The host-tumor immune conflict: from immunosuppression to resistance and destruction

The transition to the metastatic phenotype of rat lymphoma cells involves up-regulation of IL-10 receptor expression and IL-10 secretion

Interleukin 10 (IL-10) is a Th2 anti-inflammatory cytokine that participates in the regulation of the immune response at several levels. Its production has been implicated in the immunosuppression frequently observed in tumor bearing hosts. The broad spectrum of IL-10 biologic activities is mediated by its binding to its cognate receptor (IL-10R). We have already demonstrated the overproduction of IL-10 by B-cell lymphoma tumor bearing rats and, also, that IL-10 could act as a growth factor for metastatic cells. Considering the importance to unravel each feature of the complex biology of metastasis, the goal of the present study was to investigate the expression of IL-10 receptor (IL-10R), at mRNA and protein level, in primary tumor and metastatic cells from a rat B-cell lymphoma, along with the production of IL-10 by both tumor cell types. Our results indicate that IL-10, besides its immunoregulatory effect, would act as an autocrine growth factor for cells with metastatic phenotype. Also, the up-regulation of IL-10 and IL-10R expression would be part of the transition from primary tumor to the metastatic phenotype.

Chemical biology of the sugar code

A high-density coding system is essential to allow cells to communicate efficiently and swiftly through complex surface interactions. All the structural requirements for forming a wide array of signals with a system of minimal size are met by oligomers of carbohydrates. These molecules surpass amino acids and nucleotides by far in information-storing capacity and serve as ligands in biorecognition processes for the transfer of information. The results of work aiming to reveal the intricate ways in which oligosaccharide determinants of cellular glycoconjugates interact with tissue lectins and thereby trigger multifarious cellular responses (e.g. in adhesion or growth regulation) are teaching amazing lessons about the range of finely tuned activities involved. The ability of enzymes to generate an enormous diversity of biochemical signals is matched by receptor proteins (lectins), which are equally elaborate. The multiformity of lectins ensures accurate signal decoding and transmission. The exquisite refinement of both sides of the protein-carbohydrate recognition system turns the structural complexity of glycans--a demanding but essentially mastered problem for analytical chemistry--into a biochemical virtue. The emerging medical importance of protein-carbohydrate recognition, for example in combating infection and the spread of tumors or in targeting drugs, also explains why this interaction system is no longer below industrial radarscopes. Our review sketches the concept of the sugar code, with a solid description of the historical background. We also place emphasis on a distinctive feature of the code, that is, the potential of a carbohydrate ligand to adopt various defined shapes, each with its own particular ligand properties (differential conformer selection). Proper consideration of the structure and shape of the ligand enables us to envision the chemical design of potent binding partners for a target (in lectin-mediated drug delivery) or ways to block lectins of medical importance (in infection, tumor spread, or inflammation).

Modulation of human Valpha24(+)Vbeta11(+) NKT cells by age, malignancy and conventional anticancer therapies

Immunotherapy strategies aimed at increasing human Vα24⁺Vβ11⁺ natural killer T (NKT) cell numbers are currently a major focus. To provide further information towards the goal of NKT cell-based immunotherapy, we assessed the effects of age, cancer status and prior anticancer treatment on NKT cell numbers and their expansion capacity following α-galactosylceramide (α-GalCer) stimulation. The percentage and absolute number of peripheral blood NKT cells was assessed in 40 healthy donors and 109 solid cancer patients (colorectal (n=33), breast (n=10), melanoma (n=17), lung (n=8), renal cell carcinoma (n=10), other cancers (n=31)). Responsiveness to α-GalCer stimulation was also assessed in 28 of the cancer patients and 37 of the healthy donors. Natural killer T cell numbers were significantly reduced in melanoma and breast cancer patients. While NKT numbers decreased with age in healthy donors, NKT cells were decreased in these cancer subgroups despite age and sex adjustments. Prior radiation treatment was shown to contribute to the observed reduction in melanoma patients. Although cancer patient NKT cells were significantly less responsive to α-GalCer stimulation, they remained capable of substantial expansion. Natural killer T cells are therefore modulated by age, malignancy and prior anticancer treatment; however, cancer patient NKT cells remain capable of responding to α-GalCer-based immenotherapies.

Potentiation of a Dendritic Cell Vaccine for Murine Renal Cell Carcinoma by CpG Oligonucleotides

Purpose: An ideal vaccine therapy for tumors should activate both effector and memory immune responses against tumor-specific antigens. Here we investigated the effect of CpG oligodeoxynucleotides (CpG-ODN) for their ability to potentiate the activity of tumor antigen–pulsed bone marrow–derived dendritic cells (DC) in a vaccine model for the treatment of murine renal cell carcinoma (RENCA).

Experimental Design: First we evaluated the effects of a murine renal cell carcinoma (RENCA) on immune cell activity in a mouse model using in vitro assays for T-cell proliferation and natural killer cell activation. To overcome the immune suppression of the tumor, we s.c. injected groups of 10 mice with dendritic cells and tumor cells. We compared the effect of different conditioning regimens of the DCs with RENCA antigen and/or CpG-ODNs before injection by measuring tumor size twice a week.

Results: Tumor growth was shown to negatively affect spleen cell and T-cell proliferation, IFN-γ production, natural killer cell activity, and NF-κB activation in T cells. In this model, we have shown that RENCA-pulsed CpG-ODN-treated DCs were able not only to significantly reduce tumor growth but also to prevent tumor implantation in 60% of mice. Tumor-free mice were resistant to tumor challenge and the immunity conferred by the vaccine was transferable and tumor specific.

Conclusions: This data show that RENCA down-modulates the immune response, and DC vaccine therapy, in conjunction with CpG-ODN, can restore tumor-specific immunity.

Construction of recombinant eukaryotic expression plasmid containing murine CD40 ligand gene and its expression in H22 cells

AIM: To construct a recombinant murine CD40 ligand (mCD40L) eukaryotic expression vector for gene therapy and target therapy of hepatocellular carcinoma (HCC).

METHODS: mCD40L cDNA was synthesized by RT-PCR with the specific primers and directly cloned into T vector to generate middle recombinant. After digestion with restriction endonuclease, the target fragment was subcloned into the multi-clone sites of the eukaryotic vector. The constructed vector was verified by enzyme digestion and sequencing, and the product expressed was detected by RT-PCR and immunofluorescence methods.

RESULTS: The full-length mCD40L-cDNA was successfully cloned into the eukaryotic vector through electrophoresis, and mCD40L gene was integrated into the genome of infected H22 cells by RT-PCR. Murine CD40L antigen molecule was observed in the plasma of mCD40L-H22 by indirect immuno-fluorescence staining.

CONCLUSION: The recombined mCD40L eukaryotic expression vector can be expressed in H22 cell line. It provides experimental data for gene therapy and target therapy of hepatocellular carcinoma.

