorectal carcinoma were fused to allogeneic colorectal tumor cell line, COLM-6 (HLA-A2(-)/HLA-24(-)), carcinoembryonic antigen (CEA)(+), and MUC1(+) as an alternative strategy to deliver shared colorectal carcinoma antigens to dendritic cells. Stimulation of autologous T cells by the fusion cells generated with autologous dendritic cells (HLA-A2(+) and/or HLA-A24(+)) and allogeneic COLM-6 resulted in MHC class I- and MHC class II-restricted proliferation of CD4(+) and CD8(+) T cells, high levels of IFN-gamma production in both CD4(+) and CD8(+) T cells, and the simultaneous induction of CEA- and MUC1-specific CTL responses restricted by HLA-A2 and/or HLA-A24. Finally, CTL induced by dendritic cell/allogeneic COLM-6 fusion cells were able to kill autologous colorectal carcinoma by HLA-A2- and/or HLA-A24-restricted mechanisms. The demonstration of CTL activity against shared tumor-associated antigens using an allogeneic tumor cell line, COLM-6, provides that the presence of alloantigens does not prevent the development of CTL with activity against autologous colorectal carcinoma cells. The fusion of allogeneic colorectal carcinoma cell line and autologous dendritic cells could have potential applicability to the field of antitumor immunotherapy through the cross-priming against shared tumor antigens and provides a platform for adoptive immunotherapy.     

Ex vivo generation and expansion of anti-tumor cytotoxic T-cell lines derived from patients or their HLA-identical sibling

Successful ex-vivo priming and long-term maintenance of anti-tumor cytotoxic T-cell (CTL) lines are preliminary conditions for their use in approaches of adoptive immunotherapy for patients with cancer. We describe the results of a novel procedure for generating in vitro anti-tumor CTL using CD8-enriched peripheral blood mononuclear cells (PBMC) and dendritic cells (DC), pulsed with irradiated tumor cells (TC) as source of tumor antigen. Eight patients were enrolled in our study: 4 sarcoma, 2 renal cell carcinoma, 1 ovarian carcinoma and 1 breast carcinoma. Ten anti-tumor CTL-lines cytotoxic towards patient TC were generated. Five CTL-lines were obtained using both DC and PBMC from the patients (autologous setting). For 5 CTL-lines, DC derived from an HLA-identical sibling were employed (allogeneic setting): patients or siblings PBMC were used to generate CTL-lines in 2 and 3 cases, respectively,. After tumor-specific rounds of stimulation, followed by antigen-independent cycle of expansion, CTL-lines obtained in both autologous and allogeneic setting showed an expansion of the absolute number of cultured cells. In 6 of 10 CTL-lines, the majority of effector cells (>70%) were CD3+/CD8+, while in the remaining 4, 40-70% of effector cells were CD3+/CD4+. Both CD8+ and CD4+ T cells displayed anti-tumor cytotoxic activity. Spectratyping analysis of the TCR-Vbeta subfamilies revealed a preferential expansion of oligoclonal populations in 18 of 24Vbeta subfamily. Altogether these results demonstrate that our experimental approach is suitable for efficiently generating and expanding anti-solid tumor CTL to be used for adoptive immunotherapy.     

Phase I trial of adoptive immunotherapy with cytolytic T lymphocytes immunized against a tyrosinase epitope.

