scholarly journals Results of Hematopoietic Stem Cells Transplantation with Tcrαβ and CD19-Depletion from Matched Related Donors and Infusions of CD45RA Depleted Donor Lymphocytes in Pediatric Severe Aplastic Anemia

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 558-558
Author(s):  
Larisa Shelikhova ◽  
Anna Bogoyavlenskaya ◽  
Maria Ilushina ◽  
Tatiana Salimova ◽  
Kristina Antonova ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Aplastic Anemia ◽  
Median Time ◽  
Severe Aplastic Anemia ◽  
Current Standard ◽  
Hematopoietic Stem ◽  
Platelet Recovery ◽  
Memory T Cell ◽  
Intermediate Dose

Abstract Introduction HSCT from matched family donors results in most favorable outcomes among children with severe aplastic anemia (SAA). Despite overall success, morbidity, associated with acute and chronic graft-versus-host disease (GVHD) is not completely prevented with current standard of pharmacologic prophylaxis. Depletion of ab T cells from the graft prevents GVHD, and improves outcome of hematopoietic stem cell transplantation from haploidentical donors, while infusions of donor memory lymphocytes (mDLI) (CD45RA-depleted) are able to transfer pathogen-specific immunity without the risk of GVHD. We evaluated the outcomes of ab T cell depletion and add-back of intermediate-dose mDLI among the pediatric SAA recipients of matched related grafts. Materials and methods A total of 16 children with SAA (8 female, 8 male, median age 10,9 y) underwent allogenic HSCT from matched family donors (MFD) between february 2015 and may 2021. For 15 (94%) pts it was the first allo HSCT, for 1 pts it was the second HSCT. TCR αβ+/CD19+ depletion of HSCT with CliniMACS technology was implemented in all cases. The median dose of CD34+ cells was 7,1 x10 6/kg (range 2,6-13), αβ T cells - 28x10 3/kg (range 5,6-184). All pts received an additional injection of memory T-cell (CD45RA-depleted) on day 0 at 1 million T cells per kg. All patients received cyclophosphamide at 100 mg/kg, fludarabine at 100 mg/m 2, rituximab 100mg/m 2 and serotherapy with either rabbit ATG at 5 mg/kg (n-2) or horse ATG at 100 mg/kg (n-14). Post-transplant GVHD prophylaxis included calcineurin (CNI)-based regimen and abatacept 10mg/kg on days -1, +7, +14 and +28. All pts received a graft from a 10/10 HLA-matched sibling. Median time of follow-up for survivors was 1,1 years (range: 0.14 - 6.38). Results Primary engraftment was achieved in all evaluable patients (100%) with full donor chimerism, and the median time to neutrophil and platelet recovery was 11 (10-20) and 14 (11-20) days, respectively. One patient had aGVHD grade I, there were no incidence of grade II-IV aGVHD and TRM. Event-free and overall survival were 100%. CMV viremia was detected among two patients after a median of 40 (35-73) days after HSCT. No cases of ADV and Epstein-Barr virus (EBV) viremia and EBV disease were recorded. The median recovery of T cells on day+60 was 0,26 (0,04-0,9). Conclusion ab T cell-depleted transplantation with intermediate dose memory T cell add-back definitively prevents GVHD and provides a platform for safe HSCT from matched family donors in patients with SAA. Disclosures Maschan: Miltenyi Biotec: Speakers Bureau.

scholarly journals Multi-Omics Profiling Identifies Pathways Associated With CD8+ T-Cell Activation in Severe Aplastic Anemia

2022 ◽  
Vol 12 ◽  
Author(s):  
Xing You ◽  
Qiong Yang ◽  
Kai Yan ◽  
Song-Rong Wang ◽  
Rong-Rong Huang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Aplastic Anemia ◽  
T Cell Activation ◽  
Cell Activation ◽  
Transcriptional Analysis ◽  
Severe Aplastic Anemia ◽  
Sequencing Data ◽  
Hematopoietic Stem

