Melanoma-specific cytotoxic T cells generated from peripheral blood lymphocytes. Implications of a renewable source of precursors for adoptive cellular immunotherapy.

Cytotoxic T lymphocytes (CTL) specific for autologous human melanoma have been generated in vitro from peripheral blood lymphocytes (PBL) of five patients with resectable stage II malignant melanoma. The PBL were cultured with 5u/ml recombinant IL-2 and were repeatedly stimulated with irradiated fresh or cultured autologous tumor cells. Cytotoxicity was determined by four-hour chromium release assays. Specific cytotoxicity developed in 30 to 40 days, after three or four stimulations with tumor. The PBL-derived CTL are CD3+ and are mixed for CD4+ and CD8+ phenotypes. They lysed autologous melanoma and failed to lyse allogeneic melanoma, K562, or autologous lymphocytes. The lysis of autologous tumor was maintained for more than 4 months. The cells proliferated in response to autologous, but not allogeneic melanoma cells, in a dose-dependent manner. Lysis of the autologous tumor target was inhibited with w6/32, a monoclonal antibody to HLA Class I antigens. It is concluded that PBL may serve as a plentiful and renewable source of precursor cells for the generation of autologous tumor-specific CTL, which may be useful in specific adoptive cellular immunotherapy of melanoma.     

Characterization of tumor-infiltrating mononuclear cells in renal cell cancer: quantitative analysis by immunoperoxidase staining

In order to determine whether tumor-infiltrating mononuclear cells (TIM) of renal cell cancer (RCC) is suitable for adoptive immunotherapy, their number and characteristics were examined immunohistologically. TIM consisted of T cells and a smaller number of macrophages. Among T cells, CD8-positive cells were the dominant population which was reported to be more potent for the lysis of tumor cells. The number of T cells was variable: in 5 tumors no T cells were observed and in an other 5 the number of T cells were less than 2 x 10(6) cells/cm3. These results suggest that the TIM of RCC might be favorable for adoptive immunotherapy but TIM could not be available in some cases because of their small number.     

Tumor-infiltrating lymphocytes derived from human renal cell carcinoma: Clonal analysis of its characteristics

Aim:   To assess the characteristics of activated tumor-infiltrating lymphocytes (TIL), we report the isolation, growth response, and functional analysis of a CD4^- CD8⁺ TIL-clone derived from human renal cell carcinoma (RCC).
Methods:   Bulk TILs were expanded from a human RCC and the lymphocytes were separated into a CD8⁺ enriched population. Subsequently, using the limiting dilution technique, a TIL clone was established and its growth response, phenotype and cytotoxic activity were analyzed.
Results:   A clone, T16-13, by day 94 numbering 1 × 10⁷ cells, was harvested and characterized as a CD4^- CD8⁺ clone. On day 144, the cytotoxic activity of this clone against the autologous tumor was relatively high (2.3 ± 0.7 LU₃₀/10⁶ cells). Meanwhile, against allogeneic renal tumors, there was no cytotoxic activity (−0.1 LU₃₀/10⁶ cells).
Conclusions:   A TIL clone possessing modest autologous tumor-specific cytotoxicity can be isolated from human RCC. The characteristics analysis of various TIL clones may provide a better understanding of an RCC tumor microenvironment and may help to establish new modalities for the treatment of patients with metastatic kidney cancer.     

Evidence for cytotoxic T lymphocyte response against human lung cancer: reconstitution of antigenic epitope with peptide eluted from lung adenocarcinoma MHC class I

