Immunosuppressive factors in human cancer

Human MUC1 Mucin: A Multifaceted Glycoprotein

Human MUC1 mucin, a membrane-bound glycoprotein, is a major component of the ductal cell surface of normal glandular cells. MUC1 is overexpressed and aberrantly glycosylated in carcinoma cells. The role MUC1 plays in cancer progression represents two sides of one coin: on the one hand, loss of polarity and overexpression of MUC1 in cancer cells interferes with cell adhesion and shields the tumor cell from immune recognition by the cellular arm of the immune system, thus favoring metastases; on the other hand, MUC1, in essence a self-antigen, is displaced and altered in malignancy and induces immune responses. Tumor-associated MUC1 has short carbohydrate sidechains and exposed epitopes on its peptide core; it gains access to the circulation and comes into contact with the immune system provoking humoral and cellular immune responses. Natural antibodies to MUC1 present in the circulation of cancer patients may be beneficial to the patient by restricting tumor growth and dissemination: early stage breast cancer patients with a humoral response to MUC1 have a better disease-specific survival. Several MUC1 peptide vaccines, differing in vectors, carrier proteins and adjuvants, have been tested in phase I clinical trials. They are capable of inducing predominantly humoral responses to the antigen, but evidence that these immune responses may be effective against the tumor in humans is still scarce.

Immunosuppressive Factors: Role in Cancer Development and Progression

The concept of the immunological surveillance against neoplastic cells was initially proposed by Erlich in 1909 and later elaborated by Burnet. This hypothesis states that the normal function of the immune system, in particular the cell-mediated immunity, is to recognize and destroy the transformed and proliferating tumor cells. The role of cell-mediated immunity during the first steps of tumorigenesis remains controversial. However, there is certain evidence about its importance in the progression and dissemination of cancer. The frequent immunosuppressed condition of cancer patients at tumor relapse or recurrence of secondary tumors is a clinical sign supporting this hypothesis, and many studies have demonstrated a defective immune response in patients diagnosed with advanced cancer. Several mechanisms of escape from the immune surveillance have been described, including the immunoselection of tumor antigen-negative variants, the downregulation of MHC class I expression, suppressive T cells, and the elaboration of immunosuppressive cytokines and other factors. Because of the technical difficulty of isolating the very small amounts from culture supernatants or body fluids, only a few of these substances have been characterized and studied with respect to their biological activity: transforming growth factor-β (TGF-β), the protein p15E, interleukin 10 (IL-10), prostaglandin E2 (PGE2), mucins, suppressive E-receptor (SER), immunosuppressive acidic protein (IAP), and adhesion molecules. The possibility of monitoring cancer patients by testing biochemical factors related to cancer growth led to a proposal to measure a number of these factors as tumor markers. Some of them, e.g mucins, enjoy the consensus of the oncologic community, as for some indications they can help the clinician in the management of cancer patients. Except for the class of mucins, the other above-mentioned immunosuppressive factors have not found any clinical application in the laboratory routine because the information deriving from their measurement, although of speculative and scientific interest, has limited clinical value at present. Nevertheless, even if they have no impact on patient management, these substances do have a potential role to play in the study of cancer patients, and should be taken into account when developing new therapeutic strategies.

Medicinal Plants from Mexico, Central America, and the Caribbean Used as Immunostimulants

A literature review was undertaken by analyzing distinguished books, undergraduate and postgraduate theses, and peer-reviewed scientific articles and by consulting worldwide accepted scientific databases, such as SCOPUS, Web of Science, SCIELO, Medline, and Google Scholar. Medicinal plants used as immunostimulants were classified into two categories: (1) plants with pharmacological studies and (2) plants without pharmacological research. Medicinal plants with pharmacological studies of their immunostimulatory properties were subclassified into four groups as follows: (a) plant extracts evaluated for in vitro effects, (b) plant extracts with documented in vivo effects, (c) active compounds tested on in vitro studies, and (d) active compounds assayed in animal models. Pharmacological studies have been conducted on 29 of the plants, including extracts and compounds, whereas 75 plants lack pharmacological studies regarding their immunostimulatory activity. Medicinal plants were experimentally studied in vitro (19 plants) and in vivo (8 plants). A total of 12 compounds isolated from medicinal plants used as immunostimulants have been tested using in vitro (11 compounds) and in vivo (2 compounds) assays. This review clearly indicates the need to perform scientific studies with medicinal flora from Mexico, Central America, and the Caribbean, to obtain new immunostimulatory agents.

Surgical cytoreduction restores the antitumor efficacy of a Listeria monocytogenes vaccine in malignant pleural mesothelioma

Recent studies suggest that immunotherapy may offer a promising treatment strategy for early-stage malignant pleural mesothelioma (MPM), but advanced tumor burden may limit the efficacy of immunotherapy. Therefore, we hypothesized that surgical cytoreduction could restore the efficacy of vaccine-based immunotherapy for MPM. We developed a murine model of MPM through transduction of a mesothelioma cell line with mesothelin. We used this model to evaluate the efficacy of a Listeria monocytogenes vaccine expressing mesothelin. Tumor growth was significantly inhibited at four weeks in animals vaccinated two weeks prior to tumor cell inoculation as compared to those given an empty vector control (1371 ± 420 mm(3) versus 405 ± 139 mm(3); p < 0.01). Mice vaccinated one week prior to tumor challenge also displayed significant reduction in tumor volume (1227 ± 406 mm(3) versus 309 ± 173 mm(3); p < 0.01). The vaccine had no effect when administered concurrently with tumor challenge, or after tumors were established. Flow cytometry showed reduced mesothelin expression in large tumors, as well as tumor-associated immunosuppression due to increased myeloid derived suppressor cells (MDSCs). These factors may have limited vaccine efficacy for advanced disease. Surgical cytoreduction of established tumors restored the antitumor potency of the therapeutic vaccine, with significantly reduced tumor burden at post-operative day 18 (397 ± 103 mm(3) versus 1047 ± 258 mm(3); p < 0.01). We found that surgery reduced MDSCs to levels comparable to those in tumor-naïve mice. This study demonstrates that cytoreduction surgery restores the efficacy of cancer vaccines for MPM by reducing tumor-related immunosuppression that impairs immunotherapy.

Pancreatic ductal adenocarcinoma: a review of immunologic aspects

With the continued failures of both early diagnosis and treatment options for pancreatic cancer, it is now time to comprehensively evaluate the role of the immune system on the development and progression of pancreatic cancer. It is important to develop strategies that harness the molecules and cells of the immune system to treat this disease. This review will focus primarily on the role of immune cells in the development and progression of pancreatic ductal adenocarcinoma and to evaluate what is known about the interaction of immune cells with the tumor microenvironment and their role in tumor growth and metastasis. We will conclude with a brief discussion of therapy for pancreatic cancer and the potential role for immunotherapy. We hypothesize that the role of the immune system in tumor development and progression is tissue specific. Our hope is that better understanding of this process will lead to better treatments for this devastating disease.

The antitumoral effect of the American mistletoe Phoradendron serotinum (Raf.) M.C. Johnst. (Viscaceae) is associated with the release of immunity-related cytokines

ETHNOPHARMACOLOGICAL RELEVANCE

Phoradendron serotinum is commonly used in Mexican traditional medicine for the empirical treatment of cancer. However, there are no studies regarding the antitumoral or immunomodulatory activities of Phoradendron serotinum.

