Antitumor efficacy of adenocarcinoma cells engineered to produce interleukin 12 (IL-12) or other cytokines compared with exogenous IL-12

BACKGROUND: Numerous animal model studies have examined the ability of genetically engineered tumor cells to release cytokines and to elicit an immune memory against the parental tumor. Often only a single cytokine is studied, and few comparative studies have been conducted. PURPOSE: We evaluated the antitumor efficacy of adenocarcinoma cells engineered to release interleukin (IL)-12 in a mouse model system. The efficacy of this cytokine was compared with that of other cytokines released by engineered adenocarcinoma cells and that of exogenous IL-12 administered both locally and intraperitoneally. METHODS: BALB/cAnCr mice were inoculated with syngeneic parental mammary adenocarcinoma (TSA) cells in quantities sufficient to lead to tumors in all inoculated mice. TSA cells engineered to release IL-12 (TSA-IL12) were also injected into normal and selectively immunosuppressed BALB/cAnCr mice. Tumor incidence, growth, and rejection patterns were evaluated by the measurement of neoplastic masses and by the study of the histologic and ultrastructural features of the tumor site. The effects of local or intraperitoneal administration of recombinant IL-12 (rIL-12) on tumor-bearing animals were also studied. RESULTS: Most mice rejected TSA-IL12 cells through a CD8-positive, T-lymphocyte-dependent reaction associated with macrophage infiltration, vessel damage, and necrosis. The systemic immunity of mice that had rejected TSA-IL12 cells to a subsequent challenge with parental TSA cells was less efficient than that elicited by TSA cells engineered to release IL-4 or IL-10 but equivalent to that elicited by TSA cells engineered to release IL-2, IL-7, and interferon alfa. Compared with TSA cells engineered to produce other cytokines, TSA-IL12 cells were the most efficient in curing mice with established TSA tumors; injection of 0.1 million proliferating cells contralaterally to the tumor growth area cured five of 15 mice bearing 1-day-old tumors; injection of the same dose of proliferating cells into the tumor growth area cured two of 20 tumor-bearing mice. However, two 5-day courses with a nontoxic dose (0.1 microgram) of rIL-12 given intraperitoneally cured a similar proportion of these animals (six of 20). Only two of 20 mice with 7-day-old TSA tumors were cured by vaccination with proliferating TSA-IL12 cells, whereas 24 of 30 mice with such tumors were cured by intraperitoneal administration of rIL-12. CONCLUSIONS: TSA cells engineered to release IL-12 are rejected by most mice; the ensuing immune memory for TSA parental cells, however, was less efficient than that elicited by proliferating TSA cells engineered to release other cytokines (e.g., IL-4, IL-10, and possibly interferon gamma). The immune reaction elicited by TSA-IL12 cells was the most efficient in curing mice with established TSA tumors; notably though, the same or a better cure rate was obtained with rIL-12 given intraperitoneally.     

Secretion of both IL-2 and IL-4 by tumor cells results in rejection and immunity

Chronic ischemia may cause end stage renal disease, especially in older patients with atherosclerotic renal artery stenosis. Examining the pathology of the ischemic kidney is a fundamental first step toward understanding the mechanisms of this injury. In experimental renal hypoperfusion, there is evidence of a mixture of adaptive responses, tubular and endothelial cell damage and repair events. These processes are reflected in a wide spectrum of morphological changes that include atrophy, focal necrosis, epithelial regeneration, apoptosis, inflammation, interstitial fibrosis, and thrombosis. The most severe damage is seen in the outer medulla, a region with marginal oxygenation even in normal circumstances. In the usual clinical case, the effects of aging, pre-existent hypertension, and the process of atherosclerosis further complicate the pathological picture. Lesions related to these factors include arteriosclerosis, athero-emboli, various types of glomerulosclerosis, and severe tubulointerstitial damage leading to "atubular glomeruli" and regional cortical scarring (nephrosclerosis). In this article, some mechanisms determining the varied and complex pathological findings that may be observed in individual cases are outlined.     

