effector CD8+ T cells

Top PDF effector CD8+ T cells:

Checkpoint Blockade Immunotherapy Induces Dynamic Changes in PD-1−CD8+ Tumor-Infiltrating T Cells

Checkpoint Blockade Immunotherapy Induces Dynamic Changes in PD-1−CD8+ Tumor-Infiltrating T Cells

− TILs in wild type (E8i-Cre-Tcf7 fl/fl ) vs. E8i-Cre + Tcf7 fl/fl mice (data not shown); however, we found a significant decrease in the memory-precursor-like subset within PD-1 − CD8 + TILs in E8i-Cre + Tcf7 fl/fl mice (Figure 7D). This indicated an essential role for Tcf1 in the development and/or maintenance of the memory-precursor-like subset. We further observed that the frequency of OVA-specific T cells was decreased within the memory-precursor-like subset, shifting the balance towards the effector-like subset of PD-1 − CD8 + TILs (Figure 7E). Overall, the frequency of OVA- specific CD8 + TILs was significantly decreased within both PD1 − and PD-1 + CD8 + TILs in E8i-Cre + Tcf7 fl/fl mice (Figure S6A), suggesting that the defects in the memory-precursor- like subset were propagated to PD-1 + CD8 + TILs. Lastly, the poly-functionality of the memory-precursor-like subset in response to tumor antigen stimulation was reduced in the absence of Tcf1 (Figure 7F). Together these data indicated that both the maintenance and functionality of tumor antigen-specific memory-precursor-like PD-1 − cells was impaired in the absence of Tcf1 and that the defects in these cells extended to the bulk CD8 + T cell pool. Our results indicated that the memory-precursor-like PD-1 − CD8 + TIL subset expanded upon Tim-3+PD-1 blockade, potentially providing a wave of effector CD8 + T cells able to sustain an effective anti-tumor response. Given that Tcf1 regulates the maintenance of this subset, we hypothesized that Tcf1 may be essential for effective immunotherapy. To test this, we treated MC38-OVA tumor-bearing WT and E8i-Cre + Tcf7 fl/fl mice with anti Tim-3+PD-1 or isotype control antibodies. Supporting our hypothesis, the efficacy of Tim-3+PD-1 blockade
En savoir plus

35 En savoir plus

Natural killer cells promote early CD8 T cell responses against cytomegalovirus

Natural killer cells promote early CD8 T cell responses against cytomegalovirus

Our results demonstrate that NK cells can dramatically decrease the intensity and duration of pDC activation by controlling viral burden, which prevents the production of very high systemic levels of IFN-a/b, and eventually other innate cytokines, that can have detrimental effects for the host. We show that this mechanism also protects against the MCMV-mediated loss of splenic cDCs [36]. It has been reported that that both measles virus and LCMV can exploit the host’s IFN-a/b response to inhibit cDC development and drive cDC loss in vivo [19]. Our results suggest that MCMV also can induce high production of IFN-a/b to promote its own survival by ablating cDCs and delaying the activation of antiviral effector CD8 T cells. In light of this observation, it is interesting to note that MCMV has developed strategies to actively counteract the antiviral responses to IFN-a/b or IFN- c within infected cells [48], as opposed to the mechanisms employed by negative-strand RNA viruses, which act to shut down the production of these cytokines by infected cells [49] or pDCs [50]. Indeed, even though complete deficiency in IFN-a/b responses is associated with a dramatic increase in the susceptibility of mice to MCMV infection [16], it clearly appears that the benefit of high level IFN-a/b production for the host is less than that brought by an efficient NK cell response (since Klra8 mice show viral titers that are 1,000- fold lower than those seen in BALB/c mice, even though Klra8 mice produce 100-fold less IFN-a/b). Thus, it is tempting to speculate that the efficient NK cell activity driven by the Ly49H activating receptor and its ability to dampen pDC IFN-a/b production and to promote adaptive immunity is a direct host countermeasure to the subversion of the IFN-a/b response by MCMV. Altogether, our results suggest that the NK cell response governs the balance between the positive and negative effects of IFN-a/b, and eventually other innate cytokines, for the optimal orchestration of the immune response to MCMV.
En savoir plus

14 En savoir plus

Visualizing early splenic memory CD8+ T cells reactivation against intracellular bacteria in the mouse