MATERIALS AND METHODS

The in vivo toxicity of ethanolic extracts of Phoradendron serotinum (PSE) was evaluated in mice according to the Lorke procedure. The in vitro immunomodulatory effects of PSE were evaluated estimating the effects of PSE on the pinocytosis, NO production and lysosomal enzyme activity in murine macrophages RAW 264.7. The effects of PSE on the proliferation of murine splenocytes and NK cell activity were also assayed. The cytotoxic effects on TC-1 (lung murine cancer cells) were evaluated using the MTT assay, whereas the apoptotic effect of PSE on TC-1 cells was evaluated using TUNEL assay. Also, different doses of PSE were injected intraperitoneally daily into C57BL/6 mice bearing tumors of TC-1 cells during 25 days. The growth and weight of tumors was measured. In addition, the levels of IL-2, IL-6, IL-12, IL-23 and IFN-γ in murine serum and supernatants of K562 cell-murine splenocyte cocultures were measured.

RESULTS

PSE stimulated the proliferation, pinocytosis and lysosomal enzyme activity in murine macrophages with a similar potency than lypopolisaccharides 1 μg/ml. In addition, PSE stimulated the proliferation of murine splenocytes and induced the NK cell activity. PSE showed cytotoxic (IC(50)=1.9 μg/ml) and apoptotic effects against TC-1 cells. The LD(50) was 125 mg/kg by intraperitoneal route (i.p.) and 375 mg/kg by oral route. PSE administrated at 1, 5 and 10 mg/kg i.p. inhibited the tumor growth by 18%, 40% and 69%, respectively, in mice bearing TC-1 tumor. PSE increased the in vitro and in vivo release of IL-2, IL-6 and IFN-γ but lacked effect on IL-12 and IL-23 release.

CONCLUSIONS

Phoradendron serotinum shows moderate toxic effects in vivo, exerts cytotoxic and apoptotic effects on TC-1 cells. Phoradendron serotinum also has antitumor effects in mice bearing TC-1 tumor and induces immunomodulatory activities in vivo. The results suggest that antitumoral effects of PSE are related with the production of immunity-related cytokines.

Cytoreduction surgery reduces systemic myeloid suppressor cell populations and restores intratumoral immunotherapy effectiveness

Background

Multiple immunotherapy approaches have improved adaptive anti-tumor immune responses in patients with early stage disease; however, results have been less dramatic when treating patients with late stage disease. These blunted responses are likely due to a host of factors, including changes in the tumor microenvironment and systemic immunosuppressive features, which accompany advanced tumor states. We hypothesized that cytoreductive surgery could control these immunosuppressive networks and restore the potency of immunotherapy in advanced disease scenarios.

Methods

To test these hypotheses, two representative intratumoral immunotherapies (an adenoviral vector encoding a suicide gene, AdV-tk, or a type-I interferon, Ad.IFNα) were tested in murine models of lung cancer. Cytoreductive surgery was performed following treatment of advanced tumors. Mechanistic underpinnings were investigated using flow cytometry, in vivo leukocyte depletion methods and in vivo tumor neutralization assays.

Results

AdV-tk and Ad.IFNα were effective in treating early lung cancers, but had little anti-tumor effects in late stage cancers. Interestingly, in late stage scenarios, surgical cytoreduction unmasked the anti-tumor potency of both immunotherapeutic approaches. Immune mechanisms that explained restoration in anti-tumor immune responses included increased CD8 T-cell trafficking and reduced myeloid derived suppressor cell populations.

Conclusion

This study demonstrates that surgical resection combined with immunotherapy may be a rational therapeutic option for patients with advanced stage cancer.

Pancreatic ductal adenocarcinoma: a review of immunologic aspects

With the continued failures of both early diagnosis and treatment options for pancreatic cancer, it is now time to comprehensively evaluate the role of the immune system on the development and progression of pancreatic cancer. It is important to develop strategies that harness the molecules and cells of the immune system to treat this disease. This review will focus primarily on the role of immune cells in the development and progression of pancreatic ductal adenocarcinoma and to evaluate what is known about the interaction of immune cells with the tumor microenvironment and their role in tumor growth and metastasis. We will conclude with a brief discussion of therapy for pancreatic cancer and the potential role for immunotherapy. We hypothesize that the role of the immune system in tumor development and progression is tissue specific. Our hope is that better understanding of this process will lead to better treatments for this devastating disease.

Anti-tumor immunity and mechanism of immunosuppression mediated by tumor cells: role of tumor-derived soluble factors and cytokines

The immune system plays a crucial role in the protection against tumor growth and progression. However, the activation of the immune system against the neoplastic cells does not always occur and, therefore, tumor cells are able to grow and progress continually in the host. It has now been realized that tumor cells themselves produce many of the important factors that are responsible for dismounting of effective immune response. These tumor-derived soluble factors invariably subdue the functions of almost every immune cell population. Therefore, we attempted to underline the mechanism of anti-tumor immune response and immunosuppression induced by tumor cells.

IL-13 from Th2-type cells suppresses induction of antigen-specific Th1 immunity in a T-cell lymphoma

Dalton's lymphoma (DL) is a transplantable T-cell lymphoma of spontaneous origin, characterized by highly invasive and immunosuppressive property. Progression of DL cells results into an imbalance of T helper type 1 (T(h)1)/T helper type 2 (T(h)2)-type cytokine in the host, which is partly responsible for DL-induced severe immunosuppression and DL cell progression. In this study, we have shown the role of IL-13 in the regulation of T(h)1 immunity in both normal healthy and DL-bearing host. IL-13 pre-treatment inhibits the induction of 2,4-dinitro-1-fluorobenzene-induced contact hypersensitivity and delayed-type hypersensitivity (DTH) in antigen-challenged mice, which have been confirmed by neutralizing IL-13 by systemic delivery of non-signaling decoy receptor IL-13Ralpha2. Furthermore, IL-13 neutralization enhances the splenocyte proliferation, which has been inhibited by IL-13 administration. Adoptive transfer of splenocyte from IL-13-pre-treated mice and macrophages incubated with IL-13 and pulsed with antigens suppresses the DTH as well in antigen-challenged recipient mice. In addition, it also suppresses the production of pro-inflammatory cytokine and C-C chemokine in DTH footpad. Furthermore, IL-13 neutralization not only enhances the DTH reaction but also increases longevity and survival of DL-bearing host, which suggests that blocking/inactivating systemic IL-13 enhances T(h)1 immunity, and therefore, effects to diminish IL-13 production may have therapeutic value in a host bearing T-cell lymphoma.

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

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

Statins stimulate in vitro membrane FasL expression and lymphocyte apoptosis through RhoA/ROCK pathway in murine melanoma cells

The capacity of FasL molecules expressed on melanoma cells to induce lymphocyte apoptosis contributes to either antitumor immune response or escape depending on their expression level. Little is known, however, about the mechanisms regulating FasL protein expression. Using the murine B16F10 melanoma model weakly positive for FasL, we demonstrated that in vitro treatment with statins, inhibitors of 3-hydroxy-3-methylgutaryl CoA reductase, enhances membrane FasL expression. C3 exotoxin and the geranylgeranyl transferase I inhibitor GGTI-298, but not the farnesyl transferase inhibitor FTI-277, mimic this effect. The capacity of GGTI-298 and C3 exotoxin to inhibit RhoA activity prompted us to investigate the implication of RhoA in FasL expression. Inhibition of RhoA expression by small interfering RNA (siRNA) increased membrane FasL expression, whereas overexpression of constitutively active RhoA following transfection of RhoAV14 plasmid decreased it. Moreover, the inhibition of a RhoA downstream effector p160ROCK also induced this FasL overexpression. We conclude that the RhoA/ROCK pathway negatively regulates membrane FasL expression in these melanoma cells. Furthermore, we have shown that B16F10 cells, through the RhoA/ROCK pathway, promote in vitro apoptosis of Fas-sensitive A20 lymphoma cells. Our results suggest that RhoA/ROCK inhibition could be an interesting target to control FasL expression and lymphocyte apoptosis induced by melanoma cells.