Infiltrating CD8+ T lymphocytes, natural killer cells, and expression of IL-10 and TGF-beta1 in chemically induced neoplasms in male Wistar rats

The present study aimed to estimate the number of CD8+ T and natural killer (NK) infiltrating cells and the expression of interleukin-10 (IL-10) and transforming growth factor beta 1 (TGF-beta1) in chemically induced neoplasms in an initiation-promotion bioassay for carcinogenesis. Male Wistar rats were treated with N-nitrosodiethylamine, N-methyl-N-nitrosourea, N-butyl-N-(4-hydroxybutyl)nitrosamine, dihydroxy-di-N-propylnitrosamine, and 1,2-dimethylhydrazine for 4 weeks. Two groups were subsequently exposed through diet to phenobarbital (0.05%) or 2-acetylaminofluorene (0.01%) for 25 weeks. An untreated group was used as a control. Immune cells and cytokines were immunohistochemically evaluated in neoplasms and in surrounding normal tissues at the liver, kidneys, lung, and small and large intestines. When compared to the respective normal tissues, an increased number of NK cells was verified infiltrating the colon, lung, and kidney neoplasms, while the number of CD8+ T cells decreased in the intestine and lung neoplasms. Expression of IL-10 was found mainly in kidney tumors. TGF-beta1 was expressed mainly in the liver and kidneys tumors. The results indicate that the differential occurrence of immune cells between neoplastic and normal tissues could be dependent upon tumor microenvironment.

Amelioration of immune cell number depletion and potentiation of depressed detoxification system of tumor-bearing mice by curcumin

BACKGROUND

The true therapeutic benefit of the use of natural products, especially acceptable dietary components such as curcumin, which can spare the normal cells and boost host immunity, has opened new horizons in cancer prevention and treatment.

METHODS

In our model system we used Ehrlich's ascites carcinoma cells grown in peritoneal carity of Swiss albino mice and curcumin was fed every alternative day.

RESULTS

Here, we report that curcumin administration to tumor-bearing mice decreased tumor cell number significantly in a dose-dependent manner. Furthermore, tumor-induced depletion of immune cell number of the host, as was evidenced from the decrease in bone marrow progenitor as well as thymic and splenic mononuclear cell numbers, was reintrated by curcumin. In fact, curcumin inhibited tumor-induced apoptosis of both thymocytes and splenocytes thereby restoring immune cell numbers to normal level in treated Ehrlich's ascites carcinoma-bearing mice. Moreover, curcumin was not toxic to the host; rather in tumor-bearing mice it inhibited hematopoietic toxicity, acted as a hepatoprotective agent and activated depressed anti-oxidant and detoxification systems.

CONCLUSION

The ability of curcumin to regress tumor as well as to protect the host from tumor-induced immunosuppression and toxicity strongly supports the candidacy of curcumin as a potential agent for the dietary therapy of cancer.

Prostaglandin E2 Regulates the Complement Inhibitor CD55/Decay-accelerating Factor in Colorectal Cancer

Cyclooxygenase-derived prostaglandin E(2) (PGE(2)) stimulates tumor progression by modulating several proneoplastic pathways. The mechanisms by which PGE(2) promotes tumor growth and metastasis through stimulation of cell migration, invasion, and angiogenesis have been fairly well characterized. Much less is known, however, about the molecular mechanisms responsible for the immunosuppressive effects of PGE(2). We identified PGE(2) target genes and subsequently studied their biologic role in colorectal cancer cells. The complement regulatory protein decay-accelerating factor (DAF or CD55) was induced following PGE(2) treatment of LS174T colon cancer cells. Analysis of PGE(2)-mediated activation of the DAF promoter employing 5'-deletion luciferase constructs suggests that regulation occurs at the transcriptional level via a cyclic AMP/protein kinase A-dependent pathway. Nonsteroidal anti-inflammatory drugs blocked DAF expression in HCA-7 colon cancer cells, which could be restored by the addition of exogenous PGE(2). Finally, we observed an increase in DAF expression in the intestinal mucosa of Apc(Min+/-) mice treated with PGE(2) in vivo. In summary, these results indicate a novel immunosuppressive role for PGE(2) in the development of colorectal carcinomas.

Evaluation of the potential immunotoxicity of 3-monochloro-1,2-propanediol in Balb/c mice

3-Monochloro-1,2-propanediol (MCPD) is a well-known by-product of acid-hydrolyzed soy sauce during its manufacturing process. MCPD has been reported genotoxic in vitro, and reproductive toxicity and carcinogenicity in rats. However, no previous studies have investigated MCPD-induced alterations in the immune system. In the present study, MCPD was administered by gavage for 14 days at 0, 25, 50, and 100 mg/kg per day to female Balb/c mice. The antibody-mediated immune response to sheep red blood cells (SRBC) was assessed using the antibody-forming cell (AFC) assay, and splenic cell phenotypes were quantified by flow cytometry. Hematological and histopathological changes were assessed. Mitogen-stimulated spleen lymphocyte proliferation and natural killer (NK) cell activity were evaluated. The T-lymphocyte blastogenesis by concanavalin A (Con A) or anti-CD3 and B-lymphocyte blastogenesis by lipopolysaccharide (LPS) were not significantly changed. There were no significant changes in the hematological and histopathological findings of MCPD-treated mice. However, the significant decrease in thymus weight was observed in 100 mg dose group, even though that did not change body weight gain. The cellularities of spleen and thymus were significantly reduced in high-dose group. Exposure to high dose of MCPD decreased the AFC response to SRBC in mice. There was a significant decrease in NK cell activity of mice treated with high dose of MCPD. These results indicate that MCPD could modulate the immune function in Balb/c mice.

Cancer: a reproductive strategy of "ultra-selfish" genes?

A hypothesis is presented in which the process of "malignant transformation" which ultimately results in the rapidly dividing tumor(s)(cells) causing "cancer", is regarded as an evolved reproductive strategy of "ultra-selfish" (proto-)(onco-) genes, already present in the genome, or introduced by a virus.

CD1a and antitumour immune response

Primary immune response is based on the capacity of local professional antigen-presenting cells (whose prototype is represented by dendritic cells, DCs) to take up and present antigens to selected clones of T cells, but also to non-specific effector cells such as macrophages or natural killer cells. The four CD1 proteins, all of which share a limited homology to class I MHC proteins, are differently expressed in various cell types, of both mesenchymal and, as recently described, epithelial lineage. Regarding the role of CD1 molecules in the anti-tumour response, it has been reported that CD1+ dendritic cells are involved in the first steps of the primary immune response in a number of malignancies. Moreover, the presence of a high number of DCs in the tumoral or peritumoral area, as well as in the draining lymph nodes, has been shown to correlate with a better prognosis. A recent report on the presence of CD1a in metaplastic epithelial cells of Barrett esophagus introduced new questions about CD1a expression patterns. Moreover, the strong correlation between the lack of CD1a+ cells and the malignant evolution of the lesion may indicate a possible role of non-professional APCs in mediating and/or potentiating immune responses to tumours.

