Notch and wingless signaling cooperate in regulation of dendritic cell differentiation.

Dendritic cell (DC) differentiation is regulated by stroma via a network of soluble and cell-bound factors. Notch is one of the major elements of this network. Its role in DC differentiation, however, is controversial. Here, we demonstrate that activation of Notch signaling in hematopoietic progenitor cells (HPCs) promoted differentiation of conventional DCs via activation of the canonical Wingless (Wnt) pathway. Inhibition of the Wnt pathway abrogated the effect of Notch on DC differentiation. The fact that activation of the Wnt pathway in Notch-1-deficient embryonic stem cells restored DC differentiation indicates that Wnt signaling is downstream of the Notch pathway in regulating DC differentiation. Notch signaling activated the Wnt pathway in HPCs via expression of multiple members of the Frizzled family of Wnt receptors, which was directly regulated by the CSL (RPB-Jkappa) transcription factor. Thus, these data suggest a model of DC differentiation via cooperation between Wnt and Notch pathways.

Real-World Data of Palbociclib in Combination With Endocrine Therapy for the Treatment of Metastatic Breast Cancer in Men.

This report examined the benefits and risks of palbociclib plus endocrine therapy (ET) in men with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). Palbociclib was evaluated using three independent data sources: real-world data from pharmacy and medical claims, a de-identified real-world data source derived from electronic health records (EHRs), and a global safety database. From medical and pharmacy records, 1,139 men with MBC were identified; in the first-line setting, median duration of treatment was longer with palbociclib plus ET (n = 37, 8.5 months, 95% confidence interval (CI), 4.4-13.0) than ET alone (n = 214, 4.3 months, 95% CI, 3.0-5.7) and specifically, was longer with palbociclib plus letrozole (n = 26, 9.4 months, 95% CI, 4.4-14.0) than letrozole alone (n = 63, 3.0 months, 95% CI, 1.8-4.8). In the EHR-derived database, 59 men received treatment for MBC; real-world response across all lines of therapy in the metastatic setting was reported in 4 of 12 patients (33.3%) in the palbociclib plus ET group vs. 1 of 8 (12.5%) patients in the ET group. Review of the global safety database did not identify any new safety signals in palbociclib-treated men. Real-world data indicated that men with MBC benefit from palbociclib plus ET, with a safety profile consistent with previous observations in women with MBC. Collective data on palbociclib in women and men in this report, including clinical trial data, real-world data, and a well-established risk/benefit profile, led to US approval of an expansion of the palbociclib indication to include men with MBC.

Antiviral antibodies target adenovirus to phagolysosomes and amplify the innate immune response.

Adenovirus is a nonenveloped dsDNA virus that activates intracellular innate immune pathways. In vivo, adenovirus-immunized mice displayed an enhanced innate immune response and diminished virus-mediated gene delivery following challenge with the adenovirus vector AdLacZ suggesting that antiviral Abs modulate viral interactions with innate immune cells. Under naive serum conditions in vitro, adenovirus binding and internalization in macrophages and the subsequent activation of innate immune mechanisms were inefficient. In contrast to the neutralizing effect observed in nonhematopoietic cells, adenovirus infection in the presence of antiviral Abs significantly increased FcR-dependent viral internalization in macrophages. In direct correlation with the increased viral internalization, antiviral Abs amplified the innate immune response to adenovirus as determined by the expression of NF-kappaB-dependent genes, type I IFNs, and caspase-dependent IL-1beta maturation. Immune serum amplified TLR9-independent type I IFN expression and enhanced NLRP3-dependent IL-1beta maturation in response to adenovirus, confirming that antiviral Abs specifically amplify intracellular innate pathways. In the presence of Abs, confocal microscopy demonstrated increased targeting of adenovirus to LAMP1-positive phagolysosomes in macrophages but not epithelial cells. These data show that antiviral Abs subvert natural viral tropism and target the adenovirus to phagolysosomes and the intracellular innate immune system in macrophages. Furthermore, these results illustrate a cross-talk where the adaptive immune system positively regulates the innate immune system and the antiviral state.

Mechanism regulating reactive oxygen species in tumor-induced myeloid-derived suppressor cells.

