Alterations in T cells of cancer-bearers: whence specificity?

A pharmacologic perspective on newly emerging T-cell manipulation technologies

T cells are a multifaceted family pivotal in the operations of the immune system and many of its associated diseases. The pathway to understanding T cells has been marked by several pharmacological advances including the discoveries of ciclosporin, tacrolimus and the mTOR inhibitors which revolutionized transplant therapy along with providing relief for severe eczema, asthma and other immunological disorders towards the end of the last century. This article will revisit the current understanding and new developments in T cell pharmacology 10 years on from the TeGenero (TGN 1412) debacle and look at more recent successes with ex vivo antigen presenting cell incubation technologies; T cell receptor (TCR) engineering and adoptive T cell therapy both with chimaeric antibodies and also with modified T cell receptors themselves. Features of T cell biology will be explored and processes often highly unique to humans will be used to highlight what many are beginning to see as an exciting new monoclonal (T cell) frontier for drug development.

Interleukin-13 induces T helper type 2 immune responses in OVA-immunized BALB/c mice bearing a T cell lymphoma

T lymphocytes play a crucial role in the regulation of immune responses against the tumour cells. Tumour progression results in dysfunction and inhibition of T cells, which ultimately leads to impairment in the antitumour immune response. The impaired antitumour immune response in the host is represented by the decreased number of T cells and their incomplete and improper function. The immunosuppressive network in tumour-bearing host mediated by tumour cells also leads to the inequities of T cell subsets and imbalance of Th1/Th2 dichotomy. Therefore, in the present study, we sought to investigate the role of tumour progression in the development of T cell phenotype and the involvement of interleukin-13 thereof selecting Dalton's lymphoma (DL) as a tumour model. It was observed that a significant increase in the number of CD4(+) T cell population, whereas a significant decline in the CD8(+) T cells among lymphoid cell population of OVA-immunized DL-bearing BALB/c mice occurs. Similar observation was found following the administration of IL-13 to the normal healthy mice. It was further confirmed that expansion in Th2 type cells among CD4(+) T cell population occurs following the progression of tumour and administration of IL-13 to normal healthy mice by an yet to define mechanism. Therefore, it can be concluded that IL-13 has immense role in polarizing the immune responses by inducing the differentiation of Th2 type of cells.

Early expression of stem cell-associated genes within the CD8 compartment after treatment with a tumor vaccine

Using a mouse neuroblastoma cell line, we have demonstrated that vaccination of tumor-free mice with a cell-based vaccine leads to productive immunity and resistance to tumor challenge, while vaccination of tumor-bearing mice does not. The T cell immunity induced by this vaccine, as measured by in vitro assays, is amplified by the depletion of Treg. Our goal is to understand this barrier to the development of protective cellular immunity. mRNA microarray analyses of CD8(+) T cells from naïve or tumor-bearing mice undergoing vaccination were carried out with or without administering anti-CD25 antibody. Gene-expression pathway analysis revealed the presence of CD8(+) T cells expressing stem cell-associated genes early after induction of productive anti-tumor immunity in tumor-free mice, prior to any phenotypic changes, but not in tumor-bearing mice. These data demonstrate that early after the induction of productive immune response, cells within the CD8(+) T cell compartment adopt a stem cell-related genetic phenotype that correlates with increased anti-tumor function.

Signaling defects and functional impairment in T-cells from cervical cancer patients

The ability of T-lymphocytes to recognize antigens and transduce signals to the nucleus successfully is a key component in the initiation and maintenance of an immune response. The present study addressed the expression status of the signal-transducing proteins in relation to the immune impairment in cervical cancer patients. Immune response was measured by evaluating lymphocyte subpopulations CD3(+), CD4(+), and CD8(+), using flowcytometry, natural killer cell activity, using the single-cell cytotoxicity assay, lymphocyte function, using mitogenic response to PHA and T-cell activation following anti-CD3 stimulation, and production of IL-2. Expression of the T-cell signal transduction proteins, TCR-zeta, CD3-epsilon, zap-70, p(56)lck, PKC, NFkappabeta p50, Rel-A, Rel-B, and c-rel, was evaluated by using Western blot assay. A generalized depression of the immune response with respect to the different parameters evaluated was observed. Exogenous interleukin-2 (IL-2) could increase the response in all the controls and in 30% of the patients to different degrees varying from 10% to 90%. Low levels of the signaling molecules (TCR-zeta, CD3-epsilon, zap-70, p(56)lck, and PKC) and impairment in the transduction of NFkappabeta components (p50, Rel-A, Rel-B, and c-rel) to the nuclei were observed in these lymphocytes. Decreased CD4(+)/CD8(+) ratio with an increase in suppressor cells, reduced lymphocyte proliferation, and production of IL-2 suggest a defective immune regulation in cervical cancer. Impairment in the translocation of NFkappabeta p50, Rel-A, and Rel-B to the nucleus and the reduced levels of signal-transducing proteins might be responsible for the decreased production of IL-2 and immune impairment in cervical cancer patients.