Serum granulysin level as a novel prognostic marker in patients with gastric carcinoma

BACKGROUND

Granulysin is a cytolytic molecule present in human cytotoxic T cells and natural killer cell granules, and plays a key role in the cell-mediated immunity against tumor and infection. However, few studies have estimated serum granulysin concentrations in patients with solid or hematological malignancies.

METHODS

Peripheral blood samples were taken from patients with gastric carcinoma preoperatively and from healthy volunteers. Serum and tumor tissue granulysin concentrations were measured using a granulysin-specific ELISA kit in order to assess its prognostic value.

RESULTS

Both serum and tumor tissue granulysin concentrations were higher in patients with stage II or III gastric cancer and lower in patients with stage IV disease as compared to healthy controls. The low preoperative granulysin levels were associated with more frequent hepatic and peritoneal metastases, and with a poor outcome of the curative gastrectomy.

CONCLUSIONS

Preoperative serum granulysin levels reflect the status of cell-mediated immunity in patients with gastric carcinoma. It has significance as a prognostic determinant following a curative resection.

15-Deoxy-delta(12,14)-prostaglandin J(2) down-regulates CXCR4 on carcinoma cells through PPARgamma- and NFkappaB-mediated pathways

The chemokine receptor CXCR4 plays a key role in the metastasis of colorectal cancer and its growth at metastatic sites. Here, we have investigated the mechanisms by which CXCR4 on cancer cells might be regulated by eicosanoids present within the colorectal tumor microenvironment. We show that prostaglandins PGE(2), PGA(2), PGD(2), PGJ(2) and 15dPGJ(2) each down-regulates CXCR4 receptor expression on human colorectal carcinoma cells to differing degrees. The most potent of these were PGD(2) and its metabolites PGJ(2) and 15dPGJ(2). Down-regulation was most rapid with the end-product 15dPGJ(2) and was accompanied by a marked reduction in CXCR4 mRNA. 15dPGJ(2) is known to be a ligand for the nuclear receptor PPARgamma. Down-regulation of CXCR4 was also observed with the PPARgamma agonist rosiglitazone, while 15dPGJ(2)-induced CXCR4 down-regulation was substantially diminished by the PPARgamma antagonists GW9662 and T0070907. These data support the involvement of PPARgamma. However, the 15dPGJ(2) analogue CAY10410, which can act on PPARgamma but which lacks the intrinsic cyclopentenone structure found in 15dPGJ(2), down-regulated CXCR4 substantially less potently than 15dPGJ(2). The cyclopentenone grouping is known to inhibit the activity of NFkappaB. Consistent with an additional role for NFkappaB, we found that the cyclopentenone prostaglandin PGA(2) and cyclopentenone itself could also down-regulate CXCR4. Immunolocalization studies showed that the cellular context was sufficient to trigger a focal nuclear pattern of NFkappaB p50 and that 15dPGJ(2) interfered with this p50 nuclear localization. These data suggest that 15dPGJ(2) can down-regulate CXCR4 on cancer cells through both PPARgamma and NFkappaB. 15dPGJ(2), present within the tumor microenvironment, may act to down-regulate CXCR4 and impact upon the overall process of tumor expansion.

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.

Phase I clinical trial of a TGF-beta antisense-modified tumor cell vaccine in patients with advanced glioma

We performed a phase I clinical trial in grade IV astrocytoma to assess the safety of a whole-cell vaccine comprising autologous tumor cells genetically modified by a transforming growth factor-beta2 (TGF-beta2) antisense vector. Blocking secretion of the immunosuppressive molecule TGF-beta in this manner should inhibit one of the major mechanisms by which tumor cells evade immune surveillance and should lead to clinically effective antitumor immunity. Six patients with progressive WHO grade IV astrocytoma were enrolled in the trial. Patients received 2-7 subcutaneous injections of 5 x 10(6)-2 x 10(7) autologous tumor cells per injection. TGF-beta2 secretion by the tumor cells used to vaccinate patients was inhibited by 53-98%. Treatment was well tolerated with only low-grade, transient treatment-related toxicities reported. Two patients had partial regressions and two had stable disease following therapy. The overall median survival was 68 weeks. Median survival of the responding patients was 78 weeks, compared to a historic value of 47 weeks for glioma patients treated conventionally. There were indications of humoral and cellular immunity induced by the vaccine. These findings support further clinical evaluation of vaccines comprised of TGF-beta antisense-modified tumor cells.

Differences in immune cells engaged in cell-mediated immunity after chemotherapy for far advanced pancreatic cancer

OBJECTIVES

Little is known about the effects of chemotherapy on the immunity of cancer patient or the ideal timing for immunotherapy combined with chemotherapy. To address these questions, we evaluated the effect of gemcitabine and cisplatin combination chemotherapy on the immunity of pancreatic cancer patients.

METHODS

Thirteen patients with far advanced pancreatic cancer were enrolled and 7 sex- and age-matched healthy volunteers were included as a control group.

RESULTS

Compared with healthy controls, the amounts of peripheral blood mononuclear cells, dendritic cells (DCs), natural killer cells, CD4, and CD8 T cells were reduced. With this numerical suppression, NK cell cytotoxicity to K562 leukemia cells was also significantly impaired (7.7% +/- 4.9% versus 21.7% +/- 7.9% of DNA loss; P = 0.016). Serum concentrations of VEGF and interleukin-10 (IL-10) were higher than the control group (192.1 +/- 114.7 versus 50.8 +/- 39.5 pg/mL of vascular endothelial growth factor (VEGF) and 122 +/- 68.9 versus 111.4 +/- 37.4 pg/mL of IL-10). After 1 cycle of gemcitabine and cisplatin chemotherapy, the impaired immunity of patients with pancreatic cancer was restored. Specifically, the recovery of DCs occurred rapidly and exceeded the value of healthy controls. Levels of the immunosuppressive cytokines, IL-10 and VEGF, gradually decreased during chemotherapy.

CONCLUSIONS

Systemic chemotherapy seems to be beneficial for restoring the impaired immunity of patients with pancreatic cancer, and one of the ideal times to collect DCs for immunotherapy is after completing each cycle of chemotherapy.