Visualizing early splenic memory CD8+ T cells reactivation against intracellular bacteria in the mouse

for 6 hours with 106LD 50 Wt L.m or Wt L.m-OVA bacteria and their spleens sectioned and stained for collagen IV expression (Figure 9A). In order to compare if OT-I memory cells were able to join effector clusters in absence of a specific TCR trigger, we also co-stained these sections for CD8 expression and delineated 3 regions of interest: the entire splenic WP, the clusters of endogenous CD8 + T cells in the RP and the rest of the RP. Densities of OT-I cells present in these 3 regions were calculated (Figure 9B). Data show that memory OT-I cells were equally capable to join effector clusters and secrete IFN-c to the same proportion (,20% of all OT-I cells in both conditions) in mice challenged with Wt L.m and Wt L.m-OVA, indicating that the capacity of memory CD8 + T cells to cluster and provide a rapid response does not require antigen-specific re-activation of the cells (Figure 9A, B and C).Interestingly, we detected CCL3 secretion by memory OT-I cells only in the spleens isolated from animals injected with Wt L.m-OVA, suggesting that memory CD8 + T cells need antigen-specific stimuli to secrete CCL3 in contrast to IFN-c (Figure 7). Finally, we also investigated whether naı¨ve OT-I cells were able to join the effector clusters of secondary infected mice or if this capacity was restricted to memory OT-I cells. For this, we used the same experimental setup but adoptively transferred the immunized mice with 3610 6 CMTPX-labelled naı¨ve OT-I cells before re-infection. Spleens were harvested 6 hours later, and the densities of memory and naı¨ve OT-I cells were calculated in the 3 regions of interest delineated above (Figure 9A and B). Data show that naı¨ve OT-I cells failed to integrate the effector clusters in both groups of mice. However, as anticipated, naı¨ve OT-I cells aggregated in typical ‘‘activation clusters’’ only in the splenic WP of mice challenged for 24 hours with Wt L.m-OVA (Figure 10 and [15]), indicating that naive CD8 + T cell activation during a secondary response takes place in the WP yet much after memory CD8 + T cells reactivation had occurred in the RP.
En savoir plus

15 En savoir plus

Role of the Wiskott-Aldrich syndrome protein in human CD8+ T cell activation and effector function

Role of the Wiskott-Aldrich syndrome protein in human CD8+ T cell activation and effector function

The rationale for gene therapy for WAS is based on reported cases of spontaneous reverse mutations. Indeed, initial studies demonstrated spontaneous back-to-normal reversions in the WAS gene from WAS patients by deletion of an inserted repeat sequence 174 , site-specific single nucleotide reversion 175 , or frame restoration by insertion of a single nucleotide 176 . Originally, it was thought that reversion occurred only in the T lymphocyte compartment. However, a WAS patient with NK cell mosaïcism has been described 177 . Independently from the cell type that displayed the reversion, re-expression of the normal WAS protein seemed to provide a growth advantage. For T lymphocytes, revertant cells have been shown to regain functions. Indeed, the majority of revertant T cells displayed normal morphology and microvilli numbers 175 . In a revertant case recently described by our group, revertant CD4 + T cells displayed normal subcellular localization of WASP, proliferation and cytokine production upon stimulation with anti-CD3/anti-CD28-coated beads 178 . Importantly, revertant T cells appeared to localize normally within secondary hematopoietic organs (spleen and lymph nodes). In another recent WAS revertant case, a high diversity of genotypic revertants was shown in a same patient. Indeed, over 30 different second- site mutations, leading to restoration of WASP expression, have been detected in primary T cell clones from a WAS patient that carries a nonsense mutation in exon 10 of the WAS gene 179 . It has been estimated that at least 11% of WAS patients display somatic mosaïcism due to spontaneous in vivo reversion of the original mutation or second-site compensatory mutations, leading to restoration of the production of the
En savoir plus

166 En savoir plus

en
                                                                    fr

en fr Characterization of memory CD8+ T cells generated in sterile inflammatory conditions Caractérisation des lymphocytes T CD8+ générés en conditions inflammatoires stériles

Contact sensitization with DNFB establishes a persistent hapten-specific memory The second model we have used to characterize memory CD8 T cells generated in a sterile inflammatory context is the CHS reaction to the hapten 2,4-dinitrofluorobenzene (DNFB), a widely used model of DTH in which the immune response is mediated by CD8 T cells (28) that are activated under inflammatory conditions and in the absence of signals delivered by pathogens (11). In the standard model, mice are sensitized to DNFB by epicutaneous application on the ventral skin and the effector CD8 response is revealed by tissue infiltration and inflammation after a challenge with a small dose of hapten on the ear, 5 days after sensitization (29). In an initial set of experiments, we studied the development of a memory response in this model. There- fore, we extended the course of the study to include challenge time points after the effector phase that correspond to the memory phase in other experimental systems (13, 30, 31). The generation of an Ag- specific memory was evidenced by the induction of a substantial ear swelling following recall exposure to DNFB (Fig. 5). Although the inflammatory reaction 20 days after sensitization was less important than when mice were re-exposed at the peak of the primary effector response (day 5), the difference between nonsensitized and day 20- sensitized mice was highly significant. Furthermore, this memory re- sponse was maintained for another 3 wk, as animals challenged 40 days after sensitization displayed a similar hypersensitivity reaction. FIGURE 4. Naive nontransgenic mice harbor T IM -phenotype CD8 T cells. A and B, Splenocytes from nonimmunized C57BL/10 mice were stained to analyze
En savoir plus