Cancer immunotherapy

Recent scientific advances have expanded our understanding of the immune system and its response to malignant cells. The clinical goal of tumour immunotherapy is to provide either passive or active immunity against malignancies by harnessing the immune system to target tumours. Monoclonal antibodies, cytokines, cellular immunotherapy, and vaccines have increasingly become successful therapeutic agents for the treatment of solid and haematological cancers in preclinical models, clinical trials, and practice. In this article, we review recent advances in the immunotherapy of cancer, focusing on new strategies and future perspectives as well as on clinical trials attempting to enhance the efficacy of immunotherapeutic modalities and translate this knowledge into effective cancer therapies.

Restoration of Thymic Homeostasis in a Tumor-Bearing Host by in Vivo Administration of Medicinal Herb Tinospora Cordifolia

In vivo administration of alcoholic extract of medicinal plant Tinospora cordifolia (TC) to mice bearing a spontaneous T cell lymphoma designated as Dalton's lymphoma prevented tumor growth-dependent regression of thymus. TC was found to augment proliferation of thymocytes with a concomitant decrease in thymocyte apoptosis. It also resulted in a decrease in the number of Hassal's corpuscles. Restoration of thymus homeostasis was caused by TC-dependent augmentation in production of thymocyte growth promoting cytokines Interleukin-2 and Interferon-gamma from thymocytes. TC was found to downregulate thymocyte apoptosis by modulation of Caspase pathway. TC administration retarded tumor growth and prolonged survival of tumor-bearing mice. The possible mechanisms are discussed.

Adoptively transferred human lung tumor specific cytotoxic T cells can control autologous tumor growth and shape tumor phenotype in a SCID mouse xenograft model

Background

The anti-tumor efficacy of human immune effector cells, such as cytolytic T lymphocytes (CTLs), has been difficult to study in lung cancer patients in the clinical setting. Improved experimental models for the study of lung tumor-immune cell interaction as well as for evaluating the efficacy of adoptive transfer of immune effector cells are needed.

Methods

To address questions related to the in vivo interaction of human lung tumor cells and immune effector cells, we obtained an HLA class I ⁺ lung tumor cell line from a fresh surgical specimen, and using the infiltrating immune cells, isolated and characterized tumor antigen-specific, CD8⁺ CTLs. We then established a SCID mouse-human tumor xenograft model with the tumor cell line and used it to study the function of the autologous CTLs provided via adoptive transfer.

Results

The tumor antigen specific CTLs isolated from the tumor were found to have an activated memory phenotype and able to kill tumor cells in an antigen specific manner in vitro. Additionally, the tumor antigen-specific CTLs were fully capable of homing to and killing autologous tumors in vivo, and expressing IFN-γ, each in an antigen-dependent manner. A single injection of these CTLs was able to provide significant but temporary control of the growth of autologous tumors in vivo without the need for IL-2. The timing of injection of CTLs played an essential role in the outcome of tumor growth control. Moreover, immunohistochemical analysis of surviving tumor cells following CTL treatment indicated that the surviving tumor cells expressed reduced MHC class I antigens on their surface.

Conclusion

These studies confirm and extend previous studies and provide additional information regarding the characteristics of CTLs which can be found within a patient's tumor. Moreover, the in vivo model described here provides a unique window for observing events that may also occur in patients undergoing adoptive cellular immunotherapy as effector cells seek and destroy areas of tumor growth and for testing strategies to improve clinical effectiveness.

Prolactin induced reversal of glucocorticoid mediated apoptosis of immature cortical thymocytes is abrogated by induction of tumor

Glucocorticoid (GC) and prolactin (PRL) are the two neuroendocrines that regulate thymocyte differentiation and maintain the immune homeostasis during stress. We found that dexamethasone (Dex), a synthetic GC, induced apoptosis in normal immature cortical thymocytes which remained unaltered in the presence of Elrich's ascitic carcinoma (EAC). PRL protected the normal CD4+ CD8+ cortical thymocytes from Dex-induced apoptosis but failed to alter the effect of Dex in tumor-bearing mice. Dex-treated normal thymocytes became unresponsive to PRL in presence of tumor cell culture supernatant. Low binding affinity of the microsomal membranes of thymocytes to PRL and absence of the mRNA of a particular form of prolactin receptor (PRL-R) suggest the presence of a different PRL-R in CD4+ CD8+ thymocytes of EAC-bearing mice. The induction of tumor may alter the PRL-R that can be correlated with the failure of PRL in rescuing CD4+ CD8+ immature cortical thymocytes from GC induced death.

