Immune Effector Cell Populations Research Articles

Abstract A107: Elevated hinge cleavage of immunoglobulin G correlates with immune suppression and increased matrix metalloproteinases in breast tumor tissues

Abstract Growing evidence indicates that the tumor microenvironment has suppressive immune system and immune evasion is emerging as one of the cancer hallmarks. Immunoglobulin G (IgG) is an important component of human adaptive immunity in removing pathological cells including tumor cells. Recently, we reported that the cancer therapeutic antibody trastuzumab, a humanized IgG1, can be cleaved at the hinge region by matrix metalloproteinases (MMPs) in vitro, and the hinge cleaved trastuzumab (scIgG-T) showed significant loss of immune effector functions such as antibody dependent cellular cytotoxicity (ADCC) and anti-tumor efficacy in vivo (Fan et al., Breast Cancer Research 2012). The objectives of this study are 1) to investigate if the Fc hinge cleavage of IgG occurs in tumor tissues of breast cancer patients; 2) to understand the relationship among IgG Fc hinge cleavage, MMP expression, and anticancer immunity. Methods: Surgically removed fresh tumor tissues (n=23, 11 with upfront surgery and 12 with neoadjuvant therapies) from breast cancer patients with informed consent (protocol # HSC-MS-10-0580) were snap frozen in liquid nitrogen and stored in a -80oC freezer until analysis. Normal breast tissues (n=20) were obtained from an outside vendor (Cureline Inc., CA) as snap frozen tissues. Peripheral blood mononuclear cells (PBMCs) were freshly prepared from patient blood samples collected before surgery and were preserved in liquid nitrogen storage tank until analysis. Hinge cleaved IgGs were quantified by ELISA and immuno-histochemistry (IHC) detection with a panel of anti-hinge specific antibodies developed at Johnson & Johnson. MMP expression was profiled using a reverse phase protein array method (Ray Biotech Inc., CA) and populations of immune effector cells in patient PBMCs were determined by multi-color flow cytometry. Results: Levels of single hinge cleaved IgGs (scIgGs) were significantly higher in breast cancer tumor tissue than in normal breast tissue. The elevated Fc hinge cleavage of IgGs in breast tumor tissues was positively correlated with high levels of MMPs and expression of MMP-9 showed linear correlation (R=0.78) with the level of scIgGs in the tumor tissues. Notably, Fc hinge cleavage of IgGs in residual tumor tissues from patients treated with neoadjuvant therapies was similar to the levels in the normal breast tissues, while tumor tissues from patients with up-front surgery had significantly higher Fc hinge cleavage than both normal and neoadjuvant treated tumor tissues. In comparison with PBMCs from patients with the up-front surgery, PBMCs from patients with neoadjuvant therapies had an increased percentage of NK cells (CD56+) and immune cells with Fc gamma receptor IIa (CD32a) expression. In addition, percentages of immune effector cells with CD56+/CD16+ (Fc gamma receptor RIII), CD56+/CD64+ (Fc gamma receptor RI), and CD14+/CD16+ were also higher in PBMCs from patients treated with neoadjuvant therapies than those from patients with up-front surgery. Taken together, our results suggest that the reduced scIgG levels in neoadjuvant treated tumor tissue correlated with the better profiles of immune effector cells, while the increased Fc hinge cleavage in breast tumor tissue before therapeutic intervention is linked with immune suppression in the tumor microenvironment. Citation Format: Ningyan zhang, Anneliese Gonzalez, Hui Deng, Xuejun Fan, Luis Baez Vallecillo, songlin zhang, Randall Brezski, Emily Roberson, Robert Jorden, William Strohl, Zhiqiang An. Elevated hinge cleavage of immunoglobulin G correlates with immune suppression and increased matrix metalloproteinases in breast tumor tissues. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A107.

Intratracheal and oral administration of SM‐276001: A selective TLR7 agonist, leads to antitumor efficacy in primary and metastatic models of cancer

Topical TLR7 agonists such as imiquimod are highly effective for the treatment of dermatological malignancies; however, their efficacy in the treatment of nondermatological tumors has been less successful. We report that oral administration of the novel TLR7-selective small molecule agonist; SM-276001, leads to the induction of an inflammatory cytokine and chemokine milieu and to the activation of a diverse population of immune effector cells including T and B lymphocytes, NK and NKT cells. Oral administration of SM-276001 leads to the induction of IFNα, TNFα and IL-12p40 and a reduction in tumor burden in the Balb/c syngeneic Renca and CT26 models. Using the OV2944-HM-1 model of ovarian cancer which spontaneously metastasizes to the lungs following subcutaneous implantation, we evaluated the efficacy of intratracheal and oral administration of SM-276001 in an adjuvant setting following surgical resection of the primary tumor. We show that both oral and intratracheal TLR7 therapy can reduce the frequency of pulmonary metastasis, and metastasis to the axillary lymph nodes. These results demonstrate that SM-276001 is a potent selective TLR7 agonist that can induce antitumor immune responses when dosed either intratracheally or orally.