BACKGROUND: Cancer-associated, major histocompatibility complex (MHC)-restricted peptide antigens have been elucidated in human melanomas and ovarian, breast, and renal carcinomas; but relatively little is known about lung cancer antigens. METHODS: To work toward delineation of lung cancer-associated antigens, we developed tumor infiltrating lymphocytes (TILs), peripheral blood mononuclear cell-derived cytolytic T cell lines (CTL), autologous lung cancer cell lines, and normal lung cell lines from 17 patients undergoing lung cancer resections. The TILs and CTL lines were subsequently evaluated for markers of activation and specific lysis of autologous or allogeneic lung cancer cell lines or both. RESULTS: Freshly isolated TILs contained a more activated T cell population compared with the patients' peripheral blood T cells as evidenced by an increased expression of HLA-DR, CD25, and CD45RO. TILs isolated from 15 patients lysed allogeneic lung cancer lines. TILs lysed autologous lung cancer but not autologous normal lung or Epstein-Barr virus transformed B cell lines (B-LCL) in 4 of 8 cases tested, suggesting tumor specificity. A CTL line (RHPBL57.1) was generated from peripheral blood mononuclear cells of an HLA-A24(+) patient by stimulation against an established HLA-A24(+) allogeneic lung cancer cell line. RHPBL57.1 lysed the lung cancer cell line in an HLA-A24-restricted manner. Moreover, RHPBL57.1 specifically lysed autologous B-LCL pulsed with peptides, eluted from MHC class I and isolated from the HLA-A24(+) lung cancer cell line. CONCLUSIONS: TILs isolated from patients with lung cancer are predominantly an activated population of T cells with evidence of tumor and MHC class I-restricted lysis. Furthermore, we provide evidence for a lung cancer-associated, MHC class I-bound peptide antigen(s) that reconstitutes the epitope recognized by a lung cancer specific CD8(+) T cell line derived from a patient with lung cancer.     

Patterns of human tumor-infiltrating lymphocytes in 120 human cancers.

Tumor-infiltrating lymphocytes from 120 samples of human cancers, including melanoma, renal cell carcinoma, breast cancer, sarcoma, and colon cancer, were examined. The percentage of lymphocytes recovered from the cancer varied widely; that of renal cell carcinoma was higher than that of breast or colon cancer (65% vs 45%), which was higher than that of melanomas or sarcomas (30% to 35%). The types of lymphocytes before and after interleukin 2 activation showed specific patterns. CD4+ helper T cells predominated in all tumors except melanomas, which had more CD8+ cytotoxic T cells. CD16+ natural killer cells were recovered in renal cell carcinoma and sarcomas. Three different cytotoxic lymphocytes were identified among interleukin 2-activated tumor-infiltrating lymphocytes: (1) CD3+ CD16- cytotoxic T lymphocytes with cytotoxicity restricted to autologous tumor cells in melanomas, (2) CD3-CD16+ natural killer cells with vigorous major histocompatibility complex-nonrestricted cytotoxicity in renal cell carcinoma, and (3) CD3+ CD16- T cells with modest levels of major histocompatibility complex-nonstricted cytotoxicity in all cancers except melanomas. Thus, there was considerable diversity of tumor-infiltrating lymphocytes among these histologically distinct tumors with respect to magnitude of lymphocyte infiltration, phenotypic expression, and functional capacity.     

Reactivity of in-vitro-expanded alloimmune cytotoxic T lymphocytes and Qa-1-specific cytotoxic T lymphocytes against AKR leukemia in vivo

The ability of alloimmune spleen cells expanded in mixed leukocyte culture (MLC) and cloned cytotoxic T lymphocytes (CTL) to kill H-2-compatible leukemia in vivo was evaluated. In comparison with fresh alloimmune spleen cells, MLC-expanded cells had a significantly higher frequency of CTL reactive against leukemia targets in vitro. However, the reactivity of MLC-expanded cells against first-passage spontaneous AKR (H-2k) leukemia in vivo was significantly less than when an equivalent number of fresh alloimmune spleen cells was injected. Comparable antileukemia reactivity was observed in vivo only when the inoculum of MLC-expanded cells was 2-3-fold higher than that of fresh spleen cells. This relative ineffectiveness was attributed to the altered migration pattern of cultured cells in vivo. IL-2-dependent cloned CTL, specific for a normal lymphocyte antigen (Qa-1b) also present on leukemia cells, were derived from MLC-expanded cultures and tested in vivo. For cloned CTL, as with MLC-expanded cells, eradication of AKR leukemia in vivo was associated with the tissue distribution pattern of the injected effector cells. That is, an effective antileukemia reaction was achieved only in tissues in which effector and target proximity was maintained. Qa-1b-specific cloned CTL did not interfere with engraftment of autologous or allogeneic bone marrow in lethally irradiated host mice, nor did they cause any clinically evident graft-versus-host disease. These findings suggest that cloned CTL specific for a normal cell surface antigen with limited host tissue distribution, but present on tumor cells, could be used for adoptive immunotherapy, provided CTL and tumor cell proximity can be attained.     

