Search results for "Immune System"

Generation of monoclonal antibodies against human regulatory T cells.

2009

Abstract Natural CD4 + CD25 + Foxp3 + regulatory T cells (Tregs) control the activation of the immune system and therefore have become a major area of research in immunology. The generation of monoclonal antibodies against human Tregs offers the possibility to discover novel Treg-specific or Treg-associated surface markers and to identify targets for a therapeutic modulation of Tregs. Here we present a methodology optimized to efficiently induce and select mAb against human Tregs by repeated immunization of mice with Tregs from a single donor and a differential two-step flow cytometry-based hybridoma screening procedure.

Peptides of the Constant Region of Antibodies Display Fungicidal Activity

2012

Synthetic peptides with sequences identical to fragments of the constant region of different classes (IgG, IgM, IgA) of antibodies (Fc-peptides) exerted a fungicidal activity in vitro against pathogenic yeasts, such as Candida albicans, Candida glabrata, Cryptococcus neoformans, and Malassezia furfur, including caspofungin and triazole resistant strains. Alanine-substituted derivatives of fungicidal Fc-peptides, tested to evaluate the critical role of each residue, displayed unaltered, increased or decreased candidacidal activity in vitro. An Fc-peptide, included in all human IgGs, displayed a therapeutic effect against experimental mucosal and systemic candidiasis in mouse models. It is in…

Antifungal drugs influence neutrophil effector functions

2019

There is a growing body of evidence for immunomodulatory side effects of antifungal agents on different immune cells, e.g., T cells. Therefore, the aim of our study was to clarify these interactions with regard to the effector functions of polymorphonuclear neutrophils (PMN). Human PMN were preincubated with fluconazole (FLC), voriconazole (VRC), posaconazole (POS), isavuconazole (ISA), caspofungin (CAS), micafungin (MFG), conventional amphotericin B (AMB), and liposomal amphotericin B (LAMB). PMN then were analyzed by flow cytometry for activation, degranulation, and phagocytosis and by dichlorofluorescein assay to detect reactive oxygen species (ROS). Additionally, interleukin-8 (IL-8) re…

Candida biofilms on implanted biomaterials: a clinically significant problem.

2006

In recent years there has been an increasing appreciation that microbial biofilms are ubiquitous, which has resulted in a number of studies on infectious diseases from a biofilm perspective. Biofilms are defined as structured microbial communities that are attached to a surface and encased in a matrix of exopolymeric material. A wide range of biomaterials used in clinical practice have been shown to support colonization and biofilm formation by Candida spp., and the increase in Candida infections in the last decades has almost paralleled the increase and widespread use of a broad range of medical implant devices, mainly in populations with impaired host defenses. Formation of Candida biofil…

Induction of tolerogenic DCs: ‘you are what you eat’

2003

Abstract Dendritic cells (DCs) take up antigens using antigen receptors that can be divided into three major classes: C-type lectins, integrins and Fc receptors. These receptors facilitate effective presentation of MHC–peptide complexes to T cells, resulting in the induction of immune responses. However, we discuss recent evidence that some receptors also cause induction of tolerance. Signaling motifs within the receptors either block maturation of DCs or induce signals that render DCs tolerogenic. These DCs then either induce regulatory T cells or cause deletion of effector T cells, resulting in the induction of tolerance. Antigen receptors expressed by DCs might therefore have an importan…

Tumor Recognition by the Cellular Immune System: New Aspects of Tumor Immunology

1997

Targeting p53, hdm2, and CD19: vaccination and immunologic strategies.

2000

Peptides presented by class I major histocompatibility complex (MHC) molecules and derived from normal self-proteins that are expressed at elevated levels by cells from a variety of human (Hu) malignancies provide, in theory, potential target antigens for a broad-spectrum, cytotoxic T lymphocyte (CTL)-based immunotherapy of cancer and hematologic malignancies. However, as such tumor- and leukemia-associated self-proteins are also expressed at low levels in some types of normal tissues, such as thymus, spleen and lymphohemopoietic cells, these self-MHC-self-peptide complexes may also represent thymic and/or peripheral tolerogens, thereby preventing immune responses. This is particularly true…

In vivo γδ T Cell Priming to Mycobacterial Antigens by Primary Mycobacterium tuberculosis Infection and Exposure to Nonpeptidic Ligands

1999

The recognition of phosphorylated nonpeptidic microbial metabolites by Vγ9Vδ2 T cells does not appear to require the presence of MHC molecules or antigen processing, permitting rapid responses against microbial pathogens. These may constitute an important area of natural anti-infectious immunity. To provide evidence of their involvement in immune reactivities against mycobacteria, we measured the responsiveness of peripheral blood Vγ9Vδ2 T cells in children with primary Mycobacterium tuberculosis (MTB) infections. Peripheral blood mononuclear cells from 22 children with MTB infections and 16 positivity of tuberculin (PPD)-negative healthy children were exposed to nonpeptidic antigens in vit…

Separation of T-cell-stimulating activity from streptococcal M protein

1992

The superantigenic properties of M protein type 5 of Streptococcus pyogenes have been implicated as an important pathogenicity factor in streptococcal autoimmune diseases. Here we show that after a single purification step by affinity chromatography on immobilized albumin or fibrinogen, M protein has no mitogenic activity for T cells. We demonstrate that the superantigenicity of M proteins of type 5 and type 1 is due to contamination with the highly potent pyrogenic exotoxins of S. pyogenes in the range of 0.1 to 0.01%. These results raise a general caveat for work with these extremely active T-cell mitogens, because the mitogenicity of other streptococcal or staphylococcal proteins could b…

Stress protein/peptide complexes derived from autologous tumor tissue as tumor vaccines.

1999

Vaccination of inbred mice with tumor-derived stress proteins hsp70, hsp90, and gp96/grp94 elicits a protective immunity to the tumor from which the vaccine was purified. There is now comprehensive experimental evidence that the antigenicity of tumor-derived hsp70, hsp90, and gp96 preparations results from diverse arrays of endogenous peptide antigens complexed with these stress proteins. Vaccination with tumor-derived stress protein/peptide complexes leads to their uptake and processing by professional antigen-presenting cells and to presentation of associated tumor peptide antigens to cytotoxic T cells. This induces a tumor-specific cytotoxic T cell response. The attractiveness of the con…