scholarly journals Inducible RNAi in vivo reveals that the transcription factor BATF is required to initiate but not maintain CD8+ T-cell effector differentiation

2014 ◽  
Vol 112 (2) ◽  
pp. 512-517 ◽  
Author(s):  
Jernej Godec ◽  
Glenn S. Cowley ◽  
R. Anthony Barnitz ◽  
Ozan Alkan ◽  
David E. Root ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Fate ◽  
Viral Vectors ◽  
Ex Vivo ◽  
Experimental System ◽  
Gene Knockdown ◽  
Naive T Cells ◽  
Naïve T Cells

The differentiation of effector CD8+ T cells is critical for the development of protective responses to pathogens and for effective vaccines. In the first few hours after activation, naive CD8+ T cells initiate a transcriptional program that leads to the formation of effector and memory T cells, but the regulation of this process is poorly understood. Investigating the role of specific transcription factors (TFs) in determining CD8+ effector T-cell fate by gene knockdown with RNAi is challenging because naive T cells are refractory to transduction with viral vectors without extensive ex vivo stimulation, which obscures the earliest events in effector differentiation. To overcome this obstacle, we developed a novel strategy to test the function of genes in naive CD8+ T cells in vivo by creating bone marrow chimera from hematopoietic progenitors transduced with an inducible shRNA construct. Following hematopoietic reconstitution, this approach allowed inducible in vivo gene knockdown in any cell type that developed from this transduced progenitor pool. We demonstrated that lentivirus-transduced progenitor cells could reconstitute normal hematopoiesis and develop into naive CD8+ T cells that were indistinguishable from wild-type naive T cells. This experimental system enabled induction of efficient gene knockdown in vivo without subsequent manipulation. We applied this strategy to show that the TF BATF is essential for initial commitment of naive CD8+ T cells to effector development but becomes dispensable by 72h. This approach makes possible the study of gene function in vivo in unperturbed cells of hematopoietic origin that are refractory to viral transduction.

scholarly journals Antigen-independent activation of naive and memory resting T cells by a cytokine combination.

1994 ◽  
Vol 180 (3) ◽  
pp. 1159-1164 ◽  
Author(s):  
D Unutmaz ◽  
P Pileri ◽  
S Abrignani
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Effector Function ◽  
Necrosis Factor Alpha ◽  
Naive T Cells ◽  
Naïve T Cells

We investigated whether human resting T cells could be activated to proliferate and display effector function in the absence of T cell receptor occupancy. We report that combination of interleukin 2 (IL-2), tumor necrosis factor alpha, and IL-6 activated highly purified naive (CD45RA+) and memory (CD45RO+) resting CD4+ T cells to proliferate. Under this condition, memory resting T cells could also display effector function as measured by lymphokine synthesis and help for immunoglobulin production by B cells. This novel Ag-independent pathway of T cell activation may play an important role in vivo in recruiting effector T cells at the site of immune response and in maintaining the clonal size of memory T cells in the absence of antigenic stimulation. Moreover, cytokines can induce proliferation of naive T cells without switch to memory phenotype and this may help the maintenance of the peripheral pool of naive T cells.

Steady-state dendritic cells expressing cognate antigen terminate memory CD8+ T-cell responses

Blood ◽  
2008 ◽  
Vol 111 (4) ◽  
pp. 2091-2100 ◽  
Author(s):  
Tony J. Kenna ◽  
Ranjeny Thomas ◽  
Raymond J. Steptoe
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Steady State ◽  
T Cell ◽  
Developmental Plasticity ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Cognate Antigen ◽  
Costimulatory Signals

Antigen stimulation of naive T cells in conjunction with strong costimulatory signals elicits the generation of effector and memory populations. Such terminal differentiation transforms naive T cells capable of differentiating along several terminal pathways in response to pertinent environmental cues into cells that have lost developmental plasticity and exhibit heightened responsiveness. Because these cells exhibit little or no need for the strong costimulatory signals required for full activation of naive T cells, it is generally considered memory and effector T cells are released from the capacity to be inactivated. Here, we show that steady-state dendritic cells constitutively presenting an endogenously expressed antigen inactivate fully differentiated memory and effector CD8+ T cells in vivo through deletion and inactivation. These findings indicate that fully differentiated effector and memory T cells exhibit a previously unappreciated level of plasticity and provide insight into how memory and effector T-cell populations may be regulated.