辅助性T细胞和细胞毒性T淋巴细胞双表位修饰的树突状细胞肿瘤疫苗治疗胃癌的实验研究

目的研究辅助性T细胞（Th）表位和细胞毒性T淋巴细胞（CTL）双表位修饰的树突状细胞（DCs）肿瘤疫苗用于胃癌免疫治疗的效果。方法用CTL表位MAGE-341-49和Th表位MAGE-322-36混合多肽冲击DCs，每周刺激脾脏T细胞1次，4周后收集多肽特异性T细胞。流式仪分析T细胞亚群分布，测定CD4^＋T细胞识别抗原细胞因子分泌及CD8^＋T细胞杀伤肿瘤细胞效能，观察双表位修饰的DCs肿瘤疫苗治疗胃癌的保护性免疫效应。结果双表位致敏的DCs体外可同时活化CD4^＋和CD8^＋T细胞，其中CD4^＋T细胞识别肿瘤细胞小鼠前胃癌细胞株MFC后分泌大量Th1型细胞因子[干扰素（IFN）-γ，白介素（IL）-2]，CD8^＋T细胞强效杀伤MFC。双表位修饰的DCs肿瘤疫苗小鼠体内免疫治疗获得抵抗后继胃癌细胞MFC的免疫保护能力，并显著高于单一表位（CTL或Th）修饰的DC8疫苗。结论Th和CTL双表位修饰的DCs肿瘤疫苗可同时激活CD4^＋Th1细胞和CD8^＋CTL抗肿瘤免疫，有效清除胃癌细胞。     

CD40 monoclonal antibody activation of antigen-presenting cells improves therapeutic efficacy of tumor-specific T cells.

OBJECTIVE: The goal of this study was to determine whether CD40 ligation of antigen presenting cells (APCs) enhances the anti-tumor effector function of tumor draining lymph node (TDLN) T lymphocytes in an adoptive immunotherapy model. STUDY DESIGN: MCA 205 TDLNs were culture activated both in the presence and absence of a stimulatory anti-CD40 monoclonal antibody (mAb) and effector cell phenotype, cytokine secretion in vitro and therapeutic efficacy in vivo were compared. RESULTS: Anti-CD40 mAb induced upregulation of APC cell surface activation markers that promoted generation of T cells that demonstrated an increase in tumor-specific IFN-gamma secretion and a statistically significant reduction in the number of pulmonary tumors (p< 0.01) after adoptive transfer. CONCLUSION: CD40 ligation of APCs in vitro results in the generation of T cells with enhanced effector function against established pulmonary tumors in vivo. SIGNIFICANCE: These findings have direct implications in the development of effective T cell-based immunotherapy of malignant conditions in human beings.     

