Enhancing Cytotoxicity of Autologous T Cells in AML By Blockade of CTLA-4 and PD-1

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4057-4057 ◽  
Author(s):  
Kirsten Marie Boughan ◽  
Xiaohua Chen ◽  
Paul Szabolcs
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Response ◽  
Conflicts Of Interest ◽  
Expression Profiles ◽  
T Cell Response ◽  
Inhibitory Receptors

Abstract Background: AML remains a disease diagnosed in the aging population with chemotherapy followed by bone marrow transplant in some cases being the standard of care. Although response rates remain around 50-60%, treatment related mortality and disease relapse remain high. Adoptive immunotherapy, especially those targeting T cell co-inhibitory receptors, has proven successful in solid malignancies however, AML remains less explored. Our laboratory has previously demonstrated the feasibility to generate autologous AML reactive T cells in vitro (Mehta/Szabolcs; Immunotherapy 2016). It was noted that "resistant" AML blasts over expressed a number of genes associated with immunosuppressive characteristics. Over expression of these genes may induce T cell functional exhaustion. Therefore, we hypothesized that blocking PD-1 and/or CTLA-4 during co-culture with IFNg activated AML blasts, may enhance T cell activation and cytotoxicity. To test this hypothesis, we tested CTL responses against AML blasts and IFNg ELISpot formation after blocking with PD-1, CTLA-4 or both receptors, and compared the response in untreated T cells. Gene expression profiles of co-stimulatory/co-inhibitory receptors were also monitored to test for correlation. Methods: We evaluated 12 patients with newly diagnosed AML under an IRB approved protocol with written informed consent of patients. Mononuclear cell preparation was generated from fresh marrow samples or drawn from a biorepository of previously cryopreserved leukophereses. T cells were then purified using immunomagnetic CD3/CD28 beads (Life technologies) and cultivated in media with IL-2 and IL-7 for 2 weeks. AML blasts were cultured over a supporting layer of mesenchymal stromal cells (MSCs) derived from healthy BM donors for 1 week and then cryopreserved. T cells were then co-cultured with restored and irradiated autologous AML cells at an effector: target (E: T) ratio of 5:1 to 40:1. AML and T cells were co-cultured in the presence of Ipilimumab (anti-CTLA-4), or Nivolumab (anti-PD-1), or a combination of both drugs. T cells and AML were re stimulated in X-vivo 15 with IL-12, IL-15 and IL-2 weekly x 3weeks. T cell response to AML was quantitated by IFNg ELISpot assay and Europium TDA (EuTDA) CTL assays independently. Co-stimulatory/co-inhibitory expression on T cells was examined with RT-q PCR assay. Paired-sample student t test was used for statistical analysis with p<0.05. Results and Discussion: Out of 12 samples, 10 (83%) yielded viable AML cells available for cytotoxicity assay. One third (33%) of co-cultures exhibited a positive T cell response in CTL assays ("killers"). There was no difference in CTL activity by blockade of either PD-1 or CTL-4 (Fig 1). IFN-ɣ spot formation in ELISpot was observed in 4/10 samples (40%) with statistical significance noted in cells blocked with PD-1 as compared to all other blockade types (Fig 2). The results indicated that in vitro priming with autologous AML blasts or together with blocking PD-1 can enhance T cell response in 33-40%. By gene expression analysis, the ratio of co-stimulatory to co-inhibitory genes was calculated. In PD-1 blocked cells, the ratio of activation/inhibition was not impacted in T cells from "killers" (0.9; p=0.1), however, T cells from "non-killer cells" had a diminished ratio due to higher expression of co-inhibitory molecules (0.4; p=0.04) (Fig 3). This trend was also present in CTLA-4 blocked cells (0.85; p=0.4 in killers vs 0.54; p=0.03 in non-killers) (data not shown). Interestingly, dual blockage failed to influence gene expression ratio, data not shown. Conclusion: The above studies demonstrate that cytotoxicity can be achieved in T cells when primed against autologous AML. PD-1 blockade can enhance IFNg production and cytotoxic responses, but CTLA-4 and dual blockade failed to enhance T cell function. The upregulation of an inhibitory pattern of genes in T cells that did not express cytotoxicity (non-killers) could allude to an "inhibitory phenotype" that may be resistant to immunotherapy drug blockade and requires further study. Disclosures No relevant conflicts of interest to declare.