Black tea protects immunocytes from tumor-induced apoptosis by changing Bcl-2/Bax ratio

It is known that cancer is associated with altered immune function. We demonstrated earlier that black tea inhibits tumor growth in a dose-dependent manner. Here, we report that apoptosis was the cause of immunocyte death in Ehrlich's ascites carcinoma (EAC)-bearing mice and anti-tumor dose of black tea restored EAC-induced immunosuppression by inhibiting apoptosis. A search for the molecular mechanism revealed that EAC burden increased the expression of the pro-apoptotic proteins p53 and Bax in splenic lymphocytes although did not change the level of pro-proliferative protein Bcl-2. Interestingly, anti-tumor dose of black tea down-regulated p53, decreased Bax while augmenting Bcl-2 in these cells. As a result, Bcl-2/Bax ratio was increased and the immunocytes were protected from tumor-induced apoptosis. Thus, unlike many other anti-cancer agents, black tea is not only devoid of immunosuppressive effect but also acts as immuno-restorer in tumor-bearing host. These results, thus, raise the possibility of inclusion of black tea in successful therapeutic regimen against cancer.

Interleukin-6, interleukin-10, and vascular endothelial growth factor in metastatic renal cell carcinoma: prognostic value of interleukin-6--from the Groupe Francais d'Immunotherapie

PURPOSE

Few clinical prognostic factors have been identified for patients with metastatic renal cell carcinoma (MRCC), and no biomarker is known in this disease. Several endogenous cytokines have demonstrated interesting and significant correlations with survival in these patients. Our objective was to analyze the prognostic value of circulating vascular endothelial growth factor (VEGF), interleukin-10 (IL-10), and interleukin-6 (IL-6).

PATIENTS AND METHODS

Serum levels of IL-6, IL-10, and VEGF were measured in patients with MRCC. Their prognostic value for response to treatment and progression-free and overall survival was evaluated. Pretreatment samples were obtained from 138 patients of a large randomized multicentric trial. Endogenous cytokine levels were determined using immunoassays. Univariate and multivariate analyses were performed to evaluate the prognostic value of each factor further controlled by an internal validation test. Threshold values for serum IL-6 and VEGF were determined using the quartile method.

RESULTS

Serum IL-6 was detectable in 70% of the patients. IL-10 and VEGF were elevated in 8% and 71% of the patients, respectively. None of these circulating factors was correlated with response to treatment. IL-10 was not significantly correlated with progression-free or overall survival. Despite significant correlation with survival, VEGF was not an independent prognostic factor in the multivariate analysis. Finally, IL-6 was significantly correlated with progression-free survival and overall survival, and has prognostic value for overall survival.

CONCLUSION

Circulating IL-6 level appears to be an important independent prognostic factor in patients with MRCC; if confirmed in further studies, it could be considered for treatment decisions in these patients.

Skin reactivity to histamine and expression of histamine receptors mRNA in lymphocytes of healthy subjects and non-small-cell lung cancer patients before and after surgery

Histamine modulates an immunological response through stimulation of appropriate receptor--H1R proinflammatory or H2R suppressive. The participation of histamine in regulation of an immunological response in the course of neoplastic disease is determined by the expression of particular receptor. The aim of our work was the investigation of the expression of mRNA of two types of histamine receptors in peripheral blood lymphocytes and the evaluation of skin-prick test with histamine in lung cancer patients before and after surgery. The investigation was performed on 15 patients qualified to surgery before and 7-10 days after treatment and on 12 healthy subjects. Reverse transcriptase polymerase chain reaction (RT-PCR) with primers labeled with fluorescent dyes was performed. Intensity of fluorescence was expressed as relative fluorescence units (RFU). The data were analysed using ABI Prism 310 GeneScan collection software Version 3.1. Skin-prick test with histamine was evaluated after 10 min by measuring the diameter of the weal. The expression of H1R and H2R mRNA in healthy subjects was not significantly different in contrast to the lung cancer patients in which a significant prevalence of H2R mRNA expression was observed before surgery and only slightly decreased after (P < 0.001). Skin-prick test--negative in one patient before surgery, after treatment was positive in all patients and the diameter of histamine weal was significantly increased (P < 0.001). One may assume that the prevalence of the expression of H2R mRNA in patients reflects the status of immunosuppression caused by cancer. Since histamine exerts its suppressive activity trough H2R it seems reasonably to include the antagonists of this receptor to the cancer therapy which may restore a relative balance between accessibility of both types of histamine receptors.

Regulation of the trafficking of tumour-infiltrating dendritic cells by chemokines

To anticipate and initiate immune responses, dendritic cells follow a migratory route from their recruitment as sentinels into tissues, including solid tumors, then to secondary lymphoid organs where they profile the immune response. Migratory capacities--and especially chemokine responsiveness--are therefore key elements in dendritic cell biology. Here, we will review our current knowledge about tumour-infiltrating dendritic cells and the chemokine-driven migration flows in and out from tumors. Then we will discuss the consequences of the interactions between dendritic cells and tumors and the perspectives for translating our experimental knowledge of manipulating dendritic cell migratory flows into anti-cancer therapies.

Immunophenotyping of tumor-infiltrating mononuclear cells in ovarian carcinoma

Infiltrating mononuclear cells play an important role in many types of cancer. The aim of this work was to determine the immunologic characteristics of mononuclear cellular infiltrate in ovarian cancer as compared to benign ovarian tumors. Paraffin-embedded tissues obtained from 52 ovarian carcinomas and 21 benign ovarian neoplasms were examined immunohistochemically to demonstrate suppressor/cytotoxic T cells and macrophages by using CD8 and CD68 monoclonal antibodies, respectively. The mean percentage of CD8+ cells was much higher in the malignant than in the benign group (P=0.00009). Similarly, the mean level of CD68+ cells was significantly higher in carcinomas than in benign cases (P=0.006). There was a significant negative correlation between the percentage of CD8+ cells and CD68+ cells in the malignant group (P=0.000002). Conversely, no correlation could be obtained between the values of these two cell types in the benign lesions. In the malignant group, although the percentages of CD8+ cells and CD68+ cells were not related to tumor differentiation, they were significantly related to tumor type. CD8+ cells were significantly higher in the serous (P=0.02), and CD68+ cells were higher in the mucinous carcinomas (P=0.0005). CD8+ T cells and macrophages constitute a major component of the infiltrating mononuclear cells in ovarian carcinoma. Their frequency seems to be related to the tumor type rather than the degree of tumor differentiation.