In vitro induction of tumor-specific HLA class I-restricted CD8+ cytotoxic T lymphocytes from patients with locally advanced breast cancer by tumor antigen-pulsed autologous dendritic cells

BACKGROUND: Early dissemination of treatment-resistant tumor cells remains the major cause of metastatic recurrence and death in breast cancer patients. Dendritic cells (DCs) are the most powerful antigen-presenting cells, and recently DC-based vaccination has shown great promise for the treatment of human malignancies by immunological intervention. MATERIALS AND METHODS: CD8+ T lymphocytes derived from peripheral blood mononuclear cells stimulated in vitro with autologous breast tumor antigen-pulsed DCs were tested for their ability to induce a HLA class I restricted cytotoxic T lymphocyte (CTL) response against autologous tumor cells. To correlate cytotoxic activity by CTL with T cell phenotype, two-color flow cytometric analysis of surface markers and intracellular cytokine expression was performed. RESULTS: DC pulsed with breast tumor extracts consistently elicited a tumor-specific HLA class I restricted CTL response in vitro in three consecutive patients harboring locally advanced breast cancer. CTL expressed strong cytolytic activity against autologous tumor cells but did not lyse autologous Epstein Barr virus-transformed lymphoblastoid cell lines and showed variable cytotoxicity against the natural killer-sensitive cell line K-562. In all patients, two color flow cytometric analysis of surface markers and intracellular cytokine expression demonstrated that tumor-specific CTL exhibited an heterogeneous CD8+/CD56+ expression and a striking Th1 cytokine bias (IFNgamma(high)/IL-4 (low)). CONCLUSIONS: Tumor lysate-pulsed DCs can consistently stimulate specific CD8+ CTLs able to kill autologous tumor cells in patients with locally advanced breast cancer in vitro. Tumor antigen-pulsed DC-based vaccinations may be appropriate for the treatment of residual and/or chemotherapy-resistant breast cancer refractory to standard salvage treatment modalities.     

In situ characterization, clonogenic potential, and antitumor cytolytic activity of T lymphocytes infiltrating human brain cancers

Mononuclear cells infiltrating human brain tumors were isolated from seven of nine surgical biopsy specimens. These cells were small T11+, T3+ lymphocytes that did not express DR antigens or the receptor for interleukin-2. In addition, large granular lymphocytes were recovered from two of these tumors. The clonogenic potential of tumor-infiltrating lymphocytes (TIL's) was assessed by limiting-dilution analysis (LDA) using a microculture system that permits proliferation of virtually 100% of normal peripheral blood T lymphocytes (PBL-T's). In comparison to normal and autologous PBL-T's, TIL's had a strikingly reduced proliferative potential revealed by a decrease in the frequency of proliferating T lymphocyte precursors calculated by LDA. On average, only one of every 100 T cells from TIL's was able to proliferate, as compared to one of every two or all of the T cells from the patient's peripheral blood or from normal donors. Furthermore, the TIL populations showed depressed proliferative responses to the lectins phytohemagglutinin and concanavalin A and to the phorbol ester 12-0-tetradecanoyl-phorbol-13-acetate. Clonal analysis performed on the proliferating microcultures from three tumors demonstrated that the majority of these clones possessed cytolytic activity against various tumor cell targets. Among clones tested for cytolytic activities with glioma cells, four lysed cultured autologous tumor cells, and the specific lysis was greater than 50% in all cases. Numerous clones with natural killer (NK)-like activity were obtained from two TIL preparations, and the frequency of cytolytic T lymphocyte precursors with NK-like activity was determined for one of these preparations and was found to be higher than that in the patient's peripheral blood. Glioma cells grown in culture and then mixed with normal peripheral blood lymphocytes (PBL's) were capable of inhibiting the PBL's response to lectins. This inhibitory property may account in part for the observed poor clonogenicity of TIL's from brain tumors. Nevertheless, nearly all proliferating clones displayed cytotoxicity against either autologous or allogeneic tumor cell targets and may imply selective accumulation of cytolytic effector cells at the tumor site.     