scholarly journals Immunization with Apoptotic Phagocytes Containing Histoplasma capsulatum Activates Functional CD8+T Cells To Protect against Histoplasmosis

2011 ◽  
Vol 79 (11) ◽  
pp. 4493-4502 ◽  
Author(s):  
Shih-Hung Hsieh ◽  
Jr-Shiuan Lin ◽  
Juin-Hua Huang ◽  
Shang-Yang Wu ◽  
Ching-Liang Chu ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Response ◽  
Cell Activation ◽  
Histoplasma Capsulatum ◽  
T Cell Response ◽  
Content Type

ABSTRACTWe have previously revealed the protective role of CD8+T cells in host defense againstHistoplasma capsulatumin animals with CD4+T cell deficiency and demonstrated that sensitized CD8+T cells are restimulatedin vitroby dendritic cells that have ingested apoptotic macrophage-associatedHistoplasmaantigen. Here we show that immunization with apoptotic phagocytes containing heat-killedHistoplasmaefficiently activated functional CD8+T cells whose contribution was equal to that of CD4+T cells in protection againstHistoplasmachallenge. Inhibition of macrophage apoptosis due to inducible nitric oxide synthase (iNOS) deficiency or by caspase inhibitor treatment dampened the CD8+T cell but not the CD4+T cell response to pulmonaryHistoplasmainfection. In mice subcutaneously immunized with viableHistoplasmayeasts whose CD8+T cells are protective againstHistoplasmachallenge, there was heavy granulocyte and macrophage infiltration and the infiltrating cells became apoptotic. In mice subcutaneously immunized with carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled apoptotic macrophages containing heat-killedHistoplasma, the CFSE-labeled macrophage material was found to localize within dendritic cells in the draining lymph node. Moreover, depleting dendritic cells in immunized CD11c-DTR mice significantly reduced CD8+T cell activation. Taken together, our results revealed that phagocyte apoptosis in theHistoplasma-infected host is associated with CD8+T cell activation and that immunization with apoptotic phagocytes containing heat-killedHistoplasmaefficiently evokes a protective CD8+T cell response. These results suggest that employing apoptotic phagocytes as antigen donor cells is a viable approach for the development of efficacious vaccines to elicit strong CD8+T cell as well as CD4+T cell responses toHistoplasmainfection.

scholarly journals Lymphoma endothelium preferentially expresses Tim-3 and facilitates the progression of lymphoma by mediating immune evasion

2010 ◽  
Vol 207 (3) ◽  
pp. 505-520 ◽  
Author(s):  
Xiaoyuan Huang ◽  
Xiangyang Bai ◽  
Yang Cao ◽  
Jingyi Wu ◽  
Mei Huang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
B Cell Lymphoma ◽  
Global Gene Expression ◽  
T Cell Response ◽  
Th1 Polarization

Angiogenesis is increasingly recognized as an important prognosticator associated with the progression of lymphoma and as an attractive target for novel modalities. We report a previously unrecognized mechanism by which lymphoma endothelium facilitates the growth and dissemination of lymphoma by interacting with circulated T cells and suppresses the activation of CD4+ T cells. Global gene expression profiles of microdissected endothelium from lymphoma and reactive lymph nodes revealed that T cell immunoglobulin and mucin domain–containing molecule 3 (Tim-3) was preferentially expressed in lymphoma-derived endothelial cells (ECs). Clinically, the level of Tim-3 in B cell lymphoma endothelium was closely correlated to both dissemination and poor prognosis. In vitro, Tim-3+ ECs modulated T cell response to lymphoma surrogate antigens by suppressing activation of CD4+ T lymphocytes through the activation of the interleukin-6–STAT3 pathway, inhibiting Th1 polarization, and providing protective immunity. In a lymphoma mouse model, Tim-3–expressing ECs promoted the onset, growth, and dissemination of lymphoma by inhibiting activation of CD4+ T cells and Th1 polarization. Our findings strongly argue that the lymphoma endothelium is not only a vessel system but also a functional barrier facilitating the establishment of lymphoma immune tolerance. These findings highlight a novel molecular mechanism that is a potential target for enhancing the efficacy of tumor immunotherapy and controlling metastatic diseases.