Influence of cytomegalovirus infection on immune cell phenotypes in patients with common variable immunodeficiency

A subset of patients with common variable immunodeficiency (CVID) have debilitating inflammatory complications strongly associated with cytomegalovirus (CMV) infection and a hyperproliferative CMV-specific T-cell response. We studied the T-cell response to CMV and the global effect of this virus on immune effector cell populations in patients with CVID. Antibody staining, peptide stimulation, and proliferation assays were used to profile CMV-specific T-cell function. CMV infection drives the CD4/CD8 ratio inversion that is characteristic of CVID. The late effector CD8(+) T-cell subset is expanded in CMV-infected patients with CVID. This expansion is largely attributable to CMV-specific cells and correlates with inflammatory disease; within the CMV-specific population, the frequency of late effector cells correlates inversely with the frequency of cells expressing programmed death 1. Supernatants from proliferating CMV-specific CD8(+) cells from patients with inflammatory disease can confer proliferative potential on cells from patients with noninflammatory CVID and healthy subjects. Blocking experiments showed that this proliferation is mediated in part by IFN-γ and TNF-α. These data strengthen the association of CMV with inflammatory pathology in patients with CVID, explain some of the well-known T-cell abnormalities associated with this condition, and provide a plausible mechanism for the documented therapeutic activity of anti-TNF-α and antiviral chemotherapy in managing CVID-associated inflammatory disease.

Immune Response to a Variable Pathogen: A Stochastic Model with Two Interlocked Darwinian Entities

This paper presents the modeling of a host immune system, more precisely the immune effector cell and immune memory cell population, and its interaction with an invading pathogen population. It will tackle two issues of interest; on the one hand, in defining a stochastic model accounting for the inherent nature of organisms in population dynamics, namely multiplication with mutation and selection; on the other hand, in providing a description of pathogens that may vary their antigens through mutations during infection of the host. Unlike most of the literature, which models the dynamics with first-order differential equations, this paper proposes a Galton-Watson type branching process to describe stochastically by whole distributions the population dynamics of pathogens and immune cells. In the first model case, the pathogen of a given type is either eradicated or shows oscillatory chronic response. In the second model case, the pathogen shows variational behavior changing its antigen resulting in a prolonged immune reaction.

Role of Immune Cells in Brain Metastasis of Lung Cancer Cells and Neuron-Tumor Cell Interaction

Following any type of brain injury such as lesion, stroke, and tumor/cancer invasion, microglia are rapidly activated and recruited to the site of injury. Microglia is the main immune effector cell population of the central nervous system and control immune cell recruitment. However, the molecular mechanism of brain metastasis and interaction between neuron-glia-tumor cells are poorly understood. Therefore, we established an animal model for brain metastasis using human lung cancer-derived cells (HARA-B) in nude mice. Accumulation of activated microglia was observed around tumor cells depending on the size of metastatic foci and the area of the brain. In in vitro studies, conditioned medium from primary cultured mouse microglia inhibited the proliferation of tumor cells, while tumor cell-conditioned medium inhibited the proliferation of primary cultured neurons from mouse cortex. Though the responsible factors released from microglia and tumor cells are still under investigation, these studies will contribute to the understanding of the mechanism of cell-cell interaction in the brain and the possible therapeutic target for brain metastasis.

Differences in immune parameters are associated with resistance to Haemonchus contortus in Caribbean hair sheep

Caribbean hair sheep are more resistant to gastrointestinal nematodes than conventional wool breeds, but mechanisms that confer resistance are not fully understood. This study compared immune effector cell populations and antibody concentrations in 12 hair and 12 wool lambs infected with the abomasal parasite Haemonchus contortus and sacrificed at 3 or 27 days post-infection (p.i.) and 14 uninfected animals of each breed. Faecal egg counts were over 2.5-fold higher (P = 0.12) and packed cell volumes approximately 8% lower (P < 0.10) in infected wool lambs. Abomasal lymph nodes were heavier in infected animals (P < 0.05) and infected hair sheep had larger lymph nodes than infected wool sheep (P < 0.05). Tissue eosinophil concentrations were likewise larger (P = 0.07) in hair compared with wool sheep at 3 days p.i. Circulating levels of IgE and IgA in uninfected lambs were higher in hair sheep (P < 0.05) and during infection, hair sheep had higher serum IgA than wool sheep at 3, 5, and 21 days p.i. (P < 0.05). Serum IgE in infected lambs did not differ between breeds, but concentrations of IgE in lymph nodes were higher (P < 0.01) at 27 days p.i. in infected hair sheep.

