FTY720 Promotes Engraftment of Allogeneic Donor Bone Marrow Stem Cells but Impairs Thymopoiesis Resulting in Delayed Graft Rejection.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3530-3530
Author(s):  
Patricia A Taylor ◽  
Ryan M Kelly ◽  
Michael J Ehrhardt ◽  
Bruce R. Blazar
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Graft Rejection ◽  
Absolute Number ◽  
Cell Lineages ◽  
Single Positive ◽  
High Level

Abstract Abstract 3530 Poster Board III-467 FTY720 (FTY), a sphingosine-1-phosphate receptor agonist, inhibits lymphocyte egress from lymphoid tissues although the complete mechanism of its immunomodulatory effects is not fully understood. We previously published that FTY inhibited but did not prevent graft-versus-host disease by multiple mechanisms. Using the same dose and schedule (3 mg/kg orally d0-28) we evaluated FTY for its effect on allogeneic bone marrow (BM) engraftment in sublethally-irradiated mice. C57BL/6 mice were irradiated with 5.0 Gy total body irradiation (TBI) on day -1, and received 107 T-cell depleted BALB/c BM cells on day 0. At 5 wks, FTY-treated mice had a mean 84% ± 4% (mean ± SEM, n=47) donor chimerism in peripheral blood leukocytes (PBL) versus 5% ± 2% in water-treated controls (n=38, p<0.001). However, engraftment promotion was transient in most mice. PBL phenotyping at 3 months revealed that mean donor chimerism decreased to 22% ± 6%. Of the 32 mice that were >90% donor at 5 wks, only 6 were >50% donor at 3 months indicating that even high level donor chimeras were subject to delayed graft rejection. We found that although FTY promoted robust donor engraftment in the NK, myeloid and B cell lineages in BM, spleen, and lymph nodes by the first week after transplantation, thymopoiesis was severely impaired at 1 month resulting in near absent donor (and also host) thymic T cell production. FTY-treated mice had very low thymocyte cellularity (<7×106, n=10). Most thymocytes (65-85%) were host CD4 or CD8 single positive T cells. We hypothesized that upon cessation of FTY, which prevents thymocyte egress, the mature host single positive T cells were released into the periphery and mediated delayed graft rejection. Consistent with this hypothesis, the in vivo depletion of host T cells but not host NK cells, at the time of cessation of FTY treatment, abrogated the loss of the donor graft indicating that host T cells were responsible for delayed graft rejection. Also consistent with our hypothesis, and demonstrating the immune competence of the host T cells retained in the thymus, the adoptive transfer of thymocytes from FTY-treated engrafted mice into lethally-irradiated C57BL/6 recipients mediated donor BALB/c BM rejection. To further examine the mechanism of early and robust albeit transient engraftment promotion in some cell lineages, but near absent thymopoiesis, we evaluated the absolute number of donor lin−Sca-1+cKit+ stem cells in the BM at 1 month. For these experiments, an engrafted control was deemed to be a more useful comparator than water-treated mice that rejected their graft. To ensure an engrafted control using the same TBI and allogeneic cell dose parameters, control mice were given peri-transplant injections of anti-CD4 and anti-CD8, a strategy that depletes host T cells and results in durable high level donor chimeras. Consistent with reports that FTY supports migration and bone marrow homing of stem cells, FTY-treated mice had a 4.9-fold increase in the absolute number of donor lin−Sca-1+cKit+ stem cells in the BM compartment compared to anti-CD4/8-treated mice. We hypothesized that the lack of donor thymopoiesis was the result of common lymphoid progenitors being trapped in the BM compartment and unable to migrate to and/or enter the thymus. Consistent with this hypothesis, FTY-treated mice had 125-fold fewer donor-type linlocKithiCD25− early thymic progenitors (ETPs) compared to anti-CD4/8-treated control mice. In contrast to FTY-treated mice, anti-CD4/8-treated mice had evidence of vigorous donor thymopoiesis. Collectively these data indicate that although FTY supports donor stem cell migration/homing to the BM and early donor NK, myeloid and B cell engraftment, the block in donor thymopoiesis and retention of thymic host T cells result in only transient engraftment in most sublethally-irradiated mice. These data have important implications in the use of FTY in BMT and further warrant examination of thymopoiesis in patients receiving FTY for immune suppression. Disclosures: No relevant conflicts of interest to declare.

