Type D SRV‐2 virus‐specific CD8 + and CD4 ‐ CD8 ‐ T cells that regulate virus‐induced T cell proliferation in Celebes macaques

1993 ◽  
Vol 22 (2-3) ◽  
pp. 80-85
Author(s):  
A. Malley ◽  
N. Pangares ◽  
S.K. Mayo ◽  
M. Zeleny‐Pooley ◽  
J.V. Torres ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
T Cell Proliferation ◽  
Type D

scholarly journals Activation Outcomes Induced in Naïve CD8 T-Cells by Macrophages Primed via “Phagocytic” and Nonphagocytic Pathways

2008 ◽  
Vol 19 (2) ◽  
pp. 701-710 ◽  
Author(s):  
Isabel María Olazabal ◽  
Noa Beatriz Martín-Cofreces ◽  
María Mittelbrunn ◽  
Gloria Martínez del Hoyo ◽  
Balbino Alarcón ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
T Cell Proliferation ◽  
Microtubule Organizing Center ◽  
Antigen Uptake ◽  
Soluble Peptide

The array of phagocytic receptors expressed by macrophages make them very efficient at pathogen clearance, and the phagocytic process links innate with adaptive immunity. Primary macrophages modulate antigen cross-presentation and T-cell activation. We assessed ex vivo the putative role of different phagocytic receptors in immune synapse formation with CD8 naïve T-cells from OT-I transgenic mice and compared this with the administration of antigen as a soluble peptide. Macrophages that have phagocytosed antigen induce T-cell microtubule-organizing center and F-actin cytoskeleton relocalization to the contact site, as well as the recruitment of proximal T-cell receptor signals such as activated Vav1 and PKCθ. At the same doses of loaded antigen (1 μM), “phagocytic” macrophages were more efficient than peptide-antigen–loaded macrophages at forming productive immune synapses with T-cells, as indicated by active T-cell TCR/CD3 conformation, LAT phosphorylation, IL-2 production, and T-cell proliferation. Similar T-cell proliferation efficiency was obtained when low doses of soluble peptide (3–30 nM) were loaded on macrophages. These results suggest that the pathway used for antigen uptake may modulate the antigen density presented on MHC-I, resulting in different signals induced in naïve CD8 T-cells, leading either to CD8 T-cell activation or anergy.

The Novel Bispecific Diabody αCD40/αCD28 Strengthens Leukemic Dendritic Cell Induced T Cell Reactivity.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3710-3710
Author(s):  
Ilse Houtenbos ◽  
Saskia J.A.M. Santegoets ◽  
Theresia M. Westers ◽  
Quinten Waisfisz ◽  
Sergey Kipriyanov ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Dendritic Cell ◽  
Cd8 T Cells ◽  
Cluster Formation ◽  
T Cell Proliferation ◽  
Cross Linking ◽  
Bispecific Diabody ◽  
Control Protein

