scholarly journals Mycobacterium tuberculosisLipoproteins Directly Regulate Human Memory CD4+T Cell Activation via Toll-Like Receptors 1 and 2

2010 ◽  
Vol 79 (2) ◽  
pp. 663-673 ◽  
Author(s):  
Christina L. Lancioni ◽  
Qing Li ◽  
Jeremy J. Thomas ◽  
XueDong Ding ◽  
Bonnie Thiel ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Intracellular Signaling ◽  
Cell Activation ◽  
Cellular Proliferation ◽  
Cell Function ◽  
Human Memory ◽  
Cytokine Secretion ◽  
Antigen Presenting

ABSTRACTThe success ofMycobacterium tuberculosisas a pathogen relies on its ability to regulate the host immune response.M. tuberculosiscan manipulate adaptive T cell responses indirectly by modulating antigen-presenting cell (APC) function or by directly interacting with T cells. Little is known about the role ofM. tuberculosismolecules in direct regulation of T cell function. Using a biochemical approach, we identified lipoproteins LprG and LpqH as major molecules inM. tuberculosislysate responsible for costimulation of primary human CD4+T cells. In the absence of APCs, activation of memory CD4+T cells with LprG or LpqH in combination with anti-CD3 antibody induces Th1 cytokine secretion and cellular proliferation. Lipoprotein-induced T cell costimulation was inhibited by blocking antibodies to Toll-like receptor 2 (TLR2) and TLR1, indicating that human CD4+T cells can use TLR2/TLR1 heterodimers to directly respond toM. tuberculosisproducts.M. tuberculosislipoproteins induced NF-κB activation in CD4+T cells in the absence of TCR co-engagement. Thus, TLR2/TLR1 engagement alone byM. tuberculosislipoprotein triggered intracellular signaling, but upregulation of cytokine production and proliferation required co-engagement of the TCR. In conclusion, our results demonstrate thatM. tuberculosislipoproteins LprG and LpqH participate in the regulation of adaptive immunity not only by inducing cytokine secretion and costimulatory molecules in innate immune cells but also through directly regulating the activation of memory T lymphocytes.

scholarly journals Impairment of Antigen-Presenting Cell Function in Mice Lacking Expression of Ox40 Ligand

2000 ◽  
Vol 191 (2) ◽  
pp. 365-374 ◽  
Author(s):  
Kazuko Murata ◽  
Naoto Ishii ◽  
Hiroshi Takano ◽  
Shigeto Miura ◽  
Lishomwa C. Ndhlovu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Function ◽  
Critical Role ◽  
Costimulatory Molecule ◽  
Activated T Cells ◽  
Antigen Presenting

OX40 expressed on activated T cells is known to be an important costimulatory molecule on T cell activation in vitro. However, the in vivo functional significance of the interaction between OX40 and its ligand, OX40L, is still unclear. To investigate the role of OX40L during in vivo immune responses, we generated OX40L-deficient mice and a blocking anti-OX40L monoclonal antibody, MGP34. OX40L expression was demonstrated on splenic B cells after CD40 and anti-immunoglobulin (Ig)M stimulation, while only CD40 ligation was capable of inducing OX40L on dendritic cells. OX40L-deficient and MGP34-treated mice engendered apparent suppression of the recall reaction of T cells primed with both protein antigens and alloantigens and a significant reduction in keyhole limpet hemocyanin–specific IgG production. The impaired T cell priming was also accompanied by a concomitant reduction of both T helper type 1 (Th1) and Th2 cytokines. Furthermore, antigen-presenting cells (APCs) derived from the mutant mice revealed an impaired intrinsic APC function, demonstrating the importance of OX40L in both the priming and effector phases of T cell activation. Collectively, these results provide convincing evidence that OX40L, expressed on APCs, plays a critical role in antigen-specific T cell responses in vivo.

scholarly journals DNA origami demonstrate the unique stimulatory power of single pMHCs as T cell antigens

2021 ◽  
Vol 118 (4) ◽  
pp. e2016857118
Author(s):  
Joschka Hellmeier ◽  
Rene Platzer ◽  
Alexandra S. Eklund ◽  
Thomas Schlichthaerle ◽  
Andreas Karner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Intracellular Signaling ◽  
Cell Activation ◽  
Critical Factor ◽  
Dna Origami ◽  
Antigen Receptors ◽  
T Cell Antigens ◽  
Antigen Presenting

