Natural killer cells and BNT162b2 mRNA vaccine reactogenicity and durability.

Introduction: Natural killer (NK) cells can both amplify and regulate immune responses to vaccination. Studies in humans and animals have observed NK cell activation within days after mRNA vaccination. In this study, we sought to determine if baseline NK cell frequencies, phenotype, or function correlate with antibody responses or inflammatory side effects induced by the Pfizer-BioNTech COVID-19 vaccine (BNT162b2). Methods: We analyzed serum and peripheral blood mononuclear cells (PBMCs) from 188 participants in the Prospective Assessment of SARS-CoV-2 Seroconversion study, an observational study evaluating immune responses in healthcare workers. Baseline serum samples and PBMCs were collected from all participants prior to any SARS-CoV-2 infection or vaccination. Spike-specific IgG antibodies were quantified at one and six months post-vaccination by microsphere-based multiplex immunoassay. NK cell frequencies and phenotypes were assessed on pre-vaccination PBMCs from all participants by multi-color flow cytometry, and on a subset of participants at time points after the 1st and 2nd doses of BNT162b2. Inflammatory side effects were assessed by structured symptom questionnaires, and baseline NK cell functionality was quantified by an in vitro killing assay on participants that reported high or low post-vaccination symptom scores. Results: Key observations include: 1) circulating NK cells exhibit evidence of activation in the week following vaccination, 2) individuals with high symptom scores after 1st vaccination had higher pre-vaccination NK cytotoxicity indices, 3) high pre-vaccination NK cell numbers were associated with lower spike-specific IgG levels six months after two BNT162b2 doses, and 4) expression of the inhibitory marker NKG2A on immature NK cells was associated with higher antibody responses 1 and 6 months post-vaccination. Discussion: These results suggest that NK cell activation by BNT162b2 vaccination may contribute to vaccine-induced inflammatory symptoms and reduce durability of vaccine-induced antibody responses.

CD22 CAR T-cell associated hematologic toxicities, endothelial activation and relationship to neurotoxicity.

BACKGROUND: Hematologic toxicities, including coagulopathy, endothelial activation, and cytopenias, with CD19-targeted chimeric antigen receptor (CAR) T-cell therapies correlate with cytokine release syndrome (CRS) and neurotoxicity severity, but little is known about the extended toxicity profiles of CAR T-cells targeting alternative antigens. This report characterizes hematologic toxicities seen following CD22 CAR T-cells and their relationship to CRS and neurotoxicity. METHODS: We retrospectively characterized hematologic toxicities associated with CRS seen on a phase 1 study of anti-CD22 CAR T-cells for children and young adults with relapsed/refractory CD22+ hematologic malignancies. Additional analyses included correlation of hematologic toxicities with neurotoxicity and exploring effects of hemophagocytic lymphohistiocytosis-like toxicities (HLH) on bone marrow recovery and cytopenias. Coagulopathy was defined as evidence of bleeding or abnormal coagulation parameters. Hematologic toxicities were graded by Common Terminology Criteria for Adverse Events V.4.0. RESULTS: Across 53 patients receiving CD22 CAR T-cells who experienced CRS, 43 (81.1%) patients achieved complete remission. Eighteen (34.0%) patients experienced coagulopathy, of whom 16 had clinical manifestations of mild bleeding (typically mucosal bleeding) which generally subsided following CRS resolution. Three had manifestations of thrombotic microangiopathy. Patients with coagulopathy had higher peak ferritin, D-dimer, prothrombin time, international normalized ratio (INR), lactate dehydrogenase (LDH), tissue factor, prothrombin fragment F1+2 and soluble vascular cell adhesion molecule-1 (s-VCAM-1). Despite a relatively higher incidence of HLH-like toxicities and endothelial activation, overall neurotoxicity was generally less severe than reported with CD19 CAR T-cells, prompting additional analysis to explore CD22 expression in the central nervous system (CNS). Single-cell analysis revealed that in contrast to CD19 expression, CD22 is not on oligodendrocyte precursor cells or on neurovascular cells but is seen on mature oligodendrocytes. Lastly, among those attaining CR, grade 3-4 neutropenia and thrombocytopenia were seen in 65% of patients at D28. CONCLUSION: With rising incidence of CD19 negative relapse, CD22 CAR T-cells are increasingly important for the treatment of B-cell malignancies. In characterizing hematologic toxicities on CD22 CAR T-cells, we demonstrate that despite endothelial activation, coagulopathy, and cytopenias, neurotoxicity was relatively mild and that CD22 and CD19 expression in the CNS differed, providing one potential hypothesis for divergent neurotoxicity profiles. Systematic characterization of on-target off-tumor toxicities of novel CAR T-cell constructs will be vital as new antigens are targeted. TRIAL REGISTRATION NUMBER: NCT02315612.

