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

Selective Depletion of Alloreactive T Lymphocytes Using Patient-Derived Nonhematopoietic Stimulator Cells in Allograft Engineering

Background. Selective depletion of alloreactive T cells in vitro results in efficient graft-versus-host disease prophylaxis in allogeneic hematopoietic stem-cell transplantation, but it is accompanied by increased recurrence of leukemia. To spare donor T-cell-mediated graft-versus-leukemia immunity against hematopoiesis-restricted minor histocompatibility (minor-H) antigens, we explored the use of patient-derived nonhematopoietic antigen-presenting cells (APC) as allogeneic stimulators for selective allodepletion in leukemia-reactive donor T-cell lines. Methods. Primary keratinocytes, dermal fibroblasts, and bone marrow fibroblasts were generated from skin biopsies and diagnostic bone marro…

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…

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 …

Depletion of Alloreactive Donor T Lymphocytes by CD95-Mediated Activation-Induced Cell Death Retains Antileukemic, Antiviral, and Immunoregulatory T Cell Immunity

In allogeneic hematopoietic stem cell transplantation (AHSCT) graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effect are closely but not invariably linked. Thus, harnessing donor lymphocyte mediated GVL immunity and separating it from GVHD is of particular interest. Based on results obtained in murine models we have explored the CD95-mediated activation-induced cell death (AICD) strategy to selectively deplete alloreactivity in human donor T lymphocytes in vitro. Following stimulation of CD3(+) T cells isolated from HLA-A* 0201-positive donors with HLA or minor histocompatibility antigen mismatched hematopoietic or nonhematopoietic cells in the presence of agonistic anti-CD…

Functional Analyses of Human T Cell Extravasation in a Humanized NOD/SCID/IL2Rγcnull Transplantation Model.

Abstract Abstract 2448 Poster Board II-425 Donor lymphocyte graft engineering to avoid graft-versus-host (GVH) reactivity while improving graft-versus-leukemia (GVL) immunity remains of central interest in allogeneic hematopoietic stem cell transplantation (HSCT). However, appropriate models to evaluate experimental concepts of donor lymphocyte allograft engineering in vivo are missing. We, therefore, established a human-murine chimeric transplantation model using immunodeficient NOD/SCID/IL2Rγcnull (NSG) mice to evaluate GVH reactivity of human T cell grafts in vivo. Moreover, since mechanisms of immune functions resembling human GVH immunity have not yet been addressed in detail in these …

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 +…

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 …

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…

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…

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…