Severe aplastic anemia (SAA) is an autoimmune disease characterized by immune-mediated destruction of hematopoietic stem and progenitor cells. Autoreactive CD8+ T cells have been reported as the effector cells; however, the mechanisms regulating their cell activation in SAA remain largely unknown. Here, we performed proteomics and metabolomics analyses of plasma and bone marrow supernatant, together with transcriptional analysis of CD8+ T cells from SAA patients and healthy donors, to find key pathways that are involved in pathogenic CD8+ T-cell activation. We identified 21 differential proteins and 50 differential metabolites in SAA patients that were mainly involved in energy metabolism, complement and coagulation cascades, and HIF-1α signaling pathways. Interestingly, we found that these pathways are also enriched in T cells from SAA patients by analyzing available single-cell RNA sequencing data. Moreover, CD8+ T cells from SAA patients contain a highly activated CD38+ subset, which was increased in the bone marrow of SAA patients and a murine model of SAA. This subset presented enriched genes associated with the glycolysis or gluconeogenesis pathway, HIF-1α signaling pathway, and complement associated pathways, all of which were of importance in T-cell activation. In conclusion, our study reveals new pathways that may regulate CD8+ T-cell activation in SAA patients and provides potential therapeutic targets for SAA treatment.

scholarly journals Haploidentical Donor-Derived CAR-T Cells Are Safely and Effectively Co-Infused with the Haploidentical Graft, Depleted of Ab T Cells: Report of Case Series

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1736-1736
Author(s):  
Larisa Shelikhova ◽  
Olga Molostova ◽  
Arina Rakhteenko ◽  
Rimma Khismatullina ◽  
Julia Abugova ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Median Time ◽  
Lymphoblastic Leukemia ◽  
Hematopoietic Stem ◽  
Platelet Recovery ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Grade 3

Abstract Introduction Autologous chimeric antigen receptor (CAR) T cells induce high rate of deep remissions among children with relapsed/refractory B-precursor acute lymphoblastic leukemia (R/R B-ALL). In a significant proportion of patients true cure is achieved only with HSCT as post-CAR-T consolidation. Seeking to combine the cytoreductive and curative power of HSCT with the antigen-specific activity of CAR-T we devised an approach with simultaneous infusion of haploidentical ab T cell-depleted graft and CAR-T cells, derived from the same donor. The approach was offered to patients with R/R B-ALL on a compassionate use basis and here the first experience is summarized. Patients and methods A total of 11 patients with relapsed/refractory BCP-ALL (n-10) and Burkitt leukemia(n-1), (5 female, 6 male, median age 8,3 y) were treated. Three patients had relapsed BCP-ALL after both haploidentical HSCT and autologous CD19 CAR-T cell, 3 after haploidentical HSCT, 2 after autologous CD19 CAR-T cell, 3 after intensive chemotherapy +/- blinatumomab (n=2). Seven patients had CD19 and CD22 positive leukemic cells in bone marrow (MRD+ n=1, >20% blasts n=6), 2 pts had MRD-level disease with CD22 positive blast cells and 2 pts were in CR2. Peripheral blood mononuclear cells used to produce CAR T cells were provided by the patient's transplant donor. The CliniMACS Prodigy T cell transduction (TCT) process was used to produce CD19 and СD19/22CAR-T cells. Five (45%) pts received treosulfan-based myeloablative preparative regimen, while TBI-based regimen was used in 6 (55%) pts. GvHD prophylaxis included tocilizumab at 8 mg/kg on day -1 and abatacept at 10 mg/kg on day -1, +7, +14, +28. Final product was administered without cryopreservation to the patients: 10 pts received allogeneic CAR T cell with haploidentical (n=10) and match related (n=1) TCRαβ-depleted graft (CD19 CAR- T cell n=1 and CD19/22 CAR- T cell n=10). The CAR-T cell product was administered at a dose of 0,1*10 6/kg of CAR-T cells in all pts. The median dose of CD34+ cells was 8.5 x10 6/kg (range 5-15), αβ T cells - 56x10 3/kg (range 9-172). Results Primary engraftment was achieved in 10 of 11 pts (non-engraftment patient relapsed early), the median time to neutrophil and platelet recovery was 13 and 14 days, respectively. Cytokine release syndrome occurred in 7 patients (63%) and all were grade ≤3. Six patients (54%) had neurologic events (ICANS grade 3, n=1). No aGVHD 3-4 were observed, 4 pts developed grade 2 aGVHD (skin and gut). The median time to CAR-T cell peak expansion was 14 days (7-28). The median time to CAR-T cell persisted was 6 months (2-12) and B cell aplasia was 7 months. All engrafted patients achieved CR (MRD negative) at day +28 after CAR-T cell therapy, one patient died due to Mucormycosis at day +31. One patient relapsed after 2 months after HST. Eight patients are alive in CR with a median follow up 291 days (85-388). Conclusion Our early experience suggests that haploidentical CAR-T cells can be safely infused simultaneously with the hematopoietic stem cell graft on the platform of ab T cell depletion. The infusions did not compromise engraftment and GVHD control, while specific CAR-T toxicity was mild and manageable. We have documented allogeneic haploidentical CAR-T expansion and persistence. Prospective testing of the approach is warranted. Disclosures Maschan: Miltenyi Biotec: Speakers Bureau.

