Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>Abstract 4354</jats:p>
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<jats:title>Background:</jats:title>
<jats:p>Donor lymphocyte transfusion (DLT) may induce the graft-versus-leukemia (GVL) effect for patients with AML relapsed after transplant. However, the limited overall efficacy of DLT in clinical practice emphasizes the importance of identifying a specific subgroup of patients who might benefit from this treatment approach.</jats:p>
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<jats:title>Objective:</jats:title>
<jats:p>To monitor the cellular immune response after DLT, we developed an active specific immunization strategy using in vitro generated AML-trained T cells to induce a highly specific antileukemic T-cell response and thus established a novel nonradioactive assay system.</jats:p>
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<jats:title>Methods:</jats:title>
<jats:p>The myeloid blasts derived from five patients with AML relapsed post allogeneic hematopoietic stem cell transplantation (allo-HSCT) were first labeled with CFDA (5,6-carboxyfluorescein diacetate succinimidyl ester). To analyze the growth inhibitory potential of the donor T cells trained by AML cells, the myeloid blasts were induced to proliferate by means of a cytokine cocktail. The T cell mediated growth inhibitory potential was detected after 5 days by flow cytometry and correlated with [3H]-thymidine uptake.</jats:p>
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<jats:title>Results:</jats:title>
<jats:p>Here, we applied a CFDA dye to track the proliferation and expansion of AML blasts in response to the cytokine cocktail in vitro. AML-trained T cells, expressed high levels of the activation markers CD25 and CD69, and were generated to recognize the leukemic progenitor cells and inhibit cytokine-induced leukemic cell proliferation, which is an active specific immunization strategy circumventing the identification of leukemia-associated antigens. The capability of proliferation inhibition of AML-trained T cells evaluated with the nonradioactive, CFDA-based assay provided comparable results with the classic