Combined antiangiogenic and immune therapy of prostate cancer

Experimental studies of antiangiogenic or immune therapy of cancer have generated a great deal of optimism. However, the results of clinical testing of these therapies are below expectations. We hypothesized that the antitumor efficacy can be increased when immune destruction of tumor cell is combined with destruction of tumor vasculature by antiangiogenic drugs. In the present study the therapeutic efficacy of combined antiangiogenic and immune therapy has been tested against the highly aggressive, MHC class I negative murine RM1 prostate tumor. SU6668 was used as the antiangiogenic drug and recombinant murine B7.2-IgG fusion protein was used to stimulate T cell-mediated immune destruction of tumor cells. SU6668 is an inhibitor of the tyrosine kinase activity of three angiogenic receptors VEGFR2 (Flk-1/KDR), PDGFRbeta and FGFR1 that play a crucial role in tumor-induced vascularization. Our studies show that B7.2-IgG treatment of mice with established RM1 prostate tumors resulted in a significant inhibition of tumor growth. Both CD4+ and CD8+ T cells were responsible for this effect. SU6668 therapy substantially inhibited tumor vascularization and tumor growth. When tumor-bearing mice were treated with SU6668 in combination with B7.2-IgG, the antitumor effects were substantially higher than in mice treated separately with SU6668 or B7.2-IgG. Prolonged treatment of mice with SU6668 did not inhibit the immunoreactivity of T lymphocytes. On the contrary, T cells from mice treated with a combination of SU6668 and B7.2-IgG showed higher proliferative responses and cytokine production following anti-CD3 stimulation than T cells of mice treated separately with these modalities. These results indicate that antiangiogenic and immune therapies using SU6668 and B7.2-IgG are compatible and manifest complementary antitumor effects. Combined antiangiogenic and immune therapy might represent a new strategy for cancer treatment.

Impaired function of circulating dendritic cells in patients with pancreatic cancer

PURPOSE AND EXPERIMENTAL DESIGN

Dendritic cells (DCs) are important for immune surveillance and play a central role in protection against infection and malignancy. DCs comprise two subsets: DC1 (myeloid DC) and DC2 (lymphoid DC). The aim of this study is to determine whether the number and/or function of circulating DCs were decreased in patients with pancreatic cancer and to evaluate the effects of these changes in patients with locally advanced pancreatic cancer before and after chemoradiotherapy (CRT). We examined the circulating DC number and function using the peripheral blood from 29 patients with pancreatic cancer and 20 healthy control subjects. In patients who underwent CRT (n = 20), blood samples were taken before and after CRT. DCs were tested for the ability to stimulate allogeneic T lymphocytes in mixed leukocyte reaction (MLR). CD4/8, NK activity, PHA, and TGF-beta1 were also measured.

RESULTS

The number and allostimulatory activity of circulating DC1s in patients were significantly lower than those in controls. In the patients who underwent CRT, the allostimulatory activity of DC1s at post-CRT was significantly increased as compared to those at pre-CRT. The level of TGF-beta1 was also significantly decreased at post-CRT as compared to pre-CRT. There were no changes in CD4/8, NK activity and proliferative response of T lymphocytes at the peri-CRT period.

CONCLUSION

These data indicate that the number and function of circulating DCs were impaired in patients with pancreatic cancer. Chemoradiotherapy, however, improved DC function, which might be related to decreased immunosuppressive cytokine levels.

Suppression of macrophage function in AK-5 tumor transplanted animals: role of TGF-β1

Transforming growth factor-beta 1 (TGF-beta1), a multifunctional cytokine secreted by various cell types has been implicated in diverse physiologic and pathophysiologic functions, including immunological, inflammatory, and neoplastic processes. AK-5 tumor cells when injected intraperitoneally grow as ascites, causing 100% mortality. Peritoneal macrophages cocultured with AK-5 cells, in vitro showed specific suppression of tumoricidal function. We report that AK-5 cells secrete the latent form of TGF-beta1, which is converted to its active homodimeric form, causing suppression of the secretion of cytocidal molecule by macrophages thereby inhibiting their cytotoxic capabilities. When macrophages are cocultured with AK-5 cells in the presence of antibodies against TGF-beta1 or the receptor II for TGF-beta, there is significant recovery in the secretion of nitric oxide and macrophage cytotoxic potential. These results suggest a major role for TGF-beta produced by the tumor cells, in the immune escape mechanisms adopted by the AK-5 tumor cells.

Immunodeficiency and cancer: prospects for correction

Cellular immunodeficiency is associated with human cancer. Extensive reviews on cancer of the head and neck, lung, esophagus and breast convince the author that for these diseases the immunodeficiency is reasonably well established yet the mechanisms are poorly understood. Evidence indicates that other tumors are similarly associated with cellular immune deficiency. The advent of recombinant cytokines and of antitumor monoclonal antibodies has served to focus attention toward direct tumoricidal mechanisms. As tumor antigens relating to cellular and humoral immune mechanisms are being defined and vaccine strategies are increasingly being attempted, it is critical to confront issues of the mechanism of anergy and effective immunorestoration in order to maximize the potential of cellular immune response to address these tumor antigens. Intrinsic to this approach is the introduction of contrasuppressive therapy to alleviate the tumor-associated immune suppression. Encouraging attempts have been made with plasmapheresis, indomethacin, low-dose cyclophosphamide, anti CTLA-4, anti FAS ligand and, perhaps in the future, more judiciously applied chemotherapy. In contrast to the popular notion that thymic involution cannot be reversed in the adult, studies from the author's laboratory indicate that in aged hydrocortisone stressed mice, a natural Type 1-cytokine mixture (IRX-2) hastens the reversal of thymic involution and promotes T-cell responses to cytokines and mitogens. Recombinant IL-1 and IL-2 by themselves, and in combination, were inactive. Similar positive effects were observed with oral zinc, zinc-thymulin and thymosin alpha(1). The combination of a natural cytokine mixture (IRX-2) with thymosin alpha1 had a very large effect and increased the absolute number of peripheral T lymphocytes as measured in the spleen. In studies of combination immunotherapy in lymphocytopenic squamous cell head and neck cancer patients using IRX-2 (18 patients) and IRX-2 plus thymosin alpha(1) (IRX-3) in IRX-2-refractory patients (7 patients), marked increases in CD(45)RA(+) 'naïve' T cells (>250/mm(3)) were observed. These are among the first insights into how to generate T lymphocyte replacement in the adult. These and many other experimental efforts point to ways to achieve more effective immunotherapy of human cancer in the future, particularly if tumor-induced immune deficiency can be effectively addressed.

Restored T-cell activation mechanisms in human tumour-infiltrating lymphocytes from melanomas and colorectal carcinomas after exposure to interleukin-2

We investigated the effects of interleukin-2 (IL-2) exposure on T-cell signal transduction molecules and apoptosis markers in tumour-infiltrating lymphocytes (TIL) isolated from 20 melanoma and 16 colorectal carcinoma metastases and expanded in vitro for therapeutic reinfusion. Before IL-2 culture, TIL showed undetectable or very low levels of T-cell receptor (TCR) epsilon chain, p56(lck), Fas ligand (FasL) and Bax expression, while Bcl-2 values were elevated. Cancer cells were characterised by low or absent Fas and Bcl-2 and high Bax expression. Notably, they also expressed FasL. After 41-48 days of IL-2 culture, TCR epsilon chain and p56(lck) expression of TIL rose to median values of approximately 80 and 30% positive cells, respectively (P<0.001), FasL expression was detected in 45% cells from melanomas (P<0.001) and in 3% from colorectal carcinomas (P=0.09), and Bax-positive cells increased from 17.5 to 70% (P=0.005). Moreover, TCR zeta chain-positive cells were significantly increased from baseline (P=0.001), Bcl-2-positive cells dropped from 50 to 1% (P=0.007) and perforin content was high, while Fas expression was not significantly modified by IL-2 culture. In conclusion, our data suggest that the degree of immunosuppression in TIL from melanomas and colorectal carcinomas is very high, and the apoptosis markers' repertoire of cancer cells resembles that of immune-privileged tissue. Interleukin-2 culture appears to restore lymphocyte activation mechanisms, resulting in consistent FasL expression and perforin production.