Addition of Clofarabine to TLI/ATG Conditioning: Impact on Immune Reconstitution and Clinical Outcomes,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4066-4066
Author(s):  
Brett Glotzbecker ◽  
Heidi Mills ◽  
Jacalyn Rosenblatt ◽  
Robin Joyce ◽  
James Levine ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Median Time ◽  
Cd8 T Cells ◽  
Fold Increase ◽  
Disease Relapse ◽  
Platelet Recovery ◽  
Post Transplant ◽  
T Cell Reconstitution

Abstract Abstract 4066 The fundamental challenge in designing an effective conditioning regimen for allogeneic transplantation involves the prevention of disease relapse while minimizing the risk for Graft versus Host Disease (GVHD). Treatment with total lymphocyte irradiation (TLI) and anti-thymocyte globulin (ATG) has been shown to minimize the risk of GVHD through the biasing of the T cell reconstitution towards an inhibitory phenotype. However, disease relapse remains a significant concern. Clofarabine is a second generation nucleoside analog with potent cytoreductive capacity and demonstrates efficacy in hematological malignancies. In this study, we examined the combination of clofarabine, TLI and ATG with respect to T cell reconstitution, risk for GVHD and transplant outcome. Sequential cohorts of 5 patients were treated with TLI and ATG alone or in conjunction with 20 mg/m2, 30 mg/m2 or 40 mg/m2 of clofarabine for 5 days. Cyclosporine and mycophenolate mofetil were administered as GVHD prophylaxis. Twenty patients have been enrolled (5 AML/MDS, 2 ALL, 6 lymphoma, 2 CLL, 5 myeloma) and received HLA matched peripheral blood stem cells collected from related (N=11) and unrelated donors (N=9). Of 19 evaluable patients, 15 are alive with a median follow up of 665 days. Day 30 and 100 mortality was 0% for TLI and ATG and 0% and 10% for those receiving clofarabine. The maximum tolerated dose (MTD) of clofarabine was 30 mg/m2 as 2 patients experienced treatment related mortality at the 40 mg/m2 dose level. Grade 5 infections and multiorgan failure occurred in both patients. All patients demonstrated engraftment with mean bone marrow donor chimerism of 92.5% at Day 30. The first cohort's ANC did not drop below 500 cells/uL, while median time to neutrophil engraftment in the patients who received clofarabine was 9 days. The median time to platelet recovery was 11 and 12 days for patients receiving TLI and ATG alone or with clofarabine, respectively (p=0.39). T cell reconstitution studies demonstrated a significant decrease in CD4+ cells to (<200 cells/uL) persisting for more than 6 months and a more than a two fold increase in circulating CD56+ NK cells. No significant decrease in CD8 T cells in the early post-transplant period was seen in either group. The mean percentage of regulatory T cells (CD4+/25+/FoxP3+) rose in the early post-transplant period following TLI and ATG (5.5 to 14.2% from baseline to day 30; p=0.015), but not in those receiving clofarabine (8.1 to 6%; p=0.15). Assessment of T cell polarization at these time points demonstrated a two fold increase in CD8+ T cells expressing IL-4 at Day 30 in patients receiving TLI and ATG alone (p=0.04); but not following clofarabine containing conditioning. Consistent with these findings, the incidence of grade II-IV GVHD was 0% and 42% in those receiving TLI and ATG alone or in conjunction with clofarabine, respectively. cGVHD was seen in 20% and 42% of patients, respectively. In contrast, disease progression was seen in 60% of patients receiving TLI and ATG alone as compared to 27% receiving clofarabine, TLI, and ATG. In summary, the addition of clofarabine to TLI and ATG conditioning resulted in a decrease in circulating regulatory T cells, decreased CD8+ T cell expression of IL-4, and was associated with an increased risk of GVHD and a potential for a decrease in the risk of relapse. Disclosures: Chen: Genzyme: Membership on an entity's Board of Directors or advisory committees. Avigan:Genzyme: Research Funding.