Abstract Dendritic cell (DC)-based immunotherapy faces new challenges since efficacy of DC vaccines in clinical trials has been inconsistent. Strategies to improve immune responses induced by DC are currently being explored. We have recently shown the feasibility of generating fully functional DC from Acute Myeloid Leukemic (AML) blasts, but with varying expression levels of the important costimulatory molecule CD86. To overcome this variability, we developed a novel bispecific diabody (BsDb) simultaneously and agonistically targeting CD40 on AML-DC and CD28 on naïve T cells. Beside optimization of CD28-mediated signaling, the resulting cellular cross-linking was also hypothesized to increase the strength and duration of T cell/AML-DC interactions, thus increasing T cell responsiveness to AML antigens. Indeed the αCD40/αCD28-bispecific diabody provokes increased T cell-DC cluster formation as assessed by light microscopy. Significant increased cluster formation was observed when T cells and AML-DC were cocultured in presence of the BsDb as compared to T cells incubated with a control protein (46%±2 versus 22%±1 respectively, p<0.05). Prior incubation of T cells and/or AML-DC with CD28 or CD40, respectively, completely prevented cluster formation in presence of the BsDb indicating specific binding of the BsDb to CD40 and CD28. The αCD40/αCD28 BsDb significantly increases T cell proliferation induced by AML-DC as compared to the unstimulated cocultures, in a dose dependent manner, as evaluated by mixed lymphocyte reactions (fold increased T cell proliferation of cocultures stimulated with BsDb as compared to unstimulated cocultures:170%±12, p<0.05). In addition, BsDb is capable of DC maturation induction as shown by significant increased mean fluorescence index (MFI) of the maturation markers CD80 (MFI of AML-DC cultured in presence of control protein vs AML-DC cultured in presence of BsDb: 22±5 vs 12±3, p<0.05) and CD83 (4±1 vs 1.5±0.5, p<0.05). In order to determine the effect of aCD40/aCD28-bispecific diabody-mediated cross-linking of AML-derived DC and CD8+ T cells on the induction efficiency of tumor-specific CTL, AML-DC derived from the HLA-A2+ AML cell line MUTZ-3 were pre-incubated with the aCD40/aCD28-bispecific diabody, loaded with the heteroclitic variant of the aa988 epitope of hTERT, and used as stimulator cells in an HLA-A2-matched allogeneic in vitro CTL induction protocol. In total nine parallel bulk cultures, were stimulated twice with peptide-loaded MUTZ-3 DC, either pulsed with control protein or the aCD40/aCD28-bispecific diabody. hTERT988Y-specific CD8+ T cells could be detected in 5/9 individual cultures when stimulated with DC pulsed with the aCD40/aCD28-bispecific diabody, whereas in only 1/9 individual cultures hTERT988Y-specific CD8+ T cells could be detected when stimulated with DC pulsed with the control protein. Thus, priming efficacy of tumor-specific cytotoxic T cells can also be improved by cross-linking AML-DC and T cells with the αCD40/αCD28 diabody. We propose that the αCD40/αCD28-bispecific diabody can serve as a potent therapeutic tool to effectively augment anti-tumor T cell responses elicited by AML-DC.

Sirolimus and GvHD Control: the Rhesus Macaque GvHD Model Reveals That Sirolimus Preferentially Inhibits T Cell Proliferation While Permitting Breakthrough T cell Activation After MHC-Mismatched Hematopoietic Stem Cell Transplantation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2549-2549
Author(s):  
Karnail Singh ◽  
Swetha Srinivasan ◽  
Angela Panoskaltsis-Mortari ◽  
Sharon Sen ◽  
Kelly Hamby ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Granzyme B ◽  
T Cell Proliferation ◽  
Ki 67 ◽  
Post Transplant

