Search results for "Activation"
showing 10 items of 2079 documents
Perpetual proliferation of LYT-1 cells requires repetitive signals for IL-2 receptor induction by antigen-presenting cells.
1984
Abstract T cell lines with specificity for bovine insulin and ovalbumin were maintained by serial stimulation with antigen presented on irradiated syngeneic spleen cells, alternating 3 days later with subculture in IL-2 containing medium (CM). When the cultures were repetitively split in CM, with concomitant dilution of antigen-presenting cells, a gradual loss of proliferative capacity of the cells in the presence of CM was observed. Absorption studies revealed a 20-fold reduction of IL-2 receptors on the surface of T blasts assayed 12 days after antigenic stimulation as compared with day 5 blasts. This decrement in the number of IL-2 acceptor sites reflected an actual decrease in cell surf…
Characterization of lymphokine-mediated activation of macrophages for antigen presentation: studies with long-term cultured bone marrow-derived macro…
1984
In cultures of bone marrow (BM) supplemented with L cell-derived colony-stimulating factor a pure population of macrophages (M phi) differentiates, which can be further propagated with a doubling time of 3.8 days. "Young" BMM phi obtained on day 8 of culture were shown to act as antigen-presenting cells inducing the antigen-specific proliferation of the cloned T cell line ST2/K.9, whereas "old" M phi had lost this ability. However, at any time tested (up to 132 days) the presentation function of old BMM phi could be completely restored by pulsing the cells with lymphokines (LK). A duration of 11 hr for the LK-pulse was sufficient to trigger the M phi to exert an optimal presentation functio…
LFA-1 activity state on dendritic cells regulates contact duration with T cells and promotes T-cell priming.
2010
AbstractA key event in the successful induction of adaptive immune responses is the antigen-specific activation of T cells by dendritic cells (DCs). Although LFA-1 (lymphocyte function–associated antigen 1) on T cells is considered to be important for antigen-specific T-cell activation, the role for LFA-1 on DCs remains elusive. Using 2 different approaches to activate LFA-1 on DCs, either by deletion of the αL-integrin cytoplasmic GFFKR sequence or by silencing cytohesin-1–interacting protein, we now provide evidence that DCs are able to make use of active LFA-1 and can thereby control the contact duration with naive T cells. Enhanced duration of DC/T-cell interaction correlates inversely …
Coordinated Sumoylation and Ubiquitination Modulate EGF Induced EGR1 Expression and Stability
2011
Background Human early growth response-1 (EGR1) is a member of the zing-finger family of transcription factors induced by a range of molecular and environmental stimuli including epidermal growth factor (EGF). In a recently published paper we demonstrated that integrin/EGFR cross-talk was required for Egr1 expression through activation of the Erk1/2 and PI3K/Akt/Forkhead pathways. EGR1 activity and stability can be influenced by many different post-translational modifications such as acetylation, phosphorylation, ubiquitination and the recently discovered sumoylation. The aim of this work was to assess the influence of sumoylation on EGF induced Egr1 expression and/or stability. Methods We …
Transcutaneous immunization with imiquimod is amplified by CD40 ligation and results in sustained cytotoxic T-lymphocyte activation and tumor protect…
1999
Transcutaneous immunization (TCI) using ligands of Toll-like receptors (TLRs) and cytotoxic T-lymphocyte (CTL) epitopes lead to the induction of potent T-cell responses. To characterize the efficacy of TCI-mediated CTL activation, we monitored the frequency and functional activity of specific CTL induced with TCI using the ovalbumin-derived epitope SIINFEKL composed in creme containing the synthetic TLR7 ligand R-837. We found that the frequency and activity decayed rapidly 10 d post-TCI. Consistently, no significant memory T-cell formation was detectable. In a prophylactic vaccination setting, TCI was protective against a lethal challenge with ovalbumin expressing EG.7 thymoma cells when t…
Insect venom immunotherapy induces interleukin-10 production and a Th2-to-Th1 shift, and changes surface marker expression in venom-allergic subjects.