Vaccine Therapies for Pediatric Malignancies

Cancer vaccines are examples of active immunotherapy. In pediatric malignancy such active strategies may be particularly problematic because of immune suppression produced by the tumor or its intensive treatment with combined chemotherapy. Nonetheless, the expression of tumor-specific and tumor-associated antigens on a range of pediatric tumors has encouraged investigation of the approach in patients with either bulky or minimal residual disease. Here we describe promising results in neuroblastoma and acute leukemia, suing genetically modified whole cell vaccines, peptides, and dendritic cells. The difficulties of conducting and evaluating such studies in a pediatric population are also described, and a strategy for cancer vaccine development is outlined.

What is needed for effective antitumor immunotherapy? Lessons learned using Listeria monocytogenes as a live vector for HPV-associated tumors

As a vaccine vector, Listeria monocytogenes targets the innate immune system, resulting in a cytokine response that enhances antigen-presenting cell function as well as inducing a Th1 profile. It also enhances cell-mediated immunity by targeting antigen delivery in antigen-presenting cells to both the MHC class I pathway of exogenous presentation that activates CD8 T cells and the MHC class II pathway that processes antigen endogenously and presents it to CD4 T cells. In this review, we describe the development of vaccine constructs that target the human papillomavirus 16 (HPV-16) E7 antigen, and we characterize their effects on tumor regression as well as various immune parameters both innate and adaptive. In particular, we describe the effect on tumor angiogenesis, induction of antitumor suppressor factors like CD4+CD25+ T cells and regulatory cytokines TGF-beta and IL-10, homing and infiltration of antigen-specific CD8+ T cells to the tumor, and also effects of the vaccines on antigen-presenting cells, especially focusing on dendritic cell maturation and ability to influence tumor regression. We believe that the identification of several immune parameters that correlate with antitumor efficacy, and of some that have a negative correlation, may have wider application for other cancer immunotherapeutic approaches.

No alteration in NK function or zeta chain expression in NK and T cells of cervical cancer patients

OBJECTIVE

To investigate in vitro natural killer (NK) cell activity and expression of signal-transducing zeta chains in patients with cervical cancer.

PATIENTS AND METHODS

Experiments were performed with frozen lymphocytes from patients at all disease stages and from healthy controls. Thawed NK were activated by overnight incubation in interferon-gamma (IFN-gamma); activity against two target cell lines was assessed by 4-h (51)Cr release assay. Targets chosen were K562, an erythroleukemic cell line, and a cervical carcinoma cell line designated 808. T and NK cell zeta chain expression was measured by flow cytometry.

RESULTS

Patients' NK were found to be as cytotoxic as those of normal controls against cell lines K562 and 808. Patient T and NK cells did not show significant down-regulation of the zeta chain.

CONCLUSIONS

We have found no evidence to suggest that loss of zeta chains is a mechanism for immunocompromise in patients with cervical carcinoma. IFN-recoverable patient NK activity is not reduced compared to matched controls. This may be clinically relevant since NK are active against cells exhibiting class I human leukocyte antigen (HLA) down-regulation and many cervical cancers show loss of HLA.

T cell anergy and costimulation

T lymphocytes play a key role in immunity by distinguishing self from nonself peptide antigens and regulating both the cellular and humoral arms of the immune system. Acquired, antigen-specific unresponsiveness is an important mechanism by which T cell responses to antigen are regulated in vivo. Clonal anergy is the term that describes T cell unresponsiveness at the cellular level. Anergic T cells do not proliferate or secrete interleukin (IL)-2 in response to appropriate antigenic stimulation. However, anergic T cells express the IL-2 receptor, and anergy can be broken by exogenous IL-2. Anergy can be induced by submitogenic exposure to peptide antigen in the absence of a costimulatory signal provided by soluble cytokines or by interactions between costimulatory receptors on T cells and counter-receptors on antigen-presenting cells. The molecular events that mediate the induction and maintenance of T cell anergy are the focus of this review. The molecular consequences of CD28-B7 interaction are discussed as a model for the costimulatory signal that leads to T cell activation rather than the induction of anergy.

Prolactin regulates antitumor immune response through induction of tumoricidal macrophages and release of IL-12