Abstract Abstract 2549 Introduction: Given the emerging importance of sirolimus as a therapuetic for graft-versus host disease (GvHD), it is critical to rigorously define the mechanisms by which this agent impacts T cell immunity after hematopoietic stem cell transplantation (HSCT). Therefore, we have used our novel rhesus macaque model of haploidentical HSCT and GVHD to probe the mechanisms of sirolimus-mediated GvHD prevention when given as a monotherapy. The insights gained from this study will facilitate the rational design of sirolimus-containing combinatorial therapies to maximize immunosuppressive efficacy. Methods: Transplant recipients were prepared with 8Gy total body irradiation and were then infused with MHC-mismatched donor leukopheresis products(n=3, avg. 6.5×108 TNC/kg, 3.4×107 total T cells/kg). Recipients received sirolimus monotherapy (serum troughs 5–15 ng/mL) alone as post-transplant immunosuppresson. Clinical GvHD was monitored according to our standard primate GvHD scoring system and flow cytometric analysis was performed to determine the immune phenotype of sirolimus-treated recipients compared to a cohort of recipients (n= 3) that were given no GvHD immunoprophylaxis. Results: Sirolimus modestly prolonged survival after MHC-mismatched HSCT compared to no immunosuppression (>19 days versus 6.5 days in the untreated cohort, with GvHD confirmed histopathologically at the time of necropsy). We found that sirolimus significantly inhibited lymphocyte proliferation in transplant recipients: The ALC remained suppressed post-transplant (eg ALC of 0.46 × 106/mL on day 15 post-transplant versus 4.3 × 106/mL pre-transplant, with recovery of other leukocytes: WBC=5.1 × 106/mL, ANC=2.6 × 106/mL). These results suggest that sirolimus can have a profound impact on lymphocyte proliferation, inhibiting GvHD-associated lymphocyte expansion by as much as 200–300-fold compared to untreated controls. Sirolimus had a similar impact on CD4+ and CD8+ subpopulation expansion. Thus, while CD4+ T cells and CD8+ T cells expanded by as much as 300-fold and 2000-fold, respectively, without sirolimus, the expansion of these cells was significantly blunted with sirolimus, with maximal expansion of CD4+ and CD8+ T cells being 4- and 3.6-fold, respectively compared to the post-transplant nadir. Sirolimus-treated recipients also better controlled the upregulation of the proliferation marker Ki-67 on CD4+ or CD8+ T cells. Thus, while untreated recipients upregulated Ki-67 expression by as much as 10-fold after engraftment, (with >80-98% T cells expressing high levels of Ki-67 post-transplant versus 5–10% pre-transplant) sirolimus-treated recipients better controlled Ki-67 expression (17-40% Ki-67-high CD4+ and CD8+ T cells post-transplant). While the impact of sirolimus on T cell proliferation was profound, it failed to completely inhibit activation of T cells, as measured by both Granzyme B and CD127 expression. Thus, when effector CD4+ and CD8+ T cell cytotoxic potential was measured by determining expression levels of granzyme B, we found that sirolimus could not downregulate this key component of immune function and GvHD-mediated target organ damage: Granzyme B expression in both CD4+ and CD8+ CD28-/CD95+ effector T cells was unchanged despite sirolimus monotherapy. Down-regulation of CD127 expression, which identifies activated CD8+ T cells in both humans and rhesus macaques, also demonstrated resistance to sirolimus treatment. Thus, while a cohort of recipients that were treated with combined costimulation blockade and sirolimus maintained stable CD127 levels post-transplant, and untreated animals demonstrated total loss of CD127, up to 60% of CD8+ T cells in sirolimus-treated recipients down-regulated CD127, consistent with breakthrough activation of these cells despite mTOR inhibition. Discussion: These results indicate that while the predominant effect of sirolimus during GvHD prophylaxis is its striking ability to inhibit T cell proliferation, sirolimus-based immunosuppression spares some cellular signaling pathways which control T cell activation. These results imply that therapies that are combined with sirolimus during multimodal GvHD prophylaxis should be directed at inhibiting T cell activation rather than proliferation, in order to target non-redundant pathways of alloimmune activation during GvHD control. Disclosures: No relevant conflicts of interest to declare.

scholarly journals A novel model for antigen-dependent activation of normal human T cells. Transmembrane signaling by crosslinkage of the CD3/T cell receptor-alpha/beta complex with the cluster determinant 2 antigen.

1990 ◽  
Vol 171 (6) ◽  
pp. 1965-1979 ◽  
Author(s):  
M Suthanthiran
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
T Cell Proliferation ◽  
Transmembrane Signaling ◽  
Receptor Alpha ◽  
Human T Cells ◽  
Normal Human

Transmembrane signaling of normal human T cells was explored with mAbs directed at TCR, CD2, CD4, CD5, or CD8 antigens and highly purified CD4+ T cells and CD8+ T cells. Our experiments explicitly show that: (a) crosslinkage of TCR with the CD2 antigen, and not independent crosslinking of TCR and of CD2 antigen or crosslinking of either protein with the CD4 or CD8 antigen induces significant proliferation independent of co-stimulatory signals (e.g., accessory cells, recombinant lymphokines, or tumor promoter), (b) F(ab')2 fragments of mAb directed at the TCR and F(ab')2 anti-CD2, crosslinked with F(ab')2 fragments of rabbit anti-mouse IgG, promote the proliferation of highly purified T cells, (c) a prompt and sustained increase in intracellular free Ca2+ concentration results from crosslinkage of TCR with the CD2 antigen, (d) T cell proliferation induced by this novel approach is curtailed by EGTA and by direct or competitive inhibitors of PKC, (e) crosslinkage of TCR with the CD2 antigen results in the transcriptional activation and translation of the gene for IL-2 and in the expression of IL-2 receptor alpha (CD25), (f) anti-CD25 mAbs inhibit T cell proliferation initiated by crosslinkage of TCR with the CD2 antigen, and recombinant IL-2 restores the proliferative response. Our first demonstration that crosslinkage of TCR with the CD2 antigen induces proliferation of normal human CD4+ T cells and CD8+ T cells, in addition to revealing a novel activation mechanism utilizable by the two major subsets of T cells, suggest that the CD2 antigen might be targeted for the regulation of antigen-specific T cell immunity (e.g., organ transplantation).

