Adhesion of human T cells to antigen-presenting cells through SIRPβ2-CD47 interaction costimulates T-cell proliferation

Blood ◽  
2005 ◽  
Vol 105 (6) ◽  
pp. 2421-2427 ◽  
Author(s):  
Laura Piccio ◽  
William Vermi ◽  
Kent S. Boles ◽  
Anja Fuchs ◽  
Carey A. Strader ◽  
...  

AbstractSignal-regulatory proteins (SIRPs) are transmembrane glycoproteins belonging to the immunoglobulin (Ig) superfamily that are expressed in the immune and central nervous systems. SIRPα binds CD47 and inhibits the function of macrophages, dendritic cells, and granulocytes, whereas SIRPβ1 is an orphan receptor that activates the same cell types. A recently identified third member of the SIRP family, SIRPβ2, is as yet uncharacterized in terms of expression, specificity, and function. Here, we show that SIRPβ2 is expressed on T cells and activated natural killer (NK) cells and, like SIRPα, binds CD47, mediating cell-cell adhesion. Consequently, engagement of SIRPβ2 on T cells by CD47 on antigen-presenting cells results in enhanced antigen-specific T-cell proliferation.

1999 ◽  
Vol 189 (9) ◽  
pp. 1363-1372 ◽  
Author(s):  
David H. Munn ◽  
Ebrahim Shafizadeh ◽  
John T. Attwood ◽  
Igor Bondarev ◽  
Achal Pashine ◽  
...  

We have recently shown that expression of the enzyme indoleamine 2,3-dioxygenase (IDO) during murine pregnancy is required to prevent rejection of the allogeneic fetus by maternal T cells. In addition to their role in pregnancy, IDO-expressing cells are widely distributed in primary and secondary lymphoid organs. Here we show that monocytes that have differentiated under the influence of macrophage colony-stimulating factor acquire the ability to suppress T cell proliferation in vitro via rapid and selective degradation of tryptophan by IDO. IDO was induced in macrophages by a synergistic combination of the T cell–derived signals IFN-γ and CD40-ligand. Inhibition of IDO with the 1-methyl analogue of tryptophan prevented macrophage-mediated suppression. Purified T cells activated under tryptophan-deficient conditions were able to synthesize protein, enter the cell cycle, and progress normally through the initial stages of G1, including upregulation of IL-2 receptor and synthesis of IL-2. However, in the absence of tryptophan, cell cycle progression halted at a mid-G1 arrest point. Restoration of tryptophan to arrested cells was not sufficient to allow further cell cycle progression nor was costimulation via CD28. T cells could exit the arrested state only if a second round of T cell receptor signaling was provided in the presence of tryptophan. These data reveal a novel mechanism by which antigen-presenting cells can regulate T cell activation via tryptophan catabolism. We speculate that expression of IDO by certain antigen presenting cells in vivo allows them to suppress unwanted T cell responses.


2002 ◽  
Vol 196 (4) ◽  
pp. 447-457 ◽  
Author(s):  
Peter Terness ◽  
Thomas M. Bauer ◽  
Lars Röse ◽  
Christoph Dufter ◽  
Andrea Watzlik ◽  
...  

Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, is expressed in certain cells and tissues, particularly in antigen-presenting cells of lymphoid organs and in the placenta. It was shown that IDO prevents rejection of the fetus during pregnancy, probably by inhibiting alloreactive T cells, and it was suggested that IDO-expression in antigen-presenting cells may control autoreactive immune responses. Degradation of tryptophan, an essential amino acid required for cell proliferation, was reported to be the mechanism of IDO-induced T cell suppression. Because we wanted to study the action of IDO-expressing dendritic cells (DCs) on allogeneic T cells, the human IDO gene was inserted into an adenoviral vector and expressed in DCs. Transgenic DCs decreased the concentration of tryptophan, increased the concentration of kynurenine, the main tryptophan metabolite, and suppressed allogeneic T cell proliferation in vitro. Kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid, but no other IDO-induced tryptophan metabolites, suppressed the T cell response, the suppressive effects being additive. T cells, once stopped in their proliferation, could not be restimulated. Inhibition of proliferation was likely due to T cell death because suppressive tryptophan catabolites exerted a cytotoxic action on CD3+ cells. This action preferentially affected activated T cells and increased gradually with exposure time. In addition to T cells, B and natural killer (NK) cells were also killed, whereas DCs were not affected. Our findings shed light on suppressive mechanisms mediated by DCs and provide an explanation for important biological processes in which IDO activity apparently is increased, such as protection of the fetus from rejection during pregnancy and possibly T cell death in HIV-infected patients.


