Human cytotoxic T-lymphocytes specific for autologous follicular lymphoma recognize immunoglobulin in a major histocompatibility complex restricted fashion

Current advances, problems and prospects for vaccine-based immunotherapy in follicular non-Hodgkin's lymphoma

Despite advances in chemotherapy, radiotherapy and combined modality treatment, a significant proportion of non-Hodgkin's lymphomas remain incurable. The disease usually responds well to chemotherapy or radiation, but relapses are observed within months to a few years, with frequent failure of subsequent therapies. High-dose chemotherapy with or without radiation and autologous or allogeneic hematopoietic stem cell transplantation provide higher cure rates and longer remissions in certain patients with aggressive lymphomas. However, the higher treatment-related morbidity and mortality of high-dose chemotherapy has driven a search for new and more tumor-specific treatment modalities, such as immunotherapy. Tumor antigens expressed by B-cell lymphomas, such as the "idiotype antigen", are seen as unique and specific target molecules for direct lymphoma immunotherapy. This review will delineate advances, problems and prospects for approaches to anti-B cell lymphoma immunotherapy where pre-clinical studies and proof of principle have been directly translated to patient care.

Vaccine and antibody-directed T cell tumour immunotherapy

Clearer evidence for immune surveillance in malignancy and the identification of many new tumour-associated antigens (TAAs) have driven novel vaccine and antibody-targeted responses for therapy in cancer. The exploitation of active immunisation may be particularly favourable for TAA where tolerance is incomplete but passive immunisation may offer an additional strategy where the immune repertoire is affected by either tolerance or immune suppression. This review will consider how to utilise both active and passive types of therapy delivered by T cells in the context of the failure of tumour-specific immunity by presenting cancer patients. This article will outline the progress, problems and prospects of several different vaccine and antibody-targeted approaches for immunotherapy of cancer where proof of principle pre-clinical studies have been or will soon be translated into the clinic. Two examples of vaccination-based therapies where both T cell- and antibody-mediated anti-tumour responses are likely to be relevant and two examples of oncofoetal antigen-specific antibody-directed T cell therapies are described in the following sections: (1) therapeutic vaccination against human papillomavirus (HPV) antigens in cervical neoplasia; (2) B cell lymphoma vaccines including against immunoglobulin idiotype; (3) oncofoetal antigens as tumour targets for redirecting T cells with antibody strategies.

Active immunotherapy in follicular lymphoma

The antigen receptors expressed by follicular lymphomas represent tumor-specific antigens ("idiotypes"). In murine models, vaccination with tumor-derived idiotype in a variety of formulations can induce protective lymphoma-specific immunity. Phase II clinical trials in follicular lymphoma have also demonstrated idiotype-specific immune responses. Clinical data from these trials indicate sustained progression-free survival, disappearance of minimal residual disease, and even frank lymphoma regression in some cases. Phase III trials to prove the beneficial effects of active immunotherapy are currently being conducted. Additional research efforts focus on the most efficacious vaccination route and on the development of convenient methods to manufacture individual idiotype vaccines.

Role of activated host T cells in the promotion of MALT lymphoma growth

Gastric mucosa-associated lymphoid tissue (MALT) B cell lymphomas contain activated helper T cells. The evidence supports the presence of mechanisms of T cell dependence underlying the development of these lymphomas. It appears that the T cells, which activate B cells, may contribute to lymphoma pathogenesis. Co-stimulatory molecules necessary for effective B cell/T cell interaction are expressed in MALT lymphomas. The studies suggest that CD40 signaling, in combination with cytokines, is essential for the development and progression of MALT lymphomas. Activated T cells of low grade gastric MALT lymphoma, while delivering full help to B cells, are apparently deficient in two cytotoxic mechanisms involved in the concomitant control of B cell growth.

Circulating and tumor-infiltrating gamma delta T Cells in patients with B-cell lymphomas

In order to analyze the involvement of gamma delta T cells in the immune surveillance against B cell lymphomas (BCL), we investigated the proportion of circulating gamma delta T cells in 52 BCL patients using two-color flow cytometry, together with tumor-infiltrating gamma delta T cells in 22 of those patients. We found that the proportion of tumor-infiltrating gamma delta T cells in BCL patients was not different from that of lymph node gamma delta T cells in reactive hyperplasia patients. However, a decreased percentage of circulating gamma delta T cells were observed in indolent lymphoma (IL) and limited aggressive lymphoma (AL) patients when compared with normal controls. In contrast, as a result of a histogram, advanced AL patients were divided into two subgroups: the patients with increased circulating gamma delta T cells and those without any increase. However, there was no difference in the clinical features of between the two AL subgroups.