Memory Effector Cells but Not Effector Cells Derived from Naive T Cells Can Utilize a Non-Perforin and Non-FasL Pathway To Inhibit Allogeneic Progenitor Cell Function Ex-Vivo.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3029-3029
Author(s):  
Zachary F. Zimmerman ◽  
Monica V. Jones ◽  
Stephen A. Stohlman ◽  
Robert B. Levy
Keyword(s):  
T Cells ◽  
Progenitor Cell ◽  
Ex Vivo ◽  
Cell Populations ◽  
Naive T Cells ◽  
Effector Cells ◽  
Naïve T Cells ◽  
Effector Pathways ◽  
Dependent Pathway

Abstract We are interested in understanding the effector pathways used by host T cells to inhibit engraftment following allogeneic HCT. Previous work in MHC matched models found that mice deficient in either perforin or fasl continue to mediate resistance, however, the numbers of BMCs necessary to override the host barrier is less than in cytotoxically normal mice. These findings suggest both cytotoxic pathways are likely to contribute to the barrier. Notably, in the combined absence of both pathways, resistance is virtually absent. In contrast, animals which contain memory CD8 T cells can resist large numbers of BMCs regardless of the absence of both perforin and fasl pathways. The present studies examined the use of these pathways by T cell populations with respect to the inhibition of progenitor cell (PC)activity (CFU-IL3) from BMC ex-vivo to determine the relative contributions of perforin and/or fasL in inhibition mediated by effector cells derived from naive vs. memory cell populations. Effector cells were generated from unsensitized BALB/c and BALB/c-perf−/− mice as well as mice immunized against H2b alloantigens. Primary effectors from unsensitized mice and memory effectors were generated following 5 and 2–3 day MLC cultures, respectively. Effector cells were co-cultured up to 48 hrs. with BMC and then plated with rmIL-3 to elicit CFU formation. Effector cells from unsensitized BALB/c-wt mice inhibited allogeneic B6-wt CFU (>80%) as well as B6-lpr CFU (>70%) formation. Syngeneic BM was not inhibited. These data demonstrate that the perforin dependent pathway is sufficient for inhibition, consistent with in vivo resistance observed in FasL defective recipients. Effector cells generated from unsensitized BALB/c-perf−/− also effectively inhibited B6-wt CFU (>80%), consistent with a fas mediated pathway. However, in contrast to effectors generated from unsensitized BALB/C-wt mice, effector cells generated from BALB/c-perf−/−did not inhibit CFU from B6-lpr BM, suggesting that: 1) both perforin and fasl effector pathways can be utilized to inhibit CFU formation ex-vivo and, 2) in the absence of both pathways, these primary effector cells could not mediate such inhibition. As anticipated, memory effector cells from BALB/c-wt mice exhibited the same pattern as the "naive" effectors (i.e.>90% inhibition) against both B6-wt and B6-lpr BM. This finding is consistent with inhibition by perforin and/or additional effector pathways. However, memory effector cells from cytotoxically deficient BALB/c-perf−/− mice failed to mediate the same pattern of inhibition as "naive" effectors from this strain. In contrast to the inability of primary effectors to inhibit B6-lpr CFU activity, the memory effectors efficiently (i.e.>90% inhibition) inhibited CFU generation from B6-lpr BM. These findings demonstrate that unlike effector cells generated from naive T cells, memory effectors can use a non-perforin/fasL dependent pathway to inhibit allogeneic PC activity. The results are consistent with the inhibition of engraftment in vivo following conditioning and transplant into cytotoxically double (perforin + fasL) defective mice and support the notion that memory - but not primary effectors utilize a non-perforin/fasl pathway to inhibit allogeneic CFU PC function. Current experiments are examining the kinetics of CFU inhibition and precise characterization of the effector T cells.