2005 ◽  
Vol 25 (17) ◽  
pp. 7743-7757 ◽  
Author(s):  
Kei Ohnuma ◽  
Tadanori Yamochi ◽  
Masahiko Uchiyama ◽  
Kunika Nishibashi ◽  
Satoshi Iwata ◽  
...  

ABSTRACT CD26 is a T-cell costimulatory molecule with dipeptidyl peptidase IV enzyme activity in its extracellular region. We have previously reported that the addition of recombinant soluble CD26 resulted in enhanced proliferation of human T lymphocytes induced by the recall antigen tetanus toxoid (TT) via upregulation of CD86 on monocytes and that caveolin-1 was a binding protein of CD26, and the CD26-caveolin-1 interaction resulted in caveolin-1 phosphorylation (p-cav-1) as well as TT-mediated T-cell proliferation. However, the mechanism involved in this immune enhancement has not yet been elucidated. In the present work, we perform experiments to identify the molecular mechanisms by which p-cav-1 leads directly to the upregulation of CD86. Through proteomic analysis, we identify Tollip (Toll-interacting protein) and IRAK-1 (interleukin-1 receptor-associated serine/threonine kinase 1) as caveolin-1-interacting proteins in monocytes. We also demonstrate that following stimulation by exogenous CD26, Tollip and IRAK-1 dissociate from caveolin-1, and IRAK-1 is then phosphorylated in the cytosol, leading to the upregulation of CD86 via activation of NF-κB. Binding of CD26 to caveolin-1 therefore regulates signaling pathways in antigen-presenting cells to induce antigen-specific T-cell proliferation.


1984 ◽  
Vol 159 (3) ◽  
pp. 881-905 ◽  
Author(s):  
J D Ashwell ◽  
A L DeFranco ◽  
W E Paul ◽  
R H Schwartz

In this report we have examined the ability of small resting B cells to act as antigen-presenting cells (APC) to antigen-specific MHC-restricted T cells as assessed by either T cell proliferation or T cell-dependent B cell stimulation. We found that 10 of 14 in vitro antigen-specific MHC-restricted T cell clones and lines and three of four T cell hybridomas could be induced to either proliferate or secrete IL-2 in the presence of lightly irradiated (1,000 rads) purified B cells and the appropriate foreign antigen. All T cell lines and hybridomas were stimulated to proliferate or make IL-2 by macrophage- and dendritic cell-enriched populations and all T cells tested except one hybridoma caused B cell activation when stimulated with B cells as APC. Furthermore, lightly irradiated, highly purified syngeneic B cells were as potent a source of APC for inducing B cell activation as were low density dendritic and macrophage-enriched cells. Lymph node T cells freshly taken from antigen-primed animals were also found to proliferate when cultured with purified B cells and the appropriate antigen. Thus, small resting B cells can function as APC to a variety of T cells. This APC function was easily measured when the cells were irradiated with 1,000 rads, but was greatly diminished or absent when they were irradiated with 3,300 rads. Thus, the failure of some other laboratories to observe this phenomenon may be the result of the relative radiosensitivity of the antigen-presenting function of the B cells. In addition, this radiosensitivity allowed us to easily distinguish B cell antigen presentation from presentation by the dendritic cell and macrophage, as the latter was resistant to 3,300 rads. Finally, one T cell clone that failed to proliferate when B cells were used as APC was able to recruit allogeneic B cells to proliferate in the presence of syngeneic B cells and the appropriate antigen. This result suggests that there are at least two distinct pathways of activation in T cells, one that leads to T cell proliferation and one that leads to the secretion of B cell recruitment factor(s).