Immunotherapy with cytokine induced killer cells in solid and hematopoietic tumours: a pilot clinical trial

CIK cells are a novel population of efficient immune effector cells with high antitumour activity mainly due to the high proliferation of CD3(+)CD56(+) cells, so may play a role in the development of new forms of adoptive cellular immunotherapy. We started a pilot clinical trial with autologous CIK cells in patients with refractory lymphoma and metastatic solid tumours. This study was aimed at determining the feasibility of generating a sufficient number of CIK cells in heavily pretreated patients and at assessing treatment toxicity. CIK cells were generated from peripheral blood mononuclear cells (MNC) and incubated in the presence of IFN-gamma followed by OKT3 and IL-2. Treatment schedule consisted of three cycles of CIK cells infusions at an interval of 3 weeks. At present 12 patients were enrolled: 6 advanced lymphomas, 5 metastatic kidney carcinoma and 1 hepatocellular carcinoma (HCC). The median number of transferred cells per patient was 28 x 10(9) (range, 6-61). Protocol adherence was excellent and the toxicity profile was favourable. After CIK cells infusion, the absolute median count of lymphocytes, CD3(+), CD8(+) and CD3(+)CD56(+) cells significantly increased in patient's peripheral blood. Clinical outcome appeared promising: three patients had complete response (CR) and two patients had stabilization of disease with a median follow-up of 33 months (range, 9-44). These preliminary data showed that adoptive immunotherapy with CIK cells is a safe therapy with some suggestion of efficacy that significantly enhances immune functions increasing absolute numbers of effector cells without side effects. If confirmed in larger scale studies, these promising results may have a favourable impact on conventional treatment strategy of malignancies.

Asbestos fibres inhibit the in vitro activity of ymphokine-activated killer (LAK) cells from healthy individualsand patients with malignant mesothelioma

Asbestos exposure is associated with an increased incidence of several malignancies, including malignant mesothelioma (MM). This study evaluates the relationship between asbestos exposure and the in vitro generation and function of LAK cells, an immune effector cell population with powerful lytic activity against MM cells. Both serpentine (chrysotile) and amphibole (amosite and crocidolite) forms of asbestos fibres suppress LAK cell generation, viability (by 5-11%, P less than 0.02) and cell recovery (by 13-15%, P less than 0.02). However, the LAK cells generated in the presence of the amphiboles were as effective as unexposed cells in lysing both standard tumour cell targets (K562, 56.4% lysis versus 61.5%, respectively, P greater than 0.5; NS; Daudi, 60.5% lysis versus 64.5% P greater than 0.5; NS), and MM tumour cell targets (mean of three MM cell lines 48.3% versus 46.3%, P greater than 0.5; NS), whereas the function of LAK cells generated in the presence of chrysotile was significantly reduced against three out of the five tumour cell targets tested (P less than 0.03). In the presence of asbestos fibres, LAK cell function was reduced against all five tumour cell targets (P less than 0.01), irrespective of whether the cell donors were healthy individuals or patients with MM. NK cell activity was also suppressed (P less than 0.01). The serpentine form of asbestos, chrysotile, was significantly more suppressive of both effector cell functions than either of the amphiboles (P less than 0.01). These findings suggest that asbestos exposure may suppress the function and in some instances the generation of immune effector cell mechanisms, thereby increasing the risk of disease and malignancy.