Biomarkers of gut barrier dysfunction and risk of hepatocellular carcinoma in the REVEAL-HBV and REVEAL-HCV cohort studies.

Gut barrier dysfunction can result in the liver being exposed to an elevated level of gut-derived bacterial products via portal circulation. Growing evidence suggests that systemic exposure to these bacterial products promotes liver diseases including hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). However, prospective studies have not examined the association between biomarkers of gut barrier dysfunction and HCC risk in a population of hepatitis B or C viral (HBV/HCV) carriers. We investigated whether prediagnostic, circulating biomarkers of gut barrier dysfunction were associated with HCC risk, using the Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer (REVEAL)-HBV and REVEAL-HCV cohorts from Taiwan. REVEAL-HBV included 185 cases and 161 matched controls, and REVEAL-HCV 96 cases and 96 matched controls. The biomarkers quantitated were immunoglobulin A (IgA), IgG, and IgM against lipopolysaccharide (LPS) and flagellin, soluble CD14 (an LPS coreceptor), and LPS-binding protein (LBP). Odds ratios (ORs) and 95% confidence intervals (CIs) for associations between biomarker levels and HCC were calculated using multivariable-adjusted logistic regression. A doubling of the circulating levels of antiflagellin IgA or LBP was associated with a 76% to 93% increased risk of HBV-related HCC (OR per one unit change in log2 antiflagellin IgA = 1.76, 95% CI: 1.06-2.93; OR for LBP = 1.93, 95% CI: 1.10-3.38). None of the other markers were associated with an increased risk of HBV-related or HCV-related HCC. Results were similar when cases diagnosed in the first 5 years of follow-up were excluded. Our findings contribute to understanding the interplay of gut barrier dysfunction and primary liver cancer etiology.

Use of protective antigen of Bacillus anthracis as a model recombinant antigen to evaluate toll-like receptors 2, 3, 4, 7 and 9 agonists in mice using established functional antibody assays, antigen-specific antibody assays and cellular assays.

Toll-like receptor (TLR) agonists can act as immune stimulants alone or as part of alum or oil formulations. Humoral and cellular immune responses were utilized to assess quantitative and qualitative immune response enhancement by TLR agonists using recombinant protective antigen (rPA) of B. anthracis as a model antigen. To rPA, combined with aluminum hydroxide (Alhydrogel; Al(OH)3) or squalene (AddaVax™), was added one of 7 TLR agonists: TLR2 agonist Pam3CysSK4 (PamS), TLR3 agonist double stranded polyinosinic:polycytidylic acid (PolyIC), TLR4 agonists Monophosphoryl lipid A (MPLA) or glucopyranosyl lipid A (GLA), TLR7-8 agonists 3M-052 or Resiquimod (Resiq), or TLR9 agonist CPG 7909 (CPG). CD-1 or BALB/c mice received two intraperitoneal or intramuscular immunizations 14 days apart, followed by serum or spleen sampling 14 days later. All TLR agonists except PamS induced high levels of B. anthracis lethal toxin-neutralizing antibodies and immunoglobulin G (IgG) anti-PA. Some responses were >100-fold higher than those without a TLR agonist, and IP delivery (0.5 mL) induced higher TLR-mediated antibody response increases compared to IM delivery (0.05 mL). TLR7-8 and TLR9 agonists induced profound shifts of IgG anti-PA response to IgG2a or IgG2b. Compared to the 14-day immunization schedule, use of a shortened immunization schedule of only 7 days between prime and boost found that TLR9 agonist CPG in a squalene formulation maintained higher interferon-γ-positive cells than TLR4 agonist GLA. Variability in antibody responses was lower in BALB/c mice than CD-1 mice but antibody responses were higher in CD-1 mice. Lower serum 50% effective concentration (EC50) values were found for rPA-agonist formulations and squalene formulations compared to Al(OH)3 formulations. Lower EC50 values also were associated with low frequency detection of linear peptide epitopes. In summary, TLR agonists elicited cellular immune responses and markedly boosted humoral responses.