Co-Infusion of Allogeneic Cord Blood with Haploidentical CD34+ Cells Improved Transplant Outcome for Patients with Severe Aplastic Anemia Undergoing Cord Blood Transplantation

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 654-654 ◽  
Author(s):  
Nicole J. Gormley ◽  
Jennifer Wilder ◽  
Hahn Khuu ◽  
Jeremy Pantin ◽  
Theresa Donohue ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cord Blood ◽  
Aplastic Anemia ◽  
Severe Aplastic Anemia ◽  
Transplant Outcome ◽  
Neutrophil Recovery ◽  
Post Transplant ◽  
Cd34 Cells ◽  
Matched Donor

Abstract Abstract 654 Unrelated cord blood (UCB) transplantation is a useful alternative for patients with hematological malignancies or non-malignant hematological disorders lacking an HLA matched donor. However, outcomes for patients with severe aplastic anemia (SAA) undergoing either a single or dual UCB transplant have been disappointing. A recent EBMT/ Eurocord study reported engraftment and 3 year survival rates of only 51% and 38% respectively (Perrault de Latour, Biol Blood Marrow Transplant 2011). We investigated whether co-infusion of a single UCB unit with CD34+ selected cells from a haploidentical relative following a highly immunosuppressive conditioning regimen could improve transplant outcome for patients with SAA refractory to immunosuppressive therapy that lack an HLA matched donor. Subjects with SAA and life-threatening neutropenia (ANC <500) refractory to 2 or more immunosuppressive agents were eligible for enrollment if they lacked an HLA matched related or unrelated donor. Conditioning consisted of cyclophosphamide (120 mg/kg), fludarabine (125 mg/m2), equine ATG (160 mg/kg) and one dose of 200 cGy of total body irradiation. Patients received a G-CSF mobilized, T-cell depleted CD34+ selected stem cell product prepared from a haplo-identical donor using the Miltenyi CliniMacs system combined with a single ≥ 4/6 HLA antigen matched UCB unit. Eight patients with treatment refractory SAA (median age 18 years; range 9–20), including 1 patient with SAA evolved to MDS, have been transplanted. All patients were platelet and RBC transfusion-dependent with severe neutropenia (median ANC 60 neutrophils/ul; range 0–260). Patients were at high risk for graft rejection, being heavily transfused, having failed a median 3 (range 2–4) immunosuppressive regimens, and 4 (50%) were HLA alloimmunized. Six patients received a single 4/6 HLA matched UCB unit and 2 received a 5/6 HLA-matched unit. Transplanted allografts contained a median 2.9 × 107 CB TNCs/kg (range 2.6–7.3), 1.5 × 105 CB CD34+cells /kg (range 0.4–3.2), and 3.3 ×106 CD34+cells/kg (range 2.6–3.6) from the haploidentical relative. All patients achieved the primary study endpoint of donor engraftment with an ANC of >500 by day 42, 7 of 8 achieving a UCB-derived ANC >500 cells/μl. The median time to neutrophil recovery was 10 days (range 10–18 days). One patient failed to engraft with the cord unit, but has had sustained engraftment from the haploidentical donor, and is transfusion independent with a normal neutrophil count >25 months post transplant. Acute GVHD grade II developed in 2 patients and one developed limited chronic GVHD. Early T-cell engraftment was predominantly UCB in 7 cases; on day 21, T-cell chimerism was a median 100% cord in origin (range 0–100%). In contrast, myeloid chimerism at engraftment was predominantly haplo-donor in origin and showed 3 phases of engraftment: 1) early myeloid engraftment from the haplo-CD34+ cell donor 2) delayed myeloid engraftment from the cord unit resulting in dual myeloid chimerism and 3) disappearance of the haplo-donor cells with transition towards full cord donor myeloid chimerism (see figure). Mixed lymphocyte reactivity assays performed on post transplant PBMCs showed increasing alloreactivity of cord blood T-cells against the haploidentical donor during the period when myeloid chimerism transitioned towards cord, indicating that the disappearance of haplo-donor myeloid cells occurred as a consequence of rejection by engrafting cord blood T-cells. At a median follow-up of 9 months (range 75 days to 3 years), 7 patients survive, and all are transfusion–independent. One patient died 14 months after transplantation from complications related to CMV pneumonitis. In conclusion, transplantation of haploidentical CD34+ cells can shorten the time to neutrophil recovery in SAA pts undergoing a single UCB transplant. Furthermore, durable full engraftment from donor haploidentical CD34+ cells can occur in the context of cord graft failure. These data suggest co-infusion of allogeneic cord blood with haploidentical CD34+ cells can improve the outcome of UCB transplantation for SAA. Disclosures: Wilder: NCI: Funded in part by NCI contract No. HHSN261200800001E.