scholarly journals The CD8+ T-Cell Response to Lymphocytic Choriomeningitis Virus Involves the L Antigen: Uncovering New Tricks for an Old Virus

2007 ◽  
Vol 81 (10) ◽  
pp. 4928-4940 ◽  
Author(s):  
Maya F. Kotturi ◽  
Bjoern Peters ◽  
Fernando Buendia-Laysa ◽  
John Sidney ◽  
Carla Oseroff ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Response ◽  
Cellular Response ◽  
Lymphocytic Choriomeningitis ◽  
Lymphocytic Choriomeningitis Virus ◽  
T Cell Response ◽  
Ifn Γ ◽  
Lcmv Infection

ABSTRACT CD8+ T-cell responses control lymphocytic choriomeningitis virus (LCMV) infection in H-2b mice. Although antigen-specific responses against LCMV infection are well studied, we found that a significant fraction of the CD8+ CD44hi T-cell response to LCMV in H-2b mice was not accounted for by known epitopes. We screened peptides predicted to bind major histocompatibility complex class I and overlapping 15-mer peptides spanning the complete LCMV proteome for gamma interferon (IFN-γ) induction from CD8+ T cells derived from LCMV-infected H-2b mice. We identified 19 novel epitopes. Together with the 9 previously known, these epitopes account for the total CD8+ CD44hi response. Thus, bystander T-cell activation does not contribute appreciably to the CD8+ CD44hi pool. Strikingly, 15 of the 19 new epitopes were derived from the viral L polymerase, which, until now, was not recognized as a target of the cellular response induced by LCMV infection. The L epitopes induced significant levels of in vivo cytotoxicity and conferred protection against LCMV challenge. Interestingly, protection from viral challenge was best correlated with the cytolytic potential of CD8+ T cells, whereas IFN-γ production and peptide avidity appear to play a lesser role. Taken together, these findings illustrate that the LCMV-specific CD8+ T-cell response is more complex than previously appreciated.

Cultured Human B Cell APCs Expanded Using Il-4 and CD40 Ligand Preferentially Promote a Type 2 T Cell Response to Alloimmune Stimulation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2668-2668
Author(s):  
Abdul Tawab ◽  
Yoshiyuki Takahashi ◽  
Childs Richard ◽  
Kurlander J. Roger
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Response ◽  
Cd40 Ligand ◽  
T Cell Response ◽  
Ifn Γ