Immunotherapy of cancer by IL-12-based cytokine combinations

Cancer is a multi-faceted disease comprising complex interactions between neoplastic and normal cells. Over the past decade, there has been considerable progress in defining the molecular, cellular and environmental contributions to the pathophysiology of tumor development. Despite these advances, the conventional treatment of patients still generally involves surgery, radiotherapy and/or chemotherapy, and the clinical outcome for many of these efforts remains unsatisfactory. Recent studies have highlighted the feasibility of using immunotherapeutic approaches that seek to enhance host immune responses to developing tumors. These strategies include immunomodulatory cytokines, with TNF-α, type I or type II IFNs, IL-2, IL-12, IL-15 and IL-18 being among the most potent inducers of anti-tumor activity in a variety of preclinical studies. More recently, some exciting new cytokines have been characterized, such as IL-21, IL-23, IL-27 and their immunomodulatory and antitumor effects in vitro and in vivo suggest that they may have considerable promise for future immunotherapy protocols. The promise of cytokine therapy does indeed derive from the identification of these novel cytokines but even more fundamentally, the field is greatly benefiting from the ever-expanding amount of preclinical data that convincingly demonstrate synergistic and/or novel biologic effects, which may be achieved through the use of several combinations of cytokines with complementary immune-stimulating capabilities. One cytokine in particular, IL-12, holds considerable promise by virtue of the fact that it plays a central role in regulating both innate and adaptive immune responses, can by itself induce potent anticancer effects, and synergizes with several other cytokines for increased immunoregulatory and antitumor activities. This review discusses the antitumor activity of IL-12, with a special emphasis on its ability to synergize with other cytokines for enhancement of immune effector cell populations and regulation of host–tumor cell interactions and the overall tumor microenvironment.

T11TS/SLFA-3 Differentially Regulate the Population of Microglia and Brain Infiltrating Lymphocytes to Reduce Glioma by Modulating Intrinsic Bcl-2 Expression rather than p53

T11TS/SLFA-3, the glycoprotein isolated from sheep erythrocyte membrane, acts as an antineoplastic agent causing apoptotic elimination of glioma cells through cell mediated immune response. Therefore, elucidation of the proper balance in proliferation and apoptosis of neuroimmune components viz. microglia and brain infiltrating lymphocytes with the neoplastic glial cells was the fundamental issue to establish the efficacy of T11TS as a therapeutic agent in glioma. To decipher its effectivity on proliferation rate of glioma cells, expression of GFAP and cell cycle phase distribution was analyzed with propidium iodide (PI) staining. The apoptotic regulation of interacting immuno-competent microglia, lymphocytes entering into the brain and target glioma cells were elucidated by cytoplasmic DNA fragmentation assay and phosphatidylserine (PS) externalization along with intrinsic p53 and Bcl-2 modulation of the cells. With the reduction of cellular proliferation rate, sharp increase of apoptosis in consecutive doses of T11TS showed the regression of glioma, where an increase of cytosolic p53 and a decrease of Bcl-2 with doses in these neoplastic cells facilitate the process. Resident microglia, the chief immunomodulator of brain, was found to show a low and steady level of proliferation and apoptosis, furnishing it as a stable pool of cells capable of controlling immune reaction in brain compartment. However, microglia showed higher basal level of p53 compared to the other cells in study and being modulated with T11TS dose, it was found to possess a steady level of Bcl-2 that aided to maintain low rate of apoptosis. Brain infiltrating lymphocytes showed increased apoptosis in tumorigenic condition and initial treatment phase mostly due to immuno-suppressive milieu and deprivation of microglial restimulation. But the second dose of T11TS showed reduced apoptosis, enhanced activation of lymphocytes and final dose acting as a regulatory dose, which reduce the infiltrating lymphocytes by apoptotic elimination. Wide fluctuation of cytosolic p53 was observed in these lymphocytes, but anti-apoptotic Bcl-2 was found to modulate apoptosis in the cells. Thus, T11TS was found to differentially regulate the population of immune effector cells against glioma to exert effective effector function in eradication of neoplastic cells where Bcl-2 constitutively suppresses pro-apoptotic function of p53. Regulation of the direction of these balances of cellular life and death in favor of glioma killing and also maintaining homeostasis in brain tissue after reaction established T11TS as an effective therapeutic probe against glioma.

Regulatory Cells and Immunosuppressive Cytokines: Parasite-Derived Factors Induce Immune Polarization

Parasitic infections are prevalent in both tropical and subtropical areas. Most of the affected and/or exposed populations are living in developing countries where control measures are lacking or inadequately applied. Although significant progress has been made in our understanding of the immune response to parasites, no definitive step has yet been successfully done in terms of operational vaccines against parasitic diseases. Evidence accumulated during the past few years suggests that the pathology observed during parasitic infections is in part due to deregulation of normal components of the immune system, mainly cytokines, antibodies, and immune effector cell populations. A large number of studies that illustrate how parasites can modify the host immune system for their own benefit have been reported in both metazoan and protozoan parasites. The first line of defense against foreign organisms is barrier tissue such as skin, humoral factors, for instance the complement system and pentraxin, which upon activation of the complement cascade facilitate pathogen recognition by cells of innate immunity such as macrophages and DC. However, all the major groups of parasites studied have been shown to contain and/or to release factors, which interfere with both arms of the host immune system. Even some astonishing observations relate to the production by some parasites of orthologues of mammalian cytokines. Furthermore, chronic parasitic infections have led to the immunosuppressive environment that correlates with increased levels of myeloid and T suppressor cells that may limit the success of immunotherapeutic strategies based on vaccination. This minireview briefly analyzes some of the current data related to the regulatory cells and molecules derived from parasites that affect cellular function and contribute to the polarization of the immune response of the host. Special attention is given to some of the data from our laboratory illustrating the role of immunomodulatory factors released by protozoan parasites, in the induction and perpetuation of chronic disease.