CD19/22 CAR T cells in children and young adults with B-ALL: phase 1 results and development of a novel bicistronic CAR.

Remission durability following single-antigen targeted chimeric antigen receptor (CAR) T-cells is limited by antigen modulation, which may be overcome with combinatorial targeting. Building upon our experiences targeting CD19 and CD22 in B-cell acute lymphoblastic leukemia (B-ALL), we report on our phase 1 dose-escalation study of a novel murine stem cell virus (MSCV)-CD19/CD22-4-1BB bivalent CAR T-cell (CD19.22.BBζ) for children and young adults (CAYA) with B-cell malignancies. Primary objectives included toxicity and dose finding. Secondary objectives included response rates and relapse-free survival (RFS). Biologic correlatives included laboratory investigations, CAR T-cell expansion and cytokine profiling. Twenty patients, ages 5.4 to 34.6 years, with B-ALL received CD19.22.BBζ. The complete response (CR) rate was 60% (12 of 20) in the full cohort and 71.4% (10 of 14) in CAR-naïve patients. Ten (50%) developed cytokine release syndrome (CRS), with 3 (15%) having ≥ grade 3 CRS and only 1 experiencing neurotoxicity (grade 3). The 6- and 12-month RFS in those achieving CR was 80.8% (95% confidence interval [CI]: 42.4%-94.9%) and 57.7% (95% CI: 22.1%-81.9%), respectively. Limited CAR T-cell expansion and persistence of MSCV-CD19.22.BBζ compared with EF1α-CD22.BBζ prompted laboratory investigations comparing EF1α vs MSCV promoters, which did not reveal major differences. Limited CD22 targeting with CD19.22.BBζ, as evaluated by ex vivo cytokine secretion and leukemia eradication in humanized mice, led to development of a novel bicistronic CD19.28ζ/CD22.BBζ construct with enhanced cytokine production against CD22. With demonstrated safety and efficacy of CD19.22.BBζ in a heavily pretreated CAYA B-ALL cohort, further optimization of combinatorial antigen targeting serves to overcome identified limitations (www.clinicaltrials.gov #NCT03448393).

Characterization of HLH-like manifestations as a CRS variant in patients receiving CD22 CAR T cells.

Chimeric antigen receptor (CAR) T-cell toxicities resembling hemophagocytic lymphohistiocytosis (HLH) occur in a subset of patients with cytokine release syndrome (CRS). As a variant of conventional CRS, a comprehensive characterization of CAR T-cell-associated HLH (carHLH) and investigations into associated risk factors are lacking. In the context of 59 patients infused with CD22 CAR T cells where a substantial proportion developed carHLH, we comprehensively describe the manifestations and timing of carHLH as a CRS variant and explore factors associated with this clinical profile. Among 52 subjects with CRS, 21 (40.4%) developed carHLH. Clinical features of carHLH included hyperferritinemia, hypertriglyceridemia, hypofibrinogenemia, coagulopathy, hepatic transaminitis, hyperbilirubinemia, severe neutropenia, elevated lactate dehydrogenase, and occasionally hemophagocytosis. Development of carHLH was associated with preinfusion natural killer(NK) cell lymphopenia and higher bone marrow T-cell:NK cell ratio, which was further amplified with CAR T-cell expansion. Following CRS, more robust CAR T-cell and CD8 T-cell expansion in concert with pronounced NK cell lymphopenia amplified preinfusion differences in those with carHLH without evidence for defects in NK cell mediated cytotoxicity. CarHLH was further characterized by persistent elevation of HLH-associated inflammatory cytokines, which contrasted with declining levels in those without carHLH. In the setting of CAR T-cell mediated expansion, clinical manifestations and immunophenotypic profiling in those with carHLH overlap with features of secondary HLH, prompting consideration of an alternative framework for identification and management of this toxicity profile to optimize outcomes following CAR T-cell infusion.