High lytic activity against human leukemia cells after activation of allogeneic NK cells by IL-12 and IL-2

IL-12 is a novel cytokine with interesting features regarding its potential usefulness in peripheral blood stem cell transplantation and leukemia immunotherapy. We used cryopreserved leukemia cells of 18 patients with acute myelogenous (n= 14) or lymphocytic (n= 4) leukemia to investigate the effect of IL-12, alone or in combination with IL-2, on the cytolytic activity of NK cells against human leukemia targets. Effector cells were peripheral blood mononuclear cells from healthy donors which were depleted from CD3+ T cells by immunomagnetic separation. CD3-negative effector cells (mainly CD56+ NK cells) were treated for 24 h with various concentrations of IL-2 (100 U/ml to 1000 U/ml) and IL-12 (1 U/ml to 100 U/ml). Cytotoxicity was measured in a 4 h 51Cr-release assay. Whereas a two-fold enhancement of cytotoxic activity was observed after incubation with optimal doses of IL-2 or IL-12, the combination of both cytokines (500 U/ml IL-2, 100 U/ml IL-12) increased the lytic activity more than six-fold. This effect was accompanied by increased expression of cellular adhesion molecules (CD2, CD18) and CD25 on CD56+ effector cells. Of 18 leukemias investigated, five were completely resistant to lysis by effector cells activated with IL-2 or IL-12 alone. In three of these five cases, however, high cytolytic activity was observed after coincubation with IL-2 and IL-12. In comparison to allogeneic NK cells, autologous cells of three patients in remission demonstrated significantly lower cytotoxic activity. No killing of nonmalignant cells (PHA blasts) by allogeneic NK cells was observed. Our data demonstrate that IL-12 can enhance or even induce MHC-unrestricted cytotoxicity of IL-2-activated allogeneic natural killer cells. Since IL-12 has also been shown to have stem-cell mobilizing capacities, it could be used for the recruitment of both stem cells and antileukemic effector cells in the context of peripheral blood stem cell transplantation.     

Characterization of lymphokine-activated killing by human peripheral blood mononuclear cells stimulated with interleukin 2 (IL-2) analogs specific for the intermediate affinity IL-2 receptor

Interleukin 2-stimulated human peripheral blood mononuclear cells (PBMC) generate lymphokine-activated killing (LAK). Using the IL-2 analogs R38A and F42K, which interact primarily with the beta and gamma subunits of the IL-2 receptor, we assessed the roles of IL-2R beta gamma and the high-affinity IL-2 receptor complex in LAK activation. Although the kinetics of LAK activation were identical, lytic activity was approximately 30% lower and proliferation was up to 55% lower in those PBMC stimulated by R38A or F42K than in those exposed to wild-type IL-2. The percentage of cells expressing cell-surface markers such as CD3, CD4, CD8, and CD16 was not significantly different after treatment with wild-type IL-2, R38A, or F42K; however, the proportion of cells expressing IL-2R alpha increased dramatically in response to stimulation by F42K (30%) compared to stimulation by either rIL-2 or R38A (15%). In addition, by Day 7 the concentration of soluble IL-2R alpha in analog-stimulated LAK culture supernatants was 50-75% less than that from wild-type IL-2-cultured cells. These findings suggest that interaction of IL-2 with IL-2R beta gamma alone is sufficient for both proliferation and the generation of LAK, and that stimulation with subunit-specific IL-2 analogs results in differential regulation of the IL-2R alpha on human LAK cells.     

Tumour cell vaccines that secrete interleukin-2 (IL-2) and interferon gamma (IFN gamma) are recognised by T cells while resisting destruction by natural killer (NK) cells