Concurrent Treatment with Denileukin Diftitox (DD) To Deplete T-Regulatory Cells Enhances Rebound Lymphocytosis and Eosinophilia in Patients Treated with High-Dose IL-2 (HDIL-2) for Metastatic Renal Cell Cancer (MRCC).

Background: CD4+CD25+hi T cells (Treg) play a suppressive role in immune regulation. DD is an IL-2 receptor specific cytotoxin. We postulated depletion of Treg with DD may enhance immune effector cell populations after HDIL-2 treatment, including rebound lymphocytosis and also eosinophilia which has been reported to be involved in immune response to neoplasm (Mattes J Exp Med 197: 387, 2003).Methods: In this pilot study, 12 pts (8 male, median age 58 yrs) with MRCC were tx with HDIL-2 and DD in different schedules to determine safety and effect on immune response as manifested by changes in Treg, peak lymphocyte, and eosinophil counts. Pts were treated with IL-2 600,000 IU/kg Q8H on days (d) 1–5 and 15–19. Three (group A) and 4 (group B) pts were given 6 and 9ug/kg daily on d8–10 respectively, while 5 (group C) pts received 9ug/kg of DD on d −4 to −2. Nine (group D) pts with metastatic melanoma who received HDIL-2 as above but without DD were included as controls. Flow cytometry was done on days −4, 1,8,10,15,22 for group C and on days 1,8,10,15,22 for groups B, and D. CBC was obtained concurrent or within 24 hours of flow cytometry. Group A pts were evaluated for safety only and were excluded from analysis.Results: Prior to enrollment, all pts had undergone nephrectomy and four patients received interferon-alpha. One pt from group B withdrew from study and was not included in analysis. Administration of DD resulted in a median decline of 25% in Treg number (not significant). DD given before HDIL-2 was associated with a greater increase in Treg post HDIL-2. In Group C there was an increase of rebound median Treg count of 0.88k/ul compared with 0.060k/ul in group B (p=0.025). Absolute lymphocytosis was higher in the combined group getting DD compared to control (median maximal increase of 7.6 vs 4.7 k/ul, respectively) although the difference did not reach statistical significance. However, group C pts had a greater increase in absolute lymphocytosis than did group B pts in which absolute lymphocytosis actually decreased (median increase 10.6 vs. median decrease 0.4 k/ul, p=0.025). A higher peak level of eosinophilia was noted in groups B and C compared with group D (mean increase of 10.5 vs. 4.0 k/ul p=0.2). Group C had a greater peak eosinophilia than group B (11.2 vs 2.2 k/ul p=0.053) Toxicity was manageable and consistent with those seen with HDIL-2. Median HDIL-2 dose given was 21 (range, 14–28). No clinical responses were observed. Of 11 pts included in the analysis 1 pt from group A expired 68 weeks after enrollment. All remaining patients are alive. Survival from enrollment ranges from 11 to 93 weeks.Conclusion: Overall, the combination of DD and HDIL-2 results in a stimulatory effect as manifested by increased rebound lymphocytosis and eosinophilia compared to HDIL-2 alone. Administration of DD in conjunction with HDIL-2 was associated with a rebound in Treg that may be schedule and dose dependent. The results suggest an enhanced immune stimulatory effect as manifested by lymphocytosis and peak eosinophilia in group C. However, this stimulatory effect also extends to Treg that may prove detrimental clinically. Further exploration of these effects in immunotherapy naïve patients would be beneficial.