The involvement of PRL in regulating monocyte/macrophage functions is suggested by the presence of PRL-Rs in these cells. Here, we show that PRL, though it failed to activate mouse peritoneal resident macrophages (RMs), acted as a second signal and activated mouse peritoneal inflammatory macrophages (EMs) to a tumoricidal state. The cytotoxicity of mouse tumor-associated macrophages (TAMs) isolated at day 1 of tumor (Ehrlich ascites carcinoma, EAC) growth was enhanced by PRL. However, with progression of tumor growth, TAMs became nonresponsive to the hormone. PRL-induced killing of P815 target cells by EMs and TAMs was independent of TNF but correlated with the hormone-induced augmentation of NO2(-) and O2(-) release in these macrophages. Administration of PRL in vivo inhibited EAC growth and augmented NO2(-) release by TAMs. PRL synergized with the TH1 cytokine IFN-gamma, a known activator of macrophages, in inducing tumor killing and release of NO2(-) from EMs and TAMs. The hormone might activate macrophages at least partially, through the release of IFN-gamma as anti-IFN-gamma blocked IFN-gamma- as well as PRL-induced cytotoxicity in EMs. The TH2 cytokine IL-4 suppressed PRL-induced activation of macrophages. PRL induced release of IL-12 from EMs also, which suggested that the hormone might drive the TH1 response through IL-12. Our observations further suggest that PRL alone and in synergy with IFN-gamma, released through induction of IL-12, may generate tumoricidal macrophages and thus regulate the antitumor immune response of tumor hosts.

Cancer vaccines

Attempts to generate an anticancer immune response in vivo in patients with cancer have taken several forms. Although to date there have been relatively few published studies describing the effects of the approach in hematologic malignancy, that circumstance is expected to change rapidly during the next few years. In solid tumors, it is not known which, if any, of the approaches being explored will be able to produce responses of sufficient effectiveness and duration to be of general clinical value. Despite the documented increase in survival of patients developing an immune response to tumor immunization, no randomized clinical trial has been entirely convincing. As knowledge of the molecular basis of the immune response and of the immune defenses used by cancer cells improves, it is reasonable to expect to see increasing benefits from tumor vaccines, which are likely to complement, long before they replace, conventional therapies.

Loss of T-cell receptor-CD3zeta and T-cell function in tumor-infiltrating lymphocytes but not in tumor-associated lymphocytes in ovarian carcinoma

BACKGROUND

Impaired T-cell function has been noted in tumor-infiltrating lymphocytes (TIL). Recently, loss of function was found to be associated with modifications in T-cell receptor complex (TCR)-mediated signaling. A common feature is loss or reduced expression levels of the signaling chain, TCRzeta. We evaluated whether loss of function in TIL and tumor-associated lymphocytes (TAL) from patients with ovarian cancer is associated with changes in TCRzeta expression, and which factors can cause these defects.

METHODS

TIL and TAL were isolated from multiple patients and evaluated for their proliferative capacity by stimulation with a polyclonal stimulus. In addition, expression of TCRzeta and CD3epsilon was evaluated in fresh TIL and TAL by the Western blot technique. Finally, various conditions within a tumor environment were tested for their effect on TCRzeta and CD3epsilon.

RESULTS

TIL, but not TAL, were significantly impaired in their proliferative response, even when both populations were derived from the same patient (P <.05). Reduced proliferation levels were associated with loss of expression of TCRzeta but not of CD3epsilon. Exposure of normal T cells to relative ischemia or heat shock, or culture in medium without IL-2, did not significantly reduce expression of TCRzeta compared with CD3epsilon. However, coculture of T cells with tumor-derived macrophages or tumor-derived factors led to a selective loss of TCRzeta compared with CD3epsilon (P <.05). Further analysis suggested that oxides such as hydrogen peroxide secreted by macrophages may be responsible for loss of TCRzeta and high molecular weight factors secreted by certain tumors.

CONCLUSIONS

TIL but not TAL show impaired T-cell function, which is associated with loss of TCRzeta. In addition to macrophages secreting oxides, loss of TCRzeta may be caused by tumor-derived soluble factors.

A novel strategy in the elimination of disseminated melanoma cells: chimeric receptors endow T cells with tumor specificity

The application of immunotherapy to the treatment of micrometastases of melanoma has attracted growing interest in recent years. This trend reflects, at least in part, the disappointing results of conventional chemotherapy, the identification of melanoma-associated antigens suitable to be used as targets for immunotherapy, and the significant progress in our understanding of molecular processes involved in the development of an immune response. Because of the general belief that T cell immunity plays a major part in the control of tumor growth, we have recently applied a novel strategy to target cytolytic T cells to melanoma cells. The strategy bypasses the requirement of presentation of melanoma-associated-antigen-derived peptides by the major histocompatibility complex to the T cell receptor complex by permanent grafting of T cells with a recombinant, chimeric T cell receptor. The extracellular moiety of the grafted receptor contains the antigen-binding domain, consisting of a single-chain antibody fragment (scFv) derived from a monoclonal antibody specific for the high-molecular-weight melanoma-associated antigen (HMW-MAA). The intracellular receptor moiety contains the cellular activation domain, consisting of the gamma-signaling chain derived from the Fc epsilon RI receptor. Cytotoxic T cells grafted with the chimeric anti-HMW-MAA scFv-gamma signaling receptor specifically lyse HMW-MAA-positive melanoma cells in a human leukocyte antigen class I-independent fashion. The chimeric T cell receptor strategy is designed to eliminate disseminated tumor cells by the power of cytolytic T cells that physiologically penetrate tissues and that are specifically activated by the grafted receptor after binding to antigen-positive melanoma cells.