Myeloid-derived suppressor cells (MDSC) are a major component of the immune suppressive network described in cancer and many other pathological conditions. Recent studies have demonstrated that one of the major mechanisms of MDSC-induced immune suppression is mediated by reactive oxygen species (ROS). However, the mechanism of this phenomenon remained unknown. In this study, we observed a substantial up-regulation of ROS by MDSC in all of seven different tumor models and in patients with head and neck cancer. The increased ROS production by MDSC is mediated by up-regulated activity of NADPH oxidase (NOX2). MDSC from tumor-bearing mice had significantly higher expression of NOX2 subunits, primarily p47(phox) and gp91(phox), compared with immature myeloid cells from tumor-free mice. Expression of NOX2 subunits in MDSC was controlled by the STAT3 transcription factor. In the absence of NOX2 activity, MDSC lost the ability to suppress T cell responses and quickly differentiated into mature macrophages and dendritic cells. These findings expand our fundamental understanding of the biology of MDSC and may also open new opportunities for therapeutic regulation of these cells in cancer.

A Phase I trial of talazoparib in patients with advanced hematologic malignancies.

AIM: The objective of this study was to establish the maximum tolerated dose (MTD), safety, pharmacokinetics, and anti-leukemic activity of talazoparib. PATIENTS & METHODS: This Phase I, two-cohort, dose-escalation trial evaluated talazoparib monotherapy in advanced hematologic malignancies (cohort 1: acute myeloid leukemia/myelodysplastic syndrome; cohort 2: chronic lymphocytic leukemia/mantle cell lymphoma). RESULTS: Thirty-three (cohort 1: n = 25; cohort 2: n = 8) patients received talazoparib (0.1-2.0 mg once daily). The MTD was exceeded at 2.0 mg/day in cohort 1 and at 0.9 mg/day in cohort 2. Grade ≥3 adverse events were primarily hematologic. Eighteen (54.5%) patients reported stable disease. CONCLUSION: Talazoparib is relatively well tolerated in hematologic malignancies, with a similar MTD as in solid tumors, and shows preliminary anti leukemic activity.Clinical trial registration: NCT01399840 (ClinicalTrials.gov).

Antibody ligation of murine Ly-6G induces neutropenia, blood flow cessation, and death via complement-dependent and independent mechanisms.

Ly-6G is a member of the Ly-6 family of GPI-linked proteins, which is expressed on murine neutrophils. Antibodies against Ly-6G cause neutropenia, and fatal reactions also develop if mice are primed with TNF-alpha prior to antibody treatment. We have investigated the mechanisms behind these responses to Ly-6G ligation in the belief that similar mechanisms may be involved in neutropenia and respiratory disorders associated with alloantibody ligation of the related Ly-6 family member, NB1, in humans. Neutrophil adhesion, microvascular obstruction, breathing difficulties, and death initiated by anti-Ly-6G antibodies in TNF-alpha-primed mice were shown to be highly complement-dependent, partly mediated by CD11b, CD18, and FcgammaR and associated with clustering of Ly-6G. Neutrophil depletion, on the other hand, was only partly complement-dependent and was not altered by blockade of CD11b, CD18, or FcgammaR. Unlike other neutrophil-activating agents, Ly-6G ligation did not induce neutropenia via sequestration in the lungs. Cross-linking Ly-6G mimicked the responses seen with whole antibody in vivo and also activated murine neutrophils in vitro. Although this suggests that the responses are, in part, mediated by nonspecific properties of antibody ligation, neutrophil depletion requires an additional mechanism possibly specific to the natural function of Ly-6G.

Complement is an essential component of the immune response to adeno-associated virus vectors.

Adeno-associated virus (AAV) vectors are associated with relatively mild host immune responses in vivo. Although AAV induces very weak innate immune responses, neutralizing antibodies against the vector capsid and transgene still occur. To understand further the basis of the antiviral immune response to AAV vectors, studies were performed to characterize AAV interactions with macrophages. Primary mouse macrophages and human THP-1 cells transduced in vitro using an AAV serotype 2 (AAV2) vector encoding green fluorescent protein did not result in measurable transgene expression. An assessment of internalized vector genomes showed that AAV2 vector uptake was enhanced in the presence of normal but not heat-inactivated or C3-depleted mouse/human serum. Enhanced uptake in the presence of serum coincided with increased macrophage activation as determined by the expression of NF-kappaB-dependent genes such as macrophage inflammatory protein 2 (MIP-2), interleukin-1beta (IL-1beta), IL-8, and MIP-1beta. AAV vector serotypes 1 and 8 also activated human and mouse macrophages in a serum-dependent manner. Immunoprecipitation studies demonstrated the binding of iC3b complement protein to the AAV2 capsid in human serum. AAV2 did not activate the alternative pathway of the complement cascade and lacked cofactor activity for factor I-mediated degradation of C3b to iC3b. Instead, our results suggest that the AAV capsid also binds complement regulatory protein factor H. In vivo, complement receptor 1/2- and C3-deficient mice displayed impaired humoral immunity against AAV2 vectors, with a delay in antibody development and significantly lower neutralizing antibody titers. These results show that the complement system is an essential component of the host immune response to AAV.

