Administration of either anti-CD40 or interleukin-12 following lethal total body irradiation induces acute lethal toxicity affecting the gut

AbstractInterleukin (IL)-12 and antibodies against CD40 have demonstrated antitumor effects in a variety of in vivo model systems. However, both agents can also mediate significant toxicities either when used following lethal TBI or when administered in combination with other agents such as IL-2. In this study, we assessed the effects of anti-CD40 monoclonal antibody (MoAb) and IL-12 in lethally irradiated mice. Acute lethal toxicity was observed following the administration of either 10 microg anti-CD40 MoAb (FGK45) or 0.5 microg of recombinant murine (rm)IL-12 that resulted in 100% mortality of all mice within 4 to 6 days. Histological evaluation revealed destruction of the normal gut architecture in both anti-CD40 MoAb- and rmIL-12-treated mice. Analysis of serum cytokine levels in the lethally irradiated mice receiving anti-CD40 MoAb demonstrated a marked increase of interferon (IFN)-gamma and IL-12 p40, whereas mice receiving rmIL-12 demonstrated a marked increase of IFN-gamma. Lethally irradiated IL-12 p40 knock-out mice were resistant to anti-CD40-induced toxicity, suggesting that the lack of IL-12 p40 with no possibility of making functional IL- 12 p70 is key for this toxic reaction. Similarly, lethally irradiated IFN-gamma knock-out mice were completely resistant to rmIL-12-induced toxicity, suggesting that IFN-gamma is a major player in IL-12-mediated toxicity. These results suggest that both anti-CD40 MoAb and rmIL-12 induce an acute fatal toxicity characterized by similar intestinal pathology and mediated in part by IFN-gamma.Biol Blood Marrow Transplant 2002;8(6):316-25

Out-of-Sequence Signal 3 Paralyzes Primary CD4+ T-Cell-Dependent Immunity

SummaryPrimary T cell activation involves the integration of three distinct signals delivered in sequence: (1) antigen recognition, (2) costimulation, and (3) cytokine-mediated differentiation and expansion. Strong immunostimulatory events such as immunotherapy or infection induce profound cytokine release causing “bystander” T cell activation, thereby increasing the potential for autoreactivity and need for control. We show that during strong stimulation, a profound suppression of primary CD4+ T-cell-mediated immune responses ensued and was observed across preclinical models and patients undergoing high-dose interleukin-2 (IL-2) therapy. This suppression targeted naive CD4+ but not CD8+ T cells and was mediated through transient suppressor of cytokine signaling-3 (SOCS3) inhibition of the STAT5b transcription factor signaling pathway. These events resulted in complete paralysis of primary CD4+ T cell activation, affecting memory generation and induction of autoimmunity as well as impaired viral clearance. These data highlight the critical regulation of naive CD4+ T cells during inflammatory conditions

Systemic IL-12 Administration Alters Hepatic Dendritic Cell Stimulation Capabilities

The liver is an immunologically unique organ containing tolerogenic dendritic cells (DC) that maintain an immunosuppressive microenvironment. Although systemic IL-12 administration can improve responses to tumors, the effects of IL-12-based treatments on DC, in particular hepatic DC, remain incompletely understood. In this study, we demonstrate systemic IL-12 administration induces a 2–3 fold increase in conventional, but not plasmacytoid, DC subsets in the liver. Following IL-12 administration, hepatic DC became more phenotypically and functionally mature, resembling the function of splenic DC, but differed as compared to their splenic counterparts in the production of IL-12 following co-stimulation with toll-like receptor (TLR) agonists. Hepatic DCs from IL-12 treated mice acquired enhanced T cell proliferative capabilities similar to levels observed using splenic DCs. Furthermore, IL-12 administration preferentially increased hepatic T cell activation and IFNγ expression in the RENCA mouse model of renal cell carcinoma. Collectively, the data shows systemic IL-12 administration enables hepatic DCs to overcome at least some aspects of the inherently suppressive milieu of the hepatic environment that could have important implications for the design of IL-12-based immunotherapeutic strategies targeting hepatic malignancies and infections

Intratumoral IL-12 and TNF-α–Loaded Microspheres Lead To Regression of Breast Cancer and Systemic Antitumor Immunity

Background: Local, sustained delivery of cytokines at a tumor can enhance induction of antitumor immunity and may be a feasible neoadjuvant immunotherapy for breast cancer. We evaluated the ability of intratumoral poly-lactic-acid-encapsulated microspheres (PLAM) containing interleukin 12 (IL-12), tumor necrosis factor α (TNF-α), and granulocyte-macrophage colony stimulating factor (GM-CSF) in a murine model of breast cancer to generate a specific antitumor response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41401/1/10434_2004_Article_147.pd

Tumor formation by a murine macrophage cell line immortalized in vitro by v-raf and v-myc oncogenes

Murine bone marrow cells immortalized in vitro by the J2 recombinant retrovirus bearing the v-raf and v-myc oncogenes have the functional and phenotypic characteristics of macrophages. The present study was designed to determine whether these cells are tumorigenic in athymic or euthymic mice. One cloned cell line (GG2EE), that had been previously derived and characterized was used for this purpose. The results demonstrated that GG2EE cells were tumorigenic in allogeneic athymic BALB/c mice at doses of 1 7104 to 1 7107 cells per mouse regardless of the route administration. All mice utlimately died of progressive tumor growth. Conversely, the GG2EE cells were nontumorigenic or transiently tumorigenic in syngeneic euthymic C3H/HeJ mice. Further studies in BALB/c athymic mice demonstrated that the GG2EE cells were directly tumorigenic since ascites tumors (GG2EE-V) that developed expressed the H-2k surface phenotype of the injected GG2EE cells, excluding the possibility that the J2 virus constitutively produced by GG2EE cells caused in vivo transformation and therefore tumors of host cell origin. The in vivo passaged cells continued to express the M1/69, MAC-1, MAC-2, F4/80, Fc receptor and Ly5.1 antigens characterically expressed on the parental line. Biological properties including interferon-\u3b3-induced Ia expression, phagocytosis, and activation for cytotoxicity were also retained following in vivo passage. These results demonstrated that J2 virus-immortalized GG2EE cells were directly tumorigenic in athymic mice in vivo and that the macrophage phenotype was maintained in these neoplastic cells. These observations suggest that this tumor model may be valuable for the study of macrophage function as well as therapeutic approaches to oncogen-expressing retrovirus-induced tumors. \ua9 1988 Springer-Verlag