Prevention of Acute GvHD during Haplo-BMT: Evaluating the Efficacy of T-Cell Costimulation Blockade Using a Novel Rhesus Macaque Transplant Model

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3522-3522
Author(s):  
Weston Miller ◽  
Caleb E. Wheeler ◽  
Angela Panoskaltsis- Mortari ◽  
Allan Kirk ◽  
Christian P Larsen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Rhesus Macaque ◽  
Acute Gvhd ◽  
Model Systems ◽  
Costimulation Blockade ◽  
Hematopoietic Stem

Abstract Introduction: While bone marrow transplantation (BMT) offers curative therapy for many malignant and non-malignant hematologic diseases, it remains plagued by high morbidity and mortality, most prominently through the complications of graft-versus-host disease (GvHD). The field of GvHD research has been limited by a small number of clinically relevant model systems, which, until now, have focused on murine and canine models. However, many new human therapeutics, including those directed at T cell costimulation pathways, do not cross-react with targets in these model systems, limiting their utility to fully evaluate the new generation biologic anti-GvHD therapies. Methods: We have developed a fully pedigreed and MHC-typed rhesus macaque bone marrow transplant system, with which to model GvHD and its prevention. This model relies upon microsatellite typing of both autosomal chromosomes to create genetically-verified family trees and microsatellite-and allele-specific PCR-based MHC typing, with which to identify MHC haplotypes within each family group. By this methodology, full and half-sibling pairs can be identified with either full MHC matching, one MHC haplotype matching or full MHC disparity. This represents a significant advance compared to previous primate haplo-studies, which relied upon parent-offspring transplants, as it optimizes animal availability and colony stability as well as permiting the rigorous evaluation of the degree of MHC disparity on the non-shared chromosome 6. For the current study, we have concentrated on MHC haplo-identical BMT. Our preparative regimen consists of TBI (8.00 Gy with lung shielding to 6.00 Gy), which is performed on the day of transplant with hematopoietic stem cells. After transplant, donor engraftment is measured by microsatellite analysis, from both whole blood and from flow cytometrically sorted T and B cell populations. GvHD is graded using standard clinical grading scales. The immune phenotype after transplant is also measured by cell- and serum-based flow cytometric analyses. Results: Three animals have so far been studied. The first animal served as a control for TBI-based preparation. This animal exhibited both neutropenia (nadir = 0.015 × 103/uL at 12 days) and thrombocytopenia (nadir = 2 × 103/uL at 12 days) and prolonged anemia (hgb=5.8 g/dL on the day of sacrifice). This animal was sacrificed at day 29 due to prolonged pancytopenia. The second animal was transplanted with haploidentical hematopoietic stem cells (4.47 × 108 total nucleated cells/kg and 1.10 × 108 CD3+ T cells/kg) and was treated with only rapamycin for immunosuppression. He exhibited profuse diarrhea and necrotic skin changes within 8 days of transplant, coincident with early engraftment and was sacrificed at day 14. A full histologic analysis to determine the cause of these lesions (and the histopathologic extent of GvHD) is currently underway. The third animal was transplanted with haploidentical donor bone marrow (1.1 × 109 total nucleated cells/kg and 6.9 × 107 CD3+ T cells/kg), but was given T cell costimulation blockade with abatacept (targeting the CD28/B7 pathway) and an anti-CD40 antibody (targeting the CD40/CD154 pathway) in addition to rapamycin. Abatacept is currently clinically approved for treatment of rheumatoid arthritis, but has not been added to clinical GvHD regimens, largely due to the paucity of translational efficacy data. This animal is currently >43 days post-transplant, with full donor chimerism (including 100% T and B cell chimerism), without signs of GvHD: he has no rash, no diarrhea and is stable clinically. Additional animals are now being added to the study, to confirm these initial results. Conclusions: We have established a robust non-human primate model of GvHD using pedigreed and MHC-typed rhesus macaques. We have used this model to begin to test the efficacy of a novel agent combination, capable of preventing the onset and complications of acute GvHD. Preliminary results suggest that CD28- and CD40-directed costimulation blockade may be active agents for the prevention of GvHD. A large scale analysis of their efficacy and immune consequences is currently underway.

A comparison of murine T-cell–depleted adult bone marrow and full-term fetal blood cells in hematopoietic engraftment and immune reconstitution

Blood ◽  
2002 ◽  
Vol 99 (1) ◽  
pp. 364-371 ◽  
Author(s):  
Benny J. Chen ◽  
Xiuyu Cui ◽  
Gregory D. Sempowski ◽  
Maria E. Gooding ◽  
Congxiao Liu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Cord Blood ◽  
Blood Cells ◽  
Immune Reconstitution ◽  
Full Term ◽  
Fetal Blood ◽  
Adult Bone

Umbilical cord blood has been increasingly used as a source of hematopoietic stem cells. A major area of concern for the use of cord blood transplantation is the delay in myeloid and lymphoid recovery. To directly compare myeloid and lymphoid recovery using an animal model of bone marrow and cord blood as sources of stem cells, hematopoietic engraftment and immune recovery were studied following infusion of T-cell–depleted adult bone marrow or full-term fetal blood cells, as a model of cord blood in a murine allogeneic transplantation model (C57BL/6 [H-2b] → BALB/c [H-2d]). Allogeneic full-term fetal blood has poorer radioprotective capacity but greater long-term engraftment potential on a cell-to-cell basis compared with T-cell–depleted bone marrow. Allogeneic full-term fetal blood recipients had decreased absolute numbers of T, B, and dendritic cells compared with bone marrow recipients. Splenic T cells in allogeneic full-term fetal blood recipients proliferated poorly, were unable to generate cytotoxic effectors against third-party alloantigens in vitro, and failed to generate alloantigen-specific cytotoxic antibodies in vivo. In addition, reconstituting T cells in fetal blood recipients had decreased mouse T-cell receptorδ single-joint excision circles compared with bone marrow recipients. At a per-cell level, B cells from fetal blood recipients did not proliferate as well as those found in bone marrow recipients. These results suggest that full-term fetal blood can engraft allogeneic hosts across the major histocompatibility barrier with slower hematopoietic engraftment and impaired immune reconstitution.