The inoculation into mice of genetically engineered tumour cells that secrete IL-2 or IFN gamma results in rejection, while unmodified parental tumour cells grow progressively. In vivo studies demonstrated synergy between IL-2 and IFN gamma leading to the rejection of the transduced tumour cells. IL-2 is required for T cell proliferation and differentiation. IFN gamma induced the upregulation of MHC class I molecules that present peptides to CD8+ T cells. Furthermore, IFN gamma can correct defects in antigen processing. Thus, for T cells, IL-2/IFN gamma-secreting double cytokine tumour cell vaccines might serve as class I+ peptide/antigen presenting depots for developing effector cells. In contrast to T cells, NK cells exert spontaneous killing and kill class I+ targets less well than those that are class I-. For this reason, they may actually have a detrimental effect by destroying a class I+ tumour cell vaccine before adequate T cell stimulation occurs. Based upon this rationale, we tested the hypothesis that an unrecognised benefit of increased class I expression by tumour cells in response to IFN gamma secretion would be to enable cytokine-secreting vaccine cells to resist destruction by NK cells. Our results demonstrated that T cells recognised tumour cells secreting IFN gamma better than those secreting IL-2. NK cells, in contrast, were inhibited by tumour cells that secreted IFN gamma, but not by those that secreted IL-2. The findings suggest that, in addition to upregulating adhesion molecules, MHC molecules, and correcting defects in antigen presentation pathways, IFN gamma secretion may protect tumour cell vaccines from early NK-mediated destruction, keeping them available for T cell priming.     

Involvement of MHC class I molecule and ICAM-1 in the enhancement of adhesion and cytotoxic susceptibility to immune effector cells of tumor cells transfected with the interleukin (IL)-2, IL-4 or IL-6 gene

To investigate the molecular and cellular mechanisms involved in the reduced tumorigenicity and increased immunogenicity of interleukin-2 (IL-2)-, IL-4- or IL-6-gene-transfected B16 melanoma vaccine, we have analyzed the functional and phenotypic properties of these genetically engineered melanoma cells in the present study. The cytokine-gene-transfected B16 melanoma cells showed stronger adhesion to the lymphokine-activated killer (LAK) cells or cytotoxic T lymphocytes (CTL), and higher sensitivity to cytotoxicity of LAK cells or CTL. Using fluorescence-activated cell sorting analysis, we found that both MHC class I and ICAM-1 expression were increased after IL-2, IL-4 or IL-6 gene transfection. The increased level of MHC class I and ICAM-1 expression seems to be responsible for the high sensitivity of these gene-transfected B16 cells to LAK or CTL cytotoxicity because anti-(MHC class I) or anti-ICAM-1 mAb could inhibit the adhesion and cytotoxicity increment simultaneously. The CTL induction was partly inhibited by anti-ICAM-1 mAb and was completely blocked by anti-MHC class I mAb. These results suggested that the decreased tumorigenicity of IL-2-, IL- 4-, and IL-6-gene-transfected B16 melanoma cells may be partly due to the increased sensitivity to effector cell cytotoxicity mediated by increased expression of ICAM-1 or MHC class I molecules on the tumor cell surface after cytokine gene transfection.     

Differential stimulation of interleukin-12 (IL-12) and IL-10 by live and killed Helicobacter pylori in vitro and association of IL-12 production with gamma interferon-producing T cells in the human gastric mucosa

The objective of these experiments was to examine the ability of Helicobacter pylori to stimulate interleukin-10 (IL-10) or IL-12 and select for either Th1 or Th2 cells. Gastric biopsy specimens were collected from patients who were categorized with respect to the presence of H. pylori and gastric disease as well as their age, gender, medications, and other factors. As Th1 and Th2 cells are selected by IL-12 and IL-10, respectively, biopsy specimens were screened for mRNA and protein for these cytokines. Although mRNA for IL-12 and IL-10 was detected in biopsy specimens obtained from both infected and uninfected patients, IL-12 protein predominated. Levels of IL-10 and IL-12 in gastric tissue did not change in response to infection. Moreover, gamma interferon (IFN-gamma)-producing T cells were found in both the infected and the uninfected gastric mucosa. Stimulation of peripheral blood leukocytes from either infected or uninfected donors with various concentrations of live or killed H. pylori induced immunoreactive IL-12 and IL-10. After stimulation with live H. pylori, IL-12 levels increased more than 30-fold, whereas IL-10 levels increased only 2- to 5-fold, compared to cells stimulated with medium alone. Interestingly, killed H. pylori induced significantly more IL-10 (P < 0.05) than live H. pylori, while recombinant urease only induced IL-10. These results demonstrate that live H. pylori selectively stimulates the induction of IL-12 and Th1 cells that produce IFN-gamma, whereas preparations used in oral vaccines induce more IL-10 and may favor Th2 cell responses.     