Overcoming immune tolerance against multiple myeloma with lentiviral calnexin-engineered dendritic cells.

The key to successful cancer immunotherapy is to induce an effective anticancer immunity that will overcome the acquired cancer-specific immune tolerance. In this study, we found that dendritic cells (DCs) from multiple myeloma (MM) patients suppressed rather than induced a cancer cell-specific immune response. We demonstrated that CD4(+)CD25(high) T cells from MM patients suppressed the proliferation of activated peripheral blood lymphocytes. Further analysis illustrated that MM cell lysates or MM-specific idiotype immunoglobulins (MM Id-Ig) specifically induced the expansion of peripheral CD4(+)CD25(high)FoxP3(high) T regulatory (Treg) cells in vitro. Supraphysiological expression of calnexin (CNX) using lentiviral (LV) vectors in DCs of MM patients overcame the immune suppression and enhanced MM-specific CD4 and CD8 T-cell responses. However, overexpression of CNX did not affect the peripheral expansion of Treg cells stimulated by MM antigens. Thus, the immune suppression effect of Treg cells in cancer patients may be overcome by improving antigen processing in DCs, which in turn may lower the activation threshold of the immune effector cells. This concept of modulating anticancer immunity by genetically engineering cancer patients' DCs may improve immunotherapeutic regimens in cancer treatment.

Treatment Patterns and Outcomes Associated With Palbociclib Plus Letrozole for Postmenopausal Women With HR+/HER2- Advanced Breast Cancer Enrolled in an Expanded Access Program.

PURPOSE: To evaluate treatment patterns and clinical outcomes of patients who received palbociclib in combination with letrozole in any line of therapy for treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer in an expanded access program (EAP) in the United States. PATIENTS AND METHODS: A retrospective chart review study was conducted of patients previously enrolled in the palbociclib EAP. Complete data from time of initial diagnosis of metastatic breast cancer until date of chart abstraction were obtained. Clinical outcomes as assessed by site investigators included clinical benefit rate, progression-free survival, and overall survival. Survival was descriptively assessed using Kaplan-Meier methods. RESULTS: Of 238 patients enrolled in the EAP, data from 126 patients were included. Median age was 62.5 years at EAP enrollment; 25% had de novo metastatic disease. Visceral disease was present in 71% of patients. The disease of most patients was heavily pretreated; nearly 60% of patients had received 3 or more prior lines for metastatic disease before initiating palbociclib + letrozole therapy. Most patients (87%) had received prior endocrine therapy, and 68% had received prior chemotherapy for metastatic disease. Patients with prior endocrine therapy for metastatic disease had a clinical benefit rate of 30%, while those with prior chemotherapy had a 26% clinical benefit rate. Patients receiving 2 or more prior lines had 6- and 12-month progression-free survival rates of 35% and 21%, respectively, and 12- and 24-month overall survival rates of 62% and 35%, respectively. CONCLUSION: Most patients derived benefit from palbociclib + letrozole treatment despite having received multiple prior treatment lines for metastatic disease.

Expanded-Access Study of Palbociclib in Combination With Letrozole for Treatment of Postmenopausal Women With Hormone Receptor-Positive, HER2-Negative Advanced Breast Cancer.