Proliferation of CD8+ T-Cells Specific for CMV and EBV in Response to TCR Mediated Recognition of Cognate Antigen Is Inhibited by Imatinib in a Dose-Dependent Manner.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1342-1342
Author(s):  
Ruth Seggewiss ◽  
Karin Lore ◽  
Elisabeth Greiner ◽  
Magnus K. Magnusson ◽  
David A. Price ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Tyrosine Kinase ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
T Cell Proliferation ◽  
Cell Transplant ◽  
Dose Dependent

Abstract We and others have shown that the tyrosine kinase inhibitor imatinib (STI571, Gleevec®) inhibits T-cell proliferation and activation at concentrations achieved in vivo. At 10μM, imatinib inhibited T-cell receptor (TCR)-mediated proliferation of purified peripheral blood T-cells almost completely. Up-regulation of the activation markers CD25 and CD69 at 24h in response to TCR cross-linking was suppressed by imatinib at a mean IC50 of 5.4μM and 7.3μM, respectively and IL-2 production was also severely impaired. However, these assays may not fully reflect the response to clinical relevant antigens. Therefore, we chose to investigate the antigen-triggered proliferation of memory CD8+ T-cells specific for immunodominant CMV and EBV HLA-A2 peptide epitopes. We used HLA-peptide tetramers to identify healthy blood donors with detectable CMV- or EBV-specific CD8+ T-cell populations. Purified T-cells from these donors were then stimulated with the CMV peptide pp65495–503 or the EBV peptide BMFLI259–267. Antigen-induced proliferation was measured by dilution of the vital dye CFSE over a period of 4 or 8 days. The magnitude of the virusspecific CD8+ T-cell population ranged from 0.5 % to 7.1% of CD8+ T-cells for CMV and from 0.05% to 0.35% of CD8+ T-cells for EBV. Antigen-specific CD8+ T-cells from all 10 donors studied proliferated in response to the CMV peptide. In 8 from 10 donors, imatinib reduced CMV peptide induced proliferation. With increasing imatinib concentrations (range: 5 – 10μM), we observed dose dependent reduction of both the number of cells undergoing cell division and the average number of divisions completed per cell. Comparable inhibition of specific T-cell proliferation in response to the EBV-derived peptide was observed in two donors. Immunoblots demonstrated that imatinib substantially reduced tyrosine phosphorylation of ZAP70 and LAT in response to TCR-mediated activation in Jurkat T-cells. Sequence comparisons of all 90 tyrosine kinase genes in the human genome for homology in the ATP binding pocket identified Lck, which is required for ZAP70 activation, as a likely target for imatinib. Our results indicate that imatinib may interfere with clinically important T-cell effector functions. As concentrations sufficient for half-maximal inhibition of TCR signalling are achieved in vivo, imatinib could increase the risk of opportunistic infections and impact on GVH and GVL reactions post-transplantation especially when used in conjuction with other immunosuppressive agents. Therefore, close monitoring of patients on imatinib for CMV reactivation or EBV-induced lymphoproliferative diseases, especially in stem cell transplant recipients, appears warranted.