Influenza Antigens NP and M2 Confer Cross Protection to BALB/c Mice against Lethal Challenge with H1N1, Pandemic H1N1 or H5N1 Influenza A Viruses.

Influenza hemagglutinin (HA) is considered a major protective antigen of seasonal influenza vaccine but antigenic drift of HA necessitates annual immunizations using new circulating HA versions. Low variation found within conserved non-HA influenza virus (INFV) antigens may maintain protection with less frequent immunizations. Conserved antigens of influenza A virus (INFV A) that can generate cross protection against multiple INFV strains were evaluated in BALB/c mice using modified Vaccinia virus Ankara (MVA)-vectored vaccines that expressed INFV A antigens hemagglutinin (HA), matrix protein 1 (M1), nucleoprotein (NP), matrix protein 2 (M2), repeats of the external portion of M2 (M2e) or as tandem repeats (METR), and M2e with transmembrane region and cytoplasmic loop (M2eTML). Protection by combinations of non-HA antigens was equivalent to that of subtype-matched HA. Combinations of NP and forms of M2e generated serum antibody responses and protected mice against lethal INFV A challenge using PR8, pandemic H1N1 A/Mexico/4108/2009 (pH1N1) or H5N1 A/Vietnam/1203/2004 (H5N1) viruses, as demonstrated by reduced lung viral burden and protection against weight loss. The highest levels of protection were obtained with NP and M2e antigens delivered as MVA inserts, resulting in broadly protective immunity in mice and enhancement of previous natural immunity to INFV A.

Consequences of hemophagocytic lymphohistiocytosis-like cytokine release syndrome toxicities and concurrent bacteremia.

Serious bacterial infections (SBI) can lead to devastating complications with CD19 CAR T cells and cytokine release syndrome (CRS). Little is known about consequences of and risk factors for SBI with novel CAR T-cell constructs or with CRS complicated by HLH-like toxicities. We report on three patients with B-cell acute lymphoblastic leukemia treated with CD22 CAR T cells who developed SBI and CRS-associated HLH. Serum cytokine profiling revealed sustained elevations well beyond CRS resolution, suggesting ongoing systemic inflammation. Heightened inflammatory states converging with SBI contribute to poor outcomes, and recognition and prevention of extended inflammation may be needed to improve outcomes.

Evaluation of the AV7909 Anthrax Vaccine Toxicity in Sprague Dawley Rats Following Three Intramuscular Administrations.

AV7909 is a next-generation anthrax vaccine under development for post-exposure prophylaxis following suspected or confirmed Bacillus anthracis exposure, when administered in conjunction with the recommended antibacterial regimen. AV7909 consists of the FDA-approved BioThrax® vaccine (anthrax vaccine adsorbed) and an immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide adjuvant, CPG 7909. The purpose of this study was to evaluate the potential systemic and local toxicity of AV7909 when administered via repeat intramuscular injection to the right thigh muscle (biceps femoris) to male and female Sprague Dawley rats. The vaccine was administered on Days 1, 15, and 29 and the animals were assessed for treatment-related effects followed by a 2-week recovery period to evaluate the persistence or reversibility of any toxic effects. The AV7909 vaccine produced no apparent systemic toxicity based on evaluation of clinical observations, body weights, body temperature, clinical pathology, and anatomic pathology. Necrosis and inflammation were observed at the injection sites as well as in regional lymph nodes and adjacent tissues and were consistent with immune stimulation. Antibodies against B. anthracis protective antigen (PA) were detected in rats treated with the AV7909 vaccine, confirming relevance of this animal model for the assessment of systemic toxicity of AV7909. In contrast, sera of rats that received saline or soluble CPG 7909 alone were negative for anti-PA antibodies. Overall, 3 intramuscular immunizations of Sprague Dawley rats with AV7909 were well tolerated, did not induce mortality or any systemic adverse effects, and did not result in any delayed toxicity.

