Reconstitution of CD52-Negative CD4 T Cells after Alemtuzumab-Based T Cell Depleted Allogeneic Hematopoietic Stem Cell Transplantation

Abstract The human CD52 molecule is the target of the monoclonal antibody Alemtuzumab, which is used for treating patients with chemo-refractory chronic lymphocytic leukemia as well as for T cell depletion (TCD) in the context of allogeneic hematopoietic stem cell transplantation (HSCT). The molecule is expressed on the surface of lymphocytes, dendritic cells and to a lesser extent on blood-derived monocytes. Previously, investigators have demonstrated that the surface expression of CD52 on T cells is down-regulated after in vitro incubation with Alemtuzumab. By treating purified human CD4 T cells over 4 hours with 10 μg/mL Alemtuzumab in medium supplemented with 10% human AB serum in vitro…

313: A cDNA-based assay for donor-chimerism analysis of epidermal langerhans cells

Current results on the use of imatinib mesylate in patients with relapsed philadelphia chromosome positive leukemia after allogeneic or syngeneic hematopoietic stem cell transplantation

Here, we describe a patient diagnosed with chronic myelogenous leukemia who relapsed after matched unrelated donor SCT. The patient was treated with imatinib mesylate and donor lymphocyte infusions, and achieved a complete molecular remission. Additionally, safety and efficacy of imatinib mesylate in a total of 134 patients from 8 centers who underwent allogeneic or syngeneic stem cell transplantation (SCT) and had a relapse of Philadelphia chromosome positive leukemia was reviewed. Data was compiled from abstracts accepted as oral or poster presentations at the ASH (American Society of Hematology) 2001 and EBMT (European Group for Blood and Marrow Transplantation) 2001 & 2002 meetings and …

CD8-Depleted Donor-Lymphocyte Infusions After T-Cell Depleted Allogeneic Hemopoietic Stem Cell Transplantation

The use of clonal mRNA as an antigenic format for the detection of antigen-specific T lymphocytes in IFN-gamma ELISPOT assays.

Abstract Most assay systems for the quantification of antigen-specific T-cell responses in infectious, malignant and autoimmune disease depend on the peptide antigen format and are therefore restricted to known epitopes and their presenting HLA molecules. Here we tested in ELISPOT assays the application of in vitro-transcribed clonal mRNA as an alternative antigen format covering all potential epitopes of a given antigen. As model antigens, we chose pp65 of human cytomegalovirus (HCMV) and human tyrosinase (hTyr). Antigen-presenting cells (APC) were K562 cells stably transfected with single HLA class I alleles and autologous dendritic cells (DC). As effectors, we applied in vitro-generated …

Functionally Altered GPI-Anchor Negative Treg Following Alemtuzumab-Based T-Cell Depletion Are Associated with Acute Gvhd.

Abstract Abstract 3059 Introduction: The monoclonal anti-CD52antibody Alemtuzumab is frequently used for T-cell depletion (TCD) in the context of allogeneic hematopoietic stem cell transplantation (HSCT) to prevent graft versus host disease (GVHD). We previously demonstrated the long term persistence of functionally impaired glycosylphosphatidylinositol (GPI)-anchor negative effector T-cells in patients receiving high dose (100mg) Alemtuzumab in combination with a dose reduced conditioning regimen (Fludarabin + Melpahlan) (Meyer, Wagner et al. BMT 2010). Despite of Alemtuzumab-mediated TCD, half of our patients developed acute GVHD. Since regulatory T cells (Treg) play a major role for cont…

CD8-Depleted Donor Lymphocyte Infusions Convert Mixed into Complete Donor T-Cell Chimerism after T-Cell Depleted Allogeneic Stem Cell Transplantation.

Abstract Donor lymphocyte infusions (DLI) are increasingly used to treat minimal residual disease or mixed hematopoietic donor-recipient chimerism in T-cell depleted allogeneic stem cell transplantation (SCT). In addition, several clinical trials currently investigate the prophylactic application of DLI to promote donor T-cell reconstitution after transplantation. However, DLI carry a substantial risk of inducing graft-versus-host disease (GVHD). We investigate DLI heavily depleted of CD8 T cells using a clinical grade immunomagnetic in vitro procedure in an ongoing clinical study [Meyer et al., Blood2007, 109:374]. These DLI are administered in a prophylactic setting to patients with hemat…

The CD38-Positive and CD38-Negative Subsets of CD34(high)-Positive Primary Acute Myeloid Leukemia Blasts Differ Considerably in the Expression of Immune Recognition Molecules

Abstract Acute myeloid leukemia (AML) is thought to arise from a rare putative ‘leukemic stem cell’ that is capable of self-renewal and formation of leukemic blasts. Serial xenotransplantation studies in immunodeficient mice have shown that this leukemia-initiating cell resides at very low numbers within CD34(high)-positive CD38-negative AML cells. Thus, immunotherapeutic approaches successfully eradicating this cell compartment should result in cure from disease. The objective of our study was to characterize the immune phenotype of the CD38-negative and CD38-positive subsets of primary CD34(high)-positive AML blasts ex vivo. We obtained therapeutic leukapheresis products from 17 AML patie…