Immune escape mechanisms of childhood ALL and a potential countering role for DC-like leukemia cells

BACKGROUND

Pre-B ALL cells generally elicit a weak immune host response, due to poor expression of co-stimulatory molecules and/or suppression of immune function. A possible way to enhance immunogenicity of pre-B ALL cells is to convert them to DC-like cells.

METHODS

To study the effect of ALL cells on T-cell function, ALL cells were incubated with T adult cells activated by OKT3 MAb. Liquid culture of de novo pre-B ALL cells for 7 days, in a medium containing IL-1alpha, IL-3, IL-7, Flt 3 ligand (L) and tumor-necrosis factor alpha (TNF-alpha) produced DC-like cells. These were evaluated for morphology, viability, phenotype, as measured by flow cytometry, and function, including MLR.

RESULTS

Pre-B ALL cell-lines NALM-6, BALM and de novo pre-B ALL cells failed to stimulate T cells, but suppressed stimulated T cells. The DC-like cells displayed characteristic features of DCs: filiform cytoplasmic projections, and phenotypic expression of co-stimulatory molecules CD80/86, MHC Class I and II molecules, CD83 and CD1a. Genetic monoclonality study confirmed their leukemic origin. In a 5-day MLR culture, the DC-like cells potently activated allogeneic adult and cord CD4+ and CD8+ T cells. Furthermore, both CD4+ and CD8+ T cells were primed towards a Type I. No such effect was seen with unmanipulated de novo pre-B ALL cells.

DISCUSSION

DC-like cells can be generated from childhood pre-B ALL cells and are potent stimulators of adult and naïve cord CD8+ T cells via CD4+ cells. These cells may form part of an immunotherapy strategy to overcome tolerance to ALL cells.

Plasma PGE-2 levels and altered cytokine profiles in adherent peripheral blood mononuclear cells in non-small cell lung cancer (NSCLC)

INTRODUCTION

PGE-2 is constitutively produced by many non-small cell lung cancers (NSCLC) and its immunosuppressive effects have been linked to altered immune responses in lung cancer. We asked whether elevated levels of plasma PGE-2 correlated with monocyte IL10 production in the NSCLC environment. Looking for correlation in NSCLC patient blood we assayed plasma from NSCLC patients for PGE2 and IL10; we further evaluated production of IL10 by adherent mononuclear cells from a subset of these patients looking for an altered cytokine profile.

RESULTS

Our initial in vitro experiments show that monocyte IL10 induction correlates with tumor cell PGE-2 production, confirming similar reports in the literature. Data show plasma PGE-2 levels in 38 NSCLC patients are elevated compared to normal controls. Plasma IL10 levels were not significantly elevated; however, adherent monocytes derived from NSCLC patient blood did produce significantly more IL10 in 24 hr primary culture than those from normal controls (p < 0.01). The association of elevated plasma PGE-2 and monocyte derived IL-10 was not significant.

CONCLUSIONS

Elevated plasma PGE-2 and monocyte IL10 production are associated with NSCLC. The biological significance to elevated PGE-2 levels in NSCLC are unclear. Further investigation of each as a nonspecific marker for NSCLC tumor is warranted.

Adenosine suppresses alpha(4)beta(7) integrin-mediated adhesion of T lymphocytes to colon adenocarcinoma cells

The interaction of T lymphocytes with tumor cells, a key step in the antitumor immune response, is suppressed by adenosine, a nucleoside produced at increased levels within the hypoxic tumor environment. We have explored the mechanism by which adenosine interferes with the lymphocyte:tumor cell interaction. The adhesion of anti-CD3-stimulated T cells to syngeneic MCA-38 mouse colon adenocarcinoma cells did not involve LFA-1 (alpha(L)beta(2)) or VLA-5 (alpha(5)beta(1)). However, antibodies against either lymphocyte alpha(4) or beta(7) (but not beta(1)) integrin subunits, or against VCAM-1 on the tumor cells, significantly suppressed adhesion, showing that the recognition of MCA-38 cells by T cells is strongly dependent upon the association of alpha(4)beta(7) on the effector cells with VCAM-1 on the tumor targets. This association is modulated by adenosine: The ability of adenosine to suppress T cell adhesion to MCA-38 cells was lost if alpha(4)beta(7) was functionally blocked with anti-alpha(4) antibodies (i) prior to or (ii) during the adhesion assay or if (iii) alpha(+)(4) cells were depleted from the T lymphocyte population. The binding of T cells to fibronectin through alpha(4)beta(1) was not suppressed by adenosine. We conclude that adenosine partially inhibits the interaction of T lymphocytes with tumor cells by blocking the function of integrin alpha(4)beta(7).

Liver-derived dendritic cells induce donor-specific hyporesponsiveness: use of sponge implant as a cell transplant model

Spontaneously accepted mouse liver allografts are capable of protecting subsequently transplanted donor organs from rejection; however, the underlying mechanisms are unclear. Dendritic cells (DC) residing in liver grafts are likely important in tolerance induction. DC propagated from mouse liver with GM-CSF are phenotypically and functionally immature. They are poor allostimulators in MLR and prolong survival of pancreatic islet allografts. It has been problematic to perform mechanistic studies in an islet transplant model because of difficulties in obtaining sufficient graft infiltrating cells. In this study, we used a sponge allograft model [i.e.. a subcutaneously implanted sponge matrix loaded with B10 (H2b) spleen cells]. To investigate the influence of administration of donor (B10) liver-derived DC on alloimmune reactivity of C3H (H2k) hosts, sponge graft infiltrating cells (SGIC) and recipient spleen cells were isolated, and their immunophenotype and donor-specific cytotoxic T lymphocyte (CTL) activity were examined. The results illustrate that donor-specific CTL activity of T cells are lower in recipients that had received systemic treatment with liver-derived immature DC, associated with a decrease in CD8+ cell population and an increase in Gr-1+ cells in SGIC, compared with recipients treated with mature bone marrow (BM)-derived DC. Interestingly, administration of liver DC directly into the sponge did not inhibit T cell responses. These data suggest that systemic administration of donor liver DC induces donor-specific hyporesponsiveness, probably not by direct inhibition of graft infiltrating T cells. The increased Gr-1+ cells may play immune regulatory roles in induction of host donor-specific hyporesponsiveness.

Immunology of the peritoneal cavity: relevance for host-tumor relation

The peritoneal membrane, formed by a single layer of mesothelial cells, lines the largest cavity of the human body. Anatomic structures of the peritoneal cavity, along with resident leukocyte populations, play an important role in the defense against microorganisms invading by breaching the gut integrity or ascending through the female genital tract. Local immune mechanisms in the peritoneal cavity are also important in patients undergoing peritoneal dialysis and in women with endometriosis. There is now extensive evidence demonstrating the significance of peritoneal immune mechanisms in the control of metastatic spread. Leukocytes belonging to both the innate and adaptive immune systems are present in the peritoneal cavity of normal subjects as well as in patients with intra-abdominal cancer. There is now increased understanding of the mechanisms that not only allow the tumor cells to escape the detection and destruction by the host immune system, but also to use the inflammatory mechanisms to promote tumor growth and spread inside the peritoneal cavity. Malignant ascites represents a model for the study of the interaction between tumor cells and the host immune system as well for the analysis of the tumor microenviroment. The peritoneal immune system may be stimulated by intraperitoneal administration of biologic agents. This peritoneal immunotherapy may be used for palliation of malignant ascites, or as a consolidation strategy in patients with minimal residual disease.