Treg depletion with denileukin difititox (DD) enhances lymphocytosis and eosinphilia in patients treated with high-dose IL-2 (HDIL-2) for metastatic renal cell cancer (MRCC)

14627 Background: CD4+CD25+ T cells (Treg) play a suppressive role in immune regulation. DD is an IL-2 receptor specific cytotoxin. We postulated depletion of Treg with DD may enhance immune effector cell populations during HDIL-2 tx, including eosinophilia which was reported to be involved in immune response to neoplasm (Mattes et al. J Exp Med 197: 387, 2003). Methods: Seven pts (5 male, median age 58 yrs) with MRCC were tx’d with HDIL-2 and DD in different schedules to determine safety and effect on immune response as manifested by changes in Treg, lymphocyte, and peak eosinophil counts. Pts were tx’d with IL-2 600,000 IU/kg Q8H on days (d) 1–5 and 15–19. Three (group A) and 2 (group B) pts were given 6 and 9 ug/kg daily on d 8–10 respectively, while 2 (group C) pts received 9 ug/kg of DD on d -4- -2. Four (group D) pts with metastatic melanoma who received HDIL-2 as above but without DD were included as controls. Flow cytometry was done on days -4, 1,8,10,15 for group C and on days 1, 8, 10, 15, 22 for groups A, B, and D. CBC was obtained within 24 hours of flow cytometry. Results: After DD Treg increased in group A (mean change in absolute T-reg count of 16%) and decreased in groups B and C (34.5 and 20% respectively) compared to baseline. Group C trended toward a greater lymphocytosis at day 8 compared to all other groups (mean increase of 8.6 vs. 3.3 K/ul p = 0.059). A higher peak level of eosinophilia was noted in group C compared with groups A, B and D combined (mean increase of 9.9 vs. 3.0 k/ul p = 0.03). Group C demonstrated a higher mean % change in absolute number of CD8+ T-cells between onset of therapy and Day 8 compared to groups A, B, D combined (increase of 1095% vs. 496% respectively, p = 0.35). Toxicity was similar to that expected with HDIL-2. Conclusions: Administration of DD in conjunction with HDIL-2 was associated with a decrease in Treg that may be schedule and dose dependent. The results suggest an enhanced immune stimulatory effect as manifested by lymphocytosis and peak eosinophilia and CD8+ T-cells in group C. Despite small pt numbers, results suggest that pre-treatment with DD may confer an advantage. It is too early to know if laboratory results correlate to clinical benefit. [Table: see text]

Synergistic Antitumor Effects of Immune Cell-Viral Biotherapy

Targeted biological therapies hold tremendous potential for treatment of cancer, yet their use has been limited by constraints on delivery and effective tumor targeting. We combined an immune effector cell population [cytokine-induced killer (CIK) cells] with an oncolytic viral therapy to achieve directed delivery to, and regression of, tumors in both immunodeficient and immunocompetent mouse models. Preinfection of CIK cells with modified vaccinia virus resulted in a prolonged eclipse phase with the virus remaining hidden until interaction with the tumor. Whole-body imaging revealed that the cells retained their ability to traffic to and to infiltrate the tumor effectively before releasing the virus. These results illustrate the potential of combining biotherapeutics for synergistic effects that more effectively treat cancer.

IFN-Dependent Down-Regulation of the NKG2D Ligand H60 on Tumors

In this study, we show that IFN-gamma or IFN-alpha reduce expression of H60 on 3'-methylcholanthrene (MCA) sarcomas from 129/Sv mice. As determined by flow cytometry using either NKG2D tetramers or NKG2D ligand-specific mAb, H60 was identified as the NKG2D ligand most frequently expressed on these sarcomas, and its expression was selectively down-regulated by either IFN-gamma or IFN-alpha in a manner that was dose- and time-dependent and reversible. Down-regulation occurred at the transcript level and was STAT1-dependent. It also had functional consequences. IFN-gamma-treated MCA sarcomas with high levels of H60 were resistant to killing by IL-2-activated NK cells. Resistance was not solely dependent on enhanced MHC class I expression but rather also required H60 down-regulation. IFN-gamma-treated tumor cells also displayed diminished capacity to down-regulate NKG2D on freshly isolated NK cells. Transplanted tumor cells reisolated from immunocompetent mice displayed reduced H60 expression and increased MHC class I expression compared with tumor cells that were either left unmanipulated or reisolated from mice treated with neutralizing IFN-gamma-specific mAb. This report thus represents the first demonstration that certain cytokines and specifically the IFNs regulate expression of specific NKG2D ligands on murine tumors. This process most likely helps to specify the type of immune effector cell populations that participate in host-protective antitumor responses.