Aggregation Behavior of Polystyrene-Nanoparticles in Human Blood Serum and its Impact on the in vivo Distribution in Mice

The interactions between nanoparticles (NPs) and proteins in complex biological application media such as blood serum are capable of inducing aggregate formation which can lead to subsequent changes in biological activity. Here, we correlate surface charge, aggregation-tendency, and surface serum protein adsorption with cellular uptake and biodistribution in mice. Polystyrene-based NPs (80 - 170 nm) with different surface functionalizations were synthesized and incubated with human serum. Interaction of NPs with serum proteins and aggregate formation were analyzed by mass spectrometryanalysis and dynamic light-scattering. Influence of surface functionalization on specific cellular uptake an…

Prophylactic transfer of CD8-depleted donor lymphocytes after T-cell–depleted reduced-intensity transplantation

AbstractAllogeneic hematopoietic stem cell transplantation (SCT) regimens incorporating the lymphocytotoxic CD52 antibody alemtuzumab demonstrate efficient engraftment and reduced graft-versus-host disease (GVHD). However, these protocols substantially impair posttransplantation antiviral and antitumor immunity. To accelerate immune reconstitution after alemtuzumab-based reduced-intensity SCT, we administered prophylactic CD8-depleted donor lymphocyte infusions (DLIs) starting on days 60 and 120 after transplantation. DLIs were processed in an immunomagnetic good manufacturing practice depletion procedure resulting in a 2.5- to 6-log reduction in CD8 T cells. Of 23 high-risk patients with h…

Preservation of dendritic cell function upon labeling with amino functionalized polymeric nanoparticles.

Dendritic cells (DCs) are key players in eliciting immunity against antigens, therefore making them the focus of many investigations on immune responses in infections, cancer and autoimmune diseases. Nanosized materials have just recently been investigated for their use as carriers of antigens and as labeling agents for DCs. For this later use nanoparticles should be non-toxic and should most importantly not alter the physiological functions of DCs. Here we demonstrate that by the use of polymeric fluorescent nanoparticles as synthesized by the miniemulsion process immature DCs (iDCs) can be efficiently labeled intracellularly. Amino functionalized nanoparticles are more effective than carb…

Rituximab combined with DexaBEAM followed by high dose therapy as salvage therapy in patients with relapsed or refractory B-cell lymphoma: mature results of a phase II multicentre study.

Summary Salvage therapy followed by high-dose therapy (HDT) remains a mainstay for patients with relapsed lymphoma, however no optimal regimen has been defined. Here we report on the results of R-DexaBEAM (rituximab, dexamethasone, carmustine, etoposide, cytarabine, melphalan) followed by HDT. Patients aged 18–65 years, Eastern Cooperative Oncology Group performance score 0–2, with relapsed/refractory B-cell non-Hodgkin lymphoma (NHL) were eligible. R-Dexa-BEAM was given for two cycles followed by stem cell mobilization and HDT. Primary endpoint of the trial was progression-free-survival (PFS). One hundred and three patients were included: aggressive NHL (aNHL): diffuse large B-cell lymphom…

Tailoring the stealth properties of biocompatible polysaccharide nanocontainers.

Fundamental development of a biocompatible and degradable nanocarrier platform based on hydroxyethyl starch (HES) is reported. HES is a derivative of starch and possesses both high biocompatibility and improved stability against enzymatic degradation; it is used to prepare nanocapsules via the polyaddition reaction at the interface of water nanodroplets dispersed in an organic miniemulsion. The synthesized hollow nanocapsules can be loaded with hydrophilic guests in its aqueous core, tuned in size, chemically functionalized in various pathways, and show high shelf life stability. The surface of the HES nanocapsules is further functionalized with poly(ethylene glycol) via different chemistri…

Impact of DLI after In Vivo T-Cell-Depletion: Prophylactic CD8 Depleted or Preemptive CD3pos DLI?

Abstract Introduction: The combination of reduced-intensity conditioning (RIC) with in vivo T-cell depletion by alemtuzumab prior to hematopoietic stem cell transplantation (HSCT) has demonstrated efficient engraftment and reduced graft-versus-host disease (GVHD). However, this regimen is associated with slow lymphocyte recovery leading to a delayed anti-infectious and anti-malignant immunity. DLI can be used to improve immune reconstitution. Here we investigate on the impact of different DLI: prophylactic CD8-depleted DLI vs preemptive non-depleted DLI. Methods: 256 patients with different hematologic malignancies were planned for treatment with DLI after allogeneic HSCT following reduced …

29: Rapid expansion of acute myeloid leukemia-reactive cytotoxic T cells from CD8+CD62L+ blood lymphocytes of HLA-matched healthy donors in vitro

297: Establishment of a chimeric NOD-scid/IL2RγcNull transplantation-model to evaluate graft-vs-host and graft-vs-leukemia immune responses of ex vivo modified human T lymphocyte grafts