Anti-prostate specific membrane antigen designer T cells for prostate cancer therapy

BACKGROUND: Designer T cells are T lymphocytes engineered toward specific antibody-type membrane antigens through chimeric immunoglobulin-T-cell receptor (IgTCR) genes that have been used for adoptive cellular immunotherapy. We have extended this approach to prostate specific membrane antigen (PSMA) as a means to attack prostate cancer. METHODS: A chimeric anti-PSMA IgTCR gene was constructed based on an anti-PSMA monoclonal antibody, 3D8. Both T-cell lines and primary cultured human T lymphocytes were transduced with the chimeric anti-PSMA IgTCR construct and were analyzed for IgTCR expression, specific activation by PSMA, cytotoxicity against PSMA-expressing tumor cells in vitro, and retardation of tumor growth in an animal model. RESULTS: The IgTCR was incorporated into the TCR-CD3 complex and formed a functional chimeric complex. The IgTCR-modified T cells were specifically activated through the chimeric receptor with PSMA as measured by IL-2 production and increased CD25 expression and specifically lysed the PSMA-expressing prostate cancer cells in vitro as well as retarded tumor growth in an animal model. CONCLUSIONS: The anti-PSMA designer T cells exhibit an antibody-type specificity that can recognize PSMA expressing tumor cells in a MHC-independent fashion, resulting in T-cell activation, target cell lysis in vitro and inhibition of tumor growth in vivo.     

Characterization of immobilized anti-CD3 antibody-activated T lymphocytes for use in adoptive immunotherapy of patients with brain tumors.

Large numbers of T lymphocytes were successfully cultured for use in adoptive immunotherapy using immobilized anti-CD3 antibody. This method allows more than 1.5 x 10(10) T lymphocytes to be cultured within 2 weeks from only 20 ml of blood. Proliferated T lymphocytes were less cytotoxic than lymphokine-activated killer cells induced with a high dose of interleukin-2, but were more specific for autologous tumor cells as determined by cold target competition. Signal transduction of anti-CD3 antibody induced a population of CD8 positive cells, i.e. cytotoxic T lymphocytes. Adoptive immunotherapy using autologous lymphocytes requires a sufficient number of lymphocytes and high induced cytotoxic activity. This method is promising for clinical adoptive immunotherapy of patients with brain tumors.     

Lysis of autologous tumor cells by peripheral blood lymphocytes treated with interleukin 2 in patients with renal cell carcinoma

Peripheral blood lymphocytes derived from patients with renal cell carcinoma were stimulated with interleukin 2 and tested in a 4-hour 51chromium-release cytotoxicity assay against autologous cultured tumor and myeloid K562 cells. Of 23 patients autologous tumor lysis of more than 0 per cent was observed in 20 (range 5.3 to 82.8 per cent) and more than 10 per cent lysis was noted in 16. Since no significant correlation between the degree of cytotoxicity and the pathological findings of tumor stage, grade, cell type or lymphocyte infiltration in the tumor was found, it was impossible to predict from the pathological findings which tumor could be lysed by peripheral blood lymphocytes treated with interleukin 2. Comparison of natural killer cell activity against K562 of freshly prepared peripheral blood lymphocytes to that of interleukin 2-treated lymphocytes revealed significant augmentation from 23.6 +/- 9.7 to 65.2 +/- 29.1 per cent. From the kinetics study the lysis of autologous tumor cells was detectable on day 2 of interleukin 2 exposure and the peak activity was observed on day 5. A similar trend was noted in regard to K562 cell lysis. Measurements of peripheral blood lymphocyte subsets with monoclonal antibodies and argon ion laser flow cytometry resulted in a significant decrease of cells positive for OKT 4 (helper/inducer) and a significant increase of cells positive for OKT 8 (suppressor/cytotoxic) and Leu 7 (natural killer) by interleukin 2 treatment. A cold target cell inhibition test was performed in 2 patients with unlabeled autologous tumor and K562 cells as cold inhibitors. In 1 patient unlabeled K562 completely inhibited the tumor lysis but in 1 complete inhibition by autologous tumor and incomplete blockade by K562 were found. From this observation we concluded that peripheral blood lymphocytes treated with interleukin 2 lysed not only autologous tumor cells but also K562. Our results demonstrate that adoptive immunotherapy with peripheral blood lymphocytes activated by interleukin 2 in patients with renal cell carcinoma could be appropriate as a therapeutic procedure.     