Cytotoxicity of rat marrow stromal cells against malignant glioma cells

Marrow stromal cells (MSCs) have been shown to have the capacity of orthodox and unorthodox plasticity. In this study, the authors tried to access in vitro cytotoxicity of MSCs from rat and also to differentiate MSCs into immune effector cell. Rat MSCs (rMSCs) were isolated by standard methodology and were activated by interleukin-2 (IL-2), interleukin-15 (IL-15), granulocyte macrophage colony stimulating factor, and combinations, which were effector cells. Cytotoxicity of rMSCs and activated rMSCs against the target cells (9L rat glioma cell line) was estimated using visual survival cell assay. Phenotypes of these various activated cells were determined using flow cytometry. The secreted protein from effector cells was estimated by enzyme-linked immunosorbent assay. The expression of immune response-related genes in activated cells was measured. There was a significant cytotoxicity of rMSCs activated with various cytokine combinations. After various cytokine activations of rMSCs, the population of immune effector cells (CD8, CD161a) and immune reaction-related proteins (IL-4, gamma-INF) might increase. Apoptosis may be one of the lysis mechanisms of target cells by activated rMSCs. The contributing genes could be gamma-INF, FasL, and perforin. This study suggests that rMSC may be used as adoptive transfer therapy in patients suffering from malignant brain tumor, but we have to investigate orthotopic animal study for the proper translation.

Hemapoietic, immunomodulatory, antitumor, and toxicity profiles of sequential GM-CSF and IFNγ1b biotherapy and carboplatin in recurrent ovarian carcinoma

5053 Background: Monocyte/macrophages (MO/MA) are an important population of innate immune effector cells. The goal was to develop an acceptable chemoimmunotherapy regimen for ovarian carcinoma (OC) patients based on mobilization and maturation of MO/MA. Methods: Eligibility: recurrent measurable tumors, chemo-free interval ≥ 6mos, ≤ 2 chemo regimens. Immunomodulatory regimen: GM-CSF (Leukine, Berlex) starting at 400 mcg/day SC for 7 days with IFNγ1b (Actimmune, Intermune) at 100mcg SC on days 5 and 7 administered prior to and 24 hours post chemotherapy (carboplatin Paraplatin AUC 5 IV) every cycle. Immune parameters: measured by FACS analysis of MO/MA, DC, and major subsets. MA mediated tumor cell (TC) cytotoxicity and ADCC against Her2neu+ TCs measured by 3-H thymidine incorporation. Quality of life (QOL): measured using the Functional Assessment of Cancer Therapy - General and Biologic Response Modifiers (FACT-G and FACT-BRM) at 3 time points in cycle one and at 2 time points in subsequent cycles. Results: Twenty-five patients, who completed ≥ 3 courses, were evaluated in this preliminary report. Six and 4 of 25 patients (40%) experienced CR and PR, respectively. Four patients were removed from the study due to severe carboplatin allergy (2 pts), grade 3 liver toxicity (1 pt), and grade 3 fatigue (1 pt). There were significant increases in mean absolute numbers of WBC, granulocytes, and MO from baseline to d+9 after carboplatin infusion for cycle #1 (p<0.001, p<0.001, and p=0.001, respectively). There was no change in the mean platelet levels through cycle #3 (p=0.13). The numbers of certain activated MO/MA subsets were also increased but without enhancement of direct cytotoxicity or ADCC. There was no effect on general QOL, though BRM specific symptoms were significantly suppressed (p=0.03). Conclusions: This novel regimen of GM-CSF, IFNγ, and carboplatin in OC patients has an acceptable toxicity profile, while significantly increasing absolute numbers of MO and granulocytes with a shift toward more differentiated cells. Further accrual will determine response rate, time to progression, and feasibility for future development and MO/MA functionality. No significant financial relationships to disclose.

Immunoperoxidase studies of cell mediated immune effector cell populations in early Mycobacterium avium subsp. paratuberculosis infection in sheep.

Immunoperoxidase (IPX) labelling for CD4, CD8, TCR-gammadelta, WC1, CD1b, IFN-gamma, CD45R, CD56 and lysozyme was used to investigate changes in cell mediated immune effector cell populations in the intestinal Peyer's patches (PP) and mesenteric lymph nodes of lambs, 2 and 4 months after experimental infection with low doses of sheep strain Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis). The organism was cultured from the tissues of each infected lamb, but histological lesions were not present. This infection model was considered to be more representative of natural M. a. paratuberculosis infection than previous studies. Infected sheep had significantly more CD4+ cells in the mucosa, domes and interfollicular areas of the terminal ileum, and in the interfollicular areas of the jejunal Peyer's patch. Infected sheep also had significantly increased numbers of TCR-gammadelta+ cells in the mucosa and interfollicular areas of the jejunal Peyer's patch, and increased numbers of WC1+ cells in the ileal Peyer's patch. These findings are consistent with previous findings in sheep given higher doses of cattle strain M. a. paratuberculosis. Significantly fewer CD1b+ cells were present in the paracortical areas of the mesenteric lymph nodes of infected sheep, and the reduction was greater in sheep infected for 4 months compared to sheep infected for only 2 months. Down-regulation of CD1b expression may be important for the continued survival and multiplication of M. a. paratuberculosis as specific adaptive immunity develops. Across all sheep, jejunal Peyer's patches had higher numbers of CD4+, CD8+, TCR-gammadelta+, WC1+ and CD45R+ cells, and lower numbers of CD56+ fibres compared to ileal Peyer's patches. These findings confirm and extend the peculiarities of the terminal ileal Peyer's patch in the young ruminant, with possible implications for the early establishment of M. a. paratuberculosis infection.