Induction of cyclo-oxygenase-2 in non-small cell lung cancer cells by infection with DeltaE1, DeltaE3 recombinant adenovirus vectors

Infection of epithelial-derived cells by adenovirus vectors has myriad effects on cellular behavior and function. Some are relevant to the desired effect of the encoded transgene and therapeutic goals of gene therapy approach. The current experiments describe the induction of COX-2 protein and PGE-2 production by non-small cell lung cancer (NSCLC) cells following infection with a first generation (DeltaE1, DeltaE3) Ad vector. COX-2 overexpression by malignant cells has been shown to enhance cellular invasion, induce angiogenesis, regulate anti-apoptotic cellular defenses and augment immunologic resistance through production of PGE-2. Data show DeltaE1, DeltaE3, Ad5 vector infection induces dose-dependent increases in PGE-2 production by NSCLC cell lines. Data with UV/psoralen inactivated vectors and control vectors show this effect is dependent on Ad vector gene expression, but independent of the transgene expressed. Selective blockade of ERK with PD98029 abrogated induction of PGE-2 by Ad vectors. Consistent with these data, detectable increases in COX-2 protein were seen at 48 h after infection by Western blot that were paralleled by increases in the phosphorylation of ERK-1/2. UV/psoralen-inactivated vector did not induce COX-2 protein or ERK phosphorylation at 48 h. Further, an inhibitor of NF-kappa B (NFkappaB) translocation to the nucleus, SN50, had no effect on PGE-2 levels. In contrast, Ad vector infection did induce NFkappaB activity measured by NFkappaB-luciferase reporter plasmid, transfected into a NSCLC cell line. Collectively the data indicate DeltaE1, DeltaE3, Ad5 vector infection leads to ERK phosphorylation with parallel increases in COX-2 protein and PGE-2 production. These effects appear unrelated to NFkappaB and are dependent on gene expression by the vector. This information may need to be considered when defining targets for cancer gene therapy and/or the choice of viral vector.

Retinoic acid and vitamin E modulate expression and release of CD178 in carcinoma cells: consequences for induction of apoptosis in CD95-sensitive cells

CD178 (CD95-ligand) is expressed on several tumor cells and likely influences the interaction of the tumor with the host immune system. However, little is known about the mechanisms that regulate its expression on the cell surface. We have evaluated the ability of various compounds and cytokines to regulate cell surface expression and release of soluble CD178 in various carcinoma cell lines. Vitamin E succinate (VES) and retinoic acid (RA) were found to reduce CD178 surface expression, whereas interferon-gamma stimulated a slight upregulation. At 48 h, the regulation of surface CD178 by VES and RA arose from a small decrease in CD178 mRNA and to a greater extent due to an increase in the release of soluble CD178; the latter was blocked by addition of a metalloproteinase inhibitor. Accordingly, VES and RA treatment diminished the ability of tumor cells to kill CD95-sensitive cells and this effect was markedly reduced by the presence of a metalloproteinase inhibitor. Our results indicate that, in vitro, CD178 expression on the cell surface of tumor cells can be regulated by agents that alter both expression and release of the ligand. In vivo, such treatments may play an important role in the outcome of tumor sensitivity or resistance to host immune mechanisms.

Expression of tumor-associated antigen RCAS1 correlates significantly with poor prognosis in nonsmall cell lung carcinoma

BACKGROUND

RCAS1 is a recently discovered antigen molecule expressed on the membrane of cancer cells, and it acts as a ligand for a putative receptor present on immune cells such as T, B and NK cells. It has been suggested that RCAS1 expression is related to the escape of tumors from immune surveillance. In this study, the relation between RCAS1 expression and various clinicopathologic variables, including patient prognosis, was investigated in lung carcinoma through immunohistochemical analysis.

METHODS

One hundred two surgically resected nonsmall cell lung carcinoma cases were examined histopathologically by means of the monoclonal antibody 22-1-1, which is specific for RCAS1. The correlation between RCAS1 expression and the clinicopathologic features of patients was evaluated. Moreover, the correlation between RCAS1 expression and the survival of patients was analyzed by the Kaplan-Meier method log-rank test, and multivariate analysis was performed by using the Cox proportional hazard model.

RESULTS

The samples of 48 of the 102 lung carcinoma patients (47.1%) were positive for RCAS1. There were significant correlations between RCAS1 expression and either pathologic staging (P = 0.0003) or tumor differentiation (P = 0.0308). The survival time for the RCAS1-positive group was significantly shorter than that for RCAS1-negative group (P < 0.0001). Moreover, multivariate analysis for overall survival revealed that RCAS1 expression was a significantly independent prognostic factor in nonsmall cell lung carcinoma patients.

CONCLUSION

These results suggested that RCAS1 expression may play an important role in the immune escape mechanism and that RCAS1 expression may be a good indicator of poor prognosis in patients with nonsmall cell lung carcinoma.

Down regulation of T-cell-derived IL-10 production by low-dose cyclophosphamide treatment in tumor-bearing rats restores in vitro normal lymphoproliferative response

In previous reports, we demonstrated an inhibitory effect of a single low-dose of cyclophosphamide (Cy) on spontaneous and experimental metastasis of a rat lymphoma (L-TACB). This antimetastatic effect could be adoptively transferred by immune spleen cells from Cy-treated tumor-bearing rats and it was abrogated by the use of immunosuppressed hosts, suggesting an immunomodulatory effect. Subsequently, we found that increased levels of TGF-beta, IL-10 and NO were involved in tumor-induced immunosuppression by inhibiting lymphocyte proliferation. The treatment of tumor-bearing rats with low-dose Cy reduced the splenic production of these suppressive cytokines, restoring the lymphoproliferative capacity otherwise diminished during tumor growth. Here, we investigated the changes of the cytokines modulated by the Cy therapy that are responsible for the restoration of the lymphoproliferative response and determined the spleen cell type producing TGF-beta, IL-10 and NO in our experimental model. Our current results show that IL-10 and NO are produced exclusively by T lymphocytes and macrophages, respectively, whereas TGF-beta is produced by both cell types. The high level of IL-10 produced by T-cells from tumor-bearing rats is responsible for the inhibition of lymphocyte proliferation. Moreover, our results suggest that the shift from immunosuppression to immunopotentiation induced by treatment of tumor-bearing rats with a single low-dose of Cy is mediated by a reduction in T-cell derived IL-10 production, which would account, to some extent, for the antimetastatic effect of Cy treatment.