scholarly journals NOTCH and CAR Signaling Control T Cell Lineage Commitment from Pluripotent Stem Cells

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 30-30
Author(s):  
Sjoukje van der Stegen ◽  
Pieter Lindenbergh ◽  
Roseanna Petrovic ◽  
Benjamin Whitlock ◽  
Raedun Clarke ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
Research Funding ◽  
Cell Lineage ◽  
Lineage Commitment ◽  
Publicly Traded ◽  
Car T Cell ◽  
Car T ◽  
Single Positive

Chimeric Antigen Receptor (CAR) T cells are a new treatment paradigm for relapsed/refractory hematopoietic malignancies. However, their autologous nature imposes manufacturing constraints that can delay CAR T cell availability and increase their cost. We previously established proof of principle that αβ T cell-derived induced pluripotent stem cells (TiPSCs) can provide a self-renewing source for in vitro CAR T cell production (Themeli, Nat Biotechnol, 2013). The use of cloned TiPSC further enhances the feasibility of verifying genome integrity of the genetically engineered stem cells and should in principle yield highly homogenous cell products. Using αβ T cell-derived TiPSCs transduced with a well-defined CD19-specific CAR (1928z; Park, NEJM, 2018), we previously demonstrated that TiPSCs can be differentiated into CAR T cells. These T cells retained their endogenous T cell receptor (TCR) and also displayed characteristics of innate lymphoid cells. We have now examined how the timing of CAR expression as well as the CAR signaling strength influence T cell lineage commitment, enabling better control towards αβ T cell lineage commitment. αβ T cell lineage development depends in part on a precisely orchestrated interactions between NOTCH and (pre)TCR signaling, the timing and strength of which are crucial for αβ lineage commitment. Because TiPSCs harbor rearranged TCRα and TCRβ genes, mature TCR expression occurs earlier than if it required VDJ recombination, skewing differentiation towards acquiring innate features including CD4-CD8- double-negative or CD8αα single-positive phenotypes. We show that providing strong NOTCH stimulation counteracts the effects of early antigen receptor expression, facilitating CD4+CD8αβ+ double positive (DP) formation. We hypothesized that CAR signaling in the absence of ligand binding (tonic signaling) may mimic a TCR signal, the strength and timing of which could re-direct lineage commitment. We therefore investigated CARs providing different levels of signaling strength and the impact of delaying the onset of CAR expression. Tonic CAR signaling was measured in peripheral blood T cells expressing 1928z or 1928z-1XX, a construct in which the second and third ITAM in the CD3ζ domain have been mutated to be non-functional (Feucht, Nat Med, 2019), following either retroviral transduction (SFG vector) orTRAC-targeted cDNA integration, placing CAR expression under the transcriptional control of the TCRα promoter (Eyquem, Nature, 2017). CAR signaling in the absence of antigen exposure, measured by phosphorylation of ITAM3, ERK1/2 and ZAP70, was reduced by bothTRAC-targeting and reduction of functional ITAMs, with additive effects when combined inTRAC-1928z-1XX. Three of these engineering strategies (virally expressed 1928z,TRAC-1928z andTRAC-1928z-1XX) were evaluated in the context of TiPSC-derived T cell differentiation. Virally expressed 1928z (resulting in constitutive CAR expression throughout differentiation) resulted in the predominant generation of innate-like CD8αα T cells, associated with the absence of early T cell lineage markers such as CD5, CD2 and CD1a. Delayed expression of 1928z throughTRACtargeting resulted in increased CD5, CD2 and CD1a, but did not yield any more CD4+CD8αβ+ DP cells. In TiPSC expressingTRAClocus-encoded 1928z-1XX, a greater DP population emerged, from which CD8αβ single-positive T cells could be induced. Phenotypic analyses of clonal TRAC-1928z-1XX TiPSC lines further establish the interplay between CAR and NOTCH1 in determining αβ lineage commitment. Together these data show that early TCR and CAR expression skew T cell lineage commitment towards an innate-like T cell fate, which can be overcome by controlling the strength and timing of NOTCH, TCR and CAR signaling. These studies pave the way for the predetermined generation of a variety of CAR T cell types endowed with different functional attributes. Disclosures Whitlock: Fate Therapeutics Inc.:Current Employment, Current equity holder in publicly-traded company.Clarke:Fate Therapeutics Inc.:Current Employment, Current equity holder in publicly-traded company.Valamehr:Fate Therapeutics, Inc:Current Employment, Current equity holder in publicly-traded company.Riviere:Juno Therapeutics:Other: Ownership interest, Research Funding;Takeda:Research Funding;Fate Therapeutics Inc.:Consultancy, Other: Ownership interest , Research Funding;FloDesign Sonics:Consultancy, Other: Ownership interest;Atara:Research Funding.Sadelain:Atara:Patents & Royalties, Research Funding;Fate Therapeutics:Patents & Royalties, Research Funding;Mnemo:Patents & Royalties;Takeda:Patents & Royalties, Research Funding;Minerva:Other: Biotechnologies , Patents & Royalties.

