Search results for "Histocompatibility Antigens"
showing 10 items of 242 documents
Augmented antigen presentation by mouse Ia + T clone cells BK-BI-2.6.O4.1 mediated by transferrin receptors.
1996
The murine T clone cells BK-BI-2.6.O4.1 (BI/O4.1) synthesize and express MHC class II molecules constitutively. BI/O4.1 cells are able to present various protein antigens to antigen-specific CD4 + T cells. However, a 10-fold higher concentration of antigen is needed to activate specific T cells to lymphokine secretion by BI/O4.1 cells in comparison with spleen cells or with the more homogeneous population of bone marrow-derived macrophages (BMMph). The authors tested whether the reduced antigen presentation potential of BI/O4.1 cells was augmented by transferrin-mediated uptake of the model antigen ovalbumin (OVA) coupled to human ferric transferrin. It was shown that 240-fold less OVA was …
Isolation and Characterization of CD276+/HLA-E+ Human Subendocardial Mesenchymal Stem Cells from Chronic Heart Failure Patients: Analysis of Differen…
2012
Mesenchymal stem cells (MSCs) are virtually present in all postnatal organs as well as in perinatal tissues. MSCs can be differentiated toward several mature cytotypes and interestingly hold potentially relevant immunomodulatory features. Myocardial infarction results in severe tissue damage, cardiomyocyte loss, and eventually heart failure. Cellular cardiomyoplasty represents a promising approach for myocardial repair. Clinical trials using MSCs are underway for a number of heart diseases, even if their outcomes are hampered by low long-term improvements and the possible presence of complications related to cellular therapy administration. Therefore, elucidating the presence and role of MS…
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…
Acquired IFNγ resistance impairs anti-tumor immunity and gives rise to T-cell-resistant melanoma lesions
2016
Melanoma treatment has been revolutionized by antibody-based immunotherapies. IFNγ secretion by CD8+ T cells is critical for therapy efficacy having anti-proliferative and pro-apoptotic effects on tumour cells. Our study demonstrates a genetic evolution of IFNγ resistance in different melanoma patient models. Chromosomal alterations and subsequent inactivating mutations in genes of the IFNγ signalling cascade, most often JAK1 or JAK2, protect melanoma cells from anti-tumour IFNγ activity. JAK1/2 mutants further evolve into T-cell-resistant HLA class I-negative lesions with genes involved in antigen presentation silenced and no longer inducible by IFNγ. Allelic JAK1/2 losses predisposing to …
Enhanced in vivo targeting of murine nonparenchymal liver cells with monophosphoryl lipid A functionalized microcapsules.
2014
A broad spectrum of infectious liver diseases emphasizes the need of microparticles for targeted delivery of immunomodulatory substances to the liver. Microcapsules (MCs) are particularly attractive for innovative drug and vaccine formulations, enabling the combination of antigen, drugs, and adjuvants. The present study aimed to develop microcapsules characterized by an enhanced liver deposition and accelerated uptake by nonparenchymal liver cells (NPCs). Initially, two formulations of biodegradable microcapsules were synthesized from either hydroxyethyl starch (HES) or mannose. Notably, HES-MCs accumulated primarily in the liver, while mannose particles displayed a lung preference. Functio…
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…
µ-Calpain conversion of antiapoptotic Bfl-1 (BCL2A1) into a prodeath factor reveals two distinct alpha-helices inducing mitochondria-mediated apoptos…
2011
Anti-apoptotic Bfl-1 and pro-apoptotic Bax, two members of the Bcl-2 family sharing a similar structural fold, are classically viewed as antagonist regulators of apoptosis. However, both proteins were reported to be death inducers following cleavage by the cysteine protease µ-calpain. Here we demonstrate that calpain-mediated cleavage of full-length Bfl-1 induces the release of C-terminal membrane active α-helices that are responsible for its conversion into a pro-apoptotic factor. A careful comparison of the different membrane-active regions present in the Bfl-1 truncated fragments with homologous domains of Bax show that helix α5, but not α6, of Bfl-1 induces cell death and cytochrome c r…
Analysis of the MHC Class I Antigen Presentation Machinery in Human Embryonal Carcinomas: Evidence for Deficiencies in TAP, LMP and MHC Class I Expre…
1998
The expression of the major histocompatibility complex (MHC) class I antigens is suppressed in early post-implantation embryonic cells as well as in embryonal carcinoma (EC) cells, but could be upregulated by treatment with interferon (IFN)-gamma or retinoic acid. In a number of human and murine tumours, defects in the expression of the different components of the MHC class I antigen processing machinery, such as the proteasomal subunits LMP-2 and LMP-7 and the peptide transporters TAP-1 and TAP-2, account for impaired MHC class I surface expression. Here, we analysed the constitutive and IFN-gamma regulated mRNA and protein expression of the LMP, TAP and MHC class I molecules in the human …
Bipartite regulation of different components of the MHC class I antigen-processing machinery during dendritic cell maturation
2001
Dendritic cells (DC) are professional antigen-presenting cells (APC) which proceed from immature to a mature stage during their final differentiation. Immature DC are highly effective in terms of antigen uptake and processing, whereas mature DC become potent immunostimulatory cells. Until now, the expression profiles of the major components of the MHC class I antigen-processing machinery (APM) during DC development have not been well characterized. In this study, the mRNA and protein expression levels of the IFN-gamma inducible proteasome subunits, of the proteasome activators PA28, and of key components required for peptide transport and MHC class I-peptide complex assembly have been evalu…
Functional deficiencies of components of the MHC class I antigen pathway in human tumors of epithelial origin
2000
An association between oncogenic transformation and repression of different components of the MHC class I antigen processing machinery (APM) have been described in murine model systems. In order to discover whether a similar correlation exists, human tumor cell lines of distinct histology with altered ras protein were analyzed for the expression of APM components utilizing RT-PCR and Western blot analyses. A heterogeneous expression pattern of MHC class I antigens, TAP peptide transporter, proteasome subunits, proteasome activator PA28 and the chaperones calnexin, calreticulin as well as tapasin was displayed by these tumor cell lines. Single or combined deficiencies in the expression and/o…