The use of HLA-A*0201-transfected K562 as standard antigen-presenting cells for CD8+ T lymphocytes in IFN-γ ELISPOT assays

ELISPOT assays are increasingly used for a direct detection and quantification of single antigen-specific T cells in freshly isolated peripheral blood mononuclear cells (PBMC). They are particularly attractive for the monitoring of specific T lymphocyte responses in clinical trials assessing antigen-specific immunizations in patients with cancer or chronic viral infections. However, one major limitation for the broad clinical implementation of ELISPOT assays is the lack of an inexhaustible source of suitable HLA-matched antigen-presenting cells (APC). Currently available allogeneic or xenogeneic APC (such as the human lymphoid hybrid T2 or HLA-transfected insect cells) can either lead to st…

Compassionate Use of Sorafenib in Relapsed and Refractory Flt3-ITD Positive Acute Myeloid Leukemia.

Abstract Abstract 2060 Poster Board II-37 Introduction: The Flt3-internal tandem duplication can be found in up to 30% of all acute myeloid leukemia (AML) patients and confers a poor risk status characterized by an increased relapse rate and poor overall survival. Moreover, Flt3-ITD-positive AML patients relapsing after allogenic stem cell transplantation (SCT) have very limited therapeutic options. Sorafenib is a multikinase inhibitor that is approved for the treatment of metastatic renal cell and hepatocellular carcinoma. Besides targeting Raf, the platelet derived growth factor receptor (PDGFR) and the vascular endothelial growth factor receptor (VEGFR) it has also significant inhibitory…

Identification of HLA-A*0201-Restricted T Cell Epitopes Derived from the Novel Overexpressed Tumor Antigen Calcium-Activated Chloride Channel 2

Abstract Vaccination against tumor Ags may become a promising treatment modality especially in cancer types where other therapeutic approaches fail. However, diversity of tumors requires that a multitude of Ags become available. Differential expression in normal vs cancerous tissues, both at the mRNA and the protein level, may identify Ag candidates. We have previously compared transcripts from squamous cell lung cancer and normal lung tissue using differential display analysis, and found a transcript that was overexpressed in malignant cells and was identical with the calcium-activated chloride channel 2 (CLCA2) gene. We have now selected HLA-A2-restricted peptides from CLCA2, and have gen…

Serotherapy with thymoglobulin and alemtuzumab differentially influences frequency and function of natural killer cells after allogeneic stem cell transplantation

Although thymoglobulin and alemtuzumab are frequently used in hematopoietic stem cell transplantation (HSCT), little is known of their effects on NK cells, which mediate important functions in post-transplantation immunology. In the present study, we determined NK cell death in vitro using propidium iodide and Annexin V. The NK cell activity in 34 patients at day +30 after allogeneic HSCT was assessed using the CD107a assay. Alemtuzumab and thymoglobulin were similarly very potent in inducing NK cell death in vitro. Even in low concentrations (1 microg/ml) the antibodies induced apoptosis and necrosis in a relevant percentage of NK cells (30%). However, the number of tumor reactive (CD107a+…

Monitoring of anti-vaccine CD4 T cell frequencies in melanoma patients vaccinated with a MAGE-3 protein.

Abstract Quantitative evaluation of T cell responses of patients receiving antitumoral vaccination with a protein is difficult because of the large number of possible HLA-peptide combinations that could be targeted by the response. To evaluate the responses of patients vaccinated with protein MAGE-3, we have developed an approach that involves overnight stimulation of blood T cells with autologous dendritic cells loaded with the protein, sorting by flow cytometry of the T cells that produce IFN-γ, cloning of these cells, and evaluation of the number of T cell clones that secrete IFN-γ upon stimulation with the Ag. An important criterion is that T cell clones must recognize not only stimulat…

Transmission of angioimmunoblastic T-cell lymphoma by bone marrow transplant

Accidental transmission of lymphoma by bone marrow transplant is a rarely reported event [1–5], since candidates are only accepted for hematopoietic stem cell donation after a work-up that routinel...

Rapid Expansion of Acute Myeloid Leukemia-Reactive Cytotoxic T Cells from CD8+CD62L+ Blood Lymphocytes of HLA-Matched Healthy Donors In Vitro

Abstract Allogeneic cytotoxic T-lymphocyte (CTL) therapy in acute myeloid leukemia (AML) is hampered by the poor efficiency of growing leukemia-reactive CTLs from healthy donors in vitro. We established an allogeneic mini-mixed lymphocyte-leukemia culture (MLLC) approach by stimulating comparably small numbers (104/well) of CD8+ T cells isolated from healthy donors against irradiated primary AML blasts in 96-well plates. Prior to use, CD8+ T cells were immunomagnetically separated into a CD62L(high)+ subset enriched for naive precursors and central memory cells as well as a CD62L(low)+/negative subset containing effector memory cells. The culture medium contained IL-7, IL-12, and IL-15. Aft…

Consensus on performing skin biopsies, laboratory workup, evaluation of tissue samples and reporting of the results in patients with suspected cutaneous graft-versus-host disease