Whole blood assay for assessment of the mixed lymphocyte reaction

When lymphocytes from genetically different individuals are mixed together in tissue culture blast transformation occurs, a reaction known as the mixed lymphocyte reaction (MLR). The MLR is a clinically relevant in vitro assay where lymphocytes from one individual (effector, E) are incubated with the lymphocytes of another individual (stimulator, S) which have been previously rendered incapable of blast transformation by gamma-irradiation. We have standardised a whole blood (WB) MLR assay where the E lymphocytes were provided by 20 microl of WB and the S lymphocytes were provided by irradiated peripheral blood mononuclear cells (PBMCs) either as a mixed pool of 20 donor PBMCs or as single donor PBMC. The optimum number of S lymphocytes needed was comparatively higher than in the standard PBMC MLR: the optimum calculated E:S ratio was 1:20 compared to a E:S ratio of 1:1 or 3:2 in the standard PBMC MLR. In ten normal individuals the WB/PBMC MLR was similar to the standard PBMC/PBMC MLR. As a clinical example, the WB/PBMC MLR proliferative capacity of 13 patients with malignant mesothelioma was no different from the proliferative capacity of their age-sex matched controls. This standardised WB/PBMC MLR assay is a simple and more practical assay than the standard MLR assay and can be incorporated easily in clinical studies with biological end-points.

Alleviating oxidative stress in cancer immunotherapy: a role for histamine?

Interleukin-2 is a remarkable activator of lymphocytes with anti-neoplastic properties such as T-cells or natural killer cells, but tumor regression only rarely occurs in interleukin-2-treated cancer patients. In this review, we focus on interactions between monocytes/macrophages and T-cells/natural killer-cells, and in particular the role of such interactions for the outcome of cancer immunotherapy with interleukin-2. We propose that interleukin-2 therapy should be supplemented with compounds that alleviate toxicity inflicted by monocyte/macrophage-derived reactive oxygen metabolites within and around tumors. The hypothesis is founded on data demonstrating that (i) functions of intratumoral lymphocytes in many human malignant tumors are inhibited by reactive oxygen metabolites, generated by neighboring monocytes/macrophages, (ii) interleukin-2 only weakly activates T-cells or natural killer cells in an environment of oxidative stress, and (iii) inhibitors of the formation of reactive oxygen metabolites or scavengers of reactive oxygen metabolites synergize with interleukin-2 to activate these lymphocyte subsets. We also review the preclinical background to the use of histamine dihydrochloride, an inhibitor of reactive oxygen metabolite formation in monocytes/macrophages, as a supplement to cancer immunotherapy with interleukin-2.

Interpreting data on lymphocyte subsets in the blood of HIV patients - organ distribution, proliferation and migration kinetics are critical factors

Lymphocytes stay in the blood only a short time before migrating to lymphoid and nonlymphoid organs. They represent only about 2% of all lymphocytes in the body. The ratio of CD4+/CD8+ lymphocytes in the blood depends on age and genetic influences. In HIV infection not only relative but also absolute numbers of lymphocyte subsets should be determined. The different effects of proliferation and apoptosis on lymphocytes in HIV infection have to be considered. Lymphocyte levels in the blood of HIV patients do not mirror alterations in the lamina propria of the gut or lymph nodes. The dynamic aspects of lymphocyte life span and migration during HIV infection and the progression to AIDS as well as the effects of treatment have to be taken into consideration to enable a meaningful interpretation of experimental data. More data from animal models of HIV infection are needed to study these kinetic aspects.

Elevated serum free fatty acid concentrations inhibit T lymphocyte signaling

Unbound cis-unsaturated free (i.e., nonesterified) fatty acids (FFA) inhibit T lymphocyte activation in vitro and therefore may exert immunosuppressive effects. However, in blood serum the major proportion of FFA is tightly bound to albumin, whereas unbound FFA are hardly detectable. Since serum FFA elevation occurs under pathological conditions like insulin resistance or cancer, which are often associated with a disturbed immune response, we addressed the question of whether increased serum FFA concentrations could affect T lymphocyte activation under in vivo conditions. Our studies revealed that 1) addition of pure long-chain cis-unsaturated FFA in the absence of albumin inhibited calcium response in cultured Jurkat T cells. 2) In healthy volunteers, serum FFA elevation by a lipid/heparin infusion, including predominantly unsaturated fatty acids, decreased calcium response of cultured T cells in contrast to studies without heparin. 3) Most notably, stepwise increasing serum FFA by lipid/heparin infusion also inhibited calcium response of simultaneously isolated autologous peripheral blood T lymphocytes as well as their CD4(+) and CD8(+) subsets. In conclusion, our data emphasize that serum FFA elevation is able to exert immunosuppressive effects in vivo.