Adoptive T-Cell Therapy for B-Cell Acute Lymphoblastic Leukemia: Preclinical Studies

Blood ◽  
1999 ◽  
Vol 94 (10) ◽  
pp. 3531-3540 ◽  
Author(s):  
Angelo A. Cardoso ◽  
J. Pedro Veiga ◽  
Paolo Ghia ◽  
Hernani M. Afonso ◽  
W. Nicholas Haining ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Adoptive T Cell Therapy ◽  
Leukemic Cells ◽  
Acute Leukemias ◽  
T Cell Lines

We have previously shown that leukemia-specific cytotoxic T cells (CTL) can be generated from the bone marrow of most patients with B-cell precursor acute leukemias. If these antileukemia CTL are to be used for adoptive immunotherapy, they must have the capability to circulate, migrate through endothelium, home to the bone marrow, and, most importantly, lyse the leukemic cells in a leukemia-permissive bone marrow microenvironment. We demonstrate here that such antileukemia T-cell lines are overwhelmingly CD8+ and exhibit an activated phenotype. Using a transendothelial chemotaxis assay with human endothelial cells, we observed that these T cells can be recruited and transmigrate through vascular and bone marrow endothelium and that these transmigrated cells preserve their capacity to lyse leukemic cells. Additionally, these antileukemia T-cell lines are capable of adhering to autologous stromal cell layers. Finally, autologous antileukemia CTL specifically lyse leukemic cells even in the presence of autologous marrow stroma. Importantly, these antileukemia T-cell lines do not lyse autologous stromal cells. Thus, the capacity to generate anti–leukemia-specific T-cell lines coupled with the present findings that such cells can migrate, adhere, and function in the presence of the marrow microenvironment enable the development of clinical studies of adoptive transfer of antileukemia CTL for the treatment of ALL.

scholarly journals ANATOMICAL DISTRIBUTION OF T AND B LYMPHOCYTES IN THE RAT

1973 ◽  
Vol 138 (6) ◽  
pp. 1443-1465 ◽  
Author(s):  
Irving Goldschneider ◽  
D. D. McGregor
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Lymph Node ◽  
T Cell ◽  
B Cell ◽  
B Lymphocytes ◽  
Thoracic Duct ◽  
T And B Lymphocytes ◽  
White Pulp ◽  
Cell Surface Antigens

A method is described whereby antisera raised in rabbits to rat thoracic duct lymphocytes were made specific for the plasma membrane antigens of T and B lymphocytes. These lymphocyte-specific antisera were used in immunofluorescence assays to study the distribution of B and T cells in lymphocyte containing tissues and body fluids of the rat. Rabbit antirat B-cell serum (ALSB) reacted selectively with the surfaces of lymphocytes in the lymphoid follicles of lymph node cortex and in the follicles and marginal zones of splenic white pulp, but not with the surfaces of germinal center cells or plasma cells. An identical pattern of fluorescent staining was obtained with rabbit antirat Ig serum. It was shown by blocking, absorption, and immunoprecipitation studies that ALSB was composed in large part of antibodies to rat Ig, but that it contained antibodies to other B-cell antigens as well. Rabbit antirat T-cell serum (ALST) reacted selectively with the surfaces of lymphocytes in the paracortex of lymph node and in the periarteriolar sheath of spleen, and with thymocytes. ALST did not display anti-Ig activity. ALST reacted with approximately 100% thymocytes and with 90% thoracic duct, 80% lymph node, 60% blood, 50% spleen, and 10% bone marrow lymphocytes in suspensions of cells from these sources. ALSB reacted with the remainder of the lymphocytes in the suspensions, except for bone marrow in which only 59% of lymphocytes had detectable B- or T-cell surface antigens. The population of T lymphocytes in rat bone marrow was depleted by drainage of lymphocytes from a thoracic duct fistula, thereby establishing their membership in the pool of recirculating T cells. Approximately 14% of lymphocytes issuing from the thoracic duct of TxBM donors reacted with ALST. The presence in these animals of a small number of T cells, calculated to be approximately 2% of the normal value, may account for the limited capacity of TxBM rats to respond to antigens that induce a cell-mediated immune response.