Abstract In vitro stimulation of human peripheral blood B cells with recombinant IL-4 and CD40 ligand (CD40L) markedly increases their expression of MHC and costimulatory molecules, thus enhancing antigenic peptide presentation to T cells. Because these cells proliferate extensively in vitro (unlike monocytes or dendritic cells), they represent a promising and convenient reagent for the generation and maintenance of antigen-specific T cells for use in a variety of experimental or therapeutic settings. However, the impact of this type of B cell APC on cytokine production by responder T cells has hitherto not been examined. To address this issue, we stimulated normal human T cells with either allogeneic B cells (generated in vitro) or with MNCs obtained from the same donor. After 7 days, T cells were washed and re-challenged with the same APCs. The resulting alloreactive cytokine response was measured using quantitative ELISPOT methods and expressed as the frequencies of IFN-γ, IL-4, and IL-5 producing cells per thousand responder cells added. B cell- and MNC-primed cell lines both produced vigorous lymphokine responses, but B cell-stimulated T cells consistently produced more IL-5 spots (mean of 265 vs. 98/1000 responders, p<0.002) and fewer IFN-γ spots (163 vs 386/1000 cells, p<0.005) than MNC-stimulated cells. Further, the ratio of IFN-γ to IL-5 spots was almost ten-fold lower in B cell-stimulated cultures compared to MNC-induced cultures (0.67 vs. 5.2, p<0.001). ELISPOT studies assessing the ratio of IFN-γ to IL-4 spots and ELISA assays comparing IFN-γ and IL-5 levels from culture supernatants demonstrated the same pattern of marked type 2 skewing by B cells. This pattern was unaffected by the presence of anti-IL-4 antibody suggesting type 2 skewing was not mediated by IL-4. Cytokine skewing produced by B cells or MNC could be partially reversed by swapping MNC and B cells during re-stimulation on day 7, but this plasticity was markedly reduced after 3 (weekly) cycles of B cell or MNC re-stimulation in vitro. Type 2 skewing by B cells was enhanced when monocytes were removed from responder T cell populations by either depleting CD14+ positive cells or by positive selection of T cells prior to stimulation. In contrast, type 2 polarization could be prevented using recombinant IL-12. Not all cells of B-cell origin share the same propensity to type 2 skewing observed with IL-4/CD40L-stimulated B cells; under identical conditions, EBV-transformed B cells stimulated alloimmune T cells to produce a strong type 1 cytokine response comparable to that produced by MNCs. In summary, IL-4/CD40L-stimulated B cells strongly promote a type 2 T cell response during primary alloimmune challenge; this skewing can become fixed after repeated B cell stimulation. Investigators using these cells as APC should be aware of this potential phenomenon, particularly during primary T cell responses. It is also important to consider the factors described above that may exacerbate or ameliorate this effect.

Association between cetuximab response and differential immunologic gene expression signatures in colorectal cancer metastases.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 558-558 ◽  
Author(s):  
Michael Sangmin Lee ◽  
Benjamin Garrett Vincent ◽  
Autumn Jackson McRee ◽  
Hanna Kelly Sanoff
Keyword(s):  
Gene Expression ◽  
Colorectal Cancer ◽  
T Cells ◽  
T Cell ◽  
Immune Cell ◽  
Expression Profiles ◽  
Gene Set Enrichment Analysis ◽  
Activated T Cells ◽  
Gene Sets

558 Background: Different immune cell infiltrates into colorectal cancer (CRC) tumors are associated with different prognoses. Tumor-associated macrophages contribute to immune evasion and accelerated tumor progression. Conversely, tumor infiltrating lymphocytes at the invasive margin of CRC liver metastases are associated with improved outcomes with chemotherapy. Cetuximab is an IgG1 monoclonal antibody against epidermal growth factor receptor (EGFR) and stimulates antibody-dependent cellular cytotoxicity (ADCC) in vitro. However, it is unclear in humans if response to cetuximab is modulated by the immune response. We hypothesized that different immune patterns detected in gene expression profiles of CRC metastases are associated with different responses to cetuximab. Methods: We retrieved gene expression data from biopsies of metastases from 80 refractory CRC patients treated with cetuximab monotherapy (GEO GSE5851). Samples were dichotomized by cetuximab response as having either disease control (DC) or progressive disease (PD). We performed gene set enrichment analysis (GSEA) with GenePattern 3.9.4 using gene sets of immunologic signatures obtained from the Molecular Signatures Database v5.0. Results: Among the 68 patients with response annotated, 25 had DC and 43 had PD. In the PD cohort, 59/1910 immunologic gene sets had false discovery rate (FDR) < 0.1. Notably, multiple gene sets upregulated in monocyte signatures were associated with PD. Also, gene sets consistent with PD1-ligated T cells compared to control activated T cells (FDR = 0.052) or IL4-treated CD4 T cells compared to controls (FDR = 0.087) were associated with PD. Conclusions: Cetuximab-resistant patients tended to have baseline increased expression of gene signatures reflective of monocytic infiltrates, consistent with also having increased expression of the IL4-treated T-cell signature. Cetuximab resistance was also associated with increased expression of the PD1-ligated T cell signature. These preliminary findings support further evaluation of the effect of differential immune infiltrates in prognosis of metastatic CRC treated with cetuximab.

scholarly journals Role of viral infectivity in the induction of influenza virus-specific cytotoxic T cells.