Detection of T helper responses, but not of human papillomavirus-specific cytotoxic T lymphocyte responses, after peptide vaccination of patients with cervical carcinoma

Human papillomavirus type 16 (HPV16)-encoded E7 oncoprotein is constitutively expressed in cervical carcinoma cells and is required for cellular transformation to be maintained. The E7 protein, therefore, forms an attractive target for T-cell-mediated immune intervention to prevent or treat HPV16+ tumors. The authors performed a peptide-based phase I/II vaccination trial to induce anti-tumor immune responses in patients with recurrent or residual cervical carcinoma. Fifteen HLA-A*0201+ patients with HPV16+ cervical carcinoma received vaccinations with synthetic peptides representing 2 HPV16 E7-encoded, HLA-A*0201-restricted cytotoxic T lymphocyte epitopes and a pan-HLA-DR-binding T-helper epitope, PADRE, in adjuvant. No signs of toxicity were observed. Two patients had stable disease for more than 1 year after vaccination, 3 patients died of the disease during or shortly after the vaccination period, and 10 patients maintained progressive cervical carcinoma. Specific immune responses directed against the vaccine components were analyzed in peripheral blood samples. No cytotoxic T lymphocyte responses against the HPV16 E7 peptides were detectable. After vaccination, strong PADRE helper peptide-specific proliferation was detected in 4 of 12 patients. In conclusion, peptide vaccination with 2 HPV16 E7 cytotoxic T lymphocyte epitopes and a universal T helper epitope is well tolerated by patients with advanced cervical carcinoma. Despite a reduction of in vitro cytolytic or proliferative recall responses to some, but not all, conventional antigens in this patient group, peptide-specific proliferative responses were induced in 4 patients. Based on the current study, it is now feasible to perform peptide vaccination in earlier stages of HPV16-induced cervical disease.

Adjuvant histamine in cancer immunotherapy

Interleukin-2 (IL-2) is an effective activator of lymphocytes with anti-neoplastic properties such as T-cells or natural killer cells, and this property of IL-2 has formed the basis for its widespread used as an immunotherapeutic agent in human neoplastic disease. In recent years, IL-2 therapy for solid neoplastic diseases and hematopoietic cancers has been supplemented with histamine dihydrochloride with the aim of counteracting immunosuppressive signals from monocytes/macrophages. Here we review the preclinical basis for the use of histamine as an adjunct to IL-2 in cancer immunotherapy.

CD4(+), HLA class I-restricted, cytolytic T-lymphocyte clone against primary malignant melanoma cells

The involvement of HLA-class I in target cell lysis by CD4(+) cytolytic T cells (CTL) has been a controversial issue. A CTL clone of CD4 phenotype was derived from the peripheral blood lymphocytes of a patient with primary melanoma. The CTL clone stably lysed the autologous primary melanoma cells for approximately 9 months in culture. Both the Valpha2/Vbeta8 T-cell receptor and CD4 were involved in CTL cytotoxicity. Of a large panel of allogeneic primary and metastatic melanoma or colorectal carcinoma cells, autologous and allogeneic Epstein-Barr virus-transformed B cells and autologous fibroblasts, only allogeneic metastatic melanoma cells matched with the autologous tumor cells for HLA-class I (B57[17]) were lysed and induced IFN-gamma secretion by the CTL clone. Lysis of the autologous tumor cells was significantly blocked by monoclonal antibody to HLA-B17. Importantly, allogeneic, HLA-class I- and class II-unmatched melanoma cells were lysed by the CTL only following transfection of the cells with B57[17] cDNA. Our results provide direct evidence for the involvement of both CD4 and HLA-class I in tumor cell lysis by CD4(+) CTL.

The role of cytotoxic T-lymphocytes in the prevention and immune surveillance of tumors--lessons from normal and immunodeficient mice

The idea of immunological surveillance against cancer has existed for nearly 100 years but as no conclusive evidence has yet been published the importance of the cellular immune defense in the detection and removal of incipient or existing tumors is still a hotly debated subject. However, in order to select a relevant immunotherapeutic strategy in the treatment of cancer, a fundamental understanding of the basic immunologic conditions under which a tumor develops and exists is a prerequisite. Therefore, a murine model was set up that we hoped would enable us to confirm or reject the theory of immunological surveillance. A large panel of methylcholanthrene induced tumors was established in T-cell immunodeficient nude mice and congenic normal mice to study the influence of the immune system on developing tumors. As nude mice developed tumors fastest and with the highest incidence, we concluded that in this model the immune system constituted a 'tumor-suppressive factor' delaying and sometimes abrogating tumor growth, i.e. performing immune surveillance. Immunogenicity of the tumors was assessed by transplantation back to normal histocompatible mice. Tumors originating from the immunodeficient nude mice turned out to be far more immunogenic than tumors from normal mice, resulting in a high rejection rate. CD8+ cytotoxic T cells were found to be indispensable for this rejection, leading to the conclusion that the cytotoxic T cells perform immune selection in normal mice, eliminating immunogenic tumor cell variants in the incipient tumor. In this review, we discuss the difficulties facing immunotherapy when conclusions are drawn from the presented observations and hypotheses.