scholarly journals Single-cell transcriptomics dissects hematopoietic cell destruction and T cell engagement in aplastic anemia

Blood ◽  
2021 ◽  
Author(s):  
Caiying Zhu ◽  
Yu Lian ◽  
Chenchen Wang ◽  
Peng Wu ◽  
Xuan Li ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Aplastic Anemia ◽  
Single Cell ◽  
Regulatory Networks ◽  
Bone Marrow Failure ◽  
Autoimmune Disorder ◽  
Transcriptional Regulatory Networks ◽  
Dna Damage And Repair ◽  
Hematopoietic Stem

Aplastic anemia (AA) is a T cell-mediated autoimmune disorder of the hematopoietic system manifested by severe depletion of the hematopoietic stem and progenitor cells (HSPCs). Nonetheless our understanding of the complex relationship between HSPCs and T cells is still obscure, mainly limited by techniques and the sparsity of HSPCs in the context of bone marrow failure. Here we performed single-cell transcriptome analysis of residual HSPCs and T cells to identify the molecular players from AA patients. We observed that residual HSPCs in AA exhibited lineage-specific alterations in gene expression and transcriptional regulatory networks, indicating a selective disruption of distinct lineage-committed progenitor pools. In particular, HSPCs displayed frequently altered alternative splicing events and skewed patterns of polyadenylation in transcripts related to DNA damage and repair, suggesting a likely role in AA progression to myelodysplastic syndromes. We further identified cell-type-specific ligand-receptor interactions as potential mediators for ongoing HSPCs destruction by T cells. By tracking patients after immunosuppressive therapy (IST), we showed that hematopoiesis remission was incomplete accompanied by IST insensitive interactions between HSPCs and T cells as well as sustained abnormal transcription state. These data collectively constitute the transcriptomic landscape of disrupted hematopoiesis in AA at single-cell resolution, providing new insights into the molecular interactions of engaged T cells with residual HSPCs and render novel therapeutic opportunities for AA.

scholarly journals Interferon Gamma and perforin positive T cells in acquired aplastic anemia: implication in therapeutic response

2021 ◽  
Author(s):  
Vandana Sharma ◽  
Prabin Kumar ◽  
Rajiv Kumar ◽  
Sushmita Chakraborty ◽  
Manju Namdeo ◽  
...  
Keyword(s):  
T Cells ◽  
Aplastic Anemia ◽  
Interferon Gamma ◽  
Alternative Therapy ◽  
Poor Response ◽  
Severe Aplastic Anemia ◽  
Median Percentage ◽  
Hematopoietic Stem ◽  
Before And After ◽  
Ifn Γ

Abstract Acquired aplastic anemia (aAA) is an autoimmune disease, characterized by infiltration of T lymphocytes in the bone marrow with destruction of hematopoietic stem cells by the effector cells. Interferon gamma (IFN-γ) and perforin are important mediators of cell destruction. In this flow cytometry-based study, we have investigated the percentage of intracellular IFN-γ + and perforin + CD5 + T cells in peripheral blood of newly diagnosed aAA patients before and after immunosuppressive therapy (IST). Patients were categorized as per standard disease severity and response to IST. The median percentage of IFN-γ + and perforin + CD5 + T cells was higher in untreated patients compared to healthy controls. The percentage of these cells was also increased in untreated severe and very severe aplastic anemia when compared with non-severe aplastic anemia patients. In patients before and after IST the median percentage of T cells producing IFN-γ and perforin was elevated in non-responders as compared to partial plus complete responders. The higher percentage of IFN-γ + and perforin + CD5 + T cells may be useful as an early diagnostic marker for aberrant activation of immune system and predict poor response to IST in aAA patients, who will benefit from alternative therapy.