T cells detect with their T cell antigen receptors (TCRs) the presence of rare agonist peptide/MHC complexes (pMHCs) on the surface of antigen-presenting cells (APCs). How extracellular ligand binding triggers intracellular signaling is poorly understood, yet spatial antigen arrangement on the APC surface has been suggested to be a critical factor. To examine this, we engineered a biomimetic interface based on laterally mobile functionalized DNA origami platforms, which allow for nanoscale control over ligand distances without interfering with the cell-intrinsic dynamics of receptor clustering. When targeting TCRs via stably binding monovalent antibody fragments, we found the minimum signaling unit promoting efficient T cell activation to consist of two antibody-ligated TCRs within a distance of 20 nm. In contrast, transiently engaging antigenic pMHCs stimulated T cells robustly as well-isolated entities. These results identify pairs of antibody-bound TCRs as minimal receptor entities for effective TCR triggering yet validate the exceptional stimulatory potency of single isolated pMHC molecules.

scholarly journals A role for CD9 molecules in T cell activation.

1996 ◽  
Vol 184 (2) ◽  
pp. 753-758 ◽  
Author(s):  
X G Tai ◽  
Y Yashiro ◽  
R Abe ◽  
K Toyooka ◽  
C R Wood ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Activation ◽  
Cell Activation ◽  
Expression Cloning ◽  
Wild Type ◽  
Almost All ◽  
Antigen Presenting ◽  
Deficient Mice

Costimulation mediated by the CD28 molecule plays an important role in optimal activation of T cells. However, CD28-deficient mice can mount effective T cell-dependent immune responses, suggesting the existence of other costimulatory systems. In a search for other costimulatory molecules on T cells, we have developed a monoclonal antibody (mAb) that can costimulate T cells in the absence of antigen-presenting cells (APC). The molecule recognized by this mAb, 9D3, was found to be expressed on almost all mature T cells and to be a protein of approximately 24 kD molecular mass. By expression cloning, this molecule was identified as CD9, 9D3 (anti-CD9) synergized with suboptimal doses of anti-CD3 mAb in inducing proliferation by virgin T cells. Costimulation was induced by independent ligation of CD3 and CD9, suggesting that colocalization of these two molecules is not required for T cell activation. The costimulation by anti-CD9 was as potent as that by anti-CD28. Moreover, anti-CD9 costimulated in a CD28-independent way because anti-CD9 equally costimulated T cells from the CD28-deficient as well as wild-type mice. Thus, these results indicate that CD9 serves as a molecule on T cells that can deliver a potent CD28-independent costimulatory signal.

scholarly journals T cell receptor zeta/CD3-p59fyn(T)-associated p120/130 binds to the SH2 domain of p59fyn(T).

1993 ◽  
Vol 178 (6) ◽  
pp. 2107-2113 ◽  
Author(s):  
A J da Silva ◽  
O Janssen ◽  
C E Rudd
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Intracellular Signaling ◽  
Cell Activation ◽  
Cell Receptor ◽  
Sh2 Domain ◽  
T Complex

Intracellular signaling from the T cell receptor (TCR)zeta/CD3 complex is likely to be mediated by associated protein tyrosine kinases such as p59fyn(T), ZAP-70, and the CD4:p56lck and CD8:p56lck coreceptors. The nature of the signaling cascade initiated by these kinases, their specificities, and downstream targets remain to be elucidated. The TCR-zeta/CD3:p59fyn(T) complex has previously been noted to coprecipitate a 120/130-kD doublet (p120/130). This intracellular protein of unknown identity associates directly with p59fyn(T) within the receptor complex. In this study, we have shown that this interaction with p120/130 is specifically mediated by the SH2 domain (not the fyn-SH3 domain) of p59fyn(T). Further, based on the results of in vitro kinase assays, p120/130 appears to be preferentially associated with p59fyn(T) in T cells, and not with p56lck. Antibody reprecipitation studies identified p120/130 as a previously described 130-kD substrate of pp60v-src whose function and structure is unknown. TCR-zeta/CD3 induced activation of T cells augmented the tyrosine phosphorylation of p120/130 in vivo as detected by antibody and GST:fyn-SH2 fusion proteins. p120/130 represents the first identified p59fyn(T):SH2 binding substrate in T cells, and as such is likely to play a key role in the early events of T cell activation.