A spectrum of biophysical interaction modes between T cells and different antigen-presenting cells during priming in 3-D collagen and in vivo

Blood ◽  
2004 ◽  
Vol 104 (9) ◽  
pp. 2801-2809 ◽  
Author(s):  
Matthias Gunzer ◽  
Carsten Weishaupt ◽  
Anja Hillmer ◽  
Yasmin Basoglu ◽  
Peter Friedl ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Antigen Presenting Cells ◽  
Model Systems ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Antigen Presenting ◽  
Activated B Cells

Abstract For activation T cells engage antigen-presenting cells (APCs) in lymphatic tissues. The contact duration and kinetics (static versus dynamic) vary considerably in different model systems; however, it is unclear whether T cells, APCs, or the environment are responsible for the observed discrepancies. Using 3-D collagen matrices as structural scaffold, we directly compared the kinetics of T-cell engagement and activation by functionally major APC types, ie, dendritic cells (DCs) and resting or activated B cells. Resting B cells engaged T cells in long-lived (several hours), adhesive, and leukocyte function-associated antigen-1 (LFA-1)-dependent conjugates in 3-D collagen as well as in intact lymph nodes in vivo. DCs and preactivated B cells, however, supported predominantly dynamic, short-lived (minutes), and sequential contacts to T cells that were dependent on high cytoskeletal activity of the APCs but could not be inhibited by anti-LFA-1 treatment. Naive T cells were most strongly activated by DCs and activated B cells, whereas resting B cells were 100-fold less efficient to induce T-cell proliferation. Thus, in the same 3-D environment, naive T cells respond with a spectrum of different interaction modes dependent on the type and activation state of the APCs. Thereby, more dynamic interaction kinetics is positively correlated with higher T-cell priming efficiency. (Blood. 2004;104: 2801-2809)

scholarly journals B lymphocytes in vivo fail to prime naive T cells but can stimulate antigen-experienced T lymphocytes.

1993 ◽  
Vol 177 (3) ◽  
pp. 679-690 ◽  
Author(s):  
F Ronchese ◽  
B Hausmann
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Class Ii ◽  
T Cell Response ◽  
Scid Mice ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Cell Responses

The ability of B cells or macrophages and dendritic cells (DC) to elicit class II-restricted T cell responses in vivo was compared using a mouse chimera model. Severe combined immunodeficient (SCID) mice (H-2d), reconstituted either with T or T+B lymphocytes from (H-2d x H-2b) donors, were immunized subcutaneously with protein antigen (Ag) to induce a class II-restricted T cell response. The frequency and major histocompatibility complex restriction of the resulting Ag-specific T cells were analyzed to establish whether B cells were necessary for the induction of class II-restricted T cell responses, and to determine the cell type on which priming had occurred. The results indicated that: (a) B cells are not necessary for the induction of a class II-restricted T cell response in vivo, as the frequencies of interleukin 2 (IL-2)- or IL-3-secreting T cells induced in the presence or absence of B cells were comparable. (b) Activation of naive T cells requires presentation of Ag on DC; Ag presented only on B cells is not sufficient to elicit a response. No H-2b-restricted, IL-3-secreting cells could in fact be detected in SCID mice reconstituted with naive (H-2d x H-2b) T cells and nonimmune or antigen-primed (H-2d x H-2b) B cells. (c) Previously primed T cells are able to be stimulated by Ag presented by both B cells and DC. H-2b-restricted, IL-3-secreting cells could in fact be readily demonstrated in SCID mice reconstituted with antigen-primed (H-2d x H-2b) T and B cells. Irrespective of whether the T cells were naive or previously activated, B cells were able to respond with an Ag-specific immunoglobulin G response, indicating that B cells were functional and able to present Ag in order to receive specific T cell help. Therefore, it appears that B cells are not necessary and do not participate in the initial priming of T cells; however, Ag presented by B cells can reactivate previously primed T cells. Taken together, these data indicate that during the course of an immune response Ag is first presented to naive T cells via DC, and only subsequently primed T cells can be stimulated by Ag presented by B cells.