Microrna-17-92 Cluster: Novel Target for Controlling Gvhd While Preserving GVL Effect

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 845-845
Author(s):  
Yongxia Wu ◽  
David Bastian ◽  
Jessica Lauren Heinrichs ◽  
Jianing Fu ◽  
Hung Nguyen ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Cd8 T Cells ◽  
Locked Nucleic Acid ◽  
T Cell Proliferation ◽  
Allogeneic Bone

Abstract Graft-versus-host disease (GVHD) remains a life threatening complication after allogeneic hematopoietic stem cell transplantation (HCT). Donor T cells are the key pathogenic effectors in the induction of GVHD. MicroRNAs (miRs) have been shown to play an important role in orchestrating immune response, among which miR-17-92 cluster is one of the best characterized miR clusters that encodes 6 miRs including 17, 18a, 19a, 20a, 19b-1 and 92-1. Although regulatory functions of miR-17-92 cluster have been elaborated in a variety of immune responses including anti-infection, anti-tumor, and autoimmunity, the role of this miR cluster in the modulation of T-cell response to alloantigens and the development of GVHD has not been explored previously. Based on the previous report that miR-17-92 promotes Th1 responses and inhibits induced regulatory T-cell (iTreg) differentiation in vitro, we hypothesized that blockade of miR-17-92 would constrain T-cell alloresponse and attenuate GVHD. To evaluate the function of miR-17-92 on T-cell alloresponse, we utilized the mice with miR-17-92 conditional knock-out (KO) on T cells as donors, and compared the alloresponse of WT and KO T cells after allogeneic bone marrow transplantation (allo-BMT). We observed that KO T cells had substantially reduced ability to proliferate and produce IFNγ as compared to WT counterparts 4 days after cell transfer. Interestingly, CD4 but not CD8 KO T cells had increased cell death in the population of fast-dividing T cells. Thus, miR-17-92 cluster promotes activation and expansion of both CD4 and CD8 T cells, and inhibits activation-induced cell death of CD4 but not CD8 T cells at the early stage of alloresponse in vivo. We further evaluated the role of miR-17-92 on T cells in the development of acute GVHD in a fully MHC-mismatched BMT model. In sharp contrast to WT T cells that caused severe GVHD and resulted in 100% mortality of the recipients, KO T cells were impaired in causing severe GVHD reflected by mild clinical manifestations and no mortality. These observations were extended to MHC-matched but minor antigen-mismatched as well as haploidentical BMT models that are more clinically relevant. We next addressed the critical question whether T cells deficient for miR-17-92 are still capable of mediating graft-versus-leukemia (GVL) effect. Using A20 lymphoma and P815 mastocytoma cell lines, we demonstrated that the KO T cells essentially retained the GVL activity in MHC-mismatched and haploidentical BMT model, respectively. Mechanistic studies revealed that miR-17-92 promoted CD4 T-cell proliferation, survival, migration to target organs, and Th1-differentiation, but reduced Th2-differentiation and iTreg generation. However, miR-17-92 had less impact on CD8 T-cell proliferation, survival, IFNγ production, and cytolytic activity reflected by granzyme B and CD107a expression. Moreover, miR-17-92 negatively regulated TNFα production by both CD4 and CD8 T cells. We therefore conclude that miR-17-92 cluster is required for T cells to induce severe GVHD, but it is dispensable for T cells to mediate the GVL effect. To increase translational potential of our findings, we designed the locked nucleic acid (LNA) antagomirs specific for miR-17 or miR-19, which have been reported to be the key members in this cluster. We observed that the treatment with anti-miR-17 significantly inhibited T-cell expansion and IFNγ production in response to alloantigen in vivo, and anti-miR-19 was more effective. Furthermore, our ongoing experiment showed the treatment with anti-miR-17 or anti-miR-19 was able to considerably attenuate the severity of GVHD as compared to scrambled antagomir in a MHC-mismatched BMT model. Taken together, the current work reveals that miR-17-92 cluster is essential for T-cell alloresponse and GVHD development, and validates miR-17-92 cluster as promising therapeutic target for the control of GVHD while preserving GVL activity in allogeneic HCT. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Granulocytic Myeloid-Derived Suppressor Cells in Murine Models of Immune-Mediated Bone Marrow Failure