scholarly journals TRPM2 Is Not Required for T-Cell Activation and Differentiation

2022 ◽  
Vol 12 ◽  
Author(s):  
Niels C. Lory ◽  
Mikolaj Nawrocki ◽  
Martina Corazza ◽  
Joanna Schmid ◽  
Valéa Schumacher ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Transient Receptor Potential ◽  
Cell Function ◽  
Intestinal Inflammation ◽  
Activation Markers

Antigen recognition by the T-cell receptor induces a cytosolic Ca2+ signal that is crucial for T-cell function. The Ca2+ channel TRPM2 (transient receptor potential cation channel subfamily M member 2) has been shown to facilitate influx of extracellular Ca2+ through the plasma membrane of T cells. Therefore, it was suggested that TRPM2 is involved in T-cell activation and differentiation. However, these results are largely derived from in vitro studies using T-cell lines and non-physiologic means of TRPM2 activation. Thus, the relevance of TRPM2-mediated Ca2+ signaling in T cells remains unclear. Here, we use TRPM2-deficient mice to investigate the function of TRPM2 in T-cell activation and differentiation. In response to TCR stimulation in vitro, Trpm2-/- and WT CD4+ and CD8+ T cells similarly upregulated the early activation markers NUR77, IRF4, and CD69. We also observed regular proliferation of Trpm2-/- CD8+ T cells and unimpaired differentiation of CD4+ T cells into Th1, Th17, and Treg cells under specific polarizing conditions. In vivo, Trpm2-/- and WT CD8+ T cells showed equal specific responses to Listeria monocytogenes after infection of WT and Trpm2-/- mice and after transfer of WT and Trpm2-/- CD8+ T cells into infected recipients. CD4+ T-cell responses were investigated in the model of anti-CD3 mAb-induced intestinal inflammation, which allows analysis of Th1, Th17, Treg, and Tr1-cell differentiation. Here again, we detected similar responses of WT and Trpm2-/- CD4+ T cells. In conclusion, our results argue against a major function of TRPM2 in T-cell activation and differentiation.

IκB kinase 2 but not NF-κB–inducing kinase is essential for effective DC antigen presentation in the allogeneic mixed lymphocyte reaction

Blood ◽  
2003 ◽  
Vol 101 (3) ◽  
pp. 983-991 ◽  
Author(s):  
Evangelos Andreakos ◽  
Clive Smith ◽  
Claudia Monaco ◽  
Fionula M. Brennan ◽  
Brian M. Foxwell ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antigen Presentation ◽  
T Cell Activation ◽  
Cell Activation ◽  
Mixed Lymphocyte Reaction ◽  
Dominant Negative ◽  
Allogeneic Mixed Lymphocyte Reaction ◽  
Iκb Kinase ◽  
Antigen Presenting

AbstractAlthough dendritic cells (DCs) are the most potent antigen-presenting cells involved in numerous physiologic and pathologic processes, little is known about the signaling pathways that regulate DC activation and antigen-presenting function. Recently, we demonstrated that nuclear factor (NF)-κB activation is central to that process, as overexpression of IκBα blocks the allogeneic mixed lymphocyte reaction (MLR), an in vitro model of T-cell activation. In this study, we investigated the role of 2 putative NF-κB–inducing components, NF-κB–inducing kinase (NIK), and IκB kinase 2 (IKK2). Using an adenoviral gene transfer method to efficiently express dominant-negative (dn) forms of these molecules in monocyte-derived DCs, we found that IKK2dn but not NIKdn inhibited the allogeneic MLR. When DCs were fixed, this inhibitory effect of IKK2dn was lost, suggesting that IKK2 is involved in T-cell–derived signals that enhance DC antigen presentation during the allogeneic MLR period and does not have an effect on viability or differentiation state of DCs prior to coculture with T cells. One such signal is likely to be CD40 ligand (CD40L), as IKK2dn blocked CD40L but not lipopolysaccharide (LPS)–induced NF-κB activation, cytokine production, and up-regulation of costimulatory molecules and HLA-DR in DCs. In summary, our results demonstrate that IKK2 is essential for DC activation induced by CD40L or contact with allogeneic T cells, but not by LPS, whereas NIK is not required for any of these signals. In addition, our results support IKK2 as a potential therapeutic target for the down-regulation of unwanted immune responses that may occur during transplantation or autoimmunity.