Stimulation of cytotoxic T cells against idiotype immunoglobulin of malignant lymphoma with protein-pulsed or idiotype-transduced dendritic cells

Because of their hypervariable regions and somatic mutations, the antigen receptor molecules of lymphomas (idiotypes) are tumor-specific antigens and attractive targets for antilymphoma immunotherapy. For the optimal induction of human idiotype-specific cytotoxic T cells (CTL), idiotype was presented to CD8+ peripheral blood mononuclear cells by monocyte-derived autologous dendritic cells (DC) after the endocytosis of idiotype protein or by idiotype-expressing DC. Recombinant idiotype was obtained as a functionally folded Fab fragment by periplasmic expression in Escherichia coli. Idiotype-expressing DC were generated by transduction with recombinant Semliki forest virus vectors encompassing heavy- or light-chain idiotype genes. Autologous lymphoblastoid cell lines stably transfected with Epstein-Barr virus-based idiotype expression vectors were used as target cells to detect idiotype-specific lysis. CTL stimulated with idiotype-loaded DC showed strong specific, CD8-mediated, and major histocompatibility complex (MHC) class I-restricted cytotoxicity against autologous heavy- and light-chain idiotype. In contrast, stimulation with idiotype-transduced DC resulted in only moderate natural killer cell activity. These data confirm the existence of idiotype-specific CTL in patients with lymphoma, define a “good manufacturing practice”-compatible protocol for the generation of these cells without the requirement of viable lymphoma cells, and favor the processing of exogenous antigen over DC transduction for the induction of MHC I-restricted CTL against idiotypes with unknown antigenicity.

Characterization of germinal center dendritic cells in follicular lymphoma

A subset of dendritic cells called germinal center dendritic cells (GCDC) has recently been described inside germinal center from reactive lymphoid organs. We investigated this newly recognized population in follicular lymphoma (FL), which is considered to be the pathologic counterpart of germinal center B cells. Immunohistochemistry analysis with a panel of antibodies demonstrated the presence of a cell population with the peculiar GCDC phenotype in FL biopsies and a similar localization of these cells inside tumoral and reactive follicles. Therefore, we analyzed the relationships between GCDC and the other cell subsets of the tumor follicles. Some of CD4+ and CD8+ T lymphocytes present inside the follicle were found to be in close association with GCDC, suggesting a potential implication of GCDC in their activation. In addition, the distribution of GCDC inside FL and reactive follicles did not appear disrupted, in contrast to follicular dendritic cells, the other follicle dendritic cell type. Finally, we demonstrated that GCDC could be detected from FL lymph node cell suspension by flow cytometry. Taken together, these results indicate that FL development is not associated with a disappearance of GCDC or with a lack of physical interactions between GCDC and T cells inside the follicles. In addition, the fact that GCDC can be observed in FL samples by flow cytometry should allow their purification to further study their putative role in FL development and maintenance.

Rapid expression cloning of human immunoglobulin Fab fragments for the analysis of antigen specificity of B cell lymphomas and anti-idiotype lymphoma vaccination

An expression system for rapid and standardized production of human recombinant immunoglobulin Fab fragments in E. coli was developed. Functional folding of the Fab fragments was accomplished by the dicistronic expression vector pFab.gammakappa containing specialized leader sequences to direct the immunoglobulin heavy and light chains to the periplasmic bacterial space. A C-terminal hexahistidine tag of the Fd chain facilitated metal affinity chromatography and purification to homogeneity as assessed by SDS PAGE and silver staining. Specific antigen recognition by a hybridoma-derived Fab fragment was indistinguishable from that of the corresponding monoclonal antibody. This protocol may be useful for analysis of the antigen specificity of human B cells and for convenient production of lymphoma-derived idiotype protein for vaccination strategies. To obtain unmodified immunoglobulin cDNA sequences from small human biopsies for insertion into pFab.gammakappa, oligo(dG)-tailed cDNA was amplified with an oligo(dC)- and nested mu or kappa constant region-specific primers. Using single sets of primers for each class of immunoglobulin transcripts, the products of this anchored PCR reflected the relative abundance of the starting cell population and permitted reliable identification of clonal, lymphoma-derived sequences for subsequent expression cloning.