1978 ◽  
Vol 147 (4) ◽  
pp. 1236-1252 ◽  
Author(s):  
T J Braciale ◽  
K L Yap
Keyword(s):  
T Cells ◽  
Influenza Virus ◽  
T Cell ◽  
Cell Response ◽  
Infectious Virus ◽  
Cytotoxic T Cells ◽  
T Cell Response ◽  
Cytotoxic T Cell

This report examines the requirement for infectious virus in the induction of influenza virus-specific cytotoxic T cells. Infectious influenza virus was found to be highly efficient at generating both primary and secondary cytotoxic T-cell response in vivo. Inactivated influenza virus however, failed to stimulate a detectable cytotoxic T-cell response in vivo even at immunizing doses 10(5)-10(6)-fold higher than the minimum stimulatory dose of infectious virus. Likewise inactivated virus failed to sensitize target cells for T cell-mediated lysis in vitro but could stimulate a specific cytotoxic response from primed cells in vitro. Possible requirements for the induction of virus-specific cytotoxic T-cell responses are discussed in light of these observations and those of other investigators.

scholarly journals Deciphering the Plasmodium falciparum malaria-specific CD4+ T cell response: ex vivo detection of high frequencies of PD-1+TIGIT+ EXP1-specific CD4+ T cells using a novel HLA-DR11-restricted MHC class II tetramer

2021 ◽  
Author(s):  
Sophia Schulte ◽  
Janna Heide ◽  
Christin Ackermann ◽  
Sven Peine ◽  
Michael Ramharter ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
Cell Response ◽  
Cd4 T Cells ◽  
Ex Vivo ◽  
Class Ii ◽  
T Cell Response ◽  
Cd4 T Cell ◽  
Inhibitory Receptors

Abstract Relatively little is known about the ex vivo frequency and phenotype of the P. falciparum-specific CD4+ T cell response in humans. The exported protein 1 (EXP1) is expressed by plasmodia at both, the liver stage and blood stage, of infection making it a potential target for CD4+ and CD8+ effector T cells. Here, a fluorochrome-labelled HLA-DRB1*11:01-restriced MHC class II tetramer derived from the P. falciparum EXP1 (aa62-74) was established for ex vivo tetramer analysis and magnetic bead enrichment in ten patients with acute malaria. EXP1-specific CD4+ T cells were detectable in nine out of ten (90%) malaria patients expressing the HLA-DRB1*11 molecule with an average ex vivo frequency of 0.11% (0-0.22%) of total CD4+ T cells. The phenotype of EXP1-specific CD4+ T cells was further assessed using co-staining with activation (CD38, HLA-DR, CD26), differentiation (CD45RO, CCR7, KLRG1, CD127), senescence (CD57) and co-inhibitory (PD-1, TIGIT, LAG-3, TIM-3) markers as well as the ectonucleotidases CD39 and CD73. EXP1-specific tetramer+ CD4+ T cells had a distinct phenotype compared to bulk CD4+ T cells and displayed a highly activated effector memory phenotype with elevated levels of co-inhibitory receptors and activation markers: EXP1-specific CD4+ T cells universally expressed the co-inhibitory receptors PD-1 and TIGIT as well as the activation marker CD38 and showed elevated frequencies of CD39. These results demonstrate that MHC class II tetramer enrichment is a sensitive approach to investigate ex vivo antigen-specific CD4+ T cells in malaria patients that will aid further analysis of the role of CD4+ T cells during malaria.