Immunosupressive Property of Mesenchymal Stem Cells (MSCs) in Mixed Lymphocyte Reactions In Vitro.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4313-4313 ◽  
Author(s):  
Jianyong Li ◽  
Lijuan Meng ◽  
Yu Zhu ◽  
Hua Lu ◽  
Changgeng Ruan
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
T Cell Subsets ◽  
Bone Marrow Mscs ◽  
Human Bone Marrow Mscs ◽  
Mixed Lymphocyte Reactions ◽  
Activation Phase

Abstract Meesnchymal stem cells (MSCs) were successfully used in the prevention and treatment of graft versus host disease (GVHD) after allogeneic hematopoietic stem cell transplantation. To further explore the immunosuppressive property of human bone marrow (MSCs) in alloantigen-induced mixed lymphocyte reactions (MLRs) in vitro, human bone marrow MSCs and lymphocytes were prepared from healthy volunteers. MSCs were expanded in vitro in Mesencult serum free media. MSCs were cocultured with one-way MLRs and bidirectional MLRs, responder cells were labeled with carboxyfluorescein diacetate- succinimidyl ester (CFSE) in bidirectional MLRs. Cell Counting Kit-8(CCK-8)kit was used in cell proliferation detection, T-cell subsets were analyzed by flow cytometry (FCM). The results showed that MSCs were positive for CD105, CD73, CD13, CD90 and were negative for hematopoietic cell markers. In one-way MLRs, MSCs down-regulated alloantigen-induced lymphocyte expansion in a dose-dependent and MHC-independend manner. In two-way MLRs, MSCs suppressed proliferation of CFSE positive cells. T cell subsets were changed: Th2 and Tc2 were down-regulated. Th2 was reduced from 1.70% to 0.65%, and Tc2 reduced from 1.10% to 0.47%, while Th1 and Tc1 were unaffected. T cells that became CD69+, which was an early activation marker, were significantly up-regulated from 7.14% to 26.12% and CD4+CD25+T regulatory cells (CD4+CD25+Tr) were up-regulated from 4.04% to 6.19%, which indicating that suppression did not interfere with activation phase of T cells and might be mediated by CD4+CD25+Tr partly. We conclede that MSCs down-regulated alloantigen-induced lymphocyte expansion. The immunosupressive effect might involve in post-activation phase of T cells. CD4+CD25+Tr might contribute to the suppressory activity of MSCs.

Pentostatin Facilitates Fully MHC-Disparate Murine Mini-Transplantation.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3539-3539
Author(s):  
Jacopo Mariotti ◽  
Kaitlyn Ryan ◽  
Paul Massey ◽  
Nicole Buxhoeveden ◽  
Jason Foley ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Immune Suppression ◽  
Graft Rejection ◽  
Mixed Chimerism ◽  
Post Transplant

Abstract Abstract 3539 Poster Board III-476 Pentostatin has been utilized clinically in combination with irradiation for host conditioning prior to reduced-intensity allogeneic hematopoietic stem cell transplantation (allo-HSCT); however, murine models utilizing pentostatin to facilitate engraftment across fully MHC-disparate barriers have not been developed. To address this deficit in murine modeling, we first compared the immunosuppressive and immunodepleting effects of pentostatin (P) plus cyclophosphamide (C) to a regimen of fludarabine (F) plus (C) that we previously described. Cohorts of mice (n=5-10) received a three-day regimen consisting of P alone (1 mg/kg/d), F alone (100 mg/kg/d), C alone (50 mg/kg/d), or combination PC or FC. Combination PC or FC were each more effective at depleting and suppressing splenic T cells than either agent alone (depletion was quantified by flow cytometry; suppression was quantified by cytokine secretion after co-stimulation). The PC and FC regimens were similar in terms of yielding only modest myeloid suppression. However, the PC regimen was more potent in terms of depleting host CD4+ T cells (p<0.01) and CD8+ T cells (p<0.01), and suppressing their function (cytokine values are pg/ml/0.5×106 cells/ml; all comparisons p<0.05) with respect to capacity to secrete IFN-g (13±5 vs. 48±12), IL-2 (59±44 vs. 258±32), IL-4 (34±10 vs. 104±12), and IL-10 (15±3 vs. 34±5). Next, we evaluated whether T cells harvested from PC-treated and FC-treated hosts were also differentially immune suppressed in terms of capacity to mediate an alloreactive host-versus-graft rejection response (HVGR) in vivo when transferred to a secondary host. BALB/c hosts were lethally irradiated (1050 cGy; day -2), reconstituted with host-type T cells from PC- or FC-treated recipients (day -1; 0.1 × 106 T cells transferred), and challenged with fully allogeneic transplant (B6 donor bone marrow, 10 × 106 cells; day 0). In vivo HVGR was quantified on day 7 post-BMT by cytokine capture flow cytometry: absolute number of host CD4+ T cells secreting IFN-g in an allospecific manner was ([x 106/spleen]) 0.02 ± 0.008 in recipients of PC-treated T cells and 1.55 ± 0.39 in recipients of FC-treated cells (p<0.001). Similar results were obtained for allospecific host CD8+ T cells (p<0.001). Our second objective was to characterize the host immune barrier for engraftment after PC treatment. BALB/c mice were treated for 3 days with PC and transplanted with TCD B6 bone marrow. Surprisingly, such PC-treated recipients developed alloreactive T cells in vivo and ultimately rejected the graft. Because the PC-treated hosts were heavily immune depleted at the time of transplantation, we reasoned that failure to engraft might be due to host immune T cell reconstitution after PC therapy. In an experiment performed to characterize the duration of PC-induced immune depletion and suppression, we found that although immune depletion was prolonged, immune suppression was relatively transient. To develop a more immune suppressive regimen, we extended the C therapy to 14 days (50 mg/Kg) and provided a longer interval of pentostatin therapy (administered on days 1, 4, 8, and 12). This 14-day PC regimen yielded CD4+ and CD8+ T cell depletion similar to recipients of a lethal dose of TBI, more durable immune depletion, but again failed to achieve durable immune suppression, therefore resulting in HVGR and ultimate graft rejection. Finally, through intensification of C therapy (to 100 mg/Kg for 14 days), we were identified a PC regimen that was both highly immune depleting and achieved prolonged immune suppression, as defined by host inability to recover T cell IFN-g secretion for a full 14-day period after completion of PC therapy. Finally, our third objective was to determine with this optimized PC regimen might permit the engraftment of MHC disparate, TCD murine allografts. Indeed, using a BALB/c-into-B6 model, we found that mixed chimerism was achieved by day 30 and remained relatively stable through day 90 post-transplant (percent donor chimerism at days 30, 60, and 90 post-transplant were 28 ± 8, 23 ± 9, and 21 ± 7 percent, respectively). At day 90, mixed chimerism in myeloid, T, and B cell subsets was observed in the blood, spleen, and bone marrow compartments. Pentostatin therefore synergizes with cyclophosphamide to deplete, suppress, and limit immune reconstitution of host T cells, thereby allowing engraftment of T cell-depleted allografts across MHC barriers. Disclosures: No relevant conflicts of interest to declare.