Phase I Clinical Trial of an Autologous Dendritic Cell Vaccine Against HER2 Shows Safety and Preliminary Clinical Efficacy.

BACKGROUND: Despite recent advances, there is an urgent need for agents targeting HER2-expressing cancers other than breast cancer. We report a phase I study (NCT01730118) of a dendritic cell (DC) vaccine targeting HER2 in patients with metastatic cancer or bladder cancer at high risk of relapse. PATIENTS AND METHODS: Part 1 of the study enrolled patients with HER2-expressing metastatic cancer that had progressed after at least standard treatment and patients who underwent definitive treatment for invasive bladder cancer with no evidence of disease at the time of enrollment. Part 2 enrolled patients with HER2-expressing metastatic cancer who had progressed after anti-HER2 therapy. The DC vaccines were prepared from autologous monocytes and transduced with an adenoviral vector expressing the extracellular and transmembrane domains of HER2 (AdHER2). A total of five doses were planned, and adverse events were recorded in patients who received at least one dose. Objective response was evaluated by unidimensional immune-related response criteria every 8 weeks in patients who received at least two doses. Humoral and cellular immunogenicity were assessed in patients who received more than three doses. RESULTS: A total of 33 patients were enrolled at four dose levels (5 × 106, 10 × 106, 20 × 106, and 40 × 106 DCs). Median follow-up duration was 36 weeks (4-124); 10 patients completed five doses. The main reason for going off-study was disease progression. The main adverse events attributable to the vaccine were injection-site reactions. No cardiac toxicity was noted. Seven of 21 evaluable patients (33.3%) demonstrated clinical benefit (1 complete response, 1 partial response, and 5 stable disease). After ≥3 doses, an antibody response was detected in 3 of 13 patients (23.1%), including patients with complete and partial responses. Lymphocytes from 10 of 11 patients (90.9%) showed induction of anti-HER2 responses measured by the production of at least one of interferon-gamma, granzyme B, or tumor necrosis factor-alpha, and there were multifunctional responses in 8 of 11 patients (72.7%). CONCLUSIONS: The AdHER2 DC vaccine showed evidence of immunogenicity and preliminary clinical benefit in patients with HER2-expressing cancers, along with an excellent safety profile. It shows promise for further clinical applications, especially in combination regimens.

Enhanced early innate and T cell-mediated responses in subjects immunized with Anthrax Vaccine Adsorbed Plus CPG 7909 (AV7909).