175 En savoir plus

Altered Binding of Tumor Antigenic Peptides to MHC Class I Affects CD8+ T Cell–Effector Responses

Altered Binding of Tumor Antigenic Peptides to MHC Class I Affects CD8+ T Cell–Effector Responses

Protein expression of recombinant H-2D b Recombinant H-2D b is expressed both as a peptide- β2M-H-2D b single-chain trimer and as exogenously loaded MHC molecules. The single-chain trimers were constructed as previously described (30), with the C-terminus of the TRP1-M9 or K8 peptide linked to the N-terminus of mouse β2M via a 15-amino acid (GGGS) 3 linker, the C-terminus of β2M linked to the N-terminus of H-2D b with a 20 amino acid (GGGS) 4 linker, and with C- terminal BAP and His 8 tags for site-specific biotinylation and purification, respectively. The construct was cloned into the GP67A vector (BD Biosciences, 554756) for production of baculoviruses. Baculoviruses were created in SF9 cells (gift from K. Christopher Garcia) via co-transfection of BestBac 2.0 (Expression Systems 91-002) and the MHC constructs with Cellfectin II (Life Technologies 10362-100). Proteins were expressed via infection of High Five cells (gift from K. Christopher Garcia) with baculoviruses for 48 hours at 27 o C, and then purified as previously described (31). H-2D b was expressed with exogenously loaded TRP1-M9 and K8 peptides via refolding of bacterially-expressed inclusion bodies. Briefly, H-2D b and mouse β2M were each cloned into the pET28a vector (Novagen 69864-3), then expressed in BL21 DE3 E. coli (New England Biolabs, C2527I) at 37 o for 5 hours. Bacteria were pelleted via centrifugation (20 minutes at 6,000 x g), resuspended in Hepes Buffered Saline (10 mM HEPES pH 7.2, 150mM NaCl), and lysed by adding 2x volume of lysis buffer (50 mM Tris-HCl pH 8.0, 1% (v/v) Triton X-100, 1% (w/v) Sodium deoxycholic acid, 100 mM NaCl) and 10 μL Benzonase. Cells were then sonicated and centrifuged for 15 minutes at 10,000xg, leaving protein inclusion bodies. The inclusion bodies were then purified via resuspension followed by centrifugation three times in a detergent-containing wash buffer (50 mM Tris-HCl pH 8.0, 100 mM NaCl, 0.5% (v/v) Triton X-100, 1 mM Sodium EDTA, 1 mM DTT, 0.2 mM PMSF), followed by a final wash in a a detergent-free buffer (50 mM Tris-HCl pH 8.0, 1 mM Sodium EDTA, 1 mM DTT, 0.2 mM PMSF). Purified inclusion bodies were then solubilized in a urea containing buffer (20 mM Tris-HCl pH 8.0, 8 M urea, 0.5 mM EDTA, 1 mM DTT). The β2M and H-2D b inclusion bodies were then then co-refolded in the presence of TRP1-M9 or K8 peptides via the dilution method in refolding buffer (100 mM Tris pH 8.0, 400 mM Arginine hydrochloride, 0.5 mM oxidized glutathione, 5 mM reduced glutathione, 2 mM Sodium EDTA, 0.2 mM PMSF) as previously described (32). All proteins were then exchanged into HBS (100mM HEPES pH 7.2, 150 mM NaCl) and purified via size exclusion chromatography using an AKTAPure FPLC on an S200 Increase column (GE Healthcare).
En savoir plus