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

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

Natural mechanisms protecting against cancer

Carcinogenesis is a multistage process. At each step of this process, there are natural mechanisms protecting against development of cancer. The majority of cancers in humans is induced by carcinogenic factors present in our environment including our food. However, some natural substances present in our diet or synthesized in our cells are able to block, trap or decompose reactive oxygen species (ROS) participating in carcinogenesis. Carcinogens can also be removed from our cells. If DNA damage occurs, it is repaired in most of the cases. Unrepaired DNA alterations can be fixed as mutations in proliferating cells only and mutations of very few strategic genes can induce tumor formation, the most relevant are those activating proto-oncogenes and inactivating tumor suppressor genes. A series of mutations and/or epigenetic changes is required to drive transformation of a normal cell into malignant tumor. The apparently unrestricted growth has to be accompanied by a mechanism preserving telomeres which otherwise shorten with succeeding cell divisions leading to growth arrest. Tumor can not develop beyond the size of 1-2mm in diameter without the induction of angiogenesis which is regulated by natural inhibitors. To invade the surrounding tissues epithelial tumor cells have to lose some adhesion molecules keeping them attached to each other and to produce enzymes able to dissolve the elements of the basement membrane. On the other hand, acquisition of other adhesion molecules enables interaction of circulating tumor cells with endothelial cells facilitating extravasation and metastasis. One of the last barriers protecting against cancer is the activity of the immune system. Both innate and adaptive immunity participates in anti-tumor effects including the activity of natural killer (NK) cells, natural killer T cells, macrophages, neutrophils and eosinophils, complement, various cytokines, specific antibodies, and specific T cytotoxic cells. Upon activation neutrophils and macrophages are able to kill tumor cells but they can also release ROS, angiogenic and immunosuppressive substances. Many cytokines belonging to different families display anti-tumor activity but their role in natural anti-tumor defense remains largely to be established.

Ammonium trichloro(dioxoethylene-o,o')tellurate (AS101) sensitizes tumors to chemotherapy by inhibiting the tumor interleukin 10 autocrine loop

Cancer cells of different solid and hematopoietic tumors express growth factors in respective stages of tumor progression, which by autocrine and paracrine effects enable them to grow autonomously. Here we show that the murine B16 melanoma cell line and two human primary cultures of stomach adenocarcinoma and glioblastoma multiforme (GBM) constitutively secrete interleukin (IL)-10 in an autocrine/paracrine manner. This cytokine is essential for tumor cell proliferation because its neutralization decreases clonogenicity of malignant cells, whereas addition of recombinant IL-10 increases cell proliferation. The immunomodulator ammonium trichloro(dioxoethylene-o,o')tellurate (AS101) decreased cell proliferation by inhibiting IL-10. This activity was abrogated by exogenous addition of recombinant IL-10. IL-10 inhibition by AS101 results in dephosphorylation of Stat3, followed by reduced expression of Bcl-2. Moreover, these activities of AS101 are associated with sensitization of tumor cells to chemotherapeutic drugs, resulting in their increased apoptosis. More importantly, AS101 sensitizes the human aggressive GBM tumor to paclitaxel both in vitro and in vivo by virtue of IL-10 inhibition. AS101 sensitizes GBM cells to paclitaxel at concentrations that do not affect tumor cells. This sensitization can also be obtained by transfection of GBM cells with IL-10 antisense oligonucleotides. Sensitization of GBM tumors to paclitaxel (Taxol) in vivo was obtained by either AS101 or by implantation of antisense IL-10-transfected cells. The results indicate that the IL-10 autocrine/paracrine loop plays an important role in the resistance of certain tumors to chemotherapeutic drugs. Therefore, anti-IL-10 treatment modalities with compounds such as AS101, combined with chemotherapy, may be effective in the treatment of certain malignancies.

Immunobiological Characterization of N-Nitrosomethylurea-Induced Rat Breast Carcinomas: Tumoral IL-10 Expression as a Possible Immune Escape Mechanism

Improvement of immunotherapy-based protocols in cancer requires a better understanding of tumor microenvironment and tumor-host interaction. Stromal and immune cells and molecules such as cytokines, chemokines, growth factors and metalloproteases mediate tumor-host interaction determining, at least in part, tumor development. In the present study, we used an immunohistochemical approach to explore leukocyte sub-populations, cytokine profiles and costimulatory molecule expression in rat N -Nitrosomethylurea (NMU)-induced breast tumors. Our results show a strong leukocyte infiltration mainly composed of macrophages and TCR alphabeta positive T cells. We observed a weak expression of costimulatory molecules (CD80, CD86) and an absence of inflammatory cytokines (IFNgamma, TNFalpha, IP-10) and lymphocyte activation markers (CD25). Interestingly, this immunosuppressed status could be a consequence of IL-10 expression by malignant cells, as demonstrated by immunohistology and western blot analysis, which seems to be an early event during mammary carcinogenesis. Analysis of a cell line derived from an NMU-induced rat breast tumor showed that this cell line also expresses IL-10. This study shows that the NMU model of rat breast cancer could be used to evaluate different immune based therapies as well as to study the role of IL-10 in breast cancer. Furthermore, this rat breast cancer model shows an immunohistological profile similar to that found in human cancer and the fact that it develops like spontaneously arising malignancies make it interesting as a cancer model in immunobiology.

Fas ligand/Fas system in the brain: regulator of immune and apoptotic responses

Apoptosis, also known as programmed cell death, is the major type of cell death involved in normal development, regeneration, proliferation and pathologic degeneration in the central nervous system (CNS). The apoptotic process can be divided further into two pathways depending on the involvement of mitochondria and related biochemical cascades. The internal pathway of apoptosis is initiated by a variety of cytotoxic stimuli and mediated by the release of cytochrome c and subsequent activation of downstream caspases. The external pathway is mainly triggered by ligation of death receptors such as Fas, tumor necrosis factor (TNF)-related apoptosis inducing ligand-R1 (TRAIL-R1), TRAIL-R2 and TNFRp55, and mediated by direct activation of upstream caspases. The Fas-FasL system has been known as a prototypic inducer of extrinsic cell death responsible for cell-mediated cytotoxicity, peripheral immune regulation, immune privilege and "counterattack" of malignant tumor cells against the host immune system. Fas and FasL are expressed in the normal CNS, and expression increases in inflamed and degenerated brains. Like other specialized tissues such as the eye and testis, the Fas-FasL system is thought to be involved in immune suppressed status in the CNS. Expression of Fas and FasL is significantly elevated in a variety of the neurologic disorders, suggesting the possibility that this system may play roles in degenerative and inflammatory responses in the CNS. Therefore, the FasL-Fas system should be considered as a double-edged sword in the CNS: maintaining the immune suppressed status in normal brain and inducing neuronal cell death and inflammation in a variety of neurologic disorders.

Tumor cell-induced deactivation of human monocytes

Although blood monocytes exhibit significant cytotoxic activity against tumor cells, the function of tumor infiltrating macrophages (TIM) is depressed in cancer patients. This study addresses the question of how the antitumor response of human monocytes, assessed by production of cytokines (tumor necrosis factor alpha, TNF; IL-10; IL-12p40) and cytotoxicity, is altered by exposure to cancer cells. Tumor cell--pre-exposed monocytes restimulated with tumor cells showed significantly decreased production of TNF, IL-12, increased IL-10 (mRNA and release) and inhibition of IL-1 receptor-associated kinase-1 (IRAK-1) expression. This down-regulation of cytokine production was selective, as the response of pre-exposed monocytes to lipopolysaccharide (LPS) was unaffected. Treatment of tumor cell--pre-exposed monocytes with hyaluronidase (HAase) improved their depressed production of TNF, while HAase-treated cancer cells did not cause monocyte dysfunction. The response of hyaluronan (HA)--pre-exposed monocytes to stimulation with tumor cells was also inhibited. Cytotoxic activity of monocytes pretreated with cancer cells was also decreased. This study shows that tumor cells selectively deactivate monocytes and suggests that tumor cell-derived HA by blocking CD44 on monocytes inhibits their antitumor response. These observations may provide some explanation for the depressed function of TIM in human malignancy.