Serum levels of IL-12 and the production of IFN-gamma, IL-2 and IL-4 by peripheral blood mononuclear cells (PBMC) in cancer patients treated with Viscum album extract

A dysregulation between cellular immunity (Th1 cells) and humoral immunity (Th2 cells) is a characteristic of cancerous diseases. Viscum album (VA) extract has an immunomodulatory effect and can be used in the treatment of cancer patients, either following or in combination with chemo- /radiotherapy. In this pilot study, we investigated the effect of VA extract on the serum levels and production of cytokines in a group of cancer patients undergoing treatment (N = 16) in comparison with healthy untreated controls (N = 11). The serum levels of interleukin-12 (IL-12) (p40 and p70), and the production of gamma interferon (IFN-gamma), interleukin 2 (IL-2), and interleukin-4 (IL-4) in peripheral blood mononuclear cells (PBMC) were measured in patients before treatment and on days 3, 5, 8, 15, and 21-29 during therapy, and in the control group at the same time intervals over a two-week period. Cytokine levels were determined by ELISA. In cancer patients, the serum levels of IL-12 (p40 and p70) before therapy were about 3-fold higher than in controls. They increased during therapy, with a borderline significance (Wilcoxon paired signed-rank test, P = 0.06). In PBMC the production of IFN-gamma and IL-2 (before therapy respectively 3-fold and 9-fold lower than in controls) increased significantly (Wilcoxon paired signed-rank test and Mann-Whitney U-test, P < 0.05) during treatment. In PBMC, IL-4 production was in the same range as in controls, and remained unaltered during therapy. In conclusion, the results of this study show that treatment with VA extract leads an increase in Th1 cytokine levels (IFN-gamma and IL-2), which suggests that cell-mediated immunity could be positively affected.

Serum interleukin-10 levels as a prognostic factor in advanced non-small cell lung cancer patients

STUDY OBJECTIVE

To investigate the prognostic significance of interleukin (IL)-10 serum levels in advanced non-small cell lung cancer (NSCLC) patients.

DESIGN

IL-10 serum levels were measured before chemotherapy, on completion of therapy, and at follow-up by means of a commercially available enzyme-linked immunoassay. The results were then analyzed in comparison with other prognostic variables, and a model predicting overall survival (OS) and time to treatment failure (TTF) was finally generated.

SETTING

University hospital.

PATIENTS

Sixty consecutive patients with TNM stage III or IV NSCLC undergoing conventional platinum-based regimens.

RESULTS

Elevated levels of serum IL-10 were found in cancer patients with respect to healthy control subjects (17.7 +/- 4.4 vs 9.2 +/- 1.5 pg/mL, respectively; p < 0.05), with patients with metastatic disease showing significantly higher levels than patients with undisseminated cancer (21.0 +/- 4.2 vs 14.3 +/- 1.2 pg/mL, respectively; p < 0.05). Following completion of treatment, patients were classified as responders if they had achieved either one of the following: complete response, partial response, or stable disease; and nonresponders, in case of progressive disease. Retrospective analysis of basal IL-10 serum levels in these two subgroups showed a significant difference between responders and nonresponders (15.2 +/- 2.2 vs 21.4 +/- 4.2 pg/mL, respectively; p < 0.05). Moreover, a further significant increase in IL-10 serum levels was observed in nonresponders at the end of therapy (21.4 +/- 4.2 vs 26.0 +/- 4.3 pg/mL, prechemotherapy and postchemotherapy, respectively; p < 0.05), whereas values in responders were found to have significantly decreased (15.2 +/- 2.2 vs 14.8 +/- 2.2 pg/mL, prechemotherapy and postchemotherapy, respectively; p < 0.05). Using univariate and multivariate analyses, both OS and TTF were shown to be affected by the mean pathologic levels of IL-10. Stepwise regression analysis identified IL-10 serum level and stage as the prognostic factors related to OS, and IL-10 serum level and performance status as the prognostic factors related to TTF.

CONCLUSIONS

In conclusion, this study shows that the measurement of pretreatment IL-10 serum levels is of independent prognostic utility in patients with NSCLC and may be useful for detection of disease progression.

Reduced immunologic cell performance as a prognostic parameter for advanced cervical cancer

The proliferative response of lymphocytes to mitogens is known to be decreased in cancer patients; this phenomenon is thought to play an important role in disease progression, but it has not been studied as a prognostic factor in cervical cancer patients receiving treatment. Fourteen patients with advanced cervical cancer submitted to chemotherapy with cis-platinum (100 mg/m2/cycle) and bleomycin (30 mg/cycle) over three cycles every 4 weeks were evaluated. Mean follow-up time was 30 months. The following laboratory tests carried out on peripheral blood lymphocytes collected before and at the end of chemotherapy were used as prognostic factors: proliferative response of lymphocytes to phytohemagglutinin (PHA) and stimulated with interleukin 12 (IL-12), capacity of gamma interferon production (IFN-gamma), and variations in memory T cell (CD45-RO) and naive T cell (CD45-RA) subsets. A clear correlation was obtained between response to treatment, survival rates, and PHA-induced proliferative response. A significant difference was observed in the number of CD45-RO lymphocyte at the pre-chemotherapy period and IFN-gamma production at the post-chemotherapy period in the group of good responders to treatment. The use of IL-12 produced a leveling in both groups for lymphocyte proliferation, i.e., a recovery from the deficiency presented by the lymphocyte of the poor responders group. The parameters of immunologic assays, especially proliferative response, appears to be correlated with prognosis and survival rates and therefore are good discriminating factors for the selection of groups of patients that will benefit from this type of treatment. IL-12 seems to play an important role in the regulation of the antitumor immune response and should be considered for therapeutic use.

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.

Reversed CD4/CD8 ratios of tumor-infiltrating lymphocytes are correlated with the progression of human cervical carcinoma

BACKGROUND

To investigate the clinical significance of tumor-infiltrating lymphocytes (TILs) within the tumor milieu of human cervical carcinoma, the authors quantitatively measured and compared the subpopulations of lymphocytes infiltrating the neoplastic cervix.

METHODS

A total of 30 patients with Stage Ia-IIa cervical carcinoma were enrolled. TILs were isolated from tissue specimens by means of a mechanical dispersal technique, and the immunocyte subsets were quantified with dual-color flow cytometry. Bulky tumor was defined as tumor size >4 cm in greatest dimension according to the 1995 staging of the International Federation of Gynecology and Obstetrics.

RESULTS

The CD4/CD8 ratios of TILs were reversed in both cervical squamous cell carcinoma (n = 20) and cervical adenocarcinoma (n = 10). The proportion of CD4(+) T cells was significantly lower in tumors from patients with lymph node metastasis (n = 8) than in those from patients without lymph node metastasis (n = 22) (24.5 vs. 32.7, P = 0.001), as was the reversed CD4/CD8 ratio (0.50 vs. 0.81, P = 0.001). The proportion of CD4(+) T cells was much lower in bulky tumors (n = 5) than in nonbulky tumors (n = 25) (21.4 vs. 32.5, P < 0.001), reflecting in a more strongly reversed CD4/CD8 ratio (0.41 vs. 0.81, P = 0.001).

CONCLUSIONS

Decreased proportions of tumor-infiltrating CD4+ T cells with reversed CD4/CD8 ratios are highly correlated with rapid tumor growth and lymph node metastasis in cervical carcinoma. The regional immune escape is of prognostic importance with regard to cancer progression.

