Antigen mannosylation has been shown to be an effective approach to potentiate antigen immunogenicity, due to the enhanced antigen uptake and presentation by APC. To overcome disadvantages associated with conventional methods used to mannosylate antigens, we have developed a novel mannose-based antigen delivery system that utilizes a polyamidoamine (PAMAM) dendrimer. It is demonstrated that mannosylated dendrimer ovalbumin (MDO) is a potent immune inducer. With a strong binding avidity to DC, MDO potently induced OVA-specific T cell response in vitro. It was found that the immunogenicity of MDO was due not only to enhanced antigen presentation, but also to induction of DC maturation. Mice immunized with MDO generated strong OVA-specific CD4 + /CD8 + T cell and antibody responses. MDO also targeted lymph node DC to crosspresent OVA, leading to OTI CD8 + T cell proliferation. Moreover, upon challenge with B16-OVA tumor cells, tumors in mice pre-immunized with MDO either did not grow or displayed a much more delayed onset, and had slower kinetics of growth than those of OVA-immunized mice. This mannose-based antigen delivery system was applied here for the first time to the immunization study. With several advantages and exceptional adjuvanticity, we propose mannosylated dendrimer as a potential vaccine carrier.

Lung cancer is one of the most commonly reported cancers, and is known to be associated with a poor prognosis. The function of tumour-associated macrophages (TAMs) in lung cancer patients is multifaceted and the literature shows conflicting roles. (I) To analyze the Th1 and Th2 cytokine levels that contribute to the differentiation of M1 and M2 macrophage populations in the serum of patients with NSCLC versus non-cancer controls; and (II) To characterize the M1 and M2 macrophage populations within TAMs in different subtypes of NSCLC compared to non-tumour tissue. The Th1 and Th2 cytokine levels were analyzed in serum using the Bio-Plex assay. In addition, TAMs subsets from nontumour and tumour tissues were analyzed using immunohistochemistry (IHC). The level of IL-1β, IL-4, IL-6 and IL-8 was found to be increased in the serum of patients with large cell carcinoma but not in other NSCLC subtypes compared to non-cancer controls. In addition, the expression of CD68 and M2 marker CD163 was found to be increased (P≤0.0001) in all NSCLC subtypes compared to non-tumour tissues. In contrast, the expression of iNOS (M1 marker) was decreased in the tumour tissue of patients with adenocarcinoma (P≤0.01) and squamous carcinoma (P≤0.05) but not in large cell carcinoma compared to non-tumour tissue. The results of this study indicate that NSCLC might have the ability to alter phenotype within the lung tumour areas in the local environment (TAMs) but not in the bloodstream in the systemic environment (serum) except for large cell carcinoma.

SummaryMannan, a polysaccharide isolated from yeast binds to C-type lectins of the mannose receptor family, expressed by antigen-presenting cells (APCs) including dendritic cells (DCs) and macrophages. As these receptors mediate endocytosis, they have been targeted with ligands to deliver antigens into APCs to initiate immune responses. Immunization with tumour antigen MUC1 conjugated to oxidized mannan (OM) or reduced mannan (RM) induced differential immune responses in mice, and only mice immunized with OM-MUC1 elicited strong MUC1-specific cytotoxic T lymphocyte responses and protected mice from a MUC1 tumour challenge. In this study, the adjuvant effect of mannan and its derivatives including OM and RM, in comparison to lipopolysaccharide, on DCs were investigated. Mannan, OM and RM were capable of stimulating mouse bone marrow-derived DC in vitro, eliciting enhanced allogeneic T-cell proliferation and enhancing OTI/OTII peptide-specific T-cell responses. Injection of mice with mannan, OM and RM induced a mature phenotype of lymph node and splenic DCs. Analysis by reverse transcription-polymerase chain reaction indicated that Manna, OM and RM also stimulated up-regulation of inflammatory cytokines including interleukin-1b and tumour necrosis factor-a, and differential T helper 1 (Th1)/Th2 cytokines. Subsequent experiments demonstrated that activation of DCs was Toll-like receptor-4-dependent. The data presented here, together with evidence reported previously on OM and RM in induction of immune responses in vivo, suggest that OM and RM exert a dual capacity to target antigen to APCs as well as mature DCs.

CD37 is a leukocyte-specific protein belonging to the tetraspanin superfamily. Previously thought to be predominantly a B cell molecule, CD37 is shown in this study to regulate T cell proliferation. CD37-deficient (CD37−/−) T cells were notably hyperproliferative in MLR, in response to Con A, or CD3-TCR engagement particularly in the absence of CD28 costimulation. Hyperproliferation was not due to differences in memory to naive T cell ratios in CD37−/− mice, apoptosis, or TCR down-modulation. Division cycle analyses revealed CD37−/− T cells to enter first division earlier than wild-type T cells. Importantly, proliferation of CD37−/− T cells was preceded by enhanced early IL-2 production. We hypothesized CD37 to be involved in TCR signaling and this was supported by the observation that CD4/CD8-associated p56Lck kinase activity was increased in CD37−/− T cells. Remarkably, CD37 cross-linking on human T cells transduced signals that led to complete inhibition of CD3-induced proliferation. In the presence of CD28 costimulation, CD37 engagement still significantly reduced proliferation. Taken together, these results demonstrate a regulatory role for CD37 in T cell proliferation by influencing early events of TCR signaling.

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Introduction Mucin 1 (MUC1) is a high molecular weight glycoprotein overexpressed on adenocarcinoma cells and is a target for immunotherapy protocols. To date, clinical trials against MUC1 have included advanced cancer patients. Herein, we report a trial using early stage breast cancer patients and injection of oxidized mannan-MUC1.

Dendritic cells (DC) suffer a maturation defect following interaction with erythrocytes infected with malaria parasites and become unable to induce protective malaria liver-stage immunity. Here we show that, by contrast, maturation-arrested DC in vitro are capable of the successful induction of antigen-specific gamma interferon (IFN-␥) and interleukin 4 (IL-4) T-cell responses, antibody responses, and potent protection against lethal blood-stage malaria challenge in vivo. Similar results were found with DC pulsed with intact parasitized Plasmodium yoelii or Plasmodium chabaudi erythrocytes. Cross-strain protection was also induced. High levels of protection (80 to 100%) against lethal challenge were evident from 10 days after a single immunization and maintained up to 120 days. Interestingly, correlation studies versus blood-stage protection at different time points suggest that the immune effector mechanisms associated with protection could change over time. Antibody-independent, T-cell-and IL-12-associated protection was observed early after immunization, followed by antibody and IL-4-associated, IFN-␥-independent protection in long-term studies. These results indicate that DC, even when clearly susceptible to parasite-induced maturation defect effects in vitro, can be central to the induction of protection against blood-stage malaria in vivo.

In patients with IPF, breathing oxygen at FiO of 0.50 at rest seems safe. During exercise, oxygen improves exercise tolerance, alleviates exercise-induced hypoxaemia and reduces dyspnoea. A potential relationship between oxygen administration and improved skeletal muscle metabolism should be explored in future studies.