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2176-2176
Author(s):  
Xingmin Feng ◽  
Jisoo Kim ◽  
Gladys Gonzalez Matias ◽  
Zhijie Wu ◽  
Sabrina Solorzano ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Bone Marrow Failure ◽  
Suppressor Cells ◽  
T Cell Proliferation ◽  
Immune Mediated

Abstract Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of immature myeloid cells with immunoregulatory function. Limited published studies have reported conflicting data concerning the effects of MDSCs on autoimmune diseases and graft-versus-host disease. MDSCs can be divided into two major subsets, more abundant granulocytic (G-MDSCs) and monocytic (M-MDSCs). We examined G-MDSCs in murine models of human bone marrow failure (BMF). We first characterized bone marrow (BM) MDSCs from C.B10 mice. CD11b +Ly6G +Ly6C low G-MDSCs suppressed in vitro proliferation of both CD4 and CD8 T cells from C57BL/6 (B6) mice, while Ly6G +Ly6C - cells had no effect and Ly6G -Ly6C + cells increased T cell proliferation (Fig. 1A). We then tested G-MDSCs in vivo utilizing antibody-mediated cell depletion. Lymph node (LN) cells from B6 donor mice were injected into sub-lethally irradiated major histocompatibility-mismatched CByB6F1 mice to induce BMF. Anti-Ly6G antibody injection worsened cytopenias and BM hypoplasia, and they increased BM CD4 and CD8 T cell infiltration. In contrast, anti-Ly6G antibody injection in the minor histocompatibility-mismatched C.B10 BMF model improved platelet counts and reduced BM CD8 T cells. The pathogenic and protective effects in the two models correlated with differential anti-Ly6G antibody modulation of G-MDSCs: in the CByB6F1 model, anti-Ly6G antibody eradicated G-MDSCs in blood and BM while in the C.B10 model the same antibody generated a novel G-MDSC cell population, of identical Ly6C lowCD11b + phenotype but intermediate Ly6G expression, which was not present in the CByB6F1 animals after antibody injection. When we examined the efficacy of G-MDSCs in C.B10 BMF: Ly6G + cells were enriched from BM of normal C.B10 donors (94%-97% Ly6C lowLy6G +CD11b +), and injected at the time of marrow failure initiation. Mice infused with Ly6G + cells had significantly higher levels of WBC, RBC, platelets, and total BM cells, decreased BM CD4 and CD8 T cell infiltration, and improved BM cellularity. These results indicated a protective role of G-MDSCs. When G-MDSCs were injected at day 3 after LN cell infusion, treated mice again had higher levels of WBC, RBC, platelets, and total BM cells at day 14, alleviating BMF. As both prophylaxis and therapy, G-MDSCs decreased Fas expression and Annexin V binding of residual BM cells, suppressed intracellular levels of gamma interferon and tumor necrosis factor alpha, as well as cell proliferation protein Ki67 levels in BM CD4 and CD8 T cells, relative to BMF control mice. TotalSeq simultaneously detecting surface proteins and mRNA expression in whole BM mononuclear cells in the therapy model showed an increased proportion of myeloid cells and reduced proportion of T cells in marrow from G-MDSC-treated mice based on cell surface markers and marker gene expression (Fig. 1B). Gene pathway analysis revealed down-regulation of Fas expression and reduced program cell death in total BM cells and decreased expression of genes related to cell cycle in infiltrating T cells from Ly6G + cell-treated mice-both results consistent with suppression by G-MDSCs of T cell proliferation and protection of target BM cells from apoptosis. In vitro culture of T cells from B6 mice with G-MDSCs which had been isolated from C.B10 BM cells showed dose-dependent suppression of T cell proliferation. In conclusion, our results demonstrate an active role of G-MDSCs in protecting BM from immune-mediated destruction, by suppression of T cell proliferation in the BM. G-MDSCs might have clinical application as treatment in human aplastic anemia and other immune-mediated and autoimmune diseases. Figure 1 Figure 1. Disclosures Young: Novartis: Research Funding.

scholarly journals Adoptive Immunotherapy with Regulatory and Conventional T Cells in Haploidentical Transplantation Primes Dendritic Cells to Promote T Cell Alloreactivity in the Bone Marrow and Tolerance in the Periphery