Clinical significance of tumor-infiltrating lymphocytes in neoplastic progression and lymph node metastasis of human breast cancer

To investigate the clinical significance of tumor-infiltrating lymphocytes (TILs) within the tumor milieu, we quantitatively measured and compared the subpopulations of TILs in 24 patients with stage I–III breast carcinoma. Peripheral blood mononuclear cells (PBMCs), normal breast parenchyma-infiltrating lymphocytes (NILs), and TILs were isolated from tissue specimens and quantified by flow cytometry. The results showed that increased proportion of CD8⁺ T cells, with decreased proportion of CD4⁺ T cells, was significant in gated CD3⁺ TILs as compared to autologous NILs or PBMCs (P < 0.001). The tumor-infiltrating CD8⁺ T cells significantly increased with stage progression, reflected in a more strongly decreased CD4/CD8 percentage (P = 0.003). The CD4/CD8 percentage of TILs was strongly correlated with lymphovascular permeation and subsequent lymph node metastasis (P < 0.001). Increased percentages of tumor-infiltrating CD8⁺ T cells with decreased CD4/CD8 percentages are of prognostic importance for cancer progression in human breast cancer.     

Regulatory function of human CD4+ cytolytic T lymphocytes.

Allograft rejection is mediated by both CD4+ and CD8+ T cells. The lytic function of the classic CD8+ cytolytic T lymphocytes (CTL) occurs through recognition of allogeneic major histocompatibility complex (MHC) class I on the surface of the graft. CD4+ CTL recognize MHC class II through a direct recognition pathway or an indirect pathway where MHC peptides are presented in the context of self MHC class II. Lytic CD4+ cells may destroy graft tissue or, we hypothesize, the indirect CD4+ T cell may down regulate CD8+ CTL by recognition of donor MHC peptides presented by self MHC class II expressed on CD8+ T cells. To define the role of CD4+ CTL in allograft outcome we used a CD4+ CTL that is MHC class II restricted, recognizing human leucocyte antigen (HLA)-A1 and HLA-B8 peptides in the context of HLA-DR4. This line (MDSxA1/B8) will lyse DR4+ B lymphoblastoid cells (LCL) pulsed with HLA-A1/B8 peptides (amino acids 60-84 of the alpha1 domain of the MHC class I molecule). These T cells will also lyse peptide-pulsed antigen-specific T cell clones, both CD4+ and CD8+, that express HLA-DR4. These clones must process and present the MHC class I peptides for recognition and lysis to occur. These results suggest a possible mechanism to explain allograft tolerance. Lytic CD4+ T cells, that recognize donor HLA peptides through an indirect antigen presentation pathway, down-regulate donor-specific CTL through peptide-specific lysis resulting in graft tolerance.     

PD-L1 partially protects renal tubular epithelial cells from the attack of CD8+ cytotoxic T cells.