GPI-AP Deficient Cells Detected Exclusively in T Cells in Patients with Aplastic Anemia: Evidence against An Escape Mechanism for the Initial Proliferation of PIG-AMutant Hematopoietic Stem Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3197-3197
Author(s):  
Takamasa Katagiri ◽  
Zhirong Qi ◽  
Yu Kiyu ◽  
Naomi Sugimori ◽  
J. Luis Espinoza ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
Immune System ◽  
T Cell ◽  
Hematopoietic Stem Cells ◽  
Aplastic Anemia ◽  
Effector Memory ◽  
Hematopoietic Stem ◽  
Escape Theory ◽  
Effector Memory Cells

Abstract Abstract 3197 Poster Board III-134 Small populations of glycosylphosphatidylinositol-anchored protein (GPI-AP)-deficient blood cells are often detectable in the peripheral blood (PB) of patients with aplastic anemia (AA) and refractory anemia (RA) of myelodysplastic syndromes defined by the FAB classification. Such PNH-type cells are thought to be derived from PIG-A mutant hematopoietic stem cells (HSCs) that avoid the immunological attack against HSCs. Inefficient T cell responses to PNH-type cells were indeed demonstrated by a murine study. However, there is no direct evidence in support of the escape theory concerning the expansion of PIG-A mutant HSCs in such patients with bone marrow (BM) failure. If the escape theory is true, the PNH-type cells should be detected in myeloid cells derived from HSCs that are targeted by the immune system attack. The PB of 527 patients with BM failure was examined for the presence of GPI-AP deficient cells in various lineages of cells including granulocytes, erythrocytes, monocytes, T cells, B cells, and NK cells using high sensitivity flow cytometry to verify this hypothesis. PNH-type cells were detectable in at least one lineage of cells from 228 (43%) patients. Although most of the positive patients showed PNH-type cells in two or more lineages including granulocytes or monocytes, 14 patients (13 with AA and 1 with amegakaryocytic thrombocytopenia) displayed PNH-type CD48-CD55-CD59- cells only in T cells at a frequency of 0.003-0.3% of the total T cells (Figure). The PNH-type T cells were undetectable in any of 25 healthy individuals. The CD48-CD55-CD59- T cells consisted of predominantly effector memory and terminal effector memory cells with naïve phenotype cells. The phenotypic pattern of the PNH-type T cells was very similar to that of CD48-CD55-CD59- T cells from 11 patients with florid PNH but was different from that of CD48-CD55-CD59- T cells (central and effector memory cells alone) detected in 4 marrow transplant recipients who received anti-CD52 antibody (alemtuzumab) therapy as conditioning. PIG-A gene analyses of CD48-CD55-CD59- T cells revealed a single mutation in 2 patients with PNH-type T cells alone, while two different mutations were revealed in 2 patients treated with alemtuzumab. BM failure patients with PNH-type T cells alone and other BM failure patients possessing PNH-type granulocytes or monocytes showed similar clinical features characterized by predominant thrombocytopenia and good response to immunosuppressive therapy, thus suggesting an increase in the number of PNH-type cells in both groups to be associated with a similar immune pathophysiology. The escape theory cannot account for the presence of PNH-type cells exclusively in T cells in immune-mediated BM failure because T cell precursors are not the target of the immune system attack in AA. Therefore, mechanisms other than the escape theory must be considered for the initial proliferation of PIG-A mutant HSCs associated with the development of AA, such as preferential activation of dormant PIG-A mutant HSCs or T cell precursors due to the deficiency of GPI-APs that transmit negative signal Disclosures No relevant conflicts of interest to declare.

scholarly journals Novel Immunosuppressive Approach Attenuates Severe Aplastic Anemia in Mouse Lymphocyte Infusion AA Models

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2942-2942
Author(s):  
Jessica Lorente ◽  
Divya Kannegenti ◽  
Brandon Theall ◽  
Lisandra Hernandez ◽  
Esha Vallabhaneni ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
T Cell ◽  
Aplastic Anemia ◽  
Mouse Models ◽  
T Cell Responses ◽  
Effector T Cells ◽  
Hematopoietic Stem ◽  
Cell Responses ◽  
Mouse Lymphocyte