Cellular mechanisms of interleukin-12–mediated neuroblastoma regression

Background/Purpose: Interleukin-12 (IL-12) is a proinflammatory cytokine with potent antitumor effects. Previous studies from the authors laboratory showed regression of established neuroblastoma in mice vaccinated with IL-12 transduced dendritic cells (DC). Although regression was associated with intense T cell infiltration, the precise role of T cells is unknown. The purpose of this work is to study the cellular mechanisms in IL-12–mediated tumor regression. Methods: Three groups of mice (n = 12) received subcutaneous inoculation with 1 × 106 murine neuroblastoma cells (TBJ). Anti-CD4 (T helper), anti-CD8 (T cytotoxic), or antiasialo-GM1 (natural killer) antibodies were injected intravenously at 3-day intervals to deplete various immune effector cell populations. Mice in each depletion group and the control (nondepleted) group were injected intratumorally on day 7 with 1 × 106 DC IL-12–transduced DC. Tumors were harvested for morphometry and immunohistochemistry at 21 days. Results: CD4 depletion had no effect on tumor growth in either control or IL-12–vaccinated animals. In contrast, CD8-depleted animals treated with IL-12–transduced DC underwent initial regression followed by progressive tumor growth (P <.01). These tumors were smaller in size at the same time-point. However, NK cell depletion (antiasialo GM1) completely abrogated the antitumor effects of IL-12–transduced DC, leading to progressive tumor growth from the outset. There was no difference between the control and treated animals in this group. Conclusions: Contrary to our hypothesis that IL-12 DC primarily function to stimulate a T cell–mediated response, these data suggest that NK cells are essential for the initial antitumor response of animals treated with IL-12–transduced DC. CD8+ T cells appear to be necessary effector cells for complete rejection of tumor and possibly memory. NK cells are responsible for the early immune response. Furthermore, CD4+ (T helper) cells did not play any role in IL-12–induced regression. These results imply that for DC to generate an effective antitumor response against neuroblastoma both acquired and innate effector cells are required. J Pediatr Surg 38:199-204. Copyright 2003, Elsevier Science (USA). All rights reserved.

Interleukin-12 transduced dendritic cells induce regression of established murine neuroblastoma

Background/Purpose: Interleukin 12 (IL-12) is a potent proinflammatory cytokine that enhances cytotoxic T lymphocytes (CTL) and natural killer (NK) cell activity. The goal of these experiments was to assess whether adenoviral-mediated IL-12 expression by dendritic cells (DC) could induce an antitumor immune response in a murine model of neuroblastoma. Methods: Syngeneic A/J mice were inoculated subcutaneously with 1 × 106 cells from a murine neuroblastoma-derived cell line (TBJ). Murine DC were transduced in vitro with adCMV-mIL-12, and 1 × 106 cells were injected intratumorally. Tumor growth in these mice was compared with control animals injected with enhanced green-filled protein (EGFP) transduced DC or saline. The role of CTL was evaluated through cytotoxicity assays. Immunohistochemical analysis of tumor, spleen, and lymph node was performed to characterize the behavior and fate of various populations of immune effector cells in these tissues. Results: The tumors of mice injected with adIL-12 transduced DC all underwent complete regression over a 3-week period. Splenocytes isolated from mice 7 days after intratumoral injection of adIL-12 DC showed increased cytolytic activity relative to control animals in vitro. Immunohistochemistry of tumor and lymph tissue showed increased amounts of DC and T lymphocyte infiltration and a slight decrease in apoptosis relative to the control groups. Conclusions: Increased IL-12 production by DC induced a significant antitumor response in a poorly immunogenic murine neuroblastoma model. These results show the vital role of DC in the immunobiology of the disease, and that protection of these cells from tumor induced apoptosis is a critical aspect for immunotherapies treating this aggressive tumor. J Pediatr Surg 36:1285-1292. Copyright © 2001 by W.B. Saunders Company.