Multinutrient undernutrition dysregulates the resident macrophage proinflammatory cytokine network, nuclear factor-kappaB activation, and nitric oxide production

We have described previously a murine model of multinutrient undernutrition that reproduced the features of moderate human malnutrition and led to increased early dissemination of Leishmania donovani. Peritoneal cells from these malnourished mice produced decreased NO after stimulation with IFN-gamma/LPS. We hypothesized that malnutrition may cause a deficit in NF-kappaB activation, a principal transcription pathway for inducible NO synthase and proinflammatory cytokines. Macrophages from malnourished mice, stimulated with IFN-gamma/LPS, showed increased IL-6 production and decreased IL-10 and TNF-alpha production. Neutralization of TNF-alpha in macrophage cultures from the control mice mimicked the effect of malnutrition on NO and IL-10 production, whereas supplemental TNF-alpha added to cultures of macrophages from malnourished mice increased NO secretion. NF-kappaB nuclear binding activity in macrophages from the malnourished mice was reduced early after stimulation, but increased to supranormal values by 16- or 24-h poststimulation. Blocking NO production in the macrophages from the control mice reproduced the effect of malnutrition on the late activation of NF-kappaB, whereas supplemental NO decreased the late NF-kappaB activation in the malnourished mice. Thus, in macrophages from the malnourished mice, initial deficits in NF-kappaB activity probably lead to decreased TNF-alpha, which results in decreased NO; however, IL-6 is regulated independently from NF-kappaB and TNF-alpha. The late activation of NF-kappaB in the macrophages from malnourished mice is due to absence of negative feedback from NO.

Heat shock protein derived from a non-autologous tumour can be used as an anti-tumour vaccine

Antigenic cross-reactivity between certain tumours has allowed the development of more widely applicable, major histocompatibility complex-disparate (allogeneic) whole-cell vaccines. This principle should also allow heat shock proteins (hsp) derived from certain tumours (and carrying cross-reactive antigens) to be used as vaccines to generate anti-tumour immunity in a range of cancer patients. Here, hsp70 derived from gp70-antigen+ B16 melanoma generated cytotoxic-T-lymphocyte-mediated immune protection in BALB/c mice against challenge with gp70-antigen+ CT26 colorectal tumour cells. Using ovalbumin as a model tumour antigen, it is shown that hsp70 enhances peptide re-presentation by dendritic cells via class I over equimolar whole ovalbumin antigen. However, while transfection of tumour cells with inducible hsp70 increases hsp yield from tumours, it does not enhance antigen recognition via purified hsp70 nor via whole cells or their lysate.

The basic biology and immunobiology of renal cell carcinoma: considerations for the clinician

These are indeed exciting times in the study of RCC. No longer should the clinician view RCC as a single entity, nor should the researcher pose basic questions without considering the biologic diversity of this tumor. The success of novel targeted therapeutic strategies will depend on the systematic study of genetic and epigenetic events and their relationship to aberrant protein expression and function, and an understanding of the permissive microenvironment that allows the tumor to be sustained. These studies must be correlated in a rigorous fashion to clinical parameters and outcomes. Progress against this elusive tumor will require a continuous translational dialogue between laboratory and clinical investigators.

Immunologic escape and angiogenesis in human malignant melanoma

BACKGROUND

Melanoma escape mechanisms include immunosuppressive and angiogenic cytokine production.

OBJECTIVE

We sought to determine vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) expression by immunohistochemistry, and soluble circulating plasma levels of VEGF, bFGF, IL-10, and transforming growth factor-beta2 in patients with different stages of melanoma.

METHODS

Biopsy specimens from 42 patients with primary melanoma and 9 with cutaneous metastases were studied by immunohistochemistry. In another 46 patients with melanoma (8 stage I and II; 18, III; and 20, IV) and in 10 healthy control participants, bFGF, VEGF, IL-10, and transforming growth factor-beta2 circulating levels were analyzed.

RESULTS

bFGF was positive in 85% and VEGF in 47.5% of 42 primary melanomas. Of 10 patients with primary melanoma (Breslow depth 1.5-3 mm) 6 were VEGF positive and had metastases develop, whereas 4 were VEGF negative and had no metastases at 5 years of follow up. VEGF, bFGF, and IL-10 plasma levels in patients with stages III and IV melanoma were higher than the control group (P <.05 and P <.01, respectively). An inverse relationship was found between VEGF and IL-10. Specifically, in 7 patients with IL-10 levels higher than 10 pg/mL, VEGF levels were less than 49 pg/mL (P <.05); in 9 patients with VEGF levels higher than 100 pg/mL, IL-10 levels were less than 6.7 pg/mL (P <.01).

CONCLUSION

VEGF expression in 1.5- to 3.0-mm Breslow depth melanomas may be considered as an unfavorable prognostic factor. Immunosuppressive (IL-10, transforming growth factor-beta2) and proangiogenic (bFGF, VEGF) cytokines are increased in metastatic melanoma. Inverse plasma levels between IL-10 and VEGF in patients with metastatic melanoma are shown in vivo for the first time, the significance of which must be further investigated.

CD8+ T cells, NK cells and IFN-gamma are important for control of tumor with downregulated MHC class I expression by DNA vaccination

One of the major hurdles facing cancer immunotherapy is that cancers may downregulate expression of MHC class I molecules. The development of a suitable tumor model with downregulated MHC class I expression is critical for designing vaccines and immunotherapeutic strategies to control such tumors. We developed an E7-expressing murine tumor model with downregulated MHC class I expression, TC-1 P3 (A15). Using this model, we tested DNA and vaccinia vaccines for their ability to control tumors with downregulated MHC class I expression. We found that vaccination with DNA encoding E7 linked to Mycobacterial heat shock protein 70 (HSP70) generated a significant antitumor effect against TC-1 P3 (A15), while vaccination with E7/HSP70 vaccinia did not generate an appreciable antitumor effect. Lymphocyte depletion experiments revealed that both CD8+ T cells and NK cells were essential for the antitumor effect generated by E7/HSP70 DNA against TC-1 P3 (A15). Furthermore, tumor protection experiments using IFN-gamma knockout mice revealed that IFN-gamma was essential for the antitumor effect generated by E7/HSP70 DNA against TC-1 P3 (A15). Our results demonstrate that vaccination with E7/HSP70 DNA results in a significant antitumor effect against a neoplasm with downregulated MHC class I expression and the importance of CD8+ T cells, NK cells, and IFN-gamma in generating this antitumor effect.