Abstract Aplastic Anemia (AA) is an immune-mediated and life-threatening form of acquired bone marrow failure. AA ranges from moderate to severe AA, and is characterized by development and expansion of self-reactive effector T cells, which cause apoptosis of mature blood cells, progenitors and hematopoietic stem cells (HSCs). Current treatments for AA, which are not always effective or feasible, include immunosuppressive therapy (IST) and allogeneic HLA-identical sibling or well-matched unrelated donor BM transplant. Because the self-antigens triggering AA remain to be identified, mouse lymphocyte infusion models of AA with striking similarities to human AA have been developed utilizing alloantigen recognition. The AA in these models is induced by infusing lymph node cells (LNCs) from C57BL/6J mice into MHC partially mismatched F1 hybrid B6D2F1 or CByB6F1 recipients, or into minor-H antigen mismatched C.B10 recipients. The host mice develop SAA without any clinical signs of generalized GVHD, and characterized by BM infiltration and oligoclonal expansion of donor effector T cells, apoptosis of all host BM cells, severe BM aplasia and death within 3-5 weeks after LNC infusion. These preclinical mouse models represent a very useful in vivo system for testing new therapeutic approaches to treat and manage SAA. Activation of self-reactive T cells in human AA and alloreactive donor T cells in mouse AA models involves interaction of T cells with dendritic cells (DCs) as professional APCs. DCs express β2 integrin CD11b/CD18 (Mac-1), which plays an important role in inflammation, cell-mediated killing and cell activation. Notably, Mac-1 expressed on DCs is inactive and is not activated on contact with T cells. More importantly, activation of Mac-1 on DCs by Mg2+ treatment significantly reduces their T cell-activating capacity, and active CD11b represses DC cross-priming of cytotoxic T cells. Thus, activation of Mac-1 on DCs represents a potential new immunosuppressive strategy for reducing pathological T cell responses in AA. Dr. Gupta has identified novel Mac-1 agonists, termed Leukadherins (LAs1-3) that bind to and activate Mac-1. Multiple lines of experimental evidence generated by Dr. Gupta’s and Dr. Jurecic’s groups have shown that LAs have potent anti-inflammatory and immunosuppressive properties. For example, treatment with LA1 is safely and effectively reducing the onset and severity of Experimental Autoimmune Encephalomyelitis (EAE) in mice, induced by Myelin Oligodendrocyte Glycoprotein (MOG). Moreover, in EAE mice LA1 efficiently decreased the activation of myelin-reactive T cells and their IFN-γ production. We hypothesized that by activating Mac-1 on DCs LAs could effectively (a) reduce T cell-activating capacity of DCs and attenuate allo-reactive T cell responses, and (b) reduce severity of AA in mouse models. Indeed, in mixed lymphocyte reaction, which depends on stimulation of allogeneic T cells by DCs, LA1 significantly suppressed proliferation of lymph node T cells from C57BL6/J mice in the presence of irradiated splenocytes from allogeneic DBA/2J mice. SAA was induced in B6D2F1 mice by tail vein injection of 5 x 10e7 LNCs from C57BL/6J mice. The untreated AA mice died within 21 days of LNC infusion and exhibited (a) severe BM aplasia, (b) ~5-fold expansion of CD4+ T cells and >20-fold expansion of CD8+ T cells in comparison to Control B6D2F1 mice, and (c) severe depletion of HSCs (LSK CD150+ CD48- BM cells); Multipotent progenitors (MPPs, LSK CD150- CD48- BM cells); and Hematopoietic progenitors (HPC-1, LSK CD150- CD48+ cells; HPC-2, LSK CD150+ CD48+ cells). In contrast, AA mice treated IP with 1 mg/kg/day of LA1 for 7 or 21 days after LNC infusion exhibited (a) mild BM aplasia and improved BM cellularity, (b) significantly reduced expansion of CD4 (~2-fold) and CD8 (~12-fold) T cells in the BM, and (c) significantly improved frequency and total numbers of HSCs and progenitors in comparison to untreated AA mice. More importantly, treatment of AA mice with LA1 for 21 days resulted in 40-50% of AA mice surviving for more than 7 weeks after LNC infusion. These results demonstrate that treatment with LA1 can safely convert SAA into a moderate disease in preclinical mouse AA models and provide a platform for testing of LAs as new alternative or adjuvant therapy to manage ongoing AA in patients who (1) are not responding to IST and are not candidates for BMT, and/or (2) are undergoing IST and awaiting BMT. Disclosures No relevant conflicts of interest to declare.

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