Search results for "Langerhans cells"

Contact Allergens Modulate the Expression of MHC Class II Molecules on Murine Epidermal Langerhans Cells by Endocytotic Mechanisms

1992

MHC class II molecules play an important role during the sensitization phase of allergic contact dermatitis. To study the influence of contact allergens on the expression of these molecules by murine epidermal Langerhans cells (LC), we performed a flow-cytofluorometric analysis of the Ia-antigen expression after in vivo application of contact allergens. A distinct decrease in the Ia-antigen expression of the entire LC population was noticed 3 h after in vivo application of the contact allergen 2,4-dinitrofluorobenzene (DNFB). This decrease was transient and balanced 24 h after in vivo application of DNFB. A downregulation was also detectable after in vivo application of the contact allergen…

Biochemical properties of MHC class II molecules endogenously synthesized and expressed by mouse Langerhans cells

1991

The cell surface expression and biosynthesis of Langerhans cells (LC)-derived major histocompatibility complex (MHC) class II molecules from epidermal cells (EC) prepared freshly and cultured for up to 3 days was investigated. Based on the constitutive expression of MHC class II determinants by LC, a panning and magnetic bead selection procedure was employed, yielding 65% and 86% of I-A+ cells, respectively. Phenotypical and cytochemical examinations revealed that the two LC preparations were free of contaminating macrophages as well as B and T cells. Freshly prepared enriched LC were highly efficient in the stimulation of protein antigen-specific T cell clones, while LC purified from short…

Human Epidermal Langerhans Cells Replenish Skin Xenografts and Are Depleted by Alloreactive T Cells In Vivo

2011

Abstract Epidermal Langerhans cells (LC) are potent APCs surveying the skin. They are crucial regulators of T cell activation in the context of inflammatory skin disease and graft-versus-host disease (GVHD). In contrast to other dendritic cell subtypes, murine LC are able to reconstitute after local depletion without the need of peripheral blood-derived precursors. In this study, we introduce an experimental model of human skin grafted to NOD-SCID IL2Rγnull mice. In this model, we demonstrate that xenografting leads to the transient loss of LC from the human skin grafts. Despite the lack of a human hematopoietic system, human LC repopulated the xenografts 6 to 9 wk after transplantation. By…

Contact sensitizers modulate mechanisms of receptor-mediated endocytosis but not fluid-phase endocytosis in murine epidermal Langerhans cells.

1995

In order to define the influence of contact allergens on the fluid-phase endocytosis (FPE) of soluble molecules of murine epidermal Langerhans cells (LC), we studied the internalization of FITC-labeled bovine serum albumin (FITC-BSA), TRITC-labeled dextrane (TRITC-DEX) as well as horseradish peroxidase by LC. A 3-parameter flow-cytometric technique was performed for quantification of internalized FITC-BSA in LC using quantum red-labeled reagents for detection of la-antigen expression by LC and propidium iodide for exclusion of dead cells from analysis. A temperature-dependent rapid accumulation of FITC-BSA was noticed in time-course studies reaching a plateau between 1 and 2 h of in vitro c…

An approach to predictive testing of contact sensitizers in vitro by monitoring their influence on endocytotic mechanisms.

1996

Endocytotic activation of epidermal Langerhans cells (LC) by immunogenic haptens is an early event during development of allergic contact dermatitis. In this work a fast and objective flow-cytometric assay for predictive in vitro testing of contact sensitizers by monitoring their influence on endocytotic mechanisms in murine LC was developed. Epidermal cell suspensions were labelled with a monoclonal antibody directed to MHC class II molecules and pH-sensitive fluorochrome-coupled second-step reagents. For untreated LC a significant quenching of fluorescence intensity by internalization of the MHC-antibody complexes into acidic compartments was noticed. Similar results were obtained in the …

Non-coordinate synthesis of MHC class II proteins and invariant chains by epidermal Langerhans cells derived from short-term in vitro culture

1994

Epidermal cells (EC) prepared from Lewis rat skin contained 2-3% class II+, LCA+ Langerhans cells (LC). LC enriched from freshly isolated EC suspensions proved highly effective accessory cells when presenting the nominal antigen OVA to an RT1.Bl-restricted ovalbumin (OVA)-specific rat T cell clone. Short-term preculture of the EC resulted in diminished OVA presenting capacity of the LC. Flow cytometry (FCM) analysis of class II and gamma chain expression revealed an up-regulation of class II on the LC's cell surface, consistent with earlier findings in mouse and human. However, while the presence of gamma chains in mouse LC was reported to decline to negligible levels during culture we obse…

In vitro analysis of the phenotypical and functional properties of the 4F7+ cutaneous accessory dendritic cell

1995

The monoclonal antibody 4F7 detects a molecule on dermal and epidermal Ia+ dendritic cells (DCs), and some of these cells are Birbeck granule-containing cells. Here we report on the phenotypical and functional characteristics of these cells which were highly enriched by 4F7-labelled immunomagnetic beads. The ultrastructural, immunocytochemical and cytochemical analyses of these preparations showed cells with the typical characteristics of DCs. The cells were found to express the DC marker NLDC145, but not 33D1. The C3bi receptor and marker F4/80 were only expressed by epidermal 4F7+ cells. The capacity of freshly isolated 4F7+ epidermal and dermal DCs to activate allogeneic T cells in a mix…

Involvement of NO in contact hypersensitivity.

1998

The NO synthases (NOS) generate NO from L-arginine. High concentrations of NO have been shown to be responsible for tissue injury and cell death, while low concentrations of NO induce vasodilatation and other signaling effects. We have investigated the involvement of NO in contact hypersensitivity (CHS) reactions. CHS induced by treatment of BALB/c mice with the contact allergen 2,4-dinitrofluorobenzene (DNFB) was significantly reduced by the NOS inhibitor N-methyl-L-arginine (L-NMA), but not by the stereoisomer D-NMA, as shown by reduced ear swelling responses and evaluation of ear tissue sections. The CHS response was also reduced by aminoguanidine, which is known to preferentially inhibi…

Priming of Leishmania-Reactive CD8+ T cells In Vivo Does Not Require LMP7-Containing Immunoproteasomes

2012

UV Exposure Boosts Transcutaneous Immunization and Improves Tumor Immunity: Cytotoxic T-Cell Priming through the Skin

2010

Immunologic approaches to combat cancer aim at the induction of tumor-reactive immune responses to achieve long-term protection. In this context, we recently developed a transcutaneous immunization (TCI) method using the Toll-like receptor (TLR) 7 agonist imiquimod and a peptide epitope. Application onto intact skin induces potent cytotoxic T lymphocyte (CTL) responses and protection against transplanted tumors. The purpose of this study was to explore the effects of UV irradiation on imiquimod-based TCI. Here we show that skin exposure to low-dose UV light before TCI with imiquimod strongly boosts specific CTL responses leading to memory formation and enhanced tumor protection. Toward the …