A lack of evidence for down-modulation of CD3 zeta expression in colorectal carcinoma and pregnancy using multiple detection methods

Loss of the T cell receptor-associated CD3 zeta chain has been proposed as a possible mechanism of the acquired immunosuppression in both tumour-bearing hosts, and in symptomatic patients with HIV infection. However, other reports suggest that the zeta-chain loss may in part be caused by protease activity of contaminating phagocytes ex vivo. Using flow cytometry and Western blot analysis on highly purified T cells, and ensuring adequate addition of protease inhibitors, we have studied the expression of CD3zeta on peripheral blood T cells from patients with colorectal carcinoma, and compared these with normal controls, and pregnant donors, as a further example of an immunocompromised state. Immunohistochemistry was performed on tumour sections from patients with colorectal carcinoma to measure CD3zeta expression in tumour infiltrating T cells, and compared with normal mucosa and tonsil. Using these three approaches, our data provide no evidence for downregulation of CD3zeta chain expression either in colorectal carcinoma or pregnancy and suggest that this explanation is unlikely to fully account for the reduced T cell function associated with these conditions in all patients.

The growth and the control of human immunodeficiency virus in the lung: implications for highly active antiretroviral therapy

In recent years, it has become apparent that the lung is an important niche for the proliferation of human immunodeficiency virus (HIV), which may have implications for highly active antiretroviral therapy (HAART). The lung itself is a major site for the opportunistic infections associated with the progression to acquired immune deficiency syndrome (AIDS), specifically Pneumocystis carinii, Myobacterium tuberculosis and pyogenic bacteria. These cases of active pulmonary complications are direct indicators of enhanced progression to AIDS-defining illness and increased morbidity and mortality. It is therefore essential that the interaction between the lung and HIV is fully understood. Recent research indicates the lung may be a major sanctuary for the virus, with distinct evolution and replication in contrast to other target organs for HIV. In this review, we will discuss the recent findings of HIV infection, evolution, host factors involved in the control of HIV within the lung and the impact this may have on current therapy.

Expression of CD3-zeta on T-cells in primary cervical carcinoma and in metastasis-positive and -negative pelvic lymph nodes

Lymphocytic infiltrate is often present in cervical cancer lesions, possibly reflecting an ongoing, but ineffective, immune response to the tumour. Recently, evidence has accumulated for systemically impaired T-cell functions in cancer patients, associated with decreased expression of signal-transducing zeta (zeta) chain dimer molecules on circulating T-cells and NK-cells. Here, we report on the intralesional down-regulation of zeta chain expression on T-cells in cervical carcinoma. Paraffin-embedded or snap-frozen sections from 24 different cervical cancer specimens were studied. Paraffin-embedded tumour-positive (n = 7) and tumour-negative (n = 15) pelvic lymph nodes were also included in the study. Immunostaining was performed on consecutive sections with antibodies specific for CD3-epsilon or the CD3-associated zeta chain dimer. Antigen retrieval by sodium citrate/microwave treatment was essential for zeta staining of paraffin sections. The amount of zeta positive cells was quantitated and related to the number of CD3-epsilon+ cells in corresponding tumour areas. Of the 24 cervical cancer specimens studied, zeta chain dimer expression was reduced in seven cases and strongly reduced in the other 17 samples. In tonsil control sections, CD3-epsilon and CD3-zeta were always co-expressed in almost equal numbers. Also, both tumour-negative and -positive lymph nodes showed zeta chain expression which equalled that of CD3-epsilon expression. These data indicate that a decreased expression of signal-transducing zeta molecules on tumour-infiltrating T-cells is frequent in cervical cancer. The apparently unimpaired zeta chain expression within draining lymph nodes suggests that local tumour-derived factors at the primary site are instrumental in zeta chain down-regulation.