PURPOSE: Palbociclib is a cyclin-dependent kinase (CDK) 4 and 6 inhibitor that was conditionally approved in the United States (February 2015) and Canada (March 2016) with letrozole as initial endocrine-based therapy for postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer. A palbociclib expanded-access program (EAP) was initiated as an interim measure to provide drug access before commercial availability of drug. PATIENTS AND METHODS: Eligible women were 18 years or older and postmenopausal with diagnosed metastatic HR-positive, HER2-negative breast cancer and were suitable candidates for letrozole therapy. Treatment continued until disease progression, unacceptable toxicity, withdrawal of consent, or commercial availability of palbociclib. We report combined safety data in both cohorts, and patient-reported outcomes in the Canadian cohort. RESULTS: From September 2014 to May 2016, a total of 334 patients were enrolled onto the EAP. With rapid regulatory approval and transfer to commercial supply, median duration of palbociclib treatment while on study was 77 days (range, 2-245 days). At least one dose reduction occurred in 24.3% of patients, and 3.6% of patients permanently discontinued palbociclib because of treatment-emergent adverse events. The most common adverse events (> 20%) of any grade included neutropenia (66.5%), fatigue (38%), infection (25.4%), and nausea (22.5%). Grade 3/4 adverse events included neutropenia (54.5%), leukopenia (8.1%), fatigue (4.2%), anemia (3.9%), thrombocytopenia (3.6%), infection (3.3%), and febrile neutropenia (2.1%). CONCLUSION: In a real-world EAP setting, palbociclib in combination with letrozole was well tolerated, and the safety profile was consistent with other reported clinical trial literature of HR-positive, HER2-negative advanced breast cancer.

Isolation of neutrophils from mouse liver: A novel method to study effector leukocytes during inflammation.

Neutrophils are phagocytic leukocytes that represent one of the first lines of defense during infection and injury. Neutrophils emigrate into tissues during inflammation and are phenotypically different compared to cells in the circulation. To further understand the biology of tissue-recruited neutrophils, we have developed a reliable method to isolate these cells from inflamed liver. Acute liver inflammation was induced in mice by systemic treatment with adenovirus vectors. Two hours following adenovirus treatment, livers were enzymatically digested and leukocytes isolated by Percoll density gradient centrifugation. Neutrophils were then purified by negative immunomagnetic separation. Neutrophils isolated in this manner were 95% pure as determined by flow cytometry and more than 97% viable by propidium iodide staining. In order to carry out molecular studies, we extracted high quality genomic DNA and RNA from isolated neutrophils. PCR was used to successfully amplify sample genes from isolated neutrophil DNA. Isolated neutrophil RNA was used in a ribonuclease protection assay to evaluate chemokine gene expression. Neutrophils were shown to express multiple chemokine mRNA transcripts including MIP-1 beta, MIP-2 and IP-10. This work describes a novel method to isolate highly pure, viable neutrophils from pathologically inflamed tissue for subsequent detailed cellular and molecular analysis.

The induction of inflammation by adenovirus vectors used for gene therapy.

The ability to repair or enhance an individual's genetic make-up provides the sublime opportunity to ameliorate or eliminate many clinical disorders that affect mankind. Gene therapy is thus a revolutionary clinical strategy that may potentially treat an array of genetic and non-genetic diseases, as well as a novel method for drug delivery and vaccination. To these ends, adenovirus vectors are currently the most promising means to deliver specific genes of interest into target cells of the patient. A major limitation of the use of adenovirus vectors in clinical trials, however, is the rapidly induced inflammatory response against these infectious particles. This review aims to describe the cellular and molecular mechanisms involved in the adenovirus-mediated inflammatory response.

Combination of external beam radiotherapy (EBRT) with intratumoral injection of dendritic cells as neo-adjuvant treatment of high-risk soft tissue sarcoma patients.

PURPOSE: The goal of this study was to determine the effect of combination of intratumoral administration of dendritic cells (DC) and fractionated external beam radiation (EBRT) on tumor-specific immune responses in patients with soft-tissue sarcoma (STS). METHODS AND MATERIAL: Seventeen patients with large (>5 cm) high-grade STS were enrolled in the study. They were treated in the neoadjuvant setting with 5,040 cGy of EBRT, split into 28 fractions and delivered 5 days per week, combined with intratumoral injection of 10(7) DCs followed by complete resection. DCs were injected on the second, third, and fourth Friday of the treatment cycle. Clinical evaluation and immunological assessments were performed. RESULTS: The treatment was well tolerated. No patient had tumor-specific immune responses before combined EBRT/DC therapy; 9 patients (52.9%) developed tumor-specific immune responses, which lasted from 11 to 42 weeks. Twelve of 17 patients (70.6%) were progression free after 1 year. Treatment caused a dramatic accumulation of T cells in the tumor. The presence of CD4(+) T cells in the tumor positively correlated with tumor-specific immune responses that developed following combined therapy. Accumulation of myeloid-derived suppressor cells but not regulatory T cells negatively correlated with the development of tumor-specific immune responses. Experiments with (111)In labeled DCs demonstrated that these antigen presenting cells need at least 48 h to start migrating from tumor site. CONCLUSIONS: Combination of intratumoral DC administration with EBRT was safe and resulted in induction of antitumor immune responses. This suggests that this therapy is promising and needs further testing in clinical trials design to assess clinical efficacy.