Adenosine inhibits activation-induced T cell expression of CD2 and CD28 co-stimulatory molecules: role of interleukin-2 and cyclic AMP signaling pathways

Adenosine is an immunosuppressive molecule that is associated with the microenvironment of solid tumors. Mouse T cells activated with anti-CD3 antibody in the presence of adenosine with or without coformycin (to prevent adenosine breakdown by adenosine deaminase) exhibited decreased tyrosine phosphorylation of some intracellular proteins and were inhibited in their ability to proliferate and synthesize interleukin (IL)-2. In addition, adenosine interfered with activation-induced expression of the co-stimulatory molecules CD2 and CD28. Activation-induced CD2 and CD28 expression was also diminished when T cells were activated in the presence of anti-IL-2 and anti-CD25 antibodies to neutralize IL-2 bioactivity. Collectively, these data suggest that CD2 and CD28 up-regulation following T cell activation is IL-2-dependent; and that adenosine inhibits activation-induced T cell expression of CD2 and CD28 by interfering with IL-2-dependent signaling. The inhibitory effect of adenosine on activation-induced CD2 and CD28 expression could not be attributed to cyclic AMP (cAMP) accumulation resulting from the stimulation of adenylyl cyclase-coupled adenosine receptors, even though cAMP at concentrations much higher than those generated following adenosine stimulation was inhibitory for both CD2 and CD28 expression. We conclude that adenosine interferes with IL-2-dependent T cell expression of co-stimulatory molecules via a mechanism that does not involve the accumulation of intracellular cAMP.

Fas ligand expression in cervical adenocarcinoma: relevance to lymph node metastasis and tumor progression

OBJECTIVE

Adenocarcinoma of the cervix carries a worse prognosis than its squamous counterpart. In particular, tumors with lymph node metastasis have a miserably poor prognosis. Fas ligand (FasL) could allow the tumor cells to evade host immune surveillance and would thus promote tumor survival and possibly metastasis formation. We decided to compare FasL expression in cervical adenocarcinoma with lymph node status to determine whether FasL plays a role in lymph node metastases.

METHODS

Using immunohistochemistry, we investigated FasL expression in sections of formalin-fixed, paraffin-embedded tissue from 24 cervical adenocarcinomas. We also studied sections of seven cases with lymph node metastases. The percentage of FasL-positive cells in each tumor was recorded. FasL expression in cervical adenocarcinoma was compared with lymph node status. Statistical analysis was performed by using the Fisher exact test and the Kaplan-Meier method.

RESULTS

FasL expression was detected in 62.5% (15 of 24) of primary lesions. Significantly higher incidence of positive FasL reactivity was demonstrated in 10 of 11 tumors with lymph-vascular space (P = 0.0188), in 10 of 10 with deep stromal invasion (P = 0.0015), and in 8 of 9 cancers with lymph node metastasis (P = 0.0481). All 9 metastatic cervical adenocarcinoma in the lymph nodes showed FasL immunoreactivity in 60.7 +/- 17.7% of the metastatic cancer cells, and 7 (78%) of these had FasL immunoreactivity in greater than 50% of the cells. The survival times of patients with FasL-expressing cervical adenocarcinomas were significantly reduced compared to patients with low FasL-expressing tumors (P = 0.0018).

CONCLUSIONS

These findings indicate that FasL plays an important role in immune evasion, and progression and metastasis of cervical adenocarcinoma.

Potentiation of a tumor cell susceptibility to autologous CTL killing by restoration of wild-type p53 function

Inactivation of p53 has been implicated in many types of tumors particularly in non-small cell lung carcinoma, one of the most common cancers in which p53 mutation has been frequently identified. The aim of this study was to investigate the influence of p53 status on the regulation of tumor susceptibility to specific CTL-mediated cell death. For this purpose, we used a cytotoxic T lymphocyte clone, Heu127, able to lyse the human autologous lung carcinoma cell line, IGR-Heu, in a HLA-A2-restricted manner. Direct genomic DNA sequencing revealed that IGR-Heu expresses a mutated p53 at codon 132 of the exon 5 which results in the loss of p53 capacity to induce the expression of the p53-regulated gene product p21(waf/CIP1). Initial experiments demonstrated that IGR-Heu was resistant to Fas, TNF, and TRAIL apoptotic pathways. This correlated with the lack of p55 TNFRI, Fas, DR4, and DR5 expression. The effect of wild-type (wt) p53 restoration on the sensitization of IGR-Heu to autologous CTL clone lysis was investigated following infection of the tumor cell line with a recombinant adenovirus encoding the wt p53 (Adwtp53). We demonstrate that the restoration of wt p53 expression and function resulted in a significant potentiation of target cell susceptibility to CTL-mediated lysis. The wt p53-induced optimization of tumor cell killing by specific CTL involves at least in part Fas-mediated pathway via induction of CD95 expression by tumor cells but does not appear to interfere with granzyme B cytotoxic pathway.

Immunotherapy for lymphomas

A growing list of immunotherapeutic strategies is now being employed to combat lymphoid malignancies. These efforts are warranted given that B-cell lymphomas, particularly those of the common follicular subtype, are among the most "immune-responsive" of all human cancers. Although systemic cytokine therapies for B-cell malignancies have been largely disappointing to date, monoclonal antibody therapies, principally the anti-CD20 antibody rituximab, have already made enormous impact on the treatment algorithm for many B-cell lymphomas. Therapeutic vaccines targeting the tumor-specific immunoglobulin idiotype have demonstrated promising results against lymphomas in phase I/II studies and are currently being evaluated in phase III randomized trials. Additional vaccine therapies being developed include those based on dendritic cells, recombinant idiotype proteins, DNA, heat shock proteins, and gene-modified tumor cells. It is hoped that immunotherapeutic agents, used in tandem or in combination, may someday allow effective treatment of lymphoid malignancies and delay or even replace the need for conventional cytotoxic therapies.

MHC class I antigens, immune surveillance, and tumor immune escape

Oncogenic transformation in human and experimental animals is not necessarily followed by the appearance of a tumor mass. The immune system of the host can recognize tumor antigens by the presentation of small antigenic peptides to the receptor of cytotoxic T-lymphocytes (CTLs) and reject the nascent tumor. However, cancer cells can sometimes escape these specific T-cell immune responses in the course of somatic (genetic and phenotypic) clonal evolution. Among the tumor immune escape mechanisms described to date, the alterations in the expression of major histocompatibility complex (MHC) molecules play a crucial step in tumor development due to the role of MHC antigens in antigen presentation to T-lymphocytes and the regulation of natural killer cell (NK) cell function. In this work, we have (1) updated information on the mechanisms that allow CTLs to recognize tumor antigens after antigen processing by transformed cells, (2) described the altered MHC class I phenotypes that are commonly found in human tumors, (3) summarized the molecular mechanisms responsible for MHC class I alteration in human tumors, (4) provided evidence that these altered human leukocyte antigens (HLA) class I phenotypes are detectable as result of a T-cell immunoselection of HLA class I-deficient variants by an immunecompetent host, and (5) presented data indicating the MHC class I phenotype and the immunogenicity of experimental metastatic tumors change drastically when tumors develop in immunodeficient mice.