Antigen-specific regression of established tumors induced by active immunization with irradiated IL-12- but not B7-1-transfected tumor cells

Transfection of modestly immunogenic tumors to express B7 family co-stimulator molecules results in their rejection by syngeneic mice, suggesting a possible clinical application in cancer patients. Immunization of naive mice with irradiated B7-1-transfected P1.HTR cells is sufficient to induce specific cytolytic T lymphocytes (CTL) and to protect against tumor challenge. However, patients to be treated will have an existing tumor burden; thus, preclinical models should examine therapeutic efficacy in an established tumor setting. Contrary to expectations, immunization of mice with irradiated B7-1-transfected P1.HTR cells had no impact on the growth of pre-established control-transfected tumors. Mice bearing control-transfected P1.HTR tumors successfully rejected living B7-1 transfectants on the contralateral flank, demonstrating the ability of tumor-bearing mice to respond to B7 co-stimulation. Inasmuch as IL-12 is another important factor for CTL maturation, P1.HTR transfectants expressing B7-1 and/or IL-12 were then constructed. Remarkably, regression of pre-established tumors was achieved following immunization with irradiated IL-12 transfectants, even without co-expression of B7-1. Rejection required a shared antigen with the tumor used for immunization, could not be reproduced with rIL-12 alone, depended on host T lymphocytes and correlated with a high IFN-gamma-producing T cell phenotype. In addition, IL-12-facilitated tumor rejection required co-operation with a CTLA-4 ligand provided by the host, and correlated with up-regulation of B7-1 and B7-2 on host antigen-presenting cells. Thus, active immunization in the established tumor setting is benefitted greatly by the provision of IL-12, which may recruit participation of sufficient B7 co-stimulation from the host that it need not be provided exogenously.     

The relation between diabetes mellitus and IFN-gamma, IL-12 and IL-10 productions by CD4+ alpha beta T cells and monocytes in patients with pulmonary tuberculosis

Membrane glycoproteins (gps) play an important role in cell-cell interactions during epidermal maturation, and we have previously shown an up-regulation of PNA-binding gps in cultured human keratinocytes treated with interferon gamma (IFN-gamma). The protein kinase C (PKC) pathway is known to play a key role in the regulation of proliferation and differentiation of keratinocytes and is also reported to be involved in some IFN-gamma-mediated effects. In order to evaluate the cellular mechanisms and whether PNA-binding gp expression is related to the differentiative activity of the lymphokine, we studied the effects of PKC agonists and antagonists and the role of retinoic acid (RA), in the induction of these gps in cultured human keratinocytes stimulated with IFN-gamma and processed for protein analysis. The expression of PNA-binding gps was revealed by incubation of SDS-polyacrylamide gels with 125I-PNA. The PKC antagonists (H7, sphingosine) as well as RA downregulated the IFN-gamma-induced PNA-reactive gps, whereas staurosporine and TPA upregulated their expression. These results provide evidence that PNA-reactive gps are late highly IFN-gamma-sensitive markers of keratinocyte differentiation, drastically modulated through selective isoforms of PKC.     

Cross regulation by IL-10 and IL-2/IL-12 of the helper T cells and the cytolytic activity of lymphocytes from malignant effusions of lung cancer patients