Background Histopathological diagnosis including selection of lesions, the determination of the best point of time for biopsy and workup is not trivial in cutaneous graft-versus-host disease (GvHD). Objectives To develop interdisciplinary recommendations on performing, the laboratory work up and reporting of the results of skin biopsies in patients with suspected cutaneous GvHD. Methods A working group consisting of dermatopathologists, dermatologists, transplant-physicians and transplant-pathologists prepared recommendations for performing skin biopsies, laboratory workup and evaluation of tissue samples, and reporting of the results in patients with cutaneous GvHD. After achieving a conse…

Evaluation Of Alloimmune Responses In Humanized NOD/SCID/IL2rgnull Mice Following Human CD34+ Stem Cell Transplantation

Campath-1H-Based Reduced-Intensity Conditioning Followed by Allogeneic Blood Stem-Cell Transplantation and Preemptive CD8-Depleted Donor Lymphocyte Infusions.

Abstract Recent reports have demonstrated the feasibility of using the anti-CD52 antibody Campath-1H for in vivo T-cell depletion (TCD) in the context of a fludarabine/melphalan-based reduced-intensity conditioning regimen (Kottaridis et al. Blood 2000, 96:2419). Major disadvantage of this protocol is the severe immunosuppression which results in an increased rate of opportunistic infections and disease relapses. Donor lymphocyte infusions (DLI) are frequently used to overcome this limitation. The application of DLI, however, is associated with a profound risk of GvHD. Depletion of CD8+ lymphocytes from either the allotransplant or from DLI has proven feasible to reduce the incidence of GvH…

Donor CD4 T cells convert mixed to full donor T-cell chimerism and replenish the CD52-positive T-cell pool after alemtuzumab-based T-cell-depleted allo-transplantation.

Donor lymphocyte infusions (DLI) are used to resolve mixed T-cell chimerism (TCC) after allo-SCT despite a substantial risk of GVHD. We analyzed the impact of prophylactic CD8-depleted (CD8(depl)) DLI in 20 recipients of anti-CD52 alemtuzumab in vivo T-cell-depleted allografts with declining donor TCC after day +60. A total of 13 patients received CD8(depl) DLI and 7 patients did not. All but one of the DLI patients converted to complete donor T-cell chimeras, whereas only one non-DLI patient converted spontaneously. DLI induced transient acute GVHD in five and extensive chronic GVHD in two patients. These data suggest the use of CD8(depl) DLI as an effective treatment for mixed TCC, partic…

Acute myeloid leukemia (AML)-reactive cytotoxic T lymphocyte clones rapidly expanded from CD8(+) CD62L((high)+) T cells of healthy donors prevent AML engraftment in NOD/SCID IL2Rgamma(null) mice.

Objective Current in vitro techniques for isolating leukemia-reactive cytotoxic T lymphocytes (CTLs) from healthy donors are of relatively low efficiency and yield responder populations with unknown biological significance. This study aimed at the development of a more reliable approach, allowing generation and expansion of acute myeloid leukemia (AML)-reactive CTLs using primary in vitro stimulation. Materials and Methods We established allogeneic mini-mixed lymphocyte-leukemia cultures (mini-MLLCs) by stimulating donor CD8 + T cells with human leukocyte antigen (HLA) class I–matched AML blasts in microtiter plates. Before culture, CD8 + T cells were separated into CD62L (high)+ and CD62L …

Follow Up On CD8-Depleted Donor-Lymphocyte Infusions After T-Cell Depleted Allogeneic Hemopoietic Stem Cell Transplantation

We applied prophylactic CD8-depleted (CD8depl) donor lymphocyte infusions (DLI) in the setting of T-cell depleted reduced-intensity allogeneic hematopoietic stem cell transplantation (HSCT) in a phase I/II trial. T-cell depletion was carried out by the use of high-dose Alemtuzumab (100 mg or 60 mg for unrelated or sibling donor transplantation, respectively). We have demonstrated the feasibility of this approach after having treated 23 patients in this protocol (Meyer et al. Blood 2007). From 2004 to 2011, 134 patients with different hematologic diseases were included and followed for a median observation time of 1.5 years after transplantation (range, 1.5-9 years). Median age was 56 years …

Human Epidermal Langerhans Cells Replenish Skin Xenografts and Are Depleted by Alloreactive T Cells In Vivo

Abstract Epidermal Langerhans cells (LC) are potent APCs surveying the skin. They are crucial regulators of T cell activation in the context of inflammatory skin disease and graft-versus-host disease (GVHD). In contrast to other dendritic cell subtypes, murine LC are able to reconstitute after local depletion without the need of peripheral blood-derived precursors. In this study, we introduce an experimental model of human skin grafted to NOD-SCID IL2Rγnull mice. In this model, we demonstrate that xenografting leads to the transient loss of LC from the human skin grafts. Despite the lack of a human hematopoietic system, human LC repopulated the xenografts 6 to 9 wk after transplantation. By…

Characterization of Renal-Cell Carcinoma (RCC)-Reactive Cytotoxic T-Lymphocyte Responses Generated from Peripheral Blood of HLA-Matched Sibling and Unrelated Healthy Individuals in Vitro.