Phase I/II study of stage III and IV non-small cell lung cancer patients taking a specific dietary supplement

This phase I/II study evaluates the influence of selected vegetables (SV) that contain known antitumor components on the survival of stage III-IV non-small cell lung cancer (NSCLC) patients. All patients were treated with conventional therapies. SV was added to the daily diet of 5 stage I patients in the toxicity study group (TG) and 6 stage III and IV patients in the treatment group (SVG), but not to the diet of 13 stage III and IV patients in the control group (CG). Age, Karnofsky performance status (KPS), and body mass index of SVG and CG patients were comparable at entry. KPS declined in the CG patients (79 +/- 8 to 55 +/- 11) but improved in the SVG patients (75 +/- 8 to 80 +/- 13) one to three months after entry. Weight change in the CG, SVG, and TG patients was -12 +/- 5%, -2 +/- 2%, and +4 +/- 4%, respectively. The median survival time and mean survival of the CG patients were 4 and 4.8 months, but in the SVG patients they were 15.5 and 15 months (p < 0.01). No clinical signs of toxicity were found in the TG patients in the 24-month study period. Adding SV to the daily diet of NSCLC patients was found to be nontoxic and associated with improved weight maintenance, KPS, and survival of stage III and IV NSCLC patients.

Tumor-associated transforming growth factor-beta and interleukin-10 contribute to a systemic Th2 immune phenotype in pancreatic carcinoma patients

In this study, we report coexpression of transforming growth factor-beta (TGF-beta) and interleukin-10 (IL-10) in pancreatic carcinoma tissue associated with significantly elevated levels of both cytokines in the sera of pancreatic carcinoma patients. Using conditioned media (CM) of pancreatic carcinoma cells, we further demonstrate that tumor cell-derived TGF-beta and IL-10 inhibited in an additive fashion both proliferation and the development of Th1-like responses in peripheral blood mononuclear cell (PBMC) preparations derived from normal donors. The antiproliferative and Th1-suppressive activities contained in CM of pancreatic carcinoma cells were due primarily to IL-10 and/or TGF-beta, as shown by the capacity of cytokine-specific neutralizing antibodies to reverse these effects. Finally, as compared to normal controls, PBMC derived from pancreatic carcinoma patients displayed a Th2-like cytokine expression pattern upon activation with either anti-CD3 antibody or Staphylococcus aureus strain Cowan I. Taken together, these results suggest that aberrant production of TGF-beta and IL-10 in pancreatic tumor patients skews T-cell cytokine production patterns in favor of a Th2 immunophenotype.

Immunological escape mechanisms in pancreatic carcinoma

Malignancies have developed several strategies to evade immune surveillance. We have investigated pancreatic cancer cell lines and pancreatic cancer surgical specimens to evaluate possibilities of tumor escape in the Fas system, and local immune suppression. Despite Fas expression the majority of cell lines was resistant to Fas-mediated apoptosis. The Fas-associated phosphatase-1 is a strong candidate to confer Fas resistance in pancreatic cancer cells. In addition, all investigated pancreatic cancer cell lines and cancer specimens expressed Fas ligand. Fas ligand was functional in cancer cell lines as shown by coculture assays of pancreatic cancer cell lines with Jurkat cells as targets. Additional local immune suppression was demonstrated by loss of T-cell receptor/CD3-zeta chain of pancreatic cancer infiltrating T-lymphocytes. We conclude that these tumor escape mechanisms may contribute to the poor prognosis of pancreatic cancer but also represent targets for new treatment modalities.

Transitional cell carcinoma expresses high levels of Fas ligand in vivo

OBJECTIVE

To characterize the Fas-Fas ligand system, a main apoptotic pathway, in transitional cell carcinoma (TCC) of the urinary bladder, by analysing the expression of Fas and Fas ligand (FasL) in TCC samples.

MATERIALS AND METHODS

Archival paraffin-embedded tissues from 37 patients with TCC were analysed by immunohistochemistry to determine Fas and FasL expression.

RESULTS

Fas and FasL were detected on the cell surface and cytoplasm of respectively 34 (92%) and all cases analysed. The expression of Fas and FasL did not differ with the cytological grade of TCC.

CONCLUSION

The high expression of FasL in TCC, reported for the first time in the present study, suggests that FasL may contribute to the immune escape of TCC through killing Fas-bearing lymphocytes. Co-expression of Fas with FasL also suggests that TCC may have pathways resistant to Fas-mediated autocrine cell suicide.

Apoptotic Death of CD8+ T Lymphocytes After Immunization: Induction of a Suppressive Population of Mac-1+/Gr-1+ Cells

Following an infection or immunization, a primary CD8+ T cell response generally rises then falls rapidly before giving rise to a “memory” response. When we immunized mice with recombinant viral immunogens optimized to enhance the lytic capability of CD8+ T cells, we measured a profound depression in Ag-specific effector function after early restimulation. Indeed, a “mirror image” cytolytic capability was observed: the most powerful immunogens, as measured by cytolytic capacity 6 days after immunization, elicited the weakest secondary immune response when evaluated following an additional 6 days after restimulation. To understand the mechanism of this suppression, we examined the fate of splenocytes immunized with a vaccinia virus encoding Ag and IL-2 then restimulated ex vivo. We found that these splenocytes underwent an apoptotic cell death, upon early restimulation, that was not dependent on the engagement of the FasR (CD95). Unlike previously described mechanisms of “propriocidal cell death” and “clonal exhaustion,” the cell death we observed was not an inherent property of the CD8+ T cells but rather was due to a population of splenocytes that stained positive for both the Mac-1 and Gr-1 surface markers. Deletion of these cells in vitro or in vivo completely abrogated the observed suppression of cytolytic reactivity of Ag-specific CD8+ T cells. These observations could account for the apparent absence of Ag-specific immune responses after some current vaccination regimens employing powerful immunogens. Finally, our results may shed new light on a mechanism for the suppression of CD8+ T cell responses and its effect on vaccine efficacy and on immune memory.

CD4+ Lymphocytes Provide MUC1-Specific Tumor Immunity In Vivo That Is Undetectable In Vitro and Is Absent in MUC1 Transgenic Mice

A C57BL/6 mouse transgenic for human MUC1 (MUC1.Tg) was developed to evaluate MUC1-specific tumor immunity in an animal that expresses MUC1 as a normal self protein. Previous studies showed that MUC1.Tg mice, challenged with syngeneic tumors expressing MUC1 (B16.MUC1), developed progressively growing MUC1-positive tumors, whereas wild-type C57BL/6 (wt) mice developed MUC1-negative tumors at a significantly slower rate. The results of a limiting dilution CTL frequency assay were not informative, in that similar numbers of MUC1-specific CTL precursors (CTL) were detected in MUC1.Tg and wt mice. Tumor immunity in vivo was characterized by an adoptive transfer method to evaluate the degree of MUC1 or non-MUC1 tumor immunity in wt or MUC1.Tg mice. The results revealed that wt mice developed protective tumor immunity mediated by MUC1-specific CD4+ lymphocytes, while MUC1.Tg mice were functionally tolerant to MUC1 in vivo. The potential of adoptive immunotherapy to provide immunity to tumors expressing MUC1 and to produce undesirable autoimmunity in recipient MUC1.Tg mice expressing MUC1 as a self Ag was evaluated. Adoptive transfer of immune cells from wt mice primed in vivo with B16.MUC1 tumor cells into MUC1.Tg recipients resulted in significant increases in the survival of MUC1.Tg recipients compared with unmanipulated control MUC1.Tg mice challenged with B16.MUC1 tumor cells. This response was specific for MUC1 since control tumors developed at equivalent rates in recipient or control MUC1.Tg mice. No gross or histologic evidence of autoimmunity was observed in recipient MUC1.Tg mice, indicating that tumor immune responses mediated by MUC1-specific CD4+ lymphocytes spare nontransformed epithelia-expressing MUC1.