IL-21 and IL-6 Mediate Interactions Between T Cells and Malignant B Cells in the Bone Marrow Microenvironment in Waldenstrom's Macroglobulinemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1554-1554
Author(s):  
Lucy S. Hodge ◽  
Steve Ziesmer ◽  
Frank J Secreto ◽  
Zhi-Zhang Yang ◽  
Anne Novak ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Tumor Microenvironment ◽  
B Cell ◽  
Bone Marrow Microenvironment ◽  
Waldenström’S Macroglobulinemia ◽  
Waldenström's Macroglobulinemia

Abstract Abstract 1554 T cells in the tumor microenvironment influence the biology of malignant cells in many hematologic malignancies, often through cytokine-mediated interactions. Recent studies involving healthy B cells and CD4+T cells identified an interplay between IL-6 and IL-21, whereby IL-6 increased IL-21 production by T cells, driving the differentiation and IL-6 secretion of nearby B cells. In addition to their known effects on healthy B cell function, IL-6 and IL-21 have also been implicated in the pathology of various lymphomas. In Waldenstrom's macroglobulinemia (WM), IL-6 is elevated in the bone marrow and is associated with increased IgM production. However, the function of IL-21 in the WM tumor microenvironment and its relationship to IL-6 is poorly understood. Our objective in this study was to characterize IL-21 production and function in WM and to examine the role of IL-6 and IL-21 in regulating interactions between malignant B cells and T cells in the tumor microenvironment. Immunohistochemistry revealed significant IL-21 staining in bone marrows of patients with WM (n=5), but the areas of infiltration by WM in the bone marrow sections appeared negative for IL-21 staining. To better understand the origin of IL-21 in in the tumor microenvironment, IL-21 expression was assessed by PCR in the CD19−CD138− fraction of cells remaining in patient bone marrow aspirates after positive selection for malignant B cells (n=5). IL-21 transcript was detected in 4/5 samples. CD19−CD138− cells activated with anti-CD3 and anti-CD28 antibodies expressed higher levels of IL-21 transcript and secreted significantly higher levels of IL-21 protein compared to unstimulated cells, suggesting that IL-21 in the WM bone marrow is derived from activated T cells. Intracellular expression of IL-21 protein was confirmed in CD4+ and CD8+ cells within the CD19−CD138− population using flow cytometry. Furthermore, dual staining of WM bone marrow sections with antibodies against IL-21 and CD3 or CD20 revealed co-staining of IL-21 with CD3+ T cells but not with CD20+ B cells. The response of WM B cells to T-cell derived IL-21 was then assessed in positively selected CD19+CD138+ WM B cells (n=5) and in the MWCL-1 cell line. Using flow cytometry, both the IL-21 receptor and the required common gamma chain subunit were detected on all patient samples as well as on MWCL-1 cells. Treatment of MWCL-1 cells with IL-21 (100 ng/mL) for 72 h increased proliferation by 35% (p<0.05) and IgM secretion by 80% (p<0.005). Similarly, in primary CD19+CD138+ WM cells (n=5), proliferation increased on average by 38% and IgM secretion by 71%. No apoptotic effects were associated with IL-21 in WM. Characterization of STAT activation in response to IL-21 revealed significant phosphorylation of STAT3 in both CD19+CD138+ WM cells and MWCL-1 cells and was associated with increases in BLIMP-1 and XBP-1 protein and decreases in PAX5. As STAT3 activation is known to regulate IL-6, we assessed the effect of IL-21 on B cell-mediated IL-6 secretion using ELISA. IL-21 significantly increased IL-6 secretion by both primary CD19+CD138+ WM cells (n=4) and MWCL-1 cells (87.9 +/− 10.9 ng/mL vs. 297.8 +/− 129.2 ng/mL, p<0.05). Treatment with IL-6 and IL-21 together had no additional effect over IL-21 alone on proliferation or IgM secretion in MWCL-1 cells, but culturing anti-CD3/anti-CD28-activated CD19−CD138−cells from WM bone marrows with IL-6 significantly increased IL-21 secretion (n=3). Overall, these data indicate that T-cell derived IL-21 significantly promotes growth and immunoglobulin production by malignant WM B cells and that subsequent IL-6 secretion by malignant B cells may enhance the secretion of IL-21 by T cells within the bone marrow microenvironment. Disclosures: No relevant conflicts of interest to declare.