Role of autologous CD4+ T cell clones in human B non-Hodgkin's lymphoma: aborted activation and G1 blockade induced by cell-cell contact

This article describes the study of the functional relationship between auto-tumor-reactive CD4(+) T cell clones (TCC) and autologous malignant B cells. Four auto-tumor-reactive CD4(+) TCC were derived from tumor-infiltrating T lymphocytes (TIL-T) from a freshly isolated human follicular lymphoma by the following technique: total CD4(+) TIL-T were negatively purified by an immunomagnetic procedure, then CD4(+) TCC were obtained by limiting dilution in the presence of IL-2 and autologous non-irradiated follicular lymphoma cells as feeders. After expansion, these CD4(+) TCC were co-cultured with non-irradiated autologous malignant B cells. All four TCC were activated by B lymphoma cells and proliferated, as assessed by CD25 expression and cell cycle analysis. Activation and proliferation of B lymphoma cells were studied in response to activated CD4(+) T cells. Although all four TCC were able to induce B lymphoma cell activation (Ki-67 antigen induction and CD40 up-regulation), cells were subsequently blocked in G1 phase. Activation of B-NHL cells was mediated by TCR-HLA class II interaction, as shown by a blocking experiment using an anti-CD4 monoclonal antibody (mAb). Since anti-CD40 mAb with or without IL-4 did not induce proliferation of B lymphoma cells in contrast to normal B cells, we suggest that the blockade in G1 phase is due to the presence of abnormalities in B lymphoma cells. This is the first evidence that autologous reactive CD4(+) TCC can engage follicular lymphoma B cells to enter the cell cycle and induce an aborted activation stage.

Why do B cell lymphoma fail to elicit clinically sufficient T cell immune responses?

There is no doubt that human B cell lymphoma does not elicit a clinically sufficient T cell mediated immune response that results in tumor rejection. However, the mechanisms leading to this lack of T cell recognition and effector function are still not fully understood. Many potential mechanisms such as "ignorance" including "antigen silencing", "tolerance" including "infectious tolerance" and "anergy" or "immunosuppression" have been identified in different model systems and all these could, in part, account for the lack of immune recognition in B cell lymphoma. Malignant B cells are poor antigen presenting cells and T cells in close proximity to the malignant cells are hyporesponsive with detects in T cell receptor signaling and cytotoxic effector function. This review will discuss recent in vitro findings in context of in vivo data in murine model systems relevant to B cell lymphoma. Understanding these complex defects of anti-lymphoma immune responses should allow us to redefine our immunotherapeutic strategies to overcome these detects and induce clinically sufficient T cell mediated immune responses.

Auto-tumor reactive cytotoxic T-cell responses in B-cell non-Hodgkin's lymphoma

We have generated cytotoxic T-lymphocytes (CTLs) from the peripheral blood (PB) of eight B-cell non-Hodgkin's lymphoma (NHL) patients by in vitro coculture with autologous fresh tumor cells. Their functional activity was assessed in 51Cr release assay and was found to be MHC class I restricted. Our results indicate the presence of T-cells cytotoxic for autologous tumor cells in the PB of these patients but these were relatively small numbers in small lymphocytic lymphomas (SLLs). Treatment of fresh tumor cells with rIFN-gamma and rTNF-alpha alone, or in combination significantly increased their susceptibility in 4/5 cases of SLLs, and a case of diffuse large cell lymphoma and Burkitt lymphoma (BL), while, B-cell lymphoma, rich in T-cells, did not show any appreciable increase. Fresh tumor cells were also analysed for MHC class I and ICAM-1 antigens by flow cytometry, in 5/8 cases before and after cytokine treatment. Significant upregulation of MHC class I antigens but with no detectable change in ICAM-1 observed in a case of SLL and BL, correlated with enhanced susceptibility. These findings suggest the possible role of MHC class I antigens in the cytotoxic susceptibility of autologous tumor cells in B-cell NHL.

Autologous Tumor Infiltrating T Cells Cytotoxic for Follicular Lymphoma Cells Can Be Expanded In Vitro

Follicular lymphomas (FLs) rarely induce clinically significant T-cell–mediated responses. We showed that freshly isolated tumor infiltrating T cells (T-TILs) lack tumor-specific cytotoxicity. Stimulation of these T cells with FL cells in the presence of interleukin-2 (IL-2) and/or costimulation via CD28 does not lead to T-cell activation and expansion. In contrast, when stimulated with FL cells preactivated via CD40, autologous T-TILs can be expanded by the addition of exogenous IL-2. These T cells can be further expanded in vitro by the addition of exogenous IL-4, IL-7, or interferon-γ, but not IL-12. Once activated, these T cells showed FL-directed cytotoxicity in four of five patients tested. We concluded that autologous cytotoxic anti-FL–specific T cells exist, but can only be detected in vitro under optimized conditions for T-cell stimulation and expansion. This suggests that their frequency in vivo is either very low or that the microenvironment does not provide the necessary signals to activate these T cells. This model system allows dissection of the requisite conditions for activation and expansion of lymphoma-directed cytotoxicity and may permit expansion of previously activated cytotoxic T cells for adoptive transfer.