STUDY OBJECTIVE: Our previous report demonstrated that there was impairment of local cellular immunity with elevated interleukin-10 (IL-10) and undetectable IL-12 in neoplastic pleural effusion. These findings suggest that the local immune reactions favor the T-helper type 2 (Th2) pathway instead of Th1 pathway. The present study was designed to examine whether local cellular immunity could be manipulated by IL-2 and/or IL-12 treatment, and to determine their effect on the helper T-cell pathways and the cytolytic activity of the effusion-associated lymphocytes (EALs). DESIGN: Using malignant pleural effusions obtained from four patients suffering from adenocarcinoma of lung, we separated the tumor cells from the EALs with Ficol-Hypaque centrifugation, followed by Percoll density centrifugation. To test whether the cytolytic function of lymphocytes could be enhanced by culturing with IL-2 and/or IL-12, lymphocytes were incubated with recombinant IL-2 with/without IL-12 for 6 days. Following this, the tumoricidal activity was assessed in an overnight 5'chromium-release assay. Autologous tumor cells for measuring specific antitumor activity, Daudi cells susceptible to lymphokine-activated killer cells, and NK-susceptible K562 cells were used as target cells. MEASUREMENTS AND RESULTS: After treatment in vitro with IL-2, IL-12, or IL-2 plus IL-12, the Th pathway shifted from Th2 to Th1 type (increased gamma-interferon production). To further study the effect of cytokine treatment on the cytolytic activity of EALs, it was found that after 6-day culturing, the EALs failed to kill any of the three tumor targets, whereas the 6-day cultured peripheral blood lymphocytes (PBLs) gave low level of cytotoxicity against all three tumor targets. Stimulation with IL-2 alone partially restored the immunocompetence of EALs to kill the tumor targets. Stimulation with IL-12 alone showed no significant effect on their cytolytic activity. However, IL-12 synergized with IL-2 to increase the cytolytic activity of EALs and PBLs against autologous tumor targets. This synergistic effect was not found for Daudi cells and K562 cells. CONCLUSIONS: These results suggest that EALs activated with IL-12 in the presence of a low concentration of IL-2, which converted the EALs from Th2 pathway to Th1 pathway, could be an alternative source of antitumor effectors for adoptive immunotherapy of cancer.     

Use of intranasal IL-12 to target predominantly Th1 responses to nasal and Th2 responses to oral vaccines given with cholera toxin

We have investigated the effects of IL-12 and cholera toxin (CT) on the immune response to tetanus toxoid (TT) given by intranasal or oral routes. CT inhibited IL-12-induced IFN-gamma secretion both in vivo and in vitro. Intranasal administration of IL-12 to mice nasally immunized with the combined vaccine of TT and CT resulted in increased TT-specific IgG2a and IgG3 Abs, while IgG1 and IgE Ab responses were markedly reduced. This shift of the CT-induced immune response toward Th1 type was associated with TT-specific CD4+ T cells secreting IFN-gamma and reduced levels of Th2-type cytokines (i.e., IL-4, IL-5, IL-6, and IL-10). In contrast, intranasal IL-12 enhanced the CT-induced serum IgG1 and IgE Ab responses in mice given the combined vaccine orally. IFN-gamma secretion by TT-specific CD4+ T cells was also enhanced; however, Th2-type cytokine responses were predominant. Mucosal secretory IgA responses to oral or nasal vaccines were not affected by intranasal IL-12. Thus, intranasal IL-12 delivery influences Th cell subset development in mucosal inductive sites that are dependent on the route of vaccine delivery.     

Prevention of Th2-like cell responses by coadministration of IL-12 and IL-18 is associated with inhibition of antigen-induced airway hyperresponsiveness, eosinophilia, and serum IgE levels

Allergic asthma is thought to be regulated by Th2 cells, and inhibiting this response is a promising mode of intervention. Many studies have focused on differentiation of Th cells to the Th1 or Th2 subset in vitro. IL-4 is essential for Th2 development, while IL-12 induces Th1 development, which can be enhanced by IL-18. In the present study, we investigated whether IL-12 and IL-18 were able to interfere in Th2 development and the associated airway symptoms in a mouse model of allergic asthma. Mice were sensitized with OVA using a protocol that induces IgE production. Repeated challenges by OVA inhalation induced elevated serum levels of IgE, airway hyperresponsiveness, and a predominantly eosinophilic infiltrate in the bronchoalveolar lavage concomitant with the appearance of Ag-specific Th2-like cells in lung tissue and lung-draining lymph nodes. Whereas treatments with neither IL-12 nor IL-18 during the challenge period were effective, combined treatment of IL-12 and IL-18 inhibited Ag-specific Th2-like cell development. This inhibition was associated with an absence of IgE up-regulation, airway hyperresponsiveness, and cellular infiltration in the lavage. These data show that, in vivo, the synergistic action of IL-12 and IL-18 is necessary to prevent Th2-like cell differentiation, and consequently inhibits the development of airway symptoms in a mouse model of allergic asthma.     