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3224-3224
Author(s):  
Mauro Di Ianni ◽  
Raffaella Giancola ◽  
Stefano Baldoni ◽  
Francesca Ulbar ◽  
Beatrice Del Papa ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Adoptive Immunotherapy ◽  
T Cell Proliferation ◽  
Rt Pcr ◽  
Haploidentical Transplantation

In high-risk acute leukemia patients undergoing HLA haploidentical T cell-depleted tranplantation, we demonstrated that adoptive immunotherapy with donor T regulatory cells (Tregs; 2x106/kg) co-infused with conventional T cells (Tcon; 1x106/kg ) provided significant protection from acute graft-versus-host disease (aGvHD) and was associated with an almost complete control of leukemia relapse (graft versus leukemia effect, GvL) (Di Ianni et al., Blood 2011; Martelli et al., Blood 2014; Ruggeri et al., ASH 2018). In the present study we investigated whether Tregs interact with bone marrow (BM) and peripheral blood (PB) dendritic cells (DCs) and whether such interaction is responsible for GvHD protection and GvL effect. Twenty six patients (median age 54 ; 20 AML; 4 ALL; 2 MDS) transplanted between July 2016 and April 2019 were evaluated up to one year after the transplant. BM and PB DCs (using CD123 for plasmocitoid DC-pDC; CD11c for myeloid DC-mDC; CD80/CD86 for costimulatory molecules) and T cells (CD3/CD4/CD8; CD4/CD25/CD127; CD28/PD-1/TIM3) were analysed by flow-cytometry. DCs were also sorted and analysed by RT-PCR for a panel of genes involved in activation (IL-6; TNF-a; IL-12; CCR7; NOTCH ligands) vs tolerigenic (TGF-beta; PD-1/PDL1; IDO; IL-10; ICOS) pathways. To study the effects of DCs on T cell proliferation, pre-activated (with GM-CSF at 50 ng/ml, IL-4 at 800 U/ml and TNF-a at 50 ng/ml for 18 hrs) BM and PB CD1c+ DCs were co-cultured for 96 hrs with autologous CFSE labelled BM and PB CD3+ cells at a DC:CD3 ratio of 1:10. mDC numbers were significantly higher in BM than PB during the first 6 months after transplant. BM-derived mDCs expressed higher levels of the co-stimulatory receptor CD86. No differences emerged in pDCs. RT-PCR showed an activation signature in BM-DCs (significantly higher IL-6 level) and a tolerigenic signature in PB-DCs (significantly higher TGF-beta and PDL-1 levels). BM-derived CD8+ T cells displayed a higher expression of the co-stimulatory receptor CD28 than PB-derived CD8+ T cells (30.3±18.8 vs 9.2±4.9; p<0.05 ). In contrast, the expression of the immune checkpoint inhibitor PD-1 was significantly higher in both PB-derived CD4 (69%±29 vs 24±11) and CD8 (65±25 vs 4±3; p<0.05) T cells than BM-derived T lymphocytes. T cells from both BM and PB did not express the T cell exhaustion marker TIM-3. CD3/CFSE+-DCs co-cultures showed a T cell proliferation rate that was significantly higher in BM than in PB (25±7.2 vs 6.7±8.7; p<0.05). These data show that haploidentical transplantation with Treg/Tcon immunotherapy promotes the reconstitution of DCs with an activating signature in the BM and a tolerigenic signature in the PB. Human peripheral blood Tregs that are used for adoptive immunotherapy are largely CD45RO+ and express low level of CxCR4 bone marrow homing receptor. When infused in immunodeficient mice they migrate to the periphery (spleen, gut, liver) but are unable to home to the bone marrow (Ruggeri et al., ASH 2018). In conclusion, Tregs/DC interaction induce tolerance in the periphery (and may protect from GvHD). In the BM, in the absence of Tregs, DCs activate alloreactive Tcon and may favour killing of the leukemic targets. Therefore, Tregs/DC interactions may contribute to the separation between GvL effect and GvHD in the Treg based haploidentical transplantation. Disclosures No relevant conflicts of interest to declare.

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