A prognostic insight on in vivo expression of interleukin-6 in uterine cervical cancer

Interleukin-6 (IL-6) is a multifunctional cytokine with a growth promoting role in cancers. In an attempt to evaluate the prognostic significance of IL-6, we have studied the localization of this cytokine by immunohistochemical methods in normal, premalignant, and invasive cervical cancers. We stained frozen sections with a monoclonal antibody specific for human IL-6 and demonstrated that tumor cells show positivity with high intensity and stromal cells with moderate intensity. T cells and macrophages, components of the stroma that secrete IL-6, were also looked at. While T cells showed a weak positive correlation, CD68-positive macrophages showed significant positive correlation (P < 0.05) with IL-6 positivity in stroma. The patients were followed up for 40 months after treatment with standard radiotherapy regimen and showed residual tumor where pretreatment IL-6 levels were high. Our results suggest its possible candidature as a prognostic indicator of cervical cancer.

Generation of melanoma-specific cytotoxic T lymphocytes for allogeneic immunotherapy

To exploit alloreactive T-cell responses known as the graft-versus-tumor effect, allogeneic hematopoietic stem cell transplantation is being explored as experimental therapy in selected solid tumors, including metastatic melanoma. However, donor T-cell responses are often delayed and associated with severe graft-versus-host disease. Posttransplant adoptive immunotherapy using tumor-specific cytotoxic T lymphocytes (CTL) of donor origin might provide immediate graft-versus-tumor effects but not graft-versus-host disease. Therefore, the aim of the current study was to define in vitro conditions for the expansion of allogeneic major histocompatibility complex-matched CTLs targeting melanoma-associated antigens (MAA). The CTLs were generated from peripheral blood mononuclear cells (PBMCs) of HLA-A*0201+ healthy donors by repetitive stimulations with HLA-A*0201-restricted MAA-derived peptides. Melanoma reactivity, as determined by lysis of peptide-pulsed T2 cells and HLA-A2+/Ag+ melanoma cells, was detected using in vitro expanded CTL targeting MAA peptides AAGIGILTV(MT(27-35)), IMDQVPFSV(G(209-2M)), and YMDGTMSQV(T(368-376)). In contrast, FLWGPRALV(MAGE3(271)-(279)) and VLPDVFIRCV(GnT-V(nt38-67)) induced peptide-specific recognition of T2 target cells only, whereas ITDQVPFSV(G(209-217)), KTWGQYWQV(G9(154)), MLLAVLYCL(T(1-9)), and tumor lysate could not induce specific CTLs. Specific cytolytic activity was accompanied by interferon-gamma secretion. Peptide-pulsed dendritic cells were required only for the initial stimulation of CTLs and could be substituted by PBMCs during restimulations. The median expansion rate of CTL was five to six times, regardless of whether dendritic cells or PBMCs were used after the initial stimulation. The results delineate the conditions for effective ex vivo expansion of melanoma-specific CTLs from PBMCs of healthy donors to be used as an adjunct in allogeneic cell therapy of metastatic melanoma.

Inhibiting the TGF-beta signalling pathway as a means of cancer immunotherapy

Cancers have developed numerous mechanisms for escaping the immune response, either by successfully evading a fully functional immune system or by actively suppressing the immune system so that they are no longer recognised or effectively eliminated. Current evidence supports active cancer cell-mediated immunosuppression via the secretion of the potent immunosuppressive cytokine, transforming growth factor-beta (TGF-beta), as the most general and potent mechanism for human cancer cells to escape the immune system. Efforts to bypass TGF-beta-mediated immunosuppression thereby represent an attractive therapeutic strategy for the chemoprevention and treatment of human cancers, both by directly increasing the efficacy of immunosurveillance and by increasing the efficacy of current immunotherapy strategies. Current approaches are limited by their nonspecific effects on the TGF-beta signalling pathway, as TGF-beta pathways which specifically mediate immunosuppression have not yet been defined. Future efforts should be directed towards elucidating specific TGF-beta pathways so that these can be targeted for the chemoprevention and treatment of human cancers.

Transforming growth factor-beta induces apoptosis in antigen-specific CD4+ T cells prepared for adoptive immunotherapy

Transforming growth factor-beta (TGF-beta), found at the site of most tumors, has been recognized as one of the mechanisms involved in tumor immunological escape. To evaluate its impact on adoptive immunotherapy against cancer, we examined the susceptibility of tumor-specific T cells to TGF-beta in the setting of these T cells being prepared for adoptive transfer. Hepatitis B virus (HBV)-specific CD4(+) T cells were ex vivo generated by activating with HBV-transfected dendritic cells and selecting with antibodies to CD25 activation molecules, and then expanded with antibodies to CD3/CD28. These T cells expressed higher levels of the type II TGF-beta receptor than nai;ve T cells and exhibited enhanced apoptosis when exposed to TGF-beta. The underlying apoptotic pathway was linked to the dissipation of the mitochondrial inner membrane potential and activation of caspase-9. The absence of caspase-8 activity in TGF-beta-treated T cells suggests that the death receptor system may not be involved in this type of apoptosis. Interleukin-2 (IL-2), which is concomitantly administered with tumor-specific T cells in adoptive immunotherapy, was unable to protect HBV-specific CD4(+) T cells from the pro-apoptotic effect of TGF-beta when added simultaneously with TGF-beta. Interesting, IL-2-pretreated T cells displayed the type II TGF-beta receptor at lower levels and were more resistant to TGF-beta. Together, our findings indicate that the effectiveness of adoptive cancer immunotherapy may be impaired by tumor-derived TGF-beta and appropriate manipulation of exogenous IL-2 might overcome this hurdle.

Cytokines in patients with lung cancer

Lung cancer is one of the most common malignant diseases and is amongst the leading causes of death. Cell-mediated immune response and cytokines could play an important role in antitumour immunity. The aim of the study was to evaluate the cytokines', tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and IL-6, releasing capacity in patients with lung carcinoma and benign lung disease. A group of 41 patients were tested for the production of TNF-alpha, IL-1beta and IL-6 in bronchoalveolar lavage (BAL) and blood. The levels of cytokines in the lung cancer patients were: (1) in BAL - IL-6, 173 +/- 85 pg/ml; TNF-alpha, 170 +/- 116 pg/ml; and IL-1beta, 473 +/- 440 pg/ml; (2) in the blood - IL-6, 197 +/- 53 pg/ml; TNF-alpha, 311 +/- 202 pg/ml; and IL-1beta, 915 +/- 239 pg/ml. Alveolar macrophages of the patients with a lung cancer secreted significantly more cytokines, IL-6 (P = 0.0004) and IL-1beta (P = 0.0047), than alveolar macrophages of the patients with a nonmalignant lung cancer. However, significantly lower levels of cytokine production by the BAL cells were found in patients with small cell lung cancer. This production decreased further in phase IV of nonsmall cell lung cancer.