scholarly journals An intense form of homeostatic proliferation of naive CD8+ cells driven by IL-2

2007 ◽  
Vol 204 (8) ◽  
pp. 1787-1801 ◽  
Author(s):  
Jae-Ho Cho ◽  
Onur Boyman ◽  
Hee-Ok Kim ◽  
Bumsuk Hahm ◽  
Mark P. Rubinstein ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Receptor ◽  
T Cell Response ◽  
Gradual Transition ◽  
Homeostatic Proliferation ◽  
Naive T Cells ◽  
Effector Cells ◽  
Naïve T Cells

In conditions of T lymphopenia, interleukin (IL) 7 levels rise and, via T cell receptor for antigen–self–major histocompatibility complex (MHC) interaction, induce residual naive T cells to proliferate. This pattern of lymphopenia-induced “homeostatic” proliferation is typically quite slow and causes a gradual increase in total T cell numbers and differentiation into cells with features of memory cells. In contrast, we describe a novel form of homeostatic proliferation that occurs when naive T cells encounter raised levels of IL-2 and IL-15 in vivo. In this situation, CD8+ T cells undergo massive expansion and rapid differentiation into effector cells, thus closely resembling the T cell response to foreign antigens. However, the responses induced by IL-2/IL-15 are not seen in MHC-deficient hosts, implying that the responses are driven by self-ligands. Hence, homeostatic proliferation of naive T cells can be either slow or fast, with the quality of the response to self being dictated by the particular cytokine (IL-7 vs. IL-2/IL-15) concerned. The relevance of the data to the gradual transition of naive T cells into memory-phenotype (MP) cells with age is discussed.

scholarly journals Blinatumomab-Induced T Cell Activation at Single Cell Transcriptome Resolution

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3886-3886
Author(s):  
Hong Yin ◽  
Yi Huo ◽  
Zhen Sheng ◽  
Chi-Ming Li ◽  
Daniel C Ellwanger ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Single Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Ex Vivo ◽  
Target Cells ◽  
Ex Vivo Model ◽  
Naive T Cells ◽  
Naïve T Cells