scholarly journals Gammadelta T Cells Are Required for CD8+ T Cell Response to Vaccinia Viral Infection

2021 ◽  
Author(s):  
Rui Dai ◽  
Xiaopei Huang ◽  
Yiping Yang
Keyword(s):  
T Cells ◽  
T Cell ◽  
Viral Infection ◽  
T Cell Activation ◽  
Cell Response ◽  
Critical Role ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Effective Vaccine ◽  
Gammadelta T Cells

Vaccinia virus (VV) is the most studied member of the poxvirus family, is responsible for the successful elimination of smallpox worldwide, and has been developed as a vaccine vehicle for infectious diseases and cancer immunotherapy. We have previously shown that the unique potency of VV in the activation of CD8+ T cell response is dependent on efficient activation of the innate immune system through Toll-like receptor (TLR)-dependent and -independent pathways. However, it remains incompletely defined what regulate CD8+ T cell response to VV infection. In this study, we showed that gammadelta T cells play an important role in promoting CD8+ T cell response to VV infection. We found that gammadelta T cells can directly present viral antigens in the context MHC-I for CD8+ T cell activation to VV in vivo, and we further demonstrated that cell-intrinsic MyD88 signaling in gammadelta T cells is required for activation of gammadelta T cells and CD8+ T cells. These results illustrate a critical role for gammadelta T cells in the regulation of adaptive T cell response to viral infection and may shed light on the design of more effective vaccine strategies based on manipulation of gammadelta T cells.

scholarly journals Dysregulated T Cell Response in Bone Marrow Immune Micro-Environment of Patients with Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3140-3140
Author(s):  
Yu-tong Wang ◽  
Yuan Kong ◽  
Yang Song ◽  
Zheng-Fan Jiang ◽  
Xiao-jun Huang
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cell Response ◽  
Graft Function ◽  
T Cell Response ◽  
Intracellular Cytokine ◽  
Hematopoietic Stem ◽  
Poor Graft Function

Abstract Background: Poor graft function (PGF), a kind of bone marrow (BM) failure syndrome, is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nevertheless, the exact mechanisms underlying PGF remain unclear. The BM immune micro-environment is considered to be involved in the regulation of murine hematopoiesis. Dysregulated T cell response was found to suppress proliferation and induce apoptosis of hematopoietic progenitor cells in patients with aplastic anemia. Therefore, we conducted a study to analyze the alteration of T cell subpopulations in BM micro-environment of allotransplant patients. Aims: To compare the cellular compositions and function of T cells in BM micro-environment between patients with PGF and good graft function (GGF) after allo-HSCT in Peking University Institute of Hematology. Methods: Using a prospective nested case-control study, the active phenotype and memory phenotype of CD4+ T cells and CD8+ T cells in BM were analyzed by flow cytometry in 12 patients with PGF, 36 matched patients with GGF after allo-HSCT, and 15 healthy donors (HDs). Furthermore, the cytokine secretion function of CD4+ T cells and CD8+ T cells were evaluated after simulation and the level of eight Th1 and Th2 cytokines in BM plasma were detection by cytometric beads assay. Results: The demographic and clinical characteristics were similar between allo-HSCT patients with PGF and those with GGF. Although the PGF patients presented a significant lymphopenia, a notable increased percentage of activated CD8+ T cells was detected in the BM of PGF patients when compared to that in GGF patients (61.7% versus 35.0%, P =.02). Moreover, the in vitro cytokine stimulated tests demonstrated a significant higher proportion of Tc1 in PGF patients (46.1% versus 20.3% versus 28.4%, P <.005), an elevated percentage of Th1 in PGF compared with HDs (38.5% versus 21.7%, P <.005), a higher percentage of Th2 (4.5% versus 2.1% versus 2.3%, P <.005) and a dramatically decreased percentage of Tc2 in PGF (0.6% versus 2.0% versus 2.0%, P <.0001). Therefore, a significant elevation in the ratio of Th1/Th2 (19.73 versus 7.39 versus 6.91, P <.0001) and Tc1/Tc2 (67.25 versus 10.07 versus 14.57, P <.005) were observed in PGF when compared with those in GGF and HDs. The changes of IFN-gama and IL-4 levels in BM plasma detected by cytometric beads assay were in accordance with the intracellular cytokine results analyzed by flow cytometry. Summary/Conclusion: Both the in vitro intracellular cytokine testing after stimulation and the BM plasma cytokine detection provides evidence that CD4+ and CD8+ T cells were polarized towards a type-1 cytokine response in patients with PGF, suggesting that the dysfunction of T cell response in BM immune micro-environment may hamper the hematopoietic recovery after allo-HSCT. Acknowledgment: Supported by the National Natural Science Foundation of China (grant nos. 81370638&81230013), and the Beijing Municipal Science and Technology Program (grant nos. Z141100000214011& Z151100004015164& Z151100001615020). Disclosures No relevant conflicts of interest to declare.