29 En savoir plus

Contrasted TCRβ diversity of CD8+ and CD8- T cells in rainbow trout

Contrasted TCRβ diversity of CD8+ and CD8- T cells in rainbow trout

extracellular parasites. Another subset named Th17 is character- ized by the capacity to produce IL-17, IL-21 and IL-22 and plays a key role in inflammation. Once antigen is eliminated, central memory and effector memory T cells persist in the memory pool to provide systemic immune surveillance in secondary lymphoid and in non-lymphoid tissues, to react promptly in case of secondary infection. CD8 + T lymphocytes possess cytotoxic capacity and are responsible for the elimination of virus-infected and tumor cells. Following their initial expansion and subsequent clearance of the viral infection, most cytotoxic T lymphocytes (CTL) undergo apoptosis, leaving behind a small but stable pool of memory CD8 + T cells. Thus, after early double-positive thymo- cytes express both CD4 and CD8 molecules and undergo differentiation into either CD8 + CD4 2 or CD8 2 CD4 + single- positive cells, CD4 and CD8 distinguish two basic lineages of ab T lymphocytes representing T cells with heterologous functions [5]. Basic subsets of ab T cells characterized by the expression of CD4 and CD8 have been found also in fish, indicating that these markers constitute fundamental molecules of the vertebrate T cell response, together with classical MHC class I and II, CD3, CD28 and CTLA4 co-receptors. In teleost fish, CD8a was discovered first in rainbow trout where it was expressed at high levels in the thymus and at lower levels in spleen, kidney, gut, and blood leukocytes [6]. CD8a and b were later found in a number of other teleost fish species, and also in Chondrichtyans [7–10]. Although trout CD8a lacks a typical LCK binding motif in its cytoplasmic tail, it has been recently shown that the CD8 co-receptor can bind LCK as in mammals [11]. Importantly, the expression level of CD8 transcripts increases during infections and allogenic stimu- lation [12], and is correlated with lymphocyte cytotoxic activity in ginbuna crucian carp [13]. Alloantigen-specific cytotoxicity is mediated by CD8
En savoir plus

13 En savoir plus

Interconnected subsets of memory follicular helper T cells have different effector functions

Interconnected subsets of memory follicular helper T cells have different effector functions

would participate to this phenomenon since only few pMHCII + B cells can be found in the memory phase. While Ag is not required for the maintenance of immune memory 51 – 53 , we propose that Ag is important for the correct placement of memory Tfh cells in proximity to memory B cells in the B follicles of the lymphoid site draining initial Ag entry with the two memory cell compartments perceiving this interaction as memory sustaining, as opposed to an immune challenge resulting in activation and effector out- comes. This would not be peculiar to memory Tfh cells since it parallels the formation of a peripheral cellular niche of tissue-resident memory CD8 + T cells (TRM) in non-lymphoid organs. These cells, as for local memory Tfh cells, express CD69, which seems to act as an additional retention signal on TRM 54 , 55 . Moreover, it has been shown very recently that transient expression of Ag impacts TRM generation and that Ag-dependent competition shapes the repertoire of TRM 56 , 57 . Furthermore, in favor of this hypothesis, a recent study showed that Rituximab treatment resulted in a lack of naive and GC B cells in human lymph nodes without affecting the Tfh cell populations 58 . Thus, Tfh cells do not require an ongoing GC response for their maintenance. However, what the authors also showed is that Rituximab treatment had no effect on the pool of memory B cells thus confirming that memory Tfh/memory B cell interactions control the maintenance of the pool of memory lymphocytes.
En savoir plus

15 En savoir plus

Targeting p53 and histone methyltransferases restores exhausted CD8+ T cells in HCV infection

Targeting p53 and histone methyltransferases restores exhausted CD8+ T cells in HCV infection

Global transcriptional repression in T2/late HCV-speci fic CD8+ T cells. To delineate the dysfunctional features of the T2/late-chronic stage, we focused on the comparison between HCV-specific CD8+ T cells from established chronic and late- resolved patients. Most functional categories identified as dysre- gulated in the T2/late stage by GSEA were downregulated, as indicated by the negative Normalized Enrichment Score (NES) values reported in Supplementary Data 2 (T2 sheets). Gene sets significantly enriched at both T1/early and T2/late time-points but oppositely regulated (i.e., upregulated at T1 and down- regulated at T2) are outlined in Fig. 6 a. T2/late-downregulated gene sets include genes coding for genome safeguard, cell cycle/ checkpoint regulation, proteasomal degradation, mitochondrial metabolism and OXPHOS components, as well as multiple signal transducers acting downstream to TCR activation (Fig. 6 a, b and T2 Sheets in Supplementary Data 2). qPCR validation, applied to the comparison of T2/late-chronic vs. resolved HCV patients and healthy FLU controls, confirmed the expression trends revealed by microarray analysis for a subset of T cell effector (e.g., ZAP70, LAT, AKT1, and Tbet, also known asTBX21) and regulator genes (e.g., ADCY4, BATF), whereas basal expression levels or a weak upregulation were observed for the TCR regulators PD-1 and CTLA-4, respectively (Supplementary Fig. 8) 4 , 40 , 41 . To further
En savoir plus