Introduction Blinatumomab, a bi-specific T cell engager (BiTE®) combining the VH and VL domains of two antibodies against human CD19 and CD3, has been approved by U.S. Food and Drug Administration (FDA) for the treatment of patients with relapsed or refractory B precursor ALL (r/r B-ALL) for its clinical benefit demonstrated in different clinical trials. Clinical trials have also shown that there are still patients refractory to blinatumomab. It is thus important to understand the resistance mechanisms. Blinatumomab connects patients' autologous T cells and target cells to form immunologic synapse which potently triggers the activation signaling cascades in T cells and guides T cells to recognize and induce perforin/granzyme-mediated lysis of CD19+ B-ALL cells. Previous studies showed blinatumomab-mediated cytotoxicity involves different T cell subpopulations. But response of each T cell subpopulation to blinatumomab treatment remained largely unknown. Methods and Results In this study, we used 10X Genomics based single cell RNA sequencing to analyze the transcriptome of single T cells before and after blinatumomab treatment. First, ex vivo blinatumomab cytotoxicity model was established, in which healthy PBMCs were used as effector cells and cocultured with target cells (RS4;11 cells or SUP-B15 cells) at an effector-to-target cell ratio of 10:1 with 0.1 ng/mL blinatumomab. Then, PBMCs and BMMCs from 2 B-ALL patients were cultured with 10 ng/mL blinatumomab. Cells from both ex vivo model and patient samples were sequenced using 10X Genomics platform. In total, transcriptome of 17920 single T cells from the ex vivo model and 2271 single T cells from patient sample were analyzed. Based on T cell trajectory analysis, we identified four distinct populations of blinatumomab-activated T cells, which were derived from CD8+ effector memory T (TEM) cells, CD4+ central memory (TCM) cells, naïve T cells and Tregs, respectively. The differentially expressed genes in activated clusters were analyzed to reflect T cell activation mechanisms. The result showed blinatumomab induced the upregulation of aerobic glycolysis pathway (PKM, PGAM1, ENO1, GAPDH and LDHA), cytoskeleton dynamics pathway (ACTD1, ACTB, NME1 and TUBA1B), IFN-responsive pathway (GBP1, PSME2, WARS, CXCL10 and STAT1), and the upregulation of well-known immune-related genes (TNFRSF4, TNFRSF18, LAG3, CD69, IL2RA, MIR155HG, BATF, SH2D2A, LTA, NFKBIA and NDFIP2). We found blinatumomab-activated CD8+ TEM cells showed stronger cytotoxic capability than other activated populations with specific production of cytotoxic factors (PRF1, IFNG and FASLG) and cytokines (CCL2, CCL3, CCL3L1, CCL4, CCL4L2, CCL8, XCL1, XCL2, TNFSF9 and TNFSF14). Last, differential gene expression analysis revealed that co-stimulatory (TNFRSF4,TNFRSF9 and TNFRSF18) and co-inhibitory receptors (LAG3 and TIGIT) were similarly up-regulated in clusters activated from memory and naïve T cells, indicating ligand dependent T cell functional outcomes induced by blinatumomab. Conclusion In summary, we used single cell sequencing to map the blinatumomab-mediated T cell activation state transition and reveal the molecular changes in different T cell subpopulations. Memory T cells, naïve T cells and Tregs were identified functional populations after blinatumomab treatment. CD8+ TEM accounted for the majority of blinatumomab-induced cytotoxicity. Furthermore, T cell co-regulatory receptors were identified as potential targets accountable for blinatumomab sensitivity or resistance mechanisms. The study demonstrated that the collected cellular transcriptional profiles can serve as resource to explore novel strategies to enhance the efficacy of blinatumomab. Disclosures Yin: Amgen: Employment. Huo:Amgen: Employment. Sheng:Amgen: Employment. Li:Amgen: Employment. Ellwanger:Amgen: Employment. Lu:Amgen: Employment. Homann:Amgen: Employment. Wang:Amgen: Employment. Ren:Ruijin hospital: Employment.

PD-L1 Immuno-Gene Therapy Under Cell Fate Control: Persistence of Cellular Delivery Vehicle and Transgene Expression.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3580-3580
Author(s):  
Shoba Amarnath ◽  
James CM Wang ◽  
Paul R. Massey ◽  
James L. Riley ◽  
Bruce Levine ◽  
...  
Keyword(s):  
Gene Therapy ◽  
T Cells ◽  
T Cell ◽  
Cell Fate ◽  
Adoptive Transfer ◽  
Transgene Expression ◽  
Ex Vivo ◽  
Human T Cells ◽  
Cell Fate Control