Abstract Although current allo-transplantation therapy can induce considerable graft-versus-tumor (GvT) effects in RCC patients, it is also accompanied by severe, even life-threatening side effects, mainly due to graft-versus-host disease (GvHD). Efforts aiming to improve the specificity and efficiency of allogeneic cell therapy in this disease (e.g. specific donor lymphocyte infusion or vaccination) will certainly benefit from the identification of potential anti-tumor effector mechanisms and their corresponding target structures. We recently demonstrated that RCC-reactive cytotoxic T-lymphocyte (CTL) clones can be isolated from peripheral blood of healthy donors matched with the RCC stimu…

Rapid identification and sorting of viable virus-reactive CD4+ and CD8+ T cells based on antigen-triggered CD137 expression

Abstract Current methods for the detection and isolation of antigen-specific CD4 + and CD8 + T cells require the availability of peptide/MHC multimers or are restricted to cells that produce cytokines after antigen contact. Here we show that de novo cell surface expression of the TNF-receptor family member CD137 (4-1BB) identifies recently activated, but not resting, human CD4 + and CD8 + memory T cells. Maximum CD137 expression level is uniformly observed in both T-cell subsets at 24h after stimulation with antigen. In experiments with CMV and EBV-reactive T cells, we confirmed the specificity of CD137 expression by co-staining with peptide/HLA tetramers. Substantial proportions of CD137 +…

Recovery of Varicella-Zoster Virus–Specific T Cell Immunity after T Cell–Depleted Allogeneic Transplantation Requires Symptomatic Virus Reactivation

Abstract Reactivated varicella-zoster virus (VZV) infection causes herpes zoster and commonly occurs after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Because VZV-specific T cell immunity is essential to prevent virus reactivation, we developed an interferon-γ enzyme-linked immunosorbent spot (ELISPOT) assay for the sensitive detection of VZV-reactive T cells at the single-cell level ex vivo. We used this assay to monitor the frequency of VZV-reactive T cells in 17 seropositive patients during the first year after T cell–depleted allo-HSCT. The patients did not receive anti-herpesvirus prophylaxis after stem cell engraftment. Independent of the magnitude of transferred d…

High activity of sorafenib in FLT3-ITD-positive acute myeloid leukemia synergizes with allo-immune effects to induce sustained responses.

Preliminary evidence suggests that the multikinase inhibitor sorafenib has clinical activity in FLT3-ITD-positive (FLT3-ITD) acute myeloid leukemia (AML). However, the quality and sustainability of achievable remissions and clinical variables that influence the outcome of sorafenib monotherapy are largely undefined. To address these questions, we evaluated sorafenib monotherapy in 65 FLT3-ITD AML patients treated at 23 centers. All but two patients had relapsed or were chemotherapy-refractory after a median of three prior chemotherapy cycles. Twenty-nine patients (45%) had undergone prior allogeneic stem cell transplantation (allo-SCT). The documented best responses were: hematological remi…

Superior antitumor in vitro responses of allogeneic matched sibling compared with autologous patient CD8+ T cells.

AbstractAllogeneic cell therapy as a means to break immunotolerance to solid tumors is increasingly used for cancer treatment. To investigate cellular alloimmune responses in a human tumor model, primary cultures were established from renal cell carcinoma (RCC) tissues of 56 patients. In three patients with stable RCC line and human leukocyte antigen (HLA)-identical sibling donor available, allogeneic and autologous RCC reactivities were compared using mixed lymphocyte/tumor cell cultures (MLTC). Responding lymphocytes were exclusively CD8+ T cells, whereas CD4+ T cells or natural killer cells were never observed. Sibling MLTC populations showed higher proliferative and cytolytic antitumor …

Towards More Specificity and Effectivity in the Antileukemia Immune Response

Experimental and clinical studies have shown that alloreactive T-cell responses derived from donor lymphocytes can effectively eliminate leukemia cells after allogeneic hematopoietic stem cell transplantation. However, there are still too many patients in whom this graft-versus-leukemia reactivity is insufficient to prevent leukemia relapse or who suffer from severe alloreactivity to nonmalignant host tissues also mediated by donor-derived T cells. Therefore, various conceptually different approaches have been developed at the level of donor T cells in order to improve the efficacy of leukemia-directed immunity while reducing the incidence of unwanted graft-versus-host disease. As outlined …

Influence of molecular subgroups on outcome of acute myeloid leukemia with normal karyotype in 141 patients undergoing salvage allogeneic stem cell transplantation in primary induction failure or beyond first relapse

Based on molecular aberrations, in particular the NPM1 mutation (NPM1(mut)) and the FLT3 internal tandem duplication (Flt3-ITD), prognostic subgroups have been defined among patients with acute myeloid leukemia with normal karyotype. Whereas these subgroups are known to play an important role in outcome in first complete remission, and also in the indication for allogeneic stem cell transplantation, data are limited on their role after transplantation in advanced disease. To evaluate the role of molecular subgroups of acute myeloid leukemia with normal karyotype after allogeneic stem cell transplantation beyond first complete remission, we analyzed the data from 141 consecutive adults (medi…