Conditioning Intensity and T Cell Dose Determine Efficacy of CD19-Targeted T Cell-Mediated Tumor Eradication in an Immunocompetent Mouse Model of B-ALL.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2613-2613
Author(s):  
Marco L Davila ◽  
Christopher Kloss ◽  
Renier J Brentjens ◽  
Michel Sadelain
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Mouse Model ◽  
B Cell ◽  
Immunocompetent Mouse ◽  
Cell Dose ◽  
Conditioning Intensity

Abstract Abstract 2613 Recent work by our group and others demonstrates the therapeutic potential of CD19-targeted T cells to treat patients with indolent B cell malignancies. These studies make use of T cells that are genetically engineered with chimeric antigen receptors (CARs) comprising an scFv fused to various T cell activating elements. Whereas firs-generation CARs only direct T cell activation, second-generation CARs include two signal elements, such as CD3z and CD28 signaling domains (19–28z). We and our colleagues at MSKCC are currently evaluating the safety of 19–28z-transduced T cells in patients with acute leukemia (B-ALL) in a Phase I protocol (NCT01044069). Pre-clinical studies performed to date have mostly relied on xenogeneic models utilizing immunodeficient animals, which enable the evaluation of human engineered T cells but do not recapitulate all the interactions that may affect tumor eradication by CAR-modified T cells. We have therefore developed a pre-clinical immunocompetent mouse model of B-ALL, and addressed therein the impact of conditioning and T cell dose on the eradication of leukemia by syngeneic, CAR-targeted T cells. To establish an immunocompetent mouse model of B cell leukemia, we generated a clone from the lymph node of an Eμ-myc B6 transgenic mouse. The immunophenotype and gene-expression profile of clone Eμ-ALL01 is consistent with a progenitor B cell origin. Syngeneic B6 mice inoculated with this clone develop florid acute leukemia and die approximately 2–4 weeks after injection from progressive bone marrow infiltration. We created an anti-mouse CD19 CAR comprising all murine elements, including the CD8 signal peptide, a CD19-specific single chain variable fragment, the CD8 transmembrane region, and the CD28 and CD3z signaling domains. Transduction of the murine 19–28z CAR into mouse T cells was robust and successfully retargeted the T cells to B cells. In vitro assays demonstrated that m19–28 z transduced T cells mediated effective killing of CD19-expressing target cells and the production of effector cytokines such as IFNγ and TNFα. Cyclophosphamide either alone or in combination with control syngeneic T cells is insufficient to eradicate established Eμ-ALL01 in B6 mice. However, treatment with cyclophosphamide and m19–28z-transduced T cells cured nearly all mice. Mice sacrificed six months after treatment exhibited a dramatic reduction of B cells in the bone marrow (BM), blood, and spleen. The few remaining B lineage cells found in the BM had a phenotype consistent with early pro-B cells, suggesting that endogenous reconstitution of the B cell compartment was thwarted by persisting, functional m19–28z+ T cells. Thus, T cells are retained at the site of antigen expression, which is maintained through regeneration of progenitor B cells. The persisting CD19-targeted T cells in the BM exhibited a cell surface phenotype consistent with effector and central memory cells. Using B cell aplasia as a surrogate endpoint for assessing in vivo T cell function and persistence, we evaluated how conditioning chemotherapy and T cell dose determine the level of B cell depletion induced by adoptively transferred CD19-targeted T cells. Overall, increasing the cyclophosphamide or T cell dose, increased the degree and duration of B cell depletion and the number of persisting CAR-modified T cells. Significantly, increasing the T cell dose at a set cyclophosphamide level had a lesser impact than increasing the conditioning intensity for a given T cell dose. In summary, the new Eμ-ALL01 syngeneic, immunocompetent B-ALL model we describe here is a valuable tool for modeling CD19 CAR therapies. Our results indicate that m19–28z transduced T cells are effective at eradicating B-ALL tumor cells and persist long-term, preferentially in bone marrow. Our findings further establish that conditioning intensity and T cell dose directly determine B cell elimination and long-term T cell persistence. These studies in mice will serve as an important framework to further model and perfect our studies in patients with B-ALL. Disclosures: No relevant conflicts of interest to declare.