Abstract Abstract 3580 Poster Board III-517 Immune cell expression of programmed death ligand-1 (PD-L1) represents a particularly important molecular mechanism responsible for control of auto- and allo-immunity mediated by effector memory T cells expressing PD1 receptor. As such, we have reasoned that an immuno-gene therapy approach that enables T cell expression of PD-L1 will represent a novel method of immune regulation. Advantageous features of this proposed therapy include a capacity to: (1) enforce long-term, stable expression of PD-L1; (2) build-in an independent surface marker to allow specific transduced cell enrichment; (3) utilize cellular delivery vehicles comprised of highly functional T cells that persist in vivo after adoptive transfer; and (4) incorporate an enhanced cell fate control or ‘suicide’ gene to permit in vivo control of the immuno-gene therapy. Given these considerations, we developed a recombinant lentiviral vector (LV) incorporating an EF1-α promoter that first encodes the cDNA for a fusion protein consisting of human CD19 (truncated, non-signaling) combined with mutated human TMPK that efficiently activates AZT as a pro-drug (Sato et al; Mol Therapy, 2007); then, after an IRES element, the vector encodes full-length human PD-L1. LV was made after transfection of 293T cells and then concentrated and titered. Initial experiments used Jurkat cells to optimize virus infection and to confirm co-expression of CD19 and PD-L1 by flow cytometry. In previous work, we have demonstrated that ex vivo T cell expansion in rapamycin induces an anti-apoptotic phenotype that permits enhanced in vivo T cell persistence in murine models and human-into-mouse xenogeneic transplant models. As such, we established the goal of infecting primary human CD4+ T cells manufactured using ex vivo co-stimulation (anti-CD3, anti-CD28), Th1-type polarization (inclusion of IFN-α), and exposure to high-dose rapamycin (1 μM); using a 6-day culture system and subsequent anti-CD19 column purification, >90% of resultant transduced T cells expressed PD-L1. Next, we utilized a xenogeneic transplantation model (Rag2−/−γc−/− hosts) to assess in vivo persistence of the gene-modified T cells and transgene expression (10,000 T cells transferred i.v. into each host). In vivo experiment #1 demonstrated that recipients of gene-modified T cells had increased numbers of human T cells in the spleen that co-expressed CD19 and PD-L1 relative to recipients of non-transduced but identically expanded human T cells (harvested at day 5 after adoptive transfer; 38,000 cells/spleen vs. 1000 cells/spleen, p=0.02). Such in vivo harvested T cells were secondarily co-stimulated ex vivo and propagated for an additional 5 days: co-expression of CD19 and PD-L1 persisted in ∼ 50% of T cells harvested from the gene-modified T cell cohort, and T cell numbers were maintained ex vivo (yield of CD19+PD-L1+ cells, 28,600 vs. 1500; p=0.0001). In vivo experiment #2 confirmed and extended these results. At day 21 after adoptive transfer, recipients of gene-modified T cells had increased numbers of human T cells that co-expressed CD19 and PD-L1 relative to recipients of non-transduced but identically expanded human T cells in both the spleen (2800 cells/spleen vs. 390 cells/spleen, p=0.01; n=10 per cohort) and bone marrow (71,600 cells/marrow vs. 6500 cells/marrow, p=0.0001; n=10 per cohort). Such in vivo harvested T cells at day 21 after adoptive transfer were secondarily co-stimulated ex vivo and propagated for an additional 6 days: co-expression of CD19 and PD-L1 persisted in ∼ 50% of T cells harvested from the gene-modified T cell cohort, and T cell numbers were maintained ex vivo (yield of CD19+PD-L1+ cells harvested from spleen, 71,200 vs. 1800, p=0.0008; yield of CD19+PD-L1+ cells harvested from marrow, 226,000 vs. 1400, p=0.0001). Because the rapamycin-resistant T cell vehicle utilized in these experiments manifests an anti-apoptotic phenotype that confers long-term engraftment potential, it is likely that the demonstrated durability in transgene expression relates both to the efficiency of the LV method utilized and to a T cell pro-survival function. In conclusion, the LV-mediated transfer of this novel combination of CD19/TMPK fusion protein and PD-L1 results in stable transgene expression in primary human T cells in vitro and in vivo, thereby opening an avenue to assess PD-L1 mediated immuno-gene therapy under cell fate control. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Antigen-dependent and -independent Ca2+ Responses Triggered in T Cells by Dendritic Cells Compared with B Cells