The Programmed Death (PD)‐1/PD‐Ligand 1 Pathway Regulates Graft‐Versus‐Host‐Reactive CD8 T Cells After Liver Transplantation

Acute graft-versus-host disease (aGVHD) is a life-threatening complication after solid-organ transplantation, which is mediated by host-reactive donor T cells emigrating from the allograft. We report on two liver transplant recipients who developed an almost complete donor chimerism in peripheral blood and bone marrow-infiltrating T cells during aGVHD. By analyzing these T cells directly ex vivo, we found that they died by apoptosis over time without evidence of rejection by host T cells. The host-versus-donor reactivity was selectively impaired, as anti-third-party and antiviral T cells were still detectable in the host repertoire. These findings support the acquired donor-specific allotol…

Allogeneic stem cell transplantation after conditioning with treosulfan, etoposide and cyclophosphamide for patients with acute lymphoblastic leukemia (ALL) not eligible for TBI-containing regimens: a phase II-Study on behalf of the German ALL Study Group (GMALL) and the German Cooperative Transplant Study Group

Abstract Total-body-irradiation (TBI) based preparative regimens are considered as standard conditioning therapy for allogeneic stem cell transplantation (AHSC) in patients with acute lymphoblastic leukemia (ALL). Within a multi-center prospective phase II study we have investigated the toxicity and efficacy of a non-TBI-based regimen consisting of treosulfan, etoposide, and cyclophosphamide in patients with ALL. Inclusion criteria were complete remission, non-eligibility for TBI or patient’s wish to avoid TBI. Between July 2007 and August 2010, 50 patients with a median age of 46.5 years were enrolled at ten German centers. 74% of the patients were in 1. CR and 26% 2. or higher CR.The cond…

Impact of Prophylactic CD8-Depleted Donor-Lymphocyte Infusions After Allogeneic Hematopoietic Stem Cell Transplantation and Alemtuzumab Mediated T-Cell Depletion,

Abstract Abstract 4109 We have previously demonstrated that the application of CD8-depleted donor-lymphocyte infusions (DLI) is feasible after reduced-intensity conditioning and in vivo T-cell depletion by alemtuzumab. DLI overcome slow lymphocyte recovery associated with alemtuzumab-administration and improve anti-infectious immunity and reliably convert a decreasing T-cell chimerism (Meyer et al. Blood 2007 & BMT 2010). Here we provide clinical follow up data of 117 patients with different hematological diseases and a median observation time of 1 year (range, 1–86 months) post hematopoietic stem cell transplantation (HSCT). The majority of patients either suffered from an acute leukem…

Depletion of alloreactive T cells via CD69: implications on antiviral, antileukemic and immunoregulatory T lymphocytes

Selective depletion of alloreactive T cells from stem-cell allografts should abrogate graft-versus-host disease while preserving beneficial T cell specificities to facilitate engraftment and immune reconstitution. We therefore explored a refined immunomagnetic separation strategy to effectively deplete alloreactive donor lymphocytes expressing the activation antigen CD69 upon stimulation, and examined the retainment of antiviral, antileukemic, and immunoregulatory T cells. In addition to the CD69high T cell fraction, our studies retrieved two T cell subsets based on residual CD69 expression. Whereas, truly CD69(neg) cells were devoid of detectable alloresponses to original stimulators, CD69…

Rapid molecular dissection of viral and bacterial immunomes

The development of preventive or therapeutic recombinant vaccines and the generation of serodiagnostic assays for infectious diseases depend essentially on the availability of molecularly defined antigens. A major bottleneck for the identification of suitable target antigens for many pathogens is the isolation of sufficient amounts of material for subsequent genomic or proteomic screening. Applying a highly efficient expression cloning strategy to the human pathogens vaccinia virus (VV) and Chlamydia pneumoniae (CP), we demonstrate that sub-nanogram amounts of isolated nucleic acids can be utilized to determine comprehensive sets of immunodominant antigens. Remarkably, the approach not only…

186: Superior antitumor in vitro responses of allogeneic matched sibling compared to autologous patient CD8+ T cells

Allogeneic cell therapy as a means to break immunotolerance to solid tumors is increasingly used for cancer treatment. To investigate cellular alloimmune responses in a human tumor model, primary cultures were established from renal cell carcinoma (RCC) tissues of 56patients. In three patients with stable RCC line and human leukocyte antigen (HLA)-identical sibling donor available, allogeneic and autologous RCC reactivities were compared using mixed lymphocyte/ tumor cell cultures (MLTC). Responding lymphocytes were exclusively CD8 + T cells, whereas CD4 + T cells or natural killer cells were never observed. Sibling MLTC populations showed higher proliferative and cytolytic antitumor respon…

Intronic promoters and their noncoding transcripts: A new source of cancer-associated genes