HIF-1α regulates function and differentiation of myeloid-derived suppressor cells in the tumor microenvironment.

Myeloid-derived suppressor cells (MDSCs) are a major component of the immune-suppressive network described in cancer and many other pathological conditions. We demonstrate that although MDSCs from peripheral lymphoid organs and the tumor site share similar phenotype and morphology, these cells display profound functional differences. MDSC from peripheral lymphoid organs suppressed antigen-specific CD8(+) T cells but failed to inhibit nonspecific T cell function. In sharp contrast, tumor MDSC suppressed both antigen-specific and nonspecific T cell activity. The tumor microenvironment caused rapid and dramatic up-regulation of arginase I and inducible nitric oxide synthase in MDSC, which was accompanied by down-regulation of nicotinamide adenine dinucleotide phosphate-oxidase and reactive oxygen species in these cells. In contrast to MDSC from the spleen, MDSC from the tumor site rapidly differentiated into macrophages. Exposure of spleen MDSC to hypoxia resulted in the conversion of these cells to nonspecific suppressors and their preferential differentiation to macrophages. Hypoxia-inducible factor (HIF) 1α was found to be primarily responsible for the observed effects of the tumor microenvironment on MDSC differentiation and function. Thus, hypoxia via HIF-1α dramatically alters the function of MDSC in the tumor microenvironment and redirects their differentiation toward tumor-associated macrophages, hence providing a mechanistic link between different myeloid suppressive cells in the tumor microenvironment.

Anti-inflammatory triterpenoid blocks immune suppressive function of MDSCs and improves immune response in cancer.

PURPOSE: Myeloid-derived suppressor cells (MDSC) are one of the major factors responsible for immune suppression in cancer. Therefore, it would be important to identify effective therapeutic means to modulate these cells. EXPERIMENTAL DESIGN: We evaluated the effect of the synthetic triterpenoid C-28 methyl ester of 2-cyano-3,12-dioxooleana-1,9,-dien-28-oic acid (CDDO-Me; bardoxolone methyl) in MC38 colon carcinoma, Lewis lung carcinoma, and EL-4 thymoma mouse tumor models, as well as blood samples from patients with renal cell cancer and soft tissue sarcoma. Samples were also analyzed from patients with pancreatic cancer treated with CDDO-Me in combination with gemcitabine. RESULTS: CDDO-Me at concentrations of 25 to 100 nmol/L completely abrogated immune suppressive activity of MDSC in vitro. CDDO-Me reduced reactive oxygen species in MDSCs but did not affect their viability or the levels of nitric oxide and arginase. Treatment of tumor-bearing mice with CDDO-Me did not affect the proportion of MDSCs in the spleens but eliminated their suppressive activity. This effect was independent of antitumor activity. CDDO-Me treatment decreased tumor growth in mice. Experiments with severe combined immunodeficient-beige mice indicated that this effect was largely mediated by the immune system. CDDO-Me substantially enhanced the antitumor effect of a cancer vaccines. Treatment of pancreatic cancer patients with CDDO-Me did not affect the number of MDSCs in peripheral blood but significantly improved the immune response. CONCLUSIONS: CDDO-Me abrogated the immune suppressive effect of MDSCs and improved immune responses in tumor-bearing mice and cancer patients. It may represent an attractive therapeutic option by enhancing the effect of cancer immunotherapy.

Neutrophils interact with adenovirus vectors via Fc receptors and complement receptor 1.