2021 ◽  
Author(s):  
◽  
Aras Toker

<p>Glatiramer acetate (GA) is approved for the treatment of relapsing-remitting multiple sclerosis (MS), and can suppress experimental autoimmune encephalomyelitis (EAE), a murine model of human MS. GA treatment is associated with the induction of anti-inflammatory TH2 responses and with the antigen specific expansion of regulatory T cells that counteract or inhibit pathogenic events in MS and EAE. These T cell mediated mechanisms of protection are considered to be a result of modulation of antigen presenting cells (APCs) by GA, rather than direct effects on T cells. However, it is unknown if GA preferentially targets a specific APC subset or can act through multiple APCs in vivo. In addition, GA-modulated innate cells may also exhibit direct antigen non-specific suppression of autoreactive cells. One objective of this study was to identify the in vivo target cell population of GA and to assess the potential of the target cells to antigen non-specifically suppress immune responses. Fluorophor-labelled GA bound to monocytes after intravenous injections, suggesting that monocytes may be the primary target of GA in vivo. In addition, intravenous GA treatment enhanced the intrinsic ability of monocytes to suppress T cell proliferation, both in vitro and in vivo. The findings of this study therefore suggest that GA-induced monocytes may contribute to GA therapy through direct mechanisms of antigen non-specific T cell immunosuppression. A further objective of this work was to investigate the potential of an in vivo drug targeting approach. This approach was hypothesised to increase the uptake of GA by the target cells and substantially improve GA treatment through antigen specific mechanisms such as induction of TH2 or regulatory T cells. Targeting antigens to professional APCs with an anti-MHC class II antibody resulted in significantly enhanced T cell proliferation in vitro. However, no EAE suppression occurred when GA was targeted to MHC class II in vivo. In addition, targeting GA specifically to monocytes also failed to suppress EAE. These findings suggest that GA treatment may selectively modulate monocytes to enhance their ability to inhibit autoreactive T cells, which could be part of the mechanism by which GA ameliorates MS. Targeting GA to a specific cell type may not be a powerful approach to improve treatment, because increased proliferation of GA specific T cells is not sufficient for disease suppression, and conjugation to antibodies may functionally reduce GA to a mere antigen devoid of immunomodulatory capacity.</p>


1993 ◽  
Vol 90 (23) ◽  
pp. 11054-11058 ◽  
Author(s):  
D J Lenschow ◽  
G H Su ◽  
L A Zuckerman ◽  
N Nabavi ◽  
C L Jellis ◽  
...  

Effective T-cell activation requires antigen/major histocompatibility complex engagement by the T-cell receptor complex in concert with one or more costimulatory molecules. Recent studies have suggested that the B7 molecule, expressed on most antigen presenting cells, functions as a costimulatory molecule through its interaction with CD28 on T cells. Blocking the CD28/B7 interaction with CTLA4Ig inhibits T-cell activation in vitro and induces unresponsiveness. We demonstrate that another molecule(s), termed B7-2, is expressed constitutively on dendritic cells, is differentially regulated on B cells, and costimulates naive T cells responding to alloantigen. B7-2 is up-regulated by lipopolysaccharide in < 6 hr and is maximally expressed on the majority of B cells by 24 hr. In contrast, B7 is detected only on a subset of activated B cells late (48 hr) after stimulation. In addition, Con A directly induces B7-2 but not B7 expression on B cells. Finally, although both anti-B7 monoclonal antibodies and CTLA4Ig blocked T-cell proliferation to antigen-expressing B7 transfectants, only CTLA4Ig had any significant inhibitory effect on T-cell proliferation to antigens expressed on natural antigen presenting cells, such as dendritic cells. Thus, B7 is not the only costimulatory molecule capable of initiating T-cell responses since a second ligand, B7-2, can provide a necessary second signal for T-cell activation.


2006 ◽  
Vol 291 (2) ◽  
pp. G253-G259 ◽  
Author(s):  
Ahmed Metwali ◽  
Tommy Setiawan ◽  
Arthur M. Blum ◽  
Joseph Urban ◽  
David E. Elliott ◽  
...  

This study determined whether Heligmosomoides polygyrus induces intestinal regulatory T cells. Splenic T cells proliferate strongly when cultured with anti-CD3 and antigen-presenting cells (APC). Lamina propria T cells from mice with H. polygyrus mixed with normal splenic T cells from uninfected mice inhibited proliferation over 90%. Lamina propria T cells from mice without H. polygyrus only modestly affected T cell proliferation. The worm-induced regulatory T cell was CD8+ and required splenic T cell contact to inhibit proliferation. The regulation also was IL-10 independent, but TAP-dependent, suggesting that it requires major histocompatibility complex (MHC) class I interaction. Additional studies employed mice with transgenic T cells that did not express functional TGF-β receptors. The lamina propria T regulator inhibited proliferation of these transgenic T cells nearly 100%, suggesting that TGF-β signaling via the T cell was not required. CD8+ T cells were needed for worms to reverse piroxicam-induced colitis in Rag mice (T and B cell deficient) reconstituted with IL-10−/− T cells. Thus H. polygyrus induces a regulatory CD8+ lamina propria T cell that inhibits T cell proliferation and that appears to have a role in control of colitis.