scholarly journals Targeting FVIII-Specific B Cells Using BAR-Transduced Regulatory T Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 329-329 ◽  
Author(s):  
Ai-Hong Zhang ◽  
Jeong Heon Yoon ◽  
Yong Chan Kim ◽  
David W. Scott
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Neutralizing Antibodies ◽  
Conflicts Of Interest ◽  
Rational Solution ◽  
T Cell Response ◽  
Treg Suppression ◽  
Risk Patients

Abstract Up to a third of hemophilia A (HA) patients receiving therapeutic FVIII develop neutralizing antibodies termed "inhibitors". Once inhibitors develop, clinical management of HA patients becomes extremely difficult. Thus, a rational solution would be to establish FVIII-specific immune tolerance to FVIII in high risk patients. To address this issue in a mouse model of human HA, we elected to use an antigen-specific regulatory T cell (Treg) approach. Analogous to the chimeric antigen receptor (CAR) strategy successfully used in cancer immunotherapy, we have created a chimeric receptor comprising a protein antigen or its domain, linked with the transmembrane and signal transduction domains, CD28-CD3ζ. We termed this receptor "BAR" for B-cell-targeting antibody receptor. Human Tregs (CD4+CD25hiCD127low) were retrovirally transduced with a BAR containing FVIII C2 domain (C2-BAR) or FVIII A2 domain (A2-BAR) and expanded successfully in vitro. These cells stained positively with anti-C2 and anti-A2 monoclonal antibodies, respectively, and maintained Treg phenotypic markers in terms of co-expression of Foxp3 and Helios. Control human Tregs were transduced with a BAR containing chicken ovalbumin (OVA-BAR). To test the hypothesis that BAR-transduced Tregs could directly and effectively suppress the activity of specific B cells, a xenogeneic model was employed. On day 0, FVIII-/- HA mice were injected intravenously with 106 transduced human Tregs. The mice were then immunized subcutaneously on day 1 with FVIII in incomplete Freund's adjuvant, and anti-FVIII antibody development was followed. By two weeks after immunization, anti-FVIII antibodies could be detected in the control mice (n = 4). However, in the experimental group (n = 5) that received a mixture of equal number of C2-and A2-BAR Tregs, anti-FVIII antibody development was reproducibly completely blocked for at least 8 weeks. To examine the possible mechanism of BAR Treg suppression, purified B cells and T cells from "tolerized" (A2+C2-BAR) or "control" (OVA-BAR) recipients were mixed and tested for recall responses to FVIII in vitro. The results suggested that the FVIII-specific B cells were directly tolerized while the T-cell response remained intact. Taken together, we report here a successful approach utilizing FVIII-specific BAR-Tregs to directly target FVIII-specific B cells, an approach which could be adapted to address other adverse immune response as well. (Supported in part by a NIH grant HL127495) Disclosures No relevant conflicts of interest to declare.

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