21 En savoir plus

Neurons are MHC Class I-Dependent Targets for CD8 T Cells upon Neurotropic Viral Infection

Neurons are MHC Class I-Dependent Targets for CD8 T Cells upon Neurotropic Viral Infection

As recognition of peptide-MHC I complexes is essential to elicit CTL effector functions, it has long been considered that neurons were spared from CD8 T cell attack because they did not express MHC I molecules [8,9]. Recent studies, however, have challenged this view. First, accumulating evidence has revealed that MHC I expression in the developing and adult CNS can have additional non-immune functions. Indeed, neuronal MHC I molecules appear to be crucial for normal brain development, neuronal differentiation and plasticity [10,11]. In addition to their role in CNS function, it was also shown that neurons could express MHC I molecules under inflammatory conditions. For example, in Rasmussen’s encephalitis, histopathological examination of autop- sy material revealed the presence of granzyme B-containing CD8 T cells in direct apposition to MHC I positive neurons [12]. Further evidence of MHC I inducibility in neurons was provided in vitro. Indeed, it has been shown that primary cultures of neurons treated with IFN-c and electrically silenced using Tetrodotoxin (TTX) can be induced to express MHC I molecules on their surface [13]. This expression is functionally relevant, as CTL can attack peptide-pulsed neurons in an antigen-specific manner in vitro [14]. One caveat of such studies, however, is that they were performed using neurons loaded with non-limiting amounts of exogenous peptides. Moreover, CD8 T cells used in these assays were either CTL clones or lines with pre-defined epitope specificity, often derived for practical reasons from TCR- transgenic animals. CTL were also often further differentiated in vitro or restimulated in culture. Despite the above-mentioned limitations, several studies using variations of this experimental paradigm have provided considerable insight on MHC I-restricted T cell interactions with neurons [2,15]. One still unsatisfactorily
En savoir plus

15 En savoir plus

CD4 and CD8 co-receptors modulate functional avidity of CD1b-restricted T cells

CD4 and CD8 co-receptors modulate functional avidity of CD1b-restricted T cells

A small but consistent minority of T cells that do not express either CD4 or CD8 co-receptor provided proof-of-concept for MHC-independent modes of T cell activation (Porcelli et al., 1992). Specifically, invariant natural killer T (iNKT) cells recognize lipids presented by cluster of differentiation 1 (CD1) and mucosal associated invariant T (MAIT) cells recognize metabolites presented by MHC-related protein 1 (MR1) (Beckman et al., 1994; Kjer-Nielsen et al., 2012). On average, 15% of iNKT cells express CD4, 49% are double negative (DN), and roughly 34% express the CD8ɑɑ homodimer (O’Reilly et al., 2011). Among MAIT cells, 35% express CD8ɑɑ and 45% express CD8ɑβ (Gherardin et al., 2018). There is evidence that co-receptors are actively involved in antigen recognition by iNKT and MAIT cells. CD4 potentiates iNKT cell activation leading to sustained TCR signaling and potentiation of effector responses (Thedrez et al., 2007). Additionally, blocking CD8 with a monoclonal antibody leads to decreased MAIT cell responses to Escherichia coli (Kurioka et al., 2017). iNKT and MAIT cells can also be divided into distinct functional classes based on co-receptor expression. In humans, iNKT cells that express the CD4 co-receptor simultaneously secrete both Th1 and Th2 cytokines, and DN iNKT cells have a Th1 phenotype (Gumperz et al., 2002; Lee et al., 2002). CD8 MAIT cells express higher levels of granulysin, granzyme B, and perforin, suggesting that they are more potently cytotoxic (Dias et al., 2018). DN MAIT cells express less IFN-γ and more IL-17 than CD8 MAIT cells, and have a higher ROR-γt to T-bet ratio, indicative of a Th17 phenotype (Dias et al., 2018). Notably, these functional classes exist without two pathways for selection, antigen processing, and antigen presentation as in the case of MHC-I and MHC- II. Thus, despite early reports that suggested these “innate-like” T cells might be limited to the minority of T cells lacking expression of co-receptors, iNKT and MAIT cells are clearly part of the majority of T cells that express either CD4 or CD8.
En savoir plus