2019 ◽  
Vol 25 (1) ◽  
pp. 46-59 ◽  
Author(s):  
Young Suk Lee ◽  
Eduardo Davila ◽  
Tianshu Zhang ◽  
Hugh P Milmoe ◽  
Stefanie N Vogel ◽  
...  

Myeloid-derived suppressor cells (MDSCs) inhibit T cell responses and are relevant to cancer, autoimmunity and transplant biology. Anti-thymocyte globulin (ATG) is a commonly used T cell depletion agent, yet the effect of ATG on MDSCs has not been investigated. MDSCs were generated in Lewis Lung Carcinoma 1 tumor-bearing mice. MDSC development and function were assessed in vivo and in vitro with and without ATG administration. T cell suppression assays, RT-PCR, flow cytometry and arginase activity assays were used to assess MDSC phenotype and function. MDSCs increased dramatically in tumor-bearing mice and the majority of splenic MDSCs were of the polymorphonuclear subset. MDSCs potently suppressed T cell proliferation. ATG-treated mice developed 50% fewer MDSCs and these MDSCs were significantly less suppressive of T cell proliferation. In vitro, ATG directly bound 99.6% of MDSCs. CCR7, L-selectin and LFA-1 were expressed by both T cells and MDSCs, and binding of LFA-1 was inhibited by ATG pre-treatment. Arg-1 and PD-L1 transcript expression were reduced 30–40% and arginase activity decreased in ATG-pretreated MDSCs. MDSCs were bound and functionally inhibited by ATG. T cells and MDSCs expressed common Ags which were also targets of ATG. ATG may be helpful in tumor models seeking to suppress MDSCs. Alternatively, ATG may inadvertently inhibit important T cell regulatory events in autoimmunity and transplantation.


1993 ◽  
Vol 177 (1) ◽  
pp. 165-173 ◽  
Author(s):  
P Tan ◽  
C Anasetti ◽  
J A Hansen ◽  
J Melrose ◽  
M Brunvand ◽  
...  

The specificity of T lymphocyte activation is determined by engagement of the T cell receptor (TCR) by peptide/major histocompatibility complexes expressed on the antigen-presenting cell (APC). Lacking costimulation by accessory molecules on the APC, T cell proliferation does not occur and unresponsiveness to subsequent antigenic stimulus is induced. The B7/BB1 receptor on APCs binds CD28 and CTLA-4 on T cells, and provides a costimulus for T cell proliferation. Here, we show that prolonged, specific T cell hyporesponsiveness to antigenic restimulation is achieved by blocking the interaction between CD28 and B7/BB1 in human mixed leukocyte culture (MLC). Secondary T cell proliferative responses to specific alloantigen were inhibited by addition to the primary culture of monovalent Fab fragments of anti-CD28 monoclonal antibody (mAb) 9.3, which block interaction of CD28 with B7/BB1 without activating T cells. Hypo-responsiveness was also induced in MLC by CTLA4Ig, a chimeric immunoglobulin fusion protein incorporating the extracellular domain of CTLA-4 with high binding avidity for B7/BB1. Cells previously primed could also be made hyporesponsive, if exposed to alloantigen in the presence of CTLA4Ig. Maximal hyporesponsiveness was achieved in MLC after 2 d of incubation with CTLA4Ig, and was maintained for at least 27 d after removal of CTLA4Ig. Accumulation of interleukin 2 (IL-2) and interferon gamma but not IL-4 mRNA was blocked by CTLA4Ig in T cells stimulated by alloantigen. Antigen-specific responses could be restored by addition of exogenous IL-2 at the time of the secondary stimulation. Addition to primary cultures of the intact bivalent anti-CD28 mAb 9.3, or B7/BB1+ transfected CHO cells or exogenous IL-2, abrogated induction of hyporesponsiveness by CTLA4Ig. These data indicate that interaction of CD28 with B7/BB1 during TCR engagement with antigen is required to maintain T cell competence and that blocking such interaction can result in a state of T cell hyporesponsiveness.


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