NuThrax™ (Anthrax Vaccine Adsorbed with CPG 7909 Adjuvant) (AV7909) is in development. Samples obtained in a phase Ib clinical trial were tested to confirm biomarkers of innate immunity and evaluate effects of CPG 7909 (PF-03512676) on adaptive immunity. Subjects received two intramuscular doses of commercial BioThrax(®) (Anthrax Vaccine Adsorbed, AVA), or two intramuscular doses of one of four formulations of AV7909. IP-10, IL-6, and C-reactive protein (CRP) levels were elevated 24-48 h after administration of AV7909 formulations, returning to baseline by Day 7. AVA (no CPG 7909) resulted in elevated IL-6 and CRP, but not IP-10. Another marker of CpG, transiently decreased absolute lymphocyte counts (ALCs), correlated with transiently increased IP-10. Cellular recall responses to anthrax protective antigen (PA) or PA peptides were assessed by IFN-γ ELISpot assay performed on cryopreserved PBMCs obtained from subjects prior to immunization and 7 days following the second immunization (study day 21). One-half of subjects that received AV7909 with low-dose (0.25mg/dose) CPG 7909 possessed positive Day 21 T cell responses to PA. In contrast, positive T cell responses occurred at an 11% average rate (1/9) for AVA-treated subjects. Differences in cellular responses due to dose level of CPG 7909 were not associated with differences in humoral anti-PA IgG responses, which were elevated for recipients of AV7909 compared to recipients of AVA. Serum markers at 24 or 48 h (i.e. % ALC decrease, or increase in IL-6, IP-10, or CRP) correlated with the humoral (antibody) responses 1 month later, but did not correlate with cellular ELISpot responses. In summary, biomarkers of early responses to CPG 7909 were confirmed, and adding a CpG adjuvant to a vaccine administered twice resulted in increased T cell effects relative to vaccine alone. Changes in early biomarkers correlated with subsequent adaptive humoral immunity but not cellular immunity.

TLR7 agonist 852A inhibition of tumor cell proliferation is dependent on plasmacytoid dendritic cells and type I IFN.

Antitumor effects of the toll-like receptor 7 (TLR7) agonist, 852A, were evaluated. Supernatants from human peripheral blood mononuclear cells (PBMC) stimulated with 852A inhibited the proliferation of tumor cell lines Hs294T and 769-P but had no effect on others (786-O and Caki-1). Because addition of 852A directly to the Hs294T cells did not inhibit their proliferation, the mechanism(s) of inhibition of tumor cell proliferation was investigated. Low nanomolar concentrations of 852A stimulated the production of interferon-alpha (IFN-alpha), IFN-inducible protein-10 (IP-10), interleukin-1 receptor antagonist (IL-1Ra), monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) from human PBMCs. Cytokines stimulated by submicromolar concentrations of 852A were sufficient to inhibit Hs294T proliferation. At higher concentrations (3-30 microM), 852A induced the production of IL-12p70, IL-18, and IFN-gamma. PBMC cultures depleted of plasmacytoid dendritic cells (pDC) did not produce IFN-alpha, and their conditioned medium did not inhibit Hs294T proliferation. Anti-IFN-alpha/beta receptor (IFNAR) and anti-IFN-alpha antibodies partially abrogated Hs294T proliferation inhibition by 852A-stimulated PBMC supernatants, whereas separate neutralization of TRAIL, tumor necrosis factor-alpha (TNF-alpha, IFN-gamma, IFN-beta, or IFN-omega had no effect. In vivo, six doses of 852A administration significantly delayed the onset of lung colonies in a B16 melanoma model. Thus, the results demonstrate that the TLR7 agonist 852A inhibits in vitro proliferation of some tumor cells in a pDC-dependent and IFN-alpha-dependent manner and can delay tumor growth in vivo.

TLR-TLR cross talk in human PBMC resulting in synergistic and antagonistic regulation of type-1 and 2 interferons, IL-12 and TNF-alpha.

Currently, single TLR agonists are being utilized for vaccination and tumor immunotherapy. Here we investigated the effects of tandem combinations of TLR agonists on the production of cytokines with major focus on IFN-alpha, -beta, -gamma, TNF-alpha, and IL-12. Using a primary human PBMC culture system, we found that tandem combinations of TLR2-9 agonists can be inert, additive, synergistic or antagonistic. The most interesting combination was TLR2 or TLR4 agonists in combination with TLR7/8 or TLR8 agonists. TLR4-TLR7/8 combinations synergistically up-regulated IFN-gamma and IL-12, enhanced IFN-alpha and also moderately induced TNF-alpha. TLR2-TLR7/8 like TLR4-TLR7/8 synergistically up-regulated IFN-gamma but not IL-12. TLR9 agonist CpG2216 produced high IFN-alpha but failed to up regulate IFN-gamma singly or in tandem. Furthermore, TLR9-induced type-1 IFN was down regulated in combination with TLR7, or TLR8 agonists. TLR3 induced significant IFN-alpha/-beta responses when used in a complex with membrane permeability enhancer DOTAP, and additively enhanced response with agonists to TLR2, 5, 7/8, and 8. To our knowledge, this study is the first to compare cytokine responses of all the possible tandem combinations of TLR agonists in human PBMC. We identified certain combinations of TLR agonists that may or may not have advantages over single agonists, for generating an "optimal cytokine combination" preferred in combating diseases.