Relationships between cell density, glutathione and proliferation of A549 human lung adenocarcinoma cells treated with acrolein

Acrolein is a highly electrophilic alpha,beta-unsaturated aldehyde to which humans are exposed in various situations. Acrolein reacts rapidly with and depletes cellular glutathione (GSH), and is toxic to various types of cells. In the current study, the ability of acrolein to alter proliferation of A549 cells was found to be dependent on cell density as well as total cell number. Thus, 'doses' must be expressed per cell rather than as a concentration, and all related studies need to be performed by plating a constant number of cells. A549 cells were plated at various densities and treated with acrolein after 48 h. Acrolein doses up to 47 fmol/cell at the time of treatment did not cause cell lethality. However, growth of A549 cells (as shown by thymidine incorporation, alamarBlue and total protein) was inhibited at acrolein levels > 34 fmol/cell in 6-well plates seeded at 5000 cells/cm2 48 h prior to treatment. Cellular GSH levels were decreased 34% by 2 h at acrolein levels of 6.7 fmol/cell and by 65% at 47 fmol/cell. Recovery of GSH was rapid at 6.7-47 fmol/cell acrolein, returning to control levels or above by 12 h post-treatment. These data show a strong correlation between cellular GSH and proliferation. The apparent conflict with a previous study of Ramu et al., suggesting that sublethal concentrations (up to 10 microM) of acrolein inhibited the proliferation of A549 cells without a decline in total cellular GSH, arose because, while the acrolein concentration was the same in cells used for proliferation and GSH assays, GSH measurements were done in cells plated at a higher density, resulting in a much lower acrolein dose per cell. Interestingly, very low dose levels of acrolein with cells seeded at low densities stimulated cell growth despite an initial decline in GSH content. Preliminary studies with the stress genes hsp70 and gadd153 suggest that acrolein at 35 fmol/cell does not stimulate formation of their mRNA beyond the level stimulated by a 2 h incubation in serum-free medium but may actually delay or decrease the induced expression. The mechanism(s) of the inhibitory and mitogenic effects of acrolein remains to be determined, but could be due to changes in gene expression induced by this electrophile, perhaps mediated by changes in GSH.     

Diagnosis of liver metastases from colorectal adenocarcinoma. Comparison of spiral-CTAP combined with intravenous contrast-enhanced spiral-CT and SPIO-enhanced MR combined with plain MR imaging

BACKGROUND/AIMS: Doppler arterial resistance indices are used to evaluate alterations in arterial hemodynamics in the liver, spleen, and kidney. The purpose of this study was to determine the interobserver and interequipment variability of hepatic, splenic, and renal arterial Doppler resistance indices, and the influence of a cooperative training program of the operators on the reproducibility of the results. METHODS: In the first part of the study, hepatic (PI-L, RI-L), splenic (PI-S, RI-S), and renal (PI-K, RI-K) pulsatility and resistive indices were measured by echo-color-Doppler in eight control subjects and ten patients with cirrhosis by three operators using three different machines. In the second part of the study, measurements were taken by the three operators in nine controls and nine patients with cirrhosis, after cooperative training, with a single machine. RESULTS: Significant interobserver variability was present for all parameters except RI-L. Significant interequipment variability was present for all parameters except PI-S and RI-S. Only 0-3% of variance was equipment- or operator-related, while 58-72% was patient-related. Hepatic and renal coefficients of variation were similar in patients with cirrhosis and controls, while splenic coefficients of variation were higher in patients with cirrhosis than in controls. After training, differences among operators disappeared for all variables except RI-K, and the operator-related component of variance nearly disappeared for all parameters. CONCLUSIONS: Hepatic, splenic, and renal arterial resistance indices show small but significant interobserver and interequipment variability. Interobserver variability can be decreased to non-significant levels by a common training program. Thus, these indices can be widely applied to the study of arterial circulation in these organs.     

