Formation of Immune Complexes with a Tetanus-Derived B Cell Epitope Boosts Human T Cell Responses to Covalently Linked Peptides in an Ex Vivo Blood Loop System.

Enhancing T cell responses against both viral and tumor Ags requires efficient costimulation and directed delivery of peptide Ags into APCs. Long peptide vaccines are considered favorable vaccine moieties from a clinical perspective, as they can harbor more than one immunogenic epitope enabling treatment of a broader target population. In addition, longer peptides are not extracellularly loaded on MHC class I; rather, they require intracellular processing and will thereby be presented to T cells mainly by professional APCs, thereby avoiding the risk of tolerance induction.

A Restricted Role for FcγR in the Regulation of Adaptive Immunity.

By their interaction with IgG immune complexes, FcγR and complement link innate and adaptive immunity, showing functional redundancy. In complement-deficient mice, IgG downstream effector functions are often impaired, as well as adaptive immunity. Based on a variety of model systems using FcγR-knockout mice, it has been concluded that FcγRs are also key regulators of innate and adaptive immunity; however, several of the model systems underpinning these conclusions suffer from flawed experimental design.

Linking T cell epitopes to a common linear B cell epitope: A targeting and adjuvant strategy to improve T cell responses.

Immune complexes are potent mediators of cellular immunity and have been extensively studied for their disease mediating properties in humans and for their role in anti-cancer immunity. However, a viable approach to use antibody-complexed antigen as vehicle for specific immunotherapy has not yet reached clinical use. Since virtually all people have endogenous antibodies against tetanus toxoid (TTd), such commonly occurring antibodies are promising candidates to utilize for immune modulation.

IgG-mediated anaphylaxis to a synthetic long peptide vaccine containing a B cell epitope can be avoided by slow-release formulation.

Synthetic long peptides (SLP) are a promising vaccine modality to induce therapeutic T cell responses in patients with chronic infections and tumors. We studied different vaccine formulations in mice using SLP derived from carcinoembryonic Ag. We discovered that one of the SLP contains a linear Ab epitope in combination with a CD4 epitope.

Circulating specific antibodies enhance systemic cross-priming by delivery of complexed antigen to dendritic cells in vivo.

Increasing evidence suggests that antibodies can have stimulatory effects on T-cell immunity. However, the contribution of circulating antigen-specific antibodies on MHC class I cross-priming in vivo has not been conclusively established. Here, we defined the role of circulating antibodies in cross-presentation of antigen to CD8(+) T cells.

Antigen localization controls T cell-mediated tumor immunity.

Effective antitumor immunotherapy requires the identification of suitable target Ags. Interestingly, many of the tumor Ags used in clinical trials are present in preparations of secreted tumor vesicles (exosomes). In this study, we compared T cell responses elicited by murine MCA101 fibrosarcoma tumors expressing a model Ag at different localizations within the tumor cell in association with secreted vesicles (exosomes), as a nonsecreted cell-associated protein, or as secreted soluble protein.

Multifaceted effects of synthetic TLR2 ligand and Legionella pneumophilia on Treg-mediated suppression of T cell activation.

Background: Regulatory T cells (Treg) play a crucial role in maintaining immune homeostasis and self-tolerance. The immune suppressive effects of Tregs should however be limited in case effective immunity is required against pathogens or cancer cells. We previously found that the Toll-like receptor 2 (TLR2) agonist, Pam3CysSK4, directly stimulated Tregs to expand and temporarily abrogate their suppressive capabilities.

Differential Toll-like receptor recognition and induction of cytokine profile by Bifidobacterium breve and Lactobacillus strains of probiotics.

The use of probiotics as a food supplement has gained tremendous interest in the last few years as beneficial effects were reported in gut homeostasis and nutrient absorption but also in immunocompromised patients, supporting protection from colonization or infection with pathogenic bacteria or fungi. As a treatment approach for inflammatory bowel diseases, a suitable probiotic strain would ideally be one with a low immunogenic potential. Insight into the immunogenicities and types of T-cell responses induced by potentially probiotic strains allows a more rational selection of a particular strain.

Dynamics of human respiratory virus-specific CD8+ T cell responses in blood and airways during episodes of common cold.

We determined the dynamics of CD8(+) T cells specific for influenza virus and respiratory syncytial virus in blood and tracheostoma aspirates of children during the course of respiratory infections. We showed that during localized respiratory infections the ratio of activated effector CD8(+) T cells to resting memory/naive CD8(+) T cells in peripheral blood increased significantly. Furthermore, the number of effector/memory T cells specific for respiratory viruses declined in blood and increased in the airways, suggesting that these T cells redistributed from blood to airways.

Toll-like receptor signalling on Tregs: to suppress or not to suppress?

To balance self-tolerance and immunity against pathogens or tumours, the immune system depends on both activation mechanisms and down-regulatory mechanisms. Immunologists have long been focusing on activation mechanisms, and a major breakthrough was the identification of the Toll-like receptor (TLR) family of proteins. TLRs recognize conserved molecular patterns present on pathogens, including bacteria, viruses, fungi and protozoa.

Elimination of regulatory T cells is essential for an effective vaccination with tumor lysate-pulsed dendritic cells in a murine glioma model.

Both melanoma and glioma cells are of neuroectodermal origin and share common tumor associated antigens. In this article, we report that the melanocyte differentiation antigen TRP2 (tyrosinase-related protein 2) is not predominantly involved in the tumor rejection of a syngeneic murine glioma. Although GL261 glioma cells endogenously expressed TRP2 and were lysed by TRP2 specific cytotoxic T cells (CTLs) in vitro, vaccinations with TRP2 peptide-pulsed dendritic cells (DCs) could only induce minor antiglioma responses in a prophylactic setting and failed to work in a stringent setting where vaccine and tumor were administered on the same day.

CD8+ T cell responses in bronchoalveolar lavage fluid and peripheral blood mononuclear cells of infants with severe primary respiratory syncytial virus infections.

A protective role for CD8+ T cells during viral infections is generally accepted, but little is known about how CD8+ T cell responses develop during primary infections in infants, their efficacy, and how memory is established after viral clearance. We studied CD8+ T cell responses in bronchoalveolar lavage (BAL) samples and blood of infants with a severe primary respiratory syncytial virus (RSV) infection. RSV-specific CD8+ T cells with an activated effector cell phenotype: CD27+CD28+CD45RO+CCR7-CD38+HLA-DR+Granzyme B+CD127- could be identified in BAL and blood.

Human CD8(+) T cell responses against five newly identified respiratory syncytial virus-derived epitopes.

CD8(+) T lymphocytes play a major role in the clearance of respiratory syncytial virus (RSV) infections. To be able to study the primary CTL response in RSV-infected children, epitopes presented by a set of commonly used HLA alleles (HLA-A1, -A3, -B44 and -B51) were searched for. Five epitopes were characterized derived from the matrix (M), non-structural (NS2) and second matrix (M2) proteins of RSV.