Apoptotic responses in squamous carcinoma and epithelial cells to small-molecule toll-like receptor agonists evaluated with automated cytometry.

The authors describe an assay to quantitate DNA fragmentation using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) stain, adapted to a 96-well microplate format for adherent cells, and an automated high-content screening imager. The apoptotic responses to actinomycin D (a known antineoplastic agent) to imiquimod (a small-molecule toll-like receptor [TLR] 7 agonist used in skin cancer treatment) and to several structurally related TLR 7/8 agonists were evaluated in squamous carcinoma SCC15 and SCC25 cells and normal human keratinocytes. Potent proapoptotic and growth-impairing (as determined by reduced cell numbers) actions of actinomycin D (1-300 ng/mL) were discerned with the assay. Consistent with previous reports, imiquimod (at 300 microM; approximately 75 microg/mL) induced TUNEL positivity of malignant cell cultures, but this effect also occurred in normal keratinocytes. Two related TLR agonists induced apoptosis at lower concentrations. However, the concentrations of these and the imiquimod necessary to elicit cancer cell apoptosis were 300 to 1000 times higher relative to their ability to induce the secretion of an antineoplastic protein, interferon-alpha, from human blood monocytes. This TUNEL analysis allows the quantitative comparison of compounds' apoptotic activity toward adherent malignant and normal cells and may be useful for hit characterization after a screen.

Toll-like receptor (TLR) 2-9 agonists-induced cytokines and chemokines: I. Comparison with T cell receptor-induced responses.

The cells of innate and adaptive immunity, although activated by different ligands, engage in cross talk to ensure a successful immune outcome. To better understand this interaction, we examined the demographic picture of individual TLR (TLRs 2-9) -driven profiles of eleven cytokines (IFN-alpha/beta, IFN-gamma, IL-12p40/IL-12p70, IL-4, 1L-13, TNF-alpha, IL-1beta, IL-2, IL-10) and four chemokines (MCP-1, MIP1beta, IL-8, and RANTES), and compared them with direct T-cell receptor triggered responses in an assay platform using human PBMCs. We find that T-cell activation by a combination of anti-CD3/anti-CD28/PHA induced a dominant IL-2, IL-13, and Type-II interferon (IFN-gamma) response without major IL-12 and little Type-I interferon (IFN-alphabeta) release. In contrast, TLR7 and TLR9 agonists induced high levels of Type-I interferons. The highest IFN-gamma levels were displayed by TLR8 and TLR7/8 agonists, which also induced the highest levels of pro-inflammatory cytokines IL-12, TNF-alpha, and IL-1beta. Amongst endosomal TLRs, TLR7 displayed a unique profile producing weak IL-12, IFN-gamma, TNF-alpha, IL-1beta, and IL-8. TLR7 and TLR9 resembled each other in their cytokine profile but differed in MIP-1beta and MCP1 chemokine profiles. Gram positive (TLR2, TLR2/6) and gram negative (TLR4) pathogen-derived TLR agonists displayed significant similarities in profile, but not in potency. TLR5 and TLR2/6 agonists paralleled TLR2 and TLR4 in generating pro-inflammatory chemokines MCP-1, MIP-1beta, RANTES, and IL-8 but yielded weak TNF-alpha and IL-1 responses. Taken together, the data show that diverse TLR agonists, despite their operation through common pathways induce distinct cytokine/chemokine profiles that in turn have little or no overlap with TCR-mediated response.