Crossregulation between T helper cell (Th)1 and Th2: inhibition of Th2 proliferation by IFN-gamma involves interference with IL-1

The Th1-derived cytokine IFN-gamma inhibits the proliferation of Th2 lymphocytes, but the mechanism of inhibition is not known. Under certain disease conditions, an established Th2-mediated immune response is undesirable and a Th1-mediated response is beneficial. However, established Th2 cells appear to be phenotypically stable. Thus, learning more about cytokine-mediated regulation of established Th2 cells is important if deleterious immune responses are to be altered. We studied the effects of IFN-gamma on a panel of recently derived Th2 lines and clones, as well as a previously established Th2 clone, 13.26. Inhibition by IFN-gamma was observed only when there was a concomitant response to IL-1, a known costimulator of Th2. Clone 13.26 was particularly sensitive to both IL-1 and IFN-gamma, so it was studied in greater detail. We examined cytokine responses using stimulation by anti-TCR mAb-coated plates, or Ag presented by APC populations that do or do not produce IL-1. All IL-1-mediated proliferative responses of 13.26 were inhibited by IFN-gamma, whereas IL-1-independent (IL-4-associated) responses were unaffected. Our data suggest that IFN-gamma inhibits Th2 proliferation through an IL-1-dependent mechanism, and furthermore, that the costimulatory pathways used by APCs may be critical for subsequent Th cell responses to cytokines.     

Autologous human monocyte-derived dendritic cells genetically modified to express melanoma antigens elicit primary cytotoxic T cell responses in vitro: enhancement by cotransfection of genes encoding the Th1-biasing cytokines IL-12 and IFN-alpha

DNA-based immunization strategies designed to elicit cellular antitumor immunity offer an attractive alternative to protein- or peptide-based approaches. In the present study we have evaluated the feasibility of DNA vaccination for the induction of CTL reactivity to five different melanoma Ags in vitro. Cultured, monocyte-derived dendritic cells (DC) were transiently transfected with plasmid DNA encoding human MART-1/Melan-A, pMel-17/gp100, tyrosinase, MAGE-1, or MAGE-3 by particle bombardment and used to stimulate autologous PBMC responder T cells. CTL reactivity to these previously identified melanoma Ags was reproducibly generated after two or three stimulations with genetically modified DC. Co-ordinate transfection of two melanoma Ag cDNAs into DC promoted CTL responders capable of recognizing epitopes from both gene products. Coinsertion of genes encoding the Th1-biasing cytokines IL-12 or IFN-alpha consistently enhanced the magnitude of the resulting Ag-specific CTL reactivity. Importantly, DC transfected with a single melanoma Ag cDNA were capable of stimulating Ag-specific CTL reactivity restricted by multiple host MHC alleles, some of which had not been previously identified. These results support the inherent strengths of gene-based vaccine approaches that do not require prior knowledge of responder MHC haplotypes or of relevant MHC-restricted peptide epitopes. Given previous observations of in situ tumor HLA allele-loss variants, DC gene vaccine strategies may elicit a greater diversity of host therapeutic immunity, thereby enhancing the clinical utility and success of such approaches.     

Upmodulation of alpha v beta 1 integrin expression on human tumor cells by human interleukin for DA cells/leukemia inhibitory factor and oncostatin M: correlation with increased cell adhesion on fibronectin

Integrins belong to a large family of heterodimeric membrane glycoproteins which mediate cell-cell or cell-extracellular matrix interactions. These interactions could play a major role during the migration of tumor cells across the extracellular matrix and vascular endothelium and would thus appear to be requisite for the metastatic process. Pretreatment of the Foss human melanoma cell line with HILDA/LIF or OSM, two cytokines involved in acute-phase response, increased the expression of membrane alpha v beta 1 1.5-2-fold. The same phenomenon was observed on the SK-N-SH human neuroblastoma cell line. alpha v beta 1 upmodulation was concomitant with improved tumor cells attachment to the fibronectin matrix. This greater adhesion of tumor cells to fibronectin was inhibited by specific monoclonal antibodies against alpha v or beta 1 integrin subunits. Similar results were obtained after TNF-alpha treatment. Our findings demonstrate the ability of HILDA/LIF and OSM to modulate tumor cell capacity to adhere to the matrix component, suggesting a potential role for these cytokines in modulation of tumoral progression.