Neutrophils are effectors of the innate immune response to adenovirus vectors. Following the systemic administration of Cy2-labeled AdLuc in mice, flow cytometry and PCR analysis of liver leukocytes revealed that 25% of recruited neutrophils interacted with adenovirus vectors. In vitro, flow cytometry of human neutrophils incubated with Cy2-labeled AdLuc also demonstrated a significant interaction with adenovirus vectors. Fluorescence and electron microscopy confirmed vector internalization by neutrophils. The AdLuc-neutrophil interaction reduced vector transduction efficiency by more than 50% in coincubation assays in epithelium-derived cells. Adenovirus vector uptake by neutrophils occurred independently of coxsackievirus adenovirus receptor (CAR) and capsid RGD motifs, since neutrophils do not express CAR and uptake of the RGD-deleted vector AdL.PB* was similar to that of AdLuc. Furthermore, both AdLuc and AdL.PB* activated neutrophils and induced similar degrees of L-selectin shedding. Neutrophil uptake of AdLuc was dependent on the presence of complement and antibodies, since the interaction between AdLuc and neutrophils was significantly reduced when they were incubated in immunoglobulin G-depleted or heat-inactivated human serum. Blocking of complement receptor 1 (CD35) but not complement receptor 3 (CD11b/CD18) significantly reduced neutrophil uptake of AdLuc. Blocking of Fc gammaRI (CD64), Fc gammaRII (CD32), and Fc gammaRIII (CD16) individually or together also reduced neutrophil uptake of AdLuc, although less than blocking of CD35 alone. Combined CR1 and Fc receptor blockade synergistically inhibited neutrophil-AdLuc interactions close to baseline. These results demonstrate opsonin-dependent adenovirus vector interactions with neutrophils and their corresponding receptors.

Combined anticoagulant and antiselectin treatments prevent lethal intravascular coagulation.

Widespread microvascular injury followed by vessel obstruction may lead to disseminated intravascular coagulation (DIC). We describe a murine model wherein leukocytes interacting with inflamed microvessels in vivo are activated by antibodies. Treatment of tumor necrosis factor alpha (TNF-alpha)-primed mice with anti-Ly-6G antibodies reproduced many of the features of septic or traumatic shock including microvessel obstruction and coagulation, severe vasculitis, respiratory difficulties, and vascular leakage. Mice lacking either E-selectin or P-selectin were protected from this reaction as were animals treated with a combination of either selectin-blocking antibodies and heparin or a selectin antagonist plus heparin. Combined blockade of leukocyte/platelet adhesion and coagulation may provide convincing protection in DIC.

Helper-dependent adenovirus vectors elicit intact innate but attenuated adaptive host immune responses in vivo.

Helper-dependent adenovirus (HD-Ad) vectors with all adenoviral genes deleted mediate very long-term expression of therapeutic transgenes in a variety of animal models of disease. These vectors are associated with reduced toxicity and improved safety relative to traditional early region 1 deletion first-generation Ad (FG-Ad) vectors. Many studies have clearly demonstrated that FG-Ad vectors induce innate and adaptive immune responses in vivo; however, a comprehensive analysis of host immune responses to HD-Ad vectors has not yet been performed. In DBA/2 mice, intravenous injection of HD-Ad vectors encoding LacZ (HD-AdLacZ) or a murine secreted alkaline phosphatase (HD-AdSEAP) induced an early expression of inflammatory cytokine and chemokine genes in the liver, including interferon-inducible protein 10, macrophage inflammatory protein 2, and tumor necrosis factor alpha, and were expressed in a pattern similar to that induced by FG-Ad vectors encoding AdSEAP. Like AdSEAP, and consistent with the pattern of cellular gene expression, HD-AdLacZ and HD-AdSEAP induced the recruitment of CD11b-positive leukocytes to the transduced liver within hours of administration. AdSEAP also induced a second phase of liver inflammation, consisting of inflammatory gene expression and CD3-positive lymphocytic infiltrates 7 days posttransduction. In contrast, beyond 24 h no infiltrates or expression of inflammatory genes was detected in the livers of mice receiving HD-AdSEAP. Despite the lack of liver inflammation at 7 days, Ad-specific cytotoxic T lymphocytes could be detected in mice receiving HD-AdSEAP. This lack of liver inflammation was not due to reduced transduction since levels of transgene expression and the amounts of vector DNA in the liver were equivalent in mice receiving HD-AdSEAP and AdSEAP. These results demonstrate that HD-Ad vectors induce intact innate but attenuated adaptive immune responses in vivo.