1997
Abstract The current study was carried out to elucidate the immunoregulatory changes induced by venom immunotherapy (VIT) in bee or wasp allergic subjects. All subjects included in this study had a history of severe systemic allergic reactions to stings of the respective insect as well as positive skin tests with the respective venom or venom-specific IgE in the sera. Parameters assessed in peripheral blood mononuclear cells (PBMC) before and after initiation of VIT (rush therapy reaching a maintenance dose of 100 micrograms venom injected subcutaneously within 1 week) were expression of CD3, CD4, CD8, CD45RA, CD45RO, interleukin (IL)-2 receptor (R) alpha, IL-4R, IL-12R, Fc epsilon RII, CD4…
Inhibitors of apoptosis confer resistance to tumour suppression by adoptively transplanted cytotoxic T-lymphocytes in vitro and in vivo
2005
Deregulation of apoptosis signalling is commonly found in cancer and results in resistance to cytotoxic therapies. Immunotherapy is a promising strategy to eliminate resistant cancer cells. The transfer of T-lymphocytes during allogeneic stem cell transplantation is clinically explored to induce a 'graft-versus-tumor' effect (GvT). Cytotoxic T-lymphocytes (CTL), which are major effectors of GvT, eliminate cancer cells by inducing apoptosis via multiple parallel pathways. Here, we study in vitro and in vivo the susceptibility of murine cancer cells engineered to express single antiapoptotic genes to CTL-mediated cytotoxicity. Interestingly, we find that single inhibitors of caspase activatio…
Effects of hydrazyl group containing drugs on leucocyte functions: an immunoregulatory model for the hydralazine-induced lupus-like syndrome.
1985
Isoniazid (INH) and hydralazine (HYD) are transglutaminase (TGase, E.C.2.3.2.13.) substrates containing catalytically recruitable hydrazyl groups. Since they can be expected to inhibit TGase-mediated cell functions by competing with physiological substrates, their effect upon allogeneically and lectin-induced proliferation of mononucleocytes and upon zymosan-induced chemiluminescence of phagocytes was studied. Both compounds inhibited chemiluminescence in a dose-dependent manner. ID50 of HYD was consistently below 20 microM, while that of INH was above 120 microM. Proliferation of immunocompetent cells was suppressed by HYD with an ID50 of 60 microM, INH was inhibitory only above 5000 micro…
Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: An oestrogenic mycotoxin
2005
Zearalenone (ZEA) is a mycotoxin produced mainly by fungi belonging to the genus Fusarium in foods and feeds. It is frequently implicated in reproductive disorders of farm animals and occasionally in hyperoestrogenic syndromes in humans. There is evidence that ZEA and its metabolites possess oestrogenic activity in pigs, cattle and sheep. However, ZEA is of a relatively low acute toxicity after oral or interperitoneal administration in mice, rat and pig. The biotransformation for ZEA in animals involves the formation of two metabolites alpha-zearalenol (alpha-ZEA) and beta-zearalenol (beta-ZEA) which are subsequently conjugated with glucuronic acid. Moreover, ZEA has also been shown to be h…
Idelalisib Impairs TREM-1 and TLR Mediated Neutrophil Activation
2016
Abstract Introduction: Polymorphonuclear neutrophils (PMN) play an essential role in innate inflammatory processes. Their functions are strictly regulated and many activating / inhibiting mechanisms along with their pathways are only incompletely understood. Besides toll-like receptors (TLR) and NOD-like receptors (NLR), triggering receptor expressed on myeloid cells (TREM)-1 is implicated in innate immune activation of these cells and plays a role in infectious as well as non-infectious conditions. Activation of TREM-1 results in release of pro-inflammatory chemokines and cytokines, increased surface expression of cell activation markers and degranulation. In TREM-1 downstream pathways and…