Recent studies of mammalian genomes suggest that alternative promoters are associated with various disorders, including cancer. Here we present an intronic promoter of the murine proteinase 3 gene, which drives the expression of an alternative mRNA in intron 2 of the prtn3 gene. The proximal promoter sequences were identified and a series of promoter deletion constructs were used to identify the sequence elements that are required for basal promoter activity. Expression of the homeobox transcription factor CUX1 p75 isoform was found to suppress the activity of the alternative PR3 promoter. Data base analyses, multiple alignments and expression data showed that the intronic PR3 promoter is a…

Immunohistochemical markers for histopathological diagnosis and differentiation of acute cutaneous graft‐versus‐host disease

Graft-versus-host disease (GvHD) is a major complication following stem-cell or solid-organ transplantation. Accurate diagnosis of cutaneous GvHD is challenging, given that drug eruptions and viral rashes may present with similar clinical/histological manifestations. Specific markers are not available. We performed the histological examination of biopsy samples from acute GvHD (aGvHD; n = 54), Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN; n = 27), maculopapular drug eruption (MDE; n = 26) and healthy controls (n = 26). Samples of aGvHD showed a decrease in Langerhans cells (LC, p = 0.0001) and an increase in macrophages (MΦ, p = 0.0001) compared to healthy skin. Compared to …

Targeting the activation-induced antigen CD137 can selectively deplete alloreactive T cells from antileukemic and antitumor donor T-cell lines.

AbstractIn HLA-incompatible hematopoietic stem cell transplantation, alloreactive donor T cells recognizing recipient mismatch HLA cause severe graft-versus-host disease (GVHD). Strategies allowing the selective depletion of alloreactive T cells as well as the enhancement of graft-versus-malignancy immunity would be beneficial. We generated donor CD8 T-cell lines in vitro using allogeneic recipient cells mismatched at a single HLA class I allele or haplotype as stimulators. Recipient cells were obtained from acute myeloid leukemias, renal-cell carcinomas, and CD40L-induced B lymphoblasts. Resulting alloreactive T cells were activated by incubating day 21 T-cell cultures with HLA-mismatch tr…

Addressing tumour tolerance to improve cancer immunotherapy

An open-label, prospective phase I/II study evaluating the immunogenicity and safety of a ras peptide vaccine plus GM-CSF in patients with non-small cell lung cancer.

Mutations of the ras gene have been reported in 20-40% of NSCLC patients. If present, they are critical for the malignant phenotype of these tumors. Therefore, targeting them by specific vaccination is a promising therapeutic approach. In a clinical trial we screened for ras mutations in patients with NSCLC. Patients with ras-positive tumors were immunized six times intradermally with a mixture of seven peptides representing the most common ras mutations. Objectives of the study were the feasibility, efficacy and safety of the vaccination. In addition, the induction of a specific immune reaction was investigated by DTH tests, and the induction of peptide-specific T cells was tested in ex vi…

Transplantation in follicular lymphoma: not "yes or no" but "whom and when".

After years of debate, the question as to what is the optimal use of transplantation strategies in indolent lymphoma remains controversial. In the July issue of Haematologica, a study was published by the EBMT Lymphoma Working Party that aims to define indications for hematopoietic stem cell

Preemptive Transfer of GMP-Grade CD8-Depleted Donor Lymphocytes after T-Cell Depleted Reduced-Intensity Transplantation.

Abstract The combination of fludarabin (150mg/m2) / melphalan (140mg/m2) based reduced-intensity allo-transplantation (RIT) with in vivo T-cell depletion (TCD) by the anti-CD52 antibody alemtuzumab (100mg) has demonstrated efficient engraftment and reduced graft-versus-host disease (GVHD) (Kottaridis et al., Blood 2000). However, the slow lymphocyte recovery following this protocol is associated with reduced anti-infectious and antitumor immunity. In an attempt to improve immune-reconstitution after TCD / RIT, we investigated the early preemptive use of CD8-depleted donor lymphocyte infusions (DLIs). For CD8 depletion of donor leukaphereses, a new depletion protocol using clinical grade CD8…

A PCR-Based Assay for the Detection of Langerhans-Cell Chimerism after Allogeneic Stem Cell Transplantation.

Abstract Early acute GVHD of the skin frequently occurs in patients after allogeneic hematopoietic stem cell transplantation. Although T cell depletion reduces the incidence and severity, it does not completely prevent skin GVHD. This leads to a prolonged need for immunosuppressive medication in a significant number of patients. For the induction of acute GVHD, the stimulation of donor T cells by residing host antigen presenting cells such as Langerhans cells of the skin (LCs) plays a central role. The absence of donor T cells after depletion, however, seems to hamper an early switch of LCs from host to donor origin. Therefore, the monitoring of LC chimerism is of great interest. We and oth…

Identification of a Conserved HLA-A2-Restricted Decapeptide from the IE1 Protein (pUL123) of Human Cytomegalovirus

Abstract Control of human cytomegalovirus (HCMV) infection is predominantly mediated by cytolytic CD8 + T lymphocytes (CTL). Among the roughly 200 HCMV-encoded polypeptides, the tegument protein pp65 (ppUL83) and the nonstructural IE1 protein are considered to be dominant CTL targets. Yet the importance of CTL against IE1 for protective immunity against HCMV reactivation and disease has remained elusive. Analyses have been difficult, as all MHC class I presented peptides of IE1 defined so far are located in parts of the protein that are variable between viral strains. In this study a conserved decameric peptide from IE1 (P6, IE1 354–363 ) that bound to HLA-A2 was identified. Using peptide-p…

Identification of T cell epitopes by the use of rapidly generated mRNA fragments.