Autologous Tumor Infiltrating T Cells Cytotoxic for Follicular Lymphoma Cells Can Be Expanded In Vitro

Follicular lymphomas (FLs) rarely induce clinically significant T-cell–mediated responses. We showed that freshly isolated tumor infiltrating T cells (T-TILs) lack tumor-specific cytotoxicity. Stimulation of these T cells with FL cells in the presence of interleukin-2 (IL-2) and/or costimulation via CD28 does not lead to T-cell activation and expansion. In contrast, when stimulated with FL cells preactivated via CD40, autologous T-TILs can be expanded by the addition of exogenous IL-2. These T cells can be further expanded in vitro by the addition of exogenous IL-4, IL-7, or interferon-γ, but not IL-12. Once activated, these T cells showed FL-directed cytotoxicity in four of five patients tested. We concluded that autologous cytotoxic anti-FL–specific T cells exist, but can only be detected in vitro under optimized conditions for T-cell stimulation and expansion. This suggests that their frequency in vivo is either very low or that the microenvironment does not provide the necessary signals to activate these T cells. This model system allows dissection of the requisite conditions for activation and expansion of lymphoma-directed cytotoxicity and may permit expansion of previously activated cytotoxic T cells for adoptive transfer.

A phase-I clinical study of autologous tumor cells plus interleukin-2-gene-transfected allogeneic fibroblasts as a vaccine in patients with cancer

Tumor cells transfected to express immunostimulatory cytokines, or admixed with similarly modified bystander cells, are able to induce immune responses against unmodified tumor cells in animal models. For treatment of human patients, a vaccine composed of autologous tumor cells and IL-2-secreting allogeneic fibroblasts was developed. Autologous tumor cells were isolated from biopsy specimens. A clone (KMST 6.14) of an immortalized human fibroblast line that stably secreted 5290 IU IL-2 per 10(6) cells and per 24 hr was obtained by cationic lipofection with an expression construct for human IL-2 and Neo(r). Fifteen patients with refractory malignant tumors received 3-4 injections of irradiated KMST6.14 and autologous tumor cells in a phase-I clinical trial. Increasing transient inflammatory responses without systemic toxicity developed at vaccination sites and after injections with irradiated tumor cells only (p < 0.05). These sites contained a dense infiltrate of CD3+ T cells with numbers of CD4+ helper cells exceeding those of CD8+ cytotoxic T cells (CTL). CD8+ T-cell lines isolated from vaccination sites of 2 malignant melanoma patients but not of renal-cell carcinoma patients exhibited a dominant lytic activity against autologous tumor cells in vitro. CD8+ T-cell clones established from the vaccination site of 1 of 2 renal-cell carcinoma patients preferentially lysed autologous and partially matched allogeneic renal-cell carcinoma cells. In conclusion, a vaccine composed of IL-2 gene-transfected allogeneic fibroblasts and autologous tumor cells is able to enhance specific anti-tumor T-cell responses in vivo without major side-effects. Malignant melanoma and renal-cell carcinoma appear to be promising entities for testing of similar approaches in future therapeutic trials.

Vaccine strategies in non-Hodgkin's lymphomas

As described above, the most recent advances in anti-idiotype vaccination strategies have gone hand in hand with recent developments in molecular biology and other forms of cancer therapy. The techniques that are currently available in antibody engineering will greatly facilitate protein production and purification and will reduce the time and effort needed to produce the patient specific vaccines. Cytokine (gene) therapy has extensively been studied in cancer treatment and cancer vaccination and some therapeutic strategies are currently being evaluated in clinical trials (Bubenik, 1996). Combination therapy of idiotypic vaccination with cytokine therapy has recently been explored with promising results. The main focus so far has been on GM-CSF and IL-2, although other cytokines might prove to be efficient in stimulating different effector arms of the immune system. The nature of the immune response mounted by the host against the tumour and the mechanisms by which the tumour cells escape the effector functions of the immune system are not yet fully known. A better knowledge of the nature of B-cell lymphomas and the relation to the patient's immune system will therefore benefit the further development of the therapeutic strategies. Further research will provide us with a better view of how to break the immune tolerance and of which components of the immune system have to be targeted in order to obtain optimal therapeutic results.