Interleukin-2 and cancer: critical analysis of results, problems and expectations

The cancer process in a combination of two kinds of events: a multistep cellular genetic defects giving cells independent growth and great adaptation capability, a multistep interactions profiles with what is called the stromal reaction from the original in situ tumor to the invasive metastatic and angiogenic tumor. The immune system plays an important role in the control of the cancer process but always must be seen as a part integrated in the stromal reaction. In order to boost the immune system capability to treat a cancer we must never forget these cellular and tissular dimensions. Interleukins, growth factors and monoclonal antibodies are new agents are able to bring immunotherapy of cancer to reality. Interleukin 2 did not match our dreams of the ideal factor which can stimulate the defective immune system and bring the cancer evolution to an end. The little but real remissions obtained with the IL-2 high dose protocols still sustains our trust of the immune system as a critical barrier to cancer evolution but the numerous side effects reminds us that cytokines are not to be used as antibiotics and hormones. IL-2 is a regulator of the immune system at the microenvironment level, therefore flooding the blood circulation with high IL-2 doses is not appropriate. We have also to understand that IL-2 can interact directly with cancer cells and also with stromal cells (endothelial and fibroblastic cells), the outcome of IL-2 immunotherapy is not restricted to the interactions with immune cells.

[Antitumor immunity and cellular cancer therapies]

The identification of tumor specific antigens has provided important advance in tumor immunology. It is now established that specific cytotoxic T lymphocytes (CTL) and natural killer cells infiltrate tumor tissues and are effector cells able to control tumor growth. However, such a natural antitumor immunity has limited effects in cancer patients. Failure of host defenses against tumor is consecutive to several mechanisms which are becoming targets to design new immunotherapeutic approaches. CTL are critical components of the immune response to human tumors and induction of strong CTL responses is the goal of most current vaccine strategies. Effectiveness of cytokine therapy, cancer vaccines and injection of cells improving cellular immunity have been established in tumor grafted murine models. Clinical trials are underway. To day, interest is particularly focused on cell therapy: injected cells are either "ready to use" effector cells (lymphocytes) or antigen presenting cells able to induce a protective immune reaction in vivo (dendritic cells). The challenge ahead lie in the careful optimization of the most promising strategies in clinical situation.

Preserved IFN-alpha production of circulating Valpha24 NKT cells in primary lung cancer patients

Human Valpha24 NKT cells bearing an invariant Valpha24JalphaQ antigen receptor, the counterpart of murine Valpha14 NKT cells, are activated by a specific ligand, alpha-GalCer, in a CD1d-dependent manner. Here, we demonstrate decreased numbers of circulating Valpha24 NKT cells in patients with primary lung cancer compared to healthy volunteers. However, Valpha24 NKT cells and DCs from lung cancer patients were functionally normal, even in the presence of tumor. Furthermore, levels of Valpha24 NKT cells in surgically resected lung tissue appeared to be equivalent to those of Valpha14 NKT cells in the mouse lung. Levels of Valpha24 NKT cells in the tumor tissue itself were increased about 2.5 times. Administration of alpha-GalCer-pulsed DCs expanded Valpha14 NKT cells in the lung more than 10 times, and the increased levels were sustained for 1 week. This may explain the previous finding that alpha-GalCer-pulsed DCs exerted strong antitumor activity in mouse lung tumor metastatic models. The potential use of alpha-GalCer-pulsed DCs for immunotherapy aimed at activating endogenous Valpha24 NKT cells in the lung of cancer patients is discussed.

T cell adhesion and cytolysis of pancreatic cancer cells: a role for E-cadherin in immunotherapy?

Pancreatic cancer is an aggressive and potent disease, which is largely resistant to conventional forms of treatment. However, the discovery of antigens associated with pancreatic cancer cells has recently suggested the possibility that immunotherapy might become a specific and effective therapeutic option. T cells within many epithelia, including those of the pancreas, are known to express the alphaEbeta7-integrin adhesion molecule, CD103. The only characterised ligand for CD103 is E-cadherin, an epithelial adhesion molecule which exhibits reduced expression in pancreatic cancer. In our study, CD103 was found to be expressed only by activated T cells following exposure to tumour necrosis factor beta 1, a factor produced by many cancer cells. Significantly, the expression of this integrin was restricted mainly to class I major histocompatibility complex-restricted CD8+ T cells. The human pancreatic cancer cell line Panc-1 was transfected with human E-cadherin in order to generate E-cadherin negative (wild type) and positive (transfected) sub-lines. Using a sensitive flow cytometric adhesion assay it was found that the expression of both CD103 (on T cells) and E-cadherin (on cancer cells) was essential for efficient adhesion of activated T cells to pancreatic cancer cells. This adhesion process was inhibited by the addition of antibodies specific for CD103, thereby demonstrating the importance of the CD103-->E-cadherin interaction for T-cell adhesion. Using a 51Cr-release cytotoxicity assay it was found that CD103 expressing T cells lysed E-cadherin expressing Panc-1 target cells following T cell receptor stimulation; addition of antibodies specific for CD103 significantly reduced this lysis. Furthermore, absence of either CD103 from the T cells or E-cadherin expression from the cancer cells resulted in a significant reduction in cancer cell lysis. Therefore, potentially antigenic pancreatic cancer cells could evade a local anti-cancer immune response in vivo as a consequence of their loss of E-cadherin expression; this phenotypic change may also favour metastasis by reducing homotypic adhesion between adjacent cancer cells. We conclude that effective immunotherapy is likely to require upregulation of E-cadherin expression by pancreatic cancer cells or the development of cytotoxic immune cells that are less dependent on this adhesion molecule for efficient effecter function.

Analysis of the mechanisms of human cytotoxic T lymphocyte response inhibition by NO

NO is a potent cellular mediator which has been shown to modulate several immune mechanisms. Using human T lymphocytes as responder cells in a primary mixed lymphocyte reaction, we demonstrated that, at the initiation of the culture, exogenously provided NO via sodium nitroprusside, in non-toxic concentrations, inhibited both allogeneic proliferative and primary cytotoxic responses in a dose-dependent manner. In contrast, it had no effect on the cytotoxic activity of established human TCR (alpha)beta and TCR (gamma)delta cytotoxic T lymphocyte (CTL) clones. The NO inhibitory effect on primary cytotoxic T cell response correlates with inhibition of T cell blastogenesis. Furthermore, under our stimulation conditions, NO induced an inhibition of IL-2 production, an alteration of IL-2R(alpha) expression, and a down-regulation of NF-AT translocation in CD4(+) and CD8(+)allostimulated T cells. Furthermore, we demonstrate that the inhibition of allospecific CTL activity by the NO donor was at least in part related to an inhibition of granzyme B and Fas ligand transcription as revealed respectively by RNase protection and RT-PCR analysis. These results suggest that NO may function to fine tune human CD3(+) T cell activation and subsequent CTL generation.

Tumor escape from killing: role of killer inhibitory receptors and acquisition of tumor resistance to cell death

Immunotherapy of cancer has always been a very attractive fourth-modality therapeutic approach. Over the past few years, advances in the identification of tumor antigens have offered new perspectives and provided new opportunities for more accurate immunotherapy for cancer. However, when applied to patients with established tumors, it rarely leads to an objective response. This is partly due to the fact that tumors evade host immunity at both the induction and effector phases. Thus, understanding tumor escape mechanisms may be the key to successful immunotherapy for cancer. In the present review, we will focus on how the expression of killer Ig receptors (KIR) on tumor infiltrating lymphocytes can compromise their function and how tumors evade apoptotic death - two additional mechanisms of tumor escape.