Hepatic Stellate Cell Conditioned Myeloid Cells Provide a Novel Therapy for Prevention of Factor VIII Antibody Formation in the Hemophilia A Mouse Model

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4117-4117
Author(s):  
Sumantha Bhatt ◽  
Kathleen Brown ◽  
Feng Lin ◽  
Michael P Meyer ◽  
Margaret V. Ragni ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Hemophilia A ◽  
Myeloid Cells ◽  
Gm Csf ◽  
Cox 2

Abstract Abstract 4117 Background: Hemophilia is an X-linked bleeding disorder resulting from a mutation in coagulation factor VIII (F.VIII). A major drawback of current plasma-derived or recombinant F.VIII therapy is the formation of F.VIII antibodies (inhibitors). Inhibitor formation is a T cell-dependent, B cell-mediated immune response to foreign infused F.VIII. Myeloid derived suppressor cells (MDSCs) are potent suppressors of T cell and B cell responses and are currently under study for therapeutic applications in transplantation and autoimmune diseases. However, the mechanisms of MDSC development and function remain unknown, and in vitro propagation of MDSCs has been a challenge. We hypothesized that MDSCs might be effective in inhibiting F.VIII inhibitor formation in the hemophilia A model. Methods: We developed a novel method for generating MDSCs in vitro by culturing bone marrow cells from hemophilia A mice with hepatic stellate cells (HSCs), hereafter referred to as HSC-conditioned myeloid cells (H-MCs). DCs were propagated from the bone marrow with GM-CSF and IL-4, whereas H-MCs were propagated from the bone marrow with GM-CSF and HSCs. Granulocyte contaminants were removed on day 2 and the remaining monocytic populations were harvested on day 5. Expression of cell surface antigens was analyzed by flow cytometry. Arginase1 and iNOS levels were compared by qPCR, with or without LPS stimulation. The in vitro suppressive capacity of the H-MCs was determined by a mixed leukocyte reaction culture. Splenic T cells from hemophilia A mice were stimulated by irradiated DCs (at a 1–20 ratio, APC to T cell) and recombinant F.VIII. Additional irradiated DCs or H-MCs were added in graded numbers as regulators. The proliferative response was determined by 3H-thymidine incorporation. The phenotype of cultured CD4+ T cells was characterized by intracellular staining for Foxp3 and IFN-gamma and analyzed by flow cytometry. Inhibition of B cells by H-MCs was determined by a CFSE dilution assay. Purified splenic B cells were labeled with CFSE and stimulated by Ig-M and IL-4. APCs (spleen cells) or H-MCs were added at a ratio of 1:10 (APC to B cell). The proportion of proliferating B cells was determined by CFSE dilution of B220 stained cells. In the COX-2 suppression assay, CFSE labeled B cells were treated with varying concentrations of the selective inhibitor of COX-2, NS398. The suppressive effect of H-MCs on B cells in vivo was determined by simultaneously administering H-MCs (I.V) and F.VIII (I.V.) to hemophila A mice on day 0 and rechallenging with recombinant F.VIII on days 2 and 4. WT B6 mice and hemophilia A mice without H-MC transfer served as controls. Plasma anti-F.VIII antibody titers were measured on day 12 by a modified ELISA assay. Results: H-MCs expressed low levels of costimulatory molecules but high levels of the inhibitory molecule B7-H1 and immunoregulatory enzyme arginase-1. In contrast, DCs expressed high levels of costimulatory molecules and MHC class II. In vitro studies demonstrated that the H-MCs markedly inhibited antigen specific T cell proliferation induced by dendritic cells in response to recombinant F.VIII (Fig. 1). H-MCs altered the T cell response in hemophilia A mice by promoting the expansion of regulatory T cells and inhibiting IFN-γ producing CD4+ T cells. When the H-MCs were cocultured with B cells isolated from hemophilia A mice, in the presence of Ig-M and IL-4, the H-MCs abrogated B cell activation and proliferation directly (Fig. 2). H-MCs may be modulating the B cell response through the Cox-2 pathway, as inhibition of Cox-2 through NS398 led to the restoration of B cell proliferation. More importantly, adoptive transfer of H-MCs into hemophilia Amice, at the time of F.VIII infusion, markedly suppressed anti-F.VIII antibody formation (Fig. 3). Conclusion: These results suggest that HSC conditioned myeloid cells may represent a potential therapeutic approach to induction of immune tolerance in patients with hemophilia A andother immune disorders. Disclosures: No relevant conflicts of interest to declare.

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