BACKGROUND: Activated infiltrating T cells play a crucial role in nephritic inflammation via the direct interaction with proximal tubular epithelial cells (TEC). Under inflammatory conditions, major histocompatibility complex class I and II molecules are upregulated on the surface of renal TEC, enabling them to function as "non-professional" antigen-presenting cells (APC) to activate T cells, and, in turn to be targeted by cytotoxic T lymphocytes (CTL) to cause tissue damage. It is known that co-stimulatory (e.g. B7/CD28) and co-inhibitory (e.g. PD-L1/PD-1) signals regulate and determine the magnitude of T cell responses. In this study, we examined the expression of co-stimulatory molecule PD-L1 by renal TEC and the functional role of renal PD-L1/PD-1 pathway in regulating CD8+ T cell responses induced by antigen-presenting renal TEC. METHODS: Renal TEC were treated with type I and type II interferons (IFN-alpha, IFN-beta or IFN-gamma). PD-L1 expression was then determined with flow cytometry and RT-PCR. To investigate the functional role of renal epithelial PD-L1 on CD8+ CTL responses, H-2K(b)-restricted, OVA(257-264) peptide-specific CD8+ T cells isolated from OT-1 T cell receptor transgenic mice were co-incubated with IFN-stimulated, OVA(257-264) peptide-pulsed congeneic TEC. The activation of OT-1 CD8+ CTL was estimated either by IFN-gamma production in the supernatants of co-cultures or by CTL activity. RESULTS: TECs do not constitutively express PD-L1 on their surface. However, a strong and dose-dependent upregulation of PD-L1 was observed on TEC after stimulation with IFN-beta or IFN-gamma, but not with IFN-alpha. OVA(257-264) peptide pulsed-TEC were able to activate OT-1 CD8+ T cells, indicated by the high amount of IFN-gamma production and cytolysis of TEC. Blockade of epithelial PD-L1 with specific mAb significantly increased OT-1 CD8+ T cell activity, indicating that the PD-L1 pathway has a negative effect on CD8+ T cell responses. Moreover, IFN- beta- or IFN-gamma-stimulated TEC with high surface PD-L1 expression were more resistant to the cytolysis by OT-1 CTL. CONCLUSION: Together our data reveal that the renal PD-L1/PD-1 pathway has a negative effect on CD8+ CTL activation. PD-L1 might, therefore, act as a protective molecule on TEC, downregulating the cytotoxic renal parenchymal immune response.     

Generation of autologous Epstein-Barr virus-specific cytotoxic T cells for adoptive immunotherapy in solid organ transplant recipients

BACKGROUND: Epstein-Barr virus (EBV)-driven posttransplant lymphoproliferative disorders (PTLD) affect 2%-27% of solid organ transplant (SOT) recipients. Adoptive immunotherapy may have therapeutic potential in this setting, but there is little experience in generating autologous EBV-specific cytotoxic T-cell lymphocytes (EBV-CTLs) from SOT recipients, and their efficacy and persistence in an immunosuppressed environment is unknown. METHODS: EBV-CTLs were generated from eight SOT recipients, using weekly stimulations with autologous lymphoblastoid cell lines (LCLs) and interleukin-2. CTL phenotype and function were evaluated in the presence of therapeutic concentration of cyclosporin A or FK506. RESULTS: In all cases, CTLs expanded with normal kinetics. The majority was CD3+CD8+ (mean, 76%), with less than 3% of natural killer cells. All ex vivo-generated CTLs produced significantly higher killing of autologous LCLs than of HLA-mismatched LCLs (mean, 56% vs. 14% at 20:1 ratio). No lysis of autologous or allogeneic PHA blasts was observed. The CTL expansion rate was reduced in a concentration-dependent manner in the presence of immunosuppressive drugs; however, neither lytic activity nor phenotype was affected. CONCLUSIONS: Using methods that are approved for clinical application, EBV-CTLs can be generated from SOT recipients, even those with frank lymphoma, or who are receiving immunosuppressive drugs. These CTLs retain their function in the presence of immunosuppressive agents. Although in vivo efficacy, safety, and persistence can be assessed only in clinical trials, our results suggest that CTLs can be effective for the treatment of PTLD, even when immunosuppression cannot be reduced because of the high risk of graft rejection.     