CD3 hyporesponsiveness and in vitro apoptosis are features of T cells from both malignant and nonmalignant secondary lymphoid organs

There is a dogma in tumor immunology that tumor-infiltrating lymphocytes (TIL) are defective based on their lack of antitumoral efficacy in vivo and on impaired response to in vitro functional tests. However, TIL have been compared usually with peripheral blood T lymphocytes, raising doubts on the conclusions drawn. Therefore, we compared TIL from B cell non-Hodgkin's lymphomas (NHL) with T cells from nonmalignant secondary lymphoid organs. NHL-TIL were unresponsive to activation by immobilized anti-CD3 mAb, although bypassing T cell receptor (TCR)/CD3 signaling led to proliferation. The poor proliferative responses of NHL-TIL could not be explained by quantitative defects in TCRzeta expression. NHL-TIL underwent marked spontaneous apoptosis in vitro with loss of approximately 50% of cells after 24 h of culture. This was associated with downregulation of the antiapoptotic Bcl-xL and Bcl-2 proteins, whereas viable NHL-TIL maintained their expression. IL-2, anti-CD3/IL-2, and manipulation of the Fas/Fas-ligand death pathway had no effect on NHL-TIL survival. Apoptosis was not due to increased cell cycling, as NHL-TIL were quiescent, nonproliferating cells. T cells from inflammatory, nonmalignant tissues gave similar functional results to NHL-TIL, suggesting the existence of factors common to the microenvironment of these diverse pathologies. Thus, the quiescent, anergic phenotype of NHL-TIL cannot be attributed solely to tumor factors, but rather is a feature of T cells from chronic inflammatory lesions.

Peripheral T lymphocytes from women with breast cancer exhibit abnormal protein expression of several signaling molecules

We examined signaling molecules of peripheral blood T lymphocytes obtained from women with breast cancer. In 6 of 14 patients, T lymphocytes displayed an impaired ability to translocate NFêB p65 (Rel-A) following activation by anti-CD3 and IL-2. This observation was made despite normal cytoplasmic levels of the Rel-A protein. We also detected abnormally low levels of the signaling molecules T-cell receptor (TCR)-zeta, ZAP-70 and p56lck in 4 of 14 breast cancer patients, i.e., defects in T-cell signaling molecules. T lymphocytes from 6 of the 14 patients also exhibited an increased expression of the dual specificity phosphatase, map kinase phosphatase-1 (MKP-1). MKP-1 inactivates MAP kinase and therefore may interfere with the activation of c-jun and c-fos. Abnormalities of I or more signaling molecules were found in 9 of 14 patients; however, only 3 patients had T cells that exhibited all 5 defects. Our data have implications for the detection of potentially dysfunctional T cells in patients with cancer. For example, the analysis of only 1 signaling molecule may allow patients with significant defects in T-cell signaling to go unnoticed. Finally, despite impaired Rel-A translocation, T cells were capable of transcribing IL-2. Impairments in the translocation of Rel-B and c-Rel further suggest that the NFKB family members Rel-A, Rel-B and c-Rel are not required for the transcription of IL-2 in the peripheral T lymphocytes of patients with breast cancer.

Variable expression of CD3-zeta and associated protein tyrosine kinases in lymphocytes from patients with myeloid malignancies

In myeloid malignancies, T-cell and NK function has been shown to deteriorate with transformation from pre-leukaemia to advanced disease. Immune dysfunction in solid tumours has been attributed to abnormal signal transduction, possibly through altered expression of intracellular components of the TCR/CD3 complex (e.g. CD3-zeta), receptors on NK cells and their associated protein tyrosine kinases (PTKs; p56lck, p59fyn and ZAP-70). Using a flow cytometric method to detect dual-expression of surface proteins and intracellular components of the TCR/CD3 complex, we have studied 46 patients with myeloid malignancies. CD3-zeta expression was abnormal in 64% of patients, and was more prominent in those with advanced disease. Three patients with reduced CD3-zeta were analysed both pre- and post-treatment, and recovery of CD3-zeta expression was associated with successful remission induction (expression of PTKs was variable and reduced levels were seen all disease stages). The results of this study suggest that loss of signalling proteins is not a result of direct contact of leukaemic cells with lymphocytes per se or the extent of the leukaemia burden, but to a specific property of some myeloid malignancies, which is more frequently acquired with greater malignant transformation.

Immunostimulatory cytokines in somatic cells and gene therapy of cancer

The use of immunostimulatory cytokines has become an increasingly promising approach in cancer immunotherapy. The major goal is the activation of tumour-specific T lymphocytes capable of rejecting tumour cells from patients with low tumour burden or to protect patients from a recurrence of the disease. Strategies that provide high levels of immunostimulatory cytokines locally at the site of antigen have demonstrated pre-clinical and occasional clinical efficacy. Animal models using poorly immunogenic tumours revealed that tumour cells genetically engineered to produce cytokines like IL-2, IL-4, IL-7, IL-12, IFNs, GM-CSF or TNF-alpha were found to be effective in eradicating disseminated tumours. Experimental data obtained from these different animal models are reviewed here to provide an overview of this rapidly evolving field. The data obtained so far from clinical trials involving cytokine gene-modified cells have provided important information regarding the feasibility, safety, immunological effects and occasional clinical responses.