1998 ◽  
Vol 188 (8) ◽  
pp. 1473-1484 ◽  
Author(s):  
Jérôme Delon ◽  
Nadège Bercovici ◽  
Graça Raposo ◽  
Roland Liblau ◽  
Alain Trautmann
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
Mhc Class Ii ◽  
Ex Vivo ◽  
Cell Formation ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Survival Signal

Dendritic cells (DCs) are much more potent antigen (Ag)-presenting cells than resting B cells for the activation of naive T cells. The mechanisms underlying this difference have been analyzed under conditions where ex vivo DCs or B cells presented known numbers of specific Ag–major histocompatibility complex (MHC) complexes to naive CD4+ T cells from T cell antigen receptor (TCR) transgenic mice. Several hundred Ag–MHC complexes presented by B cells were necessary to elicit the formation of a few T–B conjugates with small contact zones, and the resulting individual T cell Ca2+ responses were all-or-none. In contrast, Ag-specific T cell Ca2+ responses can be triggered by DCs bearing an average of 30 Ag–MHC complexes per cell. Formation of T–DC conjugates is Ag-independent, but in the presence of the Ag, the surface of the contact zone increases and so does the amplitude of the T cell Ca2+ responses. These results suggest that Ag is better recognized by T cells on DCs essentially because T–DC adhesion precedes Ag recognition, whereas T–B adhesion requires Ag recognition. Surprisingly, we also recorded small Ca2+ responses in T cells interacting with unpulsed DCs. Using DCs purified from MHC class II knockout mice, we provide evidence that this signal is mostly due to MHC–TCR interactions. Such an Ag-independent, MHC-triggered calcium response could be a survival signal that DCs but not B cells are able to deliver to naive T cells.

scholarly journals Freshly Isolated Peyer's Patch, but Not Spleen, Dendritic Cells Produce Interleukin 10 and Induce the Differentiation of T Helper Type 2 Cells

1999 ◽  
Vol 190 (2) ◽  
pp. 229-240 ◽  
Author(s):  
Akiko Iwasaki ◽  
Brian Lee Kelsall
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Responses ◽  
Ex Vivo ◽  
T Helper ◽  
Phenotypic Analysis ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Ifn Γ

Orally administered antigens often generate immune responses that are distinct from those injected systemically. The role of antigen-presenting cells in determining the type of T helper cell response induced at mucosal versus systemic sites is unclear. Here we examine the phenotypic and functional differences between dendritic cells (DCs) freshly isolated from Peyer's patches (PP) and spleen (SP). Surface phenotypic analysis of CD11c+ DC populations revealed that PP DCs expressed higher levels of major histocompatibility complex class II molecules, but similar levels of costimulatory molecules and adhesion molecules compared with SP DCs. Freshly isolated, flow cytometrically sorted 98–100% pure CD11c+ DC populations from PP and SP were compared for their ability to stimulate naive T cells. First, PP DCs were found to be much more potent in stimulating allogeneic T cell proliferation compared with SP DCs. Second, by using naive T cells from ovalbumin peptide–specific T cell receptor transgenic mice, these ex vivo DCs derived from PP, but not from SP, were found to prime for the production of interleukin (IL)-4 and IL-10 (Th2 cytokines). In addition, PP DCs were found to prime T cells for the production of much lower levels of interferon (IFN)-γ (Th1) compared with SP DCs. The presence of neutralizing antibody against IL-10 in the priming culture dramatically enhanced IFN-γ production by T cells stimulated with PP DCs. Furthermore, stimulation of freshly isolated PP DCs via the CD40 molecule resulted in secretion of high levels of IL-10, whereas the same stimulus induced no IL-10 secretion from SP DCs. These results suggest that DCs residing in different tissues are capable of inducing distinct immune responses and that this may be related to the distinct cytokines produced by the DCs from these tissues.

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