Activation of T lymphocytes for the adoptive immunotherapy of cancer

Background: Adoptive immunotherapy of malignancy involves the passive transfer of antitumor-reactive cells into a host in order to mediate tumor regression. Based on animal models, the transfer of immune lymphoid cells can eradicate widely disseminated tumors and establish long-term systemic immunity. Critical for successful adoptive immunotherapy is the ability to isolate large numbers of immune cells. For clinical therapy, it will require the development of in vitro methods to promote the sensitization and propagation of tumor-reactive cells. However, this is formidable task since human cancers are postulated to be poorly immunogenic because of their spontaneous origins. Results: Human lymphoid cells for ex vivo activation and subsequent adoptive transfer have been derived from different sources, including peripheral blood, tumor, and lymph nodes. Peripheral blood lymphocytes can be incubated with interleukin 2 to generate lymphokine-activated killer (LAK) cells, which nonspecifically lyse autologous and allogeneic tumor cells in vitro. LAK cell therapy represented the earliest attempt to treat advanced human cancers, with encouraging results documented in patients with renal cell cancer and melanoma. From the experience, the use of more immunologically specific cellular agents with potentially greater therapeutic efficacy has been investigated. One approach uses tumor-infiltrating lymphocytes, which have been characterized experimentally to be more specific in tumor reactivity compared with LAK cells. Other techniques have involved the use of lymphoid cells derived from lymph nodes draining tumors or primed by tumor vaccines. In vitro activation of these cells with tumor antigen or anti-CD3 monoclonal antibody results in the generation of T cells that mediate the rejection of poorly immunogenic tumors in animal studies. These alternate methods are currently being evaluated in clinical studies. Conclusions: Experimentally, cellular therapy is a potent method to eradicate progressive tumors. Initial clinical studies have demonstrated that this form of therapy is technically feasible and can result in meaningful antitumor responses. Advances in this area will require improved methods to sensitize, isolate, and expand tumor-reactive T cells for adoptive transfer. Presented at the 46th Annual Cancer Symposium of The Society of Surgical Oncology, Los Angeles, California, March 18–21, 1993.     

Mesenchymal stem cells inhibit the formation of cytotoxic T lymphocytes, but not activated cytotoxic T lymphocytes or natural killer cells

BACKGROUND: Mesenchymal stem cells (MSCs) can reduce the incidence of graft-versus-host disease because of their ability to inhibit T-lymphocyte proliferation. There are no publications on the effect that MSCs have on cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, effector cells vital for the graft-versus-leukemia effect. METHODS: Cytotoxic T cells were primed in mixed lymphocyte culture (MLC) against irradiated stimulator lymphocytes, and irradiated third-party MSCs were added at different time points. The CTLs were collected, and their cytotoxic potential was analyzed in a chromium-release assay against the same stimulator cells as in the MLC. Purified NK cells were mixed with irradiated MSCs, and the lysis was measured in chromium-release assay against K562 target cells. RESULTS: We found that MSCs inhibited CTL-mediated lysis by 70% if added at the beginning of the 6-day MLC. The lysis was not affected on day 3 or in the cytotoxic phase. Furthermore, MSCs inhibited the formation of cytotoxic lymphocytes when the cells were separated in a transwell system, which indicates that the effect is mediated by a soluble factor. NK cell-mediated lysis of K562 cells was not inhibited by MSCs. MSCs did not induce proliferation of allogeneic lymphocytes, and they were not lysed by allogeneic CTLs or NK cells. CONCLUSION: Our findings indicate that MSCs escape recognition by CTLs and alloreactive NK cells, and inhibit the formation of cytotoxic T cells by secreting a soluble factor, but that they do not interfere with CTLs and NK cell lysis.     

Induction of LAK cells and CTL in patients with brain tumor and research of its clinical application

We studied whether lymphokine-activated killer (LAK) cells and cytotoxic T lymphocytes (CTL) were capable of being induced in vitro from peripheral blood lymphocytes of patients with brain tumor. The LAK cells were generated by culturing recombinant IL-2 with peripheral blood lymphocytes. The culture was continued for 72 hours; then cytotoxicity to Hela cell was examined by 4-hr 51Cr release assay. LAK cells were induced from lymphocytes of patients with brain tumor, but the cytotoxicity was rather less than that of healthy subjects, and it was accompanied by clinical deterioration. CTL was generated by co-culture of patient's peripheral blood lymphocytes and autologous brain tumor cells with addition of rIL-2. The cytotoxicity to autologous and allogenic brain tumor cells was examined by 16-hr51Cr release assay. The cytotoxicity to autologous tumor was approximately 30-40%, and there was cross reaction to allogenic tumor cells. The adoptive transfer of CTL to four patients was performed. One patient improved clinically, and on CT scan, growth of the tumor appeared to have been reduced.