PURPOSE: To study distribution and toxicity of cytolytic T lymphocytes (CTLs) against a single melanoma epitope. PATIENTS AND METHODS: CD8(+) T cells obtained by leukapheresis from 10 patients with disseminated HLA-A2.1(+), tyrosinase-positive melanomas were immunized in vitro against tyrosinase(369-377) (YMNGTMSQV). Drosophila cells transduced with HLA-A2.1, CD80, and CD54 (intracellular adhesion molecule-1) were used for priming, followed by two rounds of immunization with mononuclear cells as antigen-presenting cells. 1 x 10(8) CTL were infused intravenously (IV) on day 1. CTL frequency was measured by limiting dilutions in five patients. (111)In labeling and scintigraphy measured distribution of CTL in next five. Five days later, 1 x 10(8) CTLs were infused on 4 successive days to both groups. Immunohistology of response was judged by biopsies. RESULTS: Infusions were nontoxic. CTLs were undetectable in the blood, going to lungs within 5 minutes. At 4, 24, and 72 hours, they were found in liver and spleen. Lesions were visualized by scintiscans in one responding patient where two subcutaneous nodules were noted at 4 and 24 hours. A second patient had a partial response and remains alive with disease 2 years later. CD8(+) T cells were found in lesions of responders, associated with the presence of HLA-A2 molecules and tyrosinase. Two nonresponders without tyrosinase and HLA-A2 molecules had a paucity of CD8(+) T cells in their lesions. Whether the CD8(+) T cells in lesions of responders were those we had reinfused is uncertain. CONCLUSION: CTLs immunized against a single melanoma epitope were nontoxic but did not specifically localize to tumor sites. Nevertheless, two patients had disease regression. Additional therapeutic studies with specifically immunized CTL seem justified.     

Adoptive immunotherapy for advanced cancer patients using in vitro activated cytotoxic T lymphocytes

BACKGROUND AND OBJECTIVES: We evaluated the clinical efficacy of adoptive immunotherapy using in vitro activated cytotoxic T lymphocytes (CTL) in the treatment of patients with advanced cancer. METHODS: CTL were induced with the mixed lymphocyte and tumor cell culture method, in which lymphocytes isolated from patient peripheral blood mononuclear cells were mixed with inactivated autologous tumor cells. Activated lymphocytes were administered intravenously to 11 patients once every 2 weeks for 10 weeks (i.e., 5 doses). RESULTS: Tumor reduction and decreased tumor marker were observed in 4 patients. Notably, successful CTL induction was identified in all of these patients. In patients who did not show induction of CTL response, a decreased proportion of lymphocytes, especially CD8(+) cells, and increased levels of CD14(+) cells were frequently observed. Fluorescence-activated cell sorter analysis indicated that expression of HLA class I and costimulatory factor B7-1 molecules was diminished on tumor cells. This was partly recovered with interferon-gamma, which resulted in successful induction of a CTL response. CONCLUSIONS: It was suggested that in vitro CTL induction is difficult in patients with advanced cancer. However, once the cells were induced successfully, some favorable clinical effects were seen by the adoptive transfer of such cell populations.     

Restoration of Tumor-Specific HLA Class I Restricted Cytotoxicity in Tumor Infiltrating Lymphocytes of Advanced Breast Cancer Patients by in vitro Stimulation with Tumor Antigen-Pulsed Autologous Dendritic Cells

Breast tumor infiltrating lymphocytes (TIL) are enriched in tumor-specific cytotoxic T lymphocytes (CTL), and may represent a superior source of CTL compare to peripheral blood lymphocytes (PBL), for adoptive T cell immunotherapy of breast cancer. However, the immunocompetence of TIL and the possibility to consistently restore their tumor-specific lytic activity in vitro remains an open issue. In this study we evaluated the potential of tumor antigen-pulsed fully mature dendritic cell (DC) stimulation in restoring tumor-specific cytotoxicity in anergic TIL populations from advanced breast cancer patients. In addition we have compared tumor-specific T cell responses induced by tumor antigen-loaded DC stimulation of TIL to responses induced from PBL. Although TIL were consistently non-cytotoxic after isolation or culture in the presence of interleukin-2 (IL-2), in matched experiments from three consecutive patients, tumor-lysate-pulsed DC-stimulated CD8+ T cell derived from TIL were found to be significantly more cytotoxic than PBL (p < 0.05). In addition, cytotoxicity against autologous tumor cells was more significantly inhibited by an anti-HLA class I (W6/32) MAb in TIL compared to PBL (p < 0.05). CTL populations derived from TIL and PBL did not lyse autologous EBV-transformed lymphoblastoid cell lines, and showed negligible cytotoxicity against the NK-sensitive cell line K562. Furthermore, in both CD8+ T cell populations the majority of the tumor-specific CTL exhibited a Th1 cytokine bias (IFN-^high/IL-4^low). Taken together, these data show that tumor lysate-pulsed mature DC can consistently restore tumor-specific lytic activity in non-cytotoxic breast cancer TIL. These results may have important implications for the treatment of chemotherapy resistant breast cancer with active or adoptive immunotherapy.     