scholarly journals Hypoxia-induced PD-L1/PD-1 crosstalk impairs T-cell function in sleep apnoea

2017 ◽  
Vol 50 (4) ◽  
pp. 1700833 ◽  
Author(s):  
Carolina Cubillos-Zapata ◽  
Jose Avendaño-Ortiz ◽  
Enrique Hernandez-Jimenez ◽  
Victor Toledano ◽  
Jose Casas-Martin ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Intermittent Hypoxia ◽  
Cell Activation ◽  
Cell Function ◽  
Sleep Apnoea ◽  
Orphan Receptor ◽  
Dependent Manner ◽  
Obstructive Sleep

Obstructive sleep apnoea (OSA) is associated with higher cancer incidence, tumour aggressiveness and cancer mortality, as well as greater severity of infections, which have been attributed to an immune deregulation. We studied the expression of programmed cell death (PD)-1 receptor and its ligand (PD-L1) on immune cells from patients with OSA, and its consequences on immune-suppressing activity. We report that PD-L1 was overexpressed on monocytes and PD-1 was overexpressed on CD8+ T-cells in a severity-dependent manner. PD-L1 and PD-1 overexpression were induced in both the human in vitro and murine models of intermittent hypoxia, as well as by hypoxia-inducible factor-1α transfection. PD-L1/PD-1 crosstalk suppressed T-cell proliferation and activation of autologous T-lymphocytes and impaired the cytotoxic activity of CD8+ T-cells. In addition, monocytes from patients with OSA exhibited high levels of retinoic acid related orphan receptor, which might explain the differentiation of myeloid-derived suppressor cells. Intermittent hypoxia upregulated the PD-L1/PD-1 crosstalk in patients with OSA, resulting in a reduction in CD8+ T-cell activation and cytotoxicity, providing biological plausibility to the increased incidence and aggressiveness of cancer and the higher risk of infections described in these patients.

scholarly journals Abortive Proliferation of Rare T Cells Induced by Direct or Indirect Antigen Presentation by Rare B Cells In Vivo

1998 ◽  
Vol 187 (10) ◽  
pp. 1611-1621 ◽  
Author(s):  
Sarah E. Townsend ◽  
Christopher C. Goodnow
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Antigen Presentation ◽  
Cell Fate ◽  
T Cell Activation ◽  
Cell Activation ◽  
Antigen Presenting Cells ◽  
Antigen Presenting

Antigen-specific B cells are implicated as antigen-presenting cells in memory and tolerance responses because they capture antigens efficiently and localize to T cell zones after antigen capture. It has not been possible, however, to visualize the effect of specific B cells on specific CD4+ helper T cells under physiological conditions. We demonstrate here that rare T cells are activated in vivo by minute quantities of antigen captured by antigen-specific B cells. Antigen-activated B cells are helped under these conditions, whereas antigen-tolerant B cells are killed. The T cells proliferate and then disappear regardless of whether the B cells are activated or tolerant. We show genetically that T cell activation, proliferation, and disappearance can be mediated either by transfer of antigen from antigen-specific B cells to endogenous antigen-presenting cells or by direct B–T cell interactions. These results identify a novel antigen presentation route, and demonstrate that B cell presentation of antigen has profound effects on T cell fate that could not be predicted from in vitro studies.

scholarly journals Complete differentiation of CD8+ T cells activated locally within the transplanted liver

2006 ◽  
Vol 203 (2) ◽  
pp. 437-447 ◽  
Author(s):  
Ingo Klein ◽  
Ian Nicholas Crispe
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antigen Presentation ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Underlying Mechanism ◽  
Color Flow ◽  
Antigen Presenting ◽  
Transplantation Model

The transplanted liver elicits systemic tolerance, and the underlying mechanism may also account for the persistence of liver infections, such as malaria and viral hepatitis. These phenomena have led to the hypothesis that antigen presentation within the liver is abortive, leading to T cell tolerance or apoptosis. Here we test this hypothesis in an optimized orthotopic liver transplantation model. In direct contradiction to this model, the liver itself induces full CD8+ T cell activation and differentiation. The effects of microchimerism were neutralized by bone marrow transplantation in the liver donor, and the lack of liver-derived antigen-presenting cells was documented by eight-color flow cytometry and by sensitive functional assays. We conclude that local antigen presentation cannot explain liver tolerance. On the contrary, the liver may be an excellent priming site for naive CD8+ T cells.

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