Abstract Although the number of defined T cell epitopes of clinically relevant antigens is constantly increasing, there is still an enormous need to identify further peptides, processed from new antigens or presented by rare HLA molecules, respectively. Here we introduce a novel two-step approach for the rapid identification of T cell epitopes. It was established in the CMV infection model. From the peripheral blood of healthy donors sharing HLA-A1 according to HLA serotyping we isolated CD8 + T lymphocytes and generated dendritic cells (DCs). DCs were electroporated with CMV pp65 mRNA and tested for recognition by autologous CD8 + T lymphocytes in IFN-γ ELISPOT assays. In all 10 CMV-seropo…

Leishmaniasis, contact hypersensitivity and graft-versus-host disease: understanding the role of dendritic cell subsets in balancing skin immunity and tolerance

Dendritic cells (DC) are key elements of the immune system. In peripheral tissues, they function as sentinels taking up and processing antigens. After migration to the draining lymph nodes, the DC either present antigenic peptides by themselves or transfer them to lymph node-resident DC. The skin is the primary interface between the body and the environment and host's various DC subsets, including dermal DC (dDC) and Langerhans cells (LC). Because of their anatomical position in the epidermis, LC are believed to be responsible for induction of adaptive cutaneous immune responses. The functions of LC and dDC in the skin immune system in vivo are manifold, and it is still discussed controvers…

Proteasome-inhibited dendritic cells demonstrate improved presentation of exogenous synthetic and natural HLA-class I peptide epitopes.

The design and successful clinical implementation of cancer vaccines targeting the induction of T-cell mediated immunity is a rapidly evolving field that is hampered by an empirical selection of antigen and adjuvant. In particular, vaccines using defined tumor-associated peptide epitopes elicit only a restricted T-cell repertoire in a minority of patients. In this regard, vaccines comprising the whole spectrum of antigens presented by individual autologous tumors would be advantageous. In an in vitro model, we evaluated the capacity of naturally processed Epstein-Barr virus-transformed B-lymphoblastoid-cell line (LCL)-derived peptides to activate virus-specific CD8+ T cells of seropositive …

Human CD8+ memory and EBV-specific T cells show low alloreactivity in vitro and in CD34+ stem cell–engrafted NOD/SCID/IL-2Rγcnull mice

Current strategies in cellular immunotherapy of cancer and viral infections include the adoptive transfer of T cell receptor (TCR) and chimeric antigen receptor engineered T cells. When using transient RNA expression systems in clinical studies, multiple infusions with receptor-redirected T cells appear necessary. However, in allogeneic hematopoietic stem-cell transplantation, repeated transfer of donor-derived T cells increases the risk of alloreactive graft-versus-host disease. We investigated naive-derived (T N ), memory-derived (T M ), and Epstein Barr virus-specific (T EBV ) CD8 + T cell subsets for alloreactivity upon redirection with RNA encoding a cytomegalovirus-specific model TCR.…

Graft-Versus-Host Disease or Infection: Rapid Detection of HLA Mismatch-Reactive T Cells Ex Vivo Can Facilitate Diagnosis and Guide Therapy after Allogeneic Transplantation.

Abstract Diagnosis of graft-versus-host disease (GVHD) is mainly based on clinical features and on tissue biopsies. However, clinicians and pathologists are well aware of cases, in which GVHD cannot be distinguished from infections arising from severe immunodeficiency after allogeneic stem-cell transplantation (SCT). This may pose a deep therapeutic dilemma of whether to modify immunosuppressive treatment or to use donor lymphocyte infusion (DLI) for promoting anti-microbial immunity. We observed a 68-year-old patient with myelodysplastic syndrome who developed acute GVHD grade II of skin and gut at d+16 after T-cell depleted reduced-intensity SCT (Fig. 1). GVHD was confirmed by histology a…

Sustained remissions and low rate of BCR-ABL resistance mutations with imatinib treatment chronic myelogenous leukemia in patients treated in late chronic phase: a 5-year follow up.

The introduction of Imatinib (IM) has significantly altered the treatment for CML, although only limited follow-up results are available. As failure of Interferon-alpha had been associated with poor prognosis and results of IM-treatment in this patient group may allow earlier estimation of long-term benefits for early chronic phase patients. Therefore we prospectively analyzed the quality and duration of remissions and the rate of BCR-ABL resistance mutations occurring in patients treated with IM, if they were intolerant or refractory to interferon. Fifty-nine patients were included and median follow up is 4.75 years. Haematologic remission rate was 92% and 62% of patients achieved at least…