Generation of in vitro B-CLL specific HLA class I restricted CTL responses using autologous dendritic cells pulsed with necrotic tumor lysate

New approaches in the treatment of chronic B lymphocytic leukemia (B-CLL) have led to improved clinical response rates. In this setting there is a need to evaluate novel therapeutic approaches that aim to eradicate minimal residual B-CLL cells following an initial favorable response. The use of tumor lysate-pulsed dendritic cells (DC) represents a potentially important development in the field of cancer vaccination. B-CLL is ideally suited for DC-based vaccination since tumor cells are readily available (peripheral blood) and both known (tumor idiotype) and unknown antigens can be exploited to stimulate immune responses. In the current study we have evaluated the ability to stimulate in vitro autologous immune reactivity against target B-CLL cells using autologous DCs pulsed with B-CLL tumor lysate. Enhanced specific T cell IFN-gamma expression was detected in 9 of 14 patients evaluated. These responses were specific with increased levels of IFN-gamma mRNA measurable in T-cells stimulated with NC-DCs and not unpulsed DCs or DCs pulsed with normal B cell lysate. CTLs demonstrating increased levels of IFN-gamma mRNA also lysed autologous B-CLL targets cells in an MHC class 1-restricted manner by (51)chromium release assay. Priming target leukemic cells with CD40 ligand and IL-4 enhanced CTL killing. The effector CTL displayed negligible toxicity against NK susceptible target cells K-562 and spared CD19(+)CD5(-) normal B cells in cytotoxicity assays. The specificity of the CTL response was confirmed by blocking HLA class I molecules and cold target inhibition assays.     

Interleukin-12 Augments the Generation of Autologous Tumor-reactive CD8+ Cytotoxic T Lymphocytes from Tumor-infiltrating Lymphocytes

Human tumor-infiltrating lymphocytes (TIL) were obtained from breast cancer, renal cancer or neuroblastoma to investigate the generation of autologous tumor-reactive CD8⁺ cytotoxic T lymphocytes (CTL). When TIL were cultured with interleukin (IL)-2 (100 U/ml), the growth of TIL peaked around 8–10 days after the initiation of culture. In contrast, the proliferation of TIL cultured with IL-2 plus IL-12 peaked around 4–5 days after culture and tumor cells rapidly disappeared from the culture. To determine the generation of autologous tumor-reactive CD8⁺ CTL, TIL-derived CD8⁺ T cells were separated by FACStar. Both IL-2-activated and IL-2 plus IL-12-activated TIL-CD8⁺ T cells showed the same level of lymphokine-activated killer activity against a variety of tumor cells. However, TIL-CD8⁺ T cells activated with IL-2 plus IL-12 revealed greatly augmented cytotoxicity against autologous tumor cells compared with that induced by IL-2 alone. The autologous tumor cell-killing activity of TIL-CD8⁺ CTL was significantly inhibited by the addition of F(ab)₂ anti-CD3 monoclonal antibody, indicating that these CTL recognize autologous tumor antigen through T cell receptor. These results imply that IL-12 is a novel cytokine which facilitates the generation of autologous tumor-reactive CD8⁺ CTL from TIL.     

Induction of cytotoxic T cell response against HCA661 positive cancer cells through activation with novel HLA-A *0201 restricted epitopes

HCA661 is a cancer-testis (CT) antigen frequently expressed in human hepatocellular carcinoma (HCC). To search for immunogenic peptides of HCA661, bioinformatics analysis and CD8(+) T cell IFN-gamma ELISPOT assay were employed, and two HLA-A *0201 restricted peptides, H110 and H246, were identified. These two HCA661 peptides are naturally processed in dendritic cells (DCs) and when used for DCs loading, they are sufficient to prime autologous CD8(+) T cells to elicit cytotoxic response against HCA661(+) human cancer cells. The HCA661 peptides, H110 and H246, are hence attractive candidates for human cancer immunotherapy.