Cytotoxic T lymphocyte recognition of non-Hodgkin's B cell lymphomas

Human cytolytic T lymphocytes specific for autologous Burkitt's lymphoma express the gamma, delta T cell receptor and recognize immunoglobulin idiotype in an MHC-unrestricted manner. Antibodies against a member of the heat shock protein 70 family inhibit this specific cytotoxicity, implicating these molecules in tumor recognition and antigen presentation. Such data is relevant to the design of novel immunotherapies for cancer and provides new insights into target recognition by gamma, delta T cells.

Responses to T cell receptor/CD3 and interleukin-2 receptor stimulation are altered in T cells from B cell non-Hodgkin's lymphomas

T cells infiltrating (T-TIL) B cell non-Hodgkin's lymphomas (NHL) are thought to represent a local host response to the tumor. However, tumor progression in the presence of this T cell infiltrate suggests that the T-TIL may be functionally impaired. To address this issue we determined whether response to stimulation of T-TIL from 25 patients with NHL through the T cell receptor (TCR/CD3) and the interleukin-2 (IL-2) receptor (IL-2R) was intact, since activation of these receptors is important for proliferation and cytokine production. Our results demonstrate defects in response to stimulation via TCR/CD3 and the IL-2R in T-TIL cells from patients with NHL that were not observed with T cells from the peripheral blood. T-TIL showed minimal proliferation to anti-CD3 and only modest proliferation to IL-2 alone or when combined with anti-CD3. Moreover, cytokine production in T-TIL was impaired since stimulation through the TCR/CD3 complex did not induce mRNA for interferon gamma (IFN gamma), IL-2, IL-4 or IL-10. The functional unresponsiveness of these cells may be linked to altered signalling through the TCR/CD3 since an abnormal tyrosine phosphorylation pattern was detected in T-TIL after stimulation with anti-CD3.

Autotumour reactive T-cell clones among tumour-infiltrating T lymphocytes in B-cell non-Hodgkin's lymphomas

Seventy-three T-cell clones (TCC) were established from tumour-infiltrating lymphocytes-T (TIL-T) derived from lymph nodes involved by B-cell non-Hodgkin's lymphomas (B-NHL) in nine patients with different histological subtypes and clinical stages. 40 TCC (55%) expressed the CD25 Ag and were also able to proliferate in the presence of irradiated autologous B-NHL cells. Among them, 23 autotumour (AuTu) proliferative TCC were found not to proliferate to autologous EBV-transformed B-cell lines, indicating that the proliferative reactivity of these TCC was preferentially directed at autologous B-NHL cells. Tested against autologous B-NHL cells, only three AuTu proliferative TCC (CD8+) showed a significant level of cytotoxicity (specific lysis > 15%). In blocking experiments, the AuTu proliferative reactivity of three TCC from one patient was strongly inhibited by anti-DR and anti-DQ mAbs, whereas that of three TCC from another patient was not affected by either anti-MHC class I or class II (DR, DP, DQ) mAbs. These findings suggest that the recognition of autologous B-NHL cells by AuTu proliferative TCC may occur through MHC-restricted as well as MHC-unrestricted mechanisms.

Novel tumor-associated accessory molecules involved in the gamma/delta cytotoxic T-lymphocyte-Burkitt's lymphoma interaction

BACKGROUND

Tumor specific cytotoxic T lymphocytes (CTL) recognize antigen via the T-cell receptor (TCR). In addition, recognition requires accessory molecules involved in adhesion and signal transduction. The authors previously have characterized an autologous, Burkitt's lymphoma specific CTL line that uses the gamma-delta TCR to recognize antigen in a nonclassical context. The current study was undertaken to identify novel accessory molecules involved in this unusual TCR-tumor cell interaction.

METHODS

A panel of monoclonal antibodies was generated against a Burkitt's lymphoma cell line and was screened for inhibition of autologous, tumor specific, cytolysis by a gamma-delta CTL line. Proteins identified by these monoclonal antibodies were further characterized by fluorescent-activated cell sorter analysis, Western blot and immunoprecipitation.

RESULTS

Three known (CD5, CD43, and CD11a/CD18) and three novel (BAM-1, BAM-2, and BAM-3) cell surface molecules involved in the gamma-delta CTL-Burkitt's lymphoma interaction were identified and characterized.

CONCLUSIONS

This study identifies and provides a preliminary characterization of three novel Burkitt's lymphoma-associated molecules involved in the gamma-delta CTL-tumor cell interaction and demonstrates that CD5, CD43, and CD11a/CD18 are involved in this interaction. It is likely that other unidentified accessory molecules are also involved in this and other effector cell-tumor interactions. Identification of such molecules may be useful in the design of new immunotherapeutic approaches.