43 En savoir plus

CD8+ Tumor-Infiltrating T Cells Are Trapped in the Tumor-Dendritic Cell Network

CD8+ Tumor-Infiltrating T Cells Are Trapped in the Tumor-Dendritic Cell Network

After adoptive transfer into MCA-OVA–bearing mice, tumor- specific CD8 + T cells were primed in the draining lymph node and infiltrated the tumor but failed to control tumor growth [24]. Mice preconditioning by CP treatment efficiently increased priming of T cells and tumor infiltration but had only a transient control in tumor progression associated with a rapid loss of effector functions. We deciphered antitumor-specific T cell infiltration after chemotherapy by following their interactions with TuDCs using two-photon real-time imaging technology on explanted tumor tissues. We used the CD11c- YFP transgenic mice and showed that YFP + cells were distributed in the whole parenchyma, exhibited reduced displacements but strong protrusive activity that allowed interconnections, and generated a net- work of ramified TuDCs like that described previously for macrophages [31]. CP induces dendritic cell (DC) precursor expansion and activa- tion between 10 and 15 days after treatment, which correlates with increased T cell antitumor activity [32–36]. After CP treatment, we observed an accumulation of an immature Ly6C high myeloid popula- tion in the YFP − myeloid cell compartment. The possible overlap of this Ly6c high subset with the myeloid-derived suppressor cell Gr1 + population may lead to confused interpretations and warrants caution. Nakasone et al. observed CCR2-dependent infiltration of myeloid cells after chemotherapy in a mammary carcinoma model and a delayed tumor relapse in CCR2-deficient mice [37], suggesting that after de novo infiltration of mobilized inflammatory monocytes, these last
En savoir plus

16 En savoir plus

HLA-E-Restricted Cross-Recognition of Allogeneic Endothelial Cells by CMV-Associated CD8 T Cells: A Potential Risk Factor following Transplantation

HLA-E-Restricted Cross-Recognition of Allogeneic Endothelial Cells by CMV-Associated CD8 T Cells: A Potential Risk Factor following Transplantation

1 Inserm, U892, Nantes, France, 2 Univ Nantes, Nantes, France, 3 CNRS, UMR 6299, Nantes, France, 4 Inserm, U1064, Nantes, France, 5 CHU Nantes, Nantes, France Abstract Although association between CMV infection and allograft rejection is well admitted, the precise mechanisms involved remain uncertain. Here, we report the characterization of an alloreactive HLA-E-restricted CD8 T cell population that was detected in the PBL of a kidney transplant patient after its CMV conversion. This monoclonal CD8 T cell population represents a sizable fraction in the blood (3% of PBL) and is characterized by an effector-memory phenotype and the expression of multiple NK receptors. Interestingly, these unconventional T cells display HLA-E-dependent reactivity against peptides derived from the leader sequences of both various HCMV-UL40 and allogeneic classical HLA-I molecules. Consequently, while HLA-E-restricted CD8 T cells have potential to contribute to the control of CMV infection in vivo, they may also directly mediate graft rejection through recognition of peptides derived from allogeneic HLA-I molecules on graft cells. Therefore, as HLA-E expression in nonlymphoid organs is mainly restricted to endothelial cells, we investigated the reactivity of this HLA-E-restricted T cell population towards allogeneic endothelial cells. We clearly demonstrated that CMV- associated HLA-E-restricted T cells efficiently recognized and killed allogeneic endothelial cells in vitro. Moreover, our data indicate that this alloreactivity is tightly regulated by NK receptors, especially by inhibitory KIR2DL2 that strongly prevents TCR-induced activation through recognition of HLA-C molecules. Hence, a better evaluation of the role of CMV-associated HLA-E-restricted T cells in transplantation and of the impact of HLA-genotype, especially HLA-C, on their alloreactivity may determine whether they indeed represent a risk factor following organ transplantation.
En savoir plus

15 En savoir plus

Synergistic targeting of breast cancer stem-like cells by human γδ T cells and CD8+ T cells

Synergistic targeting of breast cancer stem-like cells by human γδ T cells and CD8+ T cells

Figure 3 IFN- γ-dependent sensitisation of CSC-like cells to antigen-specific CD8 + T cells. (a) FluM1-transduced CSC-like cells and non-CSCs were mixed in equal numbers, and used as targets for killing by FluM1-speci fic CD8 + T cells at different effector:target (E:T) ratios. Speci fic killing of CellVue and PKH67- labelled target cells was assessed by live/dead staining and analysed by flow cytometry. Data shown are from a triplicate experiment representative of two independent experiments. Signi ficance of differences was calculated by two-way ANOVA. (b) MHC class I (HLA-ABC) and CD54 expression levels on the cell surface of non-CSCs and CSC-like cells as determined by flow cytometry. Bar diagrams show means+s.d. from three independent experiments. MFI, mean fluorescence intensity. (c) MHC class I and CD54 expression levels on CSC-like cells after overnight sensitisation with 100 U ml − 1 recombinant human IFN- γ
En savoir plus

11 En savoir plus

Transcriptional regulation of effector CD8+ T cell differentiation and molecular dysfunction during HIV-1 infection

Transcriptional regulation of effector CD8+ T cell differentiation and molecular dysfunction during HIV-1 infection

3.1.1 Clinical Course of HIV infection HIV infection is characterized by a peak in plasma viremia, usually reaching more than a million RNA copies/ml, and occurring 3-4 weeks after HIV entry. This period is characterized by non-specific flu-like symptoms and coincides with decreased numbers of circulating CD4+ T cells (McMichael, Borrow et al. 2010). The partial viral control correlates temporally with an HIV-specific CD8+ T cell response which peaks just prior to the decline in viremia and is important in maintaining the viral load at stable levels (Koup, Safrit et al. 1994). This essential role of CD8+ T cells in controlling HIV disease progression has been confirmed in non-human primate models (Matano, Shibata et al. 1998; Jin, Bauer et al. 1999; Schmitz, Kuroda et al. 1999). Indeed, it has been shown that depletion of CD8+ T cells leads to a rapid increase in viremia while upon reappearance of CD8+ T cells, viremia decreases during acute and chronic SIV (Jin, Bauer et al. 1999; Schmitz, Kuroda et al. 1999). Chronic HIV infection, also known as the latent phase, lasts an average of 10 years and begins when the viral load decreases and CD4 T cell counts are stabilized. Throughout this phase, CD4+ T cells are gradually depleted from the circulation (McMichael, Borrow et al. 2010). When CD4+ T cells numbers decrease below 200 cells/μl, the immune system is susceptible to opportunistic infections and tumors and this immune dysfunction leads to AIDS. The rate of this depletion varies from one individual to another, for reasons that remain to be fully elucidated (Sun, Williams et al. 2004). The depletion of CD4+ T cells is thought to contribute to the inability of CD8+ T cells to mount effective responses and control viremia during chronic infection.
En savoir plus

192 En savoir plus

Involvement of CD8+ T Cells in Multiple Sclerosis

Involvement of CD8+ T Cells in Multiple Sclerosis

the blood of MS patients has also been evidenced, suggesting a specific involvement in the disease ( 32 ). Recently, it has been shown that more than 80% of these cells are mucosal-associated invariant T (MAIT) cells. MAIT cells are a subset of innate effector memory T cells bearing a semi-invariant TCR (Vα7.2-Jα33/12/20) in humans ( 77 – 82 ). They are restricted to the MHC class-I related protein I (MR1) and have antimicro- bial properties both in vitro and in vivo ( 83 – 86 ). Although they have been correlated with various autoimmune diseases ( 87 – 90 ), their implication, especially in MS ( 32 , 91 , 92 ), remain elusive. MAIT cells are present in the CNS of MS patients, but at very low frequencies compared to in the blood ( 92 – 94 ). This argues against a particular implication of this IL-17-producing CD8 +
En savoir plus

10 En savoir plus

Activation of tolerogenic dendritic cells in the tumor draining lymph CD8+ T cells engineered to express CD40 ligand

Activation of tolerogenic dendritic cells in the tumor draining lymph CD8+ T cells engineered to express CD40 ligand

One problem that limits the efficacy of adoptive T cell therapies is rapid tolerization or deletion of transferred tumor-reactive T cells in cancer patients. Although recent studies have shown that younger or central memory-like CD8 + T cells are more potent and persist longer than effector memory-like T cells in the setting of ACT (44,45), their increased requirement for costimulatory support may heighten the influence of tolerogenic DCs on these transferred cells. Because of its critical and natural role in DC activation, CD40 ligation has been explored to activate tolerogenic DCs in the tumor environment. Although systemic administration of agonist anti-CD40 antibodies has been shown to replace the need for CD4 + T cell help (12-14), boost CD8 + T cell responses to tumors and break peripheral self-tolerance (15-17), there is also evidence that it can induce immune suppression (18-21). Similarly, we found that systemic administration of an agonist anti-CD40 antibody in TRP-SIY mice initially stimulated an anti-tumor CD8 + T cell response, but eventually led to severe immune suppression, in the context of an influenza infection (Fig. 1). In addition, systemic anti-CD40 administration is associated with significant side effects (data not shown). The complicated and variable outcomes of systemic CD40 ligation in immune responses highlight the need to induce CD40 ligation locally in the tumor tissue.
En savoir plus

17 En savoir plus

Expansion of the CD8 memory T cells : implications for the self-renewal gene Hoxb4

Expansion of the CD8 memory T cells : implications for the self-renewal gene Hoxb4

i Résumé Les cellules CD8 T mémoire (Tm) offrent une protection tout au long de la vie contre les infections récurrentes. Elles sont maintenues grâce à des mécanismes d'auto-renouvellement. Les cellules souches hématopoïétiques (CSH) peuvent aussi s'auto-renouveller lentement, en assurant leur maintenance à long terme. Les deux types de cellules utilisent la moelle osseuse comme principale niche de prolifération. CD8 Tm et CSH partagent partiellement un profil transcriptionnel, y compris certains gènes connus pour contrôler l'auto-renouvellement. Les gènes Hox, dont Hoxb4 qui est un activateur puissant de l’expansion des CSH in vitro et in vivo, sont exprimés par les CSH. Basé sur les similitudes entre les CSH et les cellules Tm, nous émettons l'hypothèse que les gènes impliqués dans l’auto-renouvellement des CSH, comme Hoxb4, favoriseront l'expansion des cellules CD8 Tm. Pour tester cette hypothèse, nous avons déterminé l'effet de la surexpression de Hoxb4 dans les cellules T à partir de souris transgéniques jeunes et âgées, et sur la prise de greffe et le maintien des cellules CD8 Tm après leur transplantation dans des souris immunocompétentes ou immunosupprimées.
En savoir plus

113 En savoir plus

Function of the immunoregulatory CD4-CD8- T cells in the context of autoimmune diabetes

Function of the immunoregulatory CD4-CD8- T cells in the context of autoimmune diabetes

Appendix 1, Figure 8), we hypothesized that DN T cells migrated to the pancreas where they could eliminate autoreactive B cells. Indeed, autoreactive B cells are defined by their ability to produce autoantibodies and present self-antigens to autoreactive T cells thereby activating them (Figure 6), both of which are implicated in autoimmune diabetes development. Therefore, the elimination of such autoreactive B cells could explain the inhibition of autoimmune diabetes following DN T cell transfer. Indeed, the transferred DN T cells could be tracked to the pancreatic lymph nodes as early as 24 hours, and for at least 4 weeks, post-transfer where we observed a preferential accumulation of the transferred DN T cells in comparison to both the skin-draining and mesenteric lymph nodes (Article 2, Supplementary Figure 5). This accumulation correlated with a higher proportion of transferred DN T cells expressing the activation marker CD69 (Article 2, Figure 4B) and having entered cellular division, demonstrated by carboxyfluorescein succinimidyl ester (CFSE) staining (Article 2, Figure 4C). Together with our findings that non-transgenic DN T cells exhibit an activated phenotype ex vivo (Article 2, Supplementary Figure 2), which is representative of an ability to recognize self-antigens, and their ability to kill B cells presenting islet antigen (Article 2, Figure 2B), these results suggest that DN T cells recognize islet antigens presented in the pancreatic lymph node thus inducing their preferential activation, proliferation and accumulation at this site.
En savoir plus

241 En savoir plus

CD8[superscript +] T-cell Responses Rapidly Select for Antigen-Negative Tumor Cells in the Prostate

CD8[superscript +] T-cell Responses Rapidly Select for Antigen-Negative Tumor Cells in the Prostate

Figure 1. Prostate infiltrating T cells gradually lose contact with antigen-expressing tumor cells. 2C T cells were adoptively transferred into TRP-SIY mice followed by WSN-SIY infection. Eleven, 35 and 50 dpt, prostate sections were stained with anti-Thy1.1 (brown), X-gal (blue) and eosin (red). A. Representative stains for Thy1.1 (left), isotype control (center) and β-gal (right) of prostate sections of TRP-SIY mice 11 dpt. Scale bars, 100μm. B-D. The areas of Thy1.1 and β-gal staining were quantified as described in the Materials and Methods. Shown are percentages (mean ± SD) of area within the prostate tissue that stain positive for Thy1.1 + 2C T cells at indicated time point (B). Representative images of Thy1.1 and β-gal stains of prostate sections of a mouse 11 dpt (C). Thy1.1 staining was classified as either in contact with β-gal + cells (contact, highlighted in yellow), within a prostate gland containing β-gal + cells (β-gal + gland), within a prostate gland that does not contain β-gal staining (β-gal - gland), in the interglandular interstitial space (interstitial space), or within the lumen of the prostate gland (lumen). The boxed areas are shown in higher magnifications. Scale bars, 100μm and 30μm in low and high magnifications, respectively. The areas of Thy1.1 stain in each category were quantified and shown as percentages of total Thy1.1 + area (mean ± SD) (D). The numbers of mice analyzed in each group for B and D are indicated.
En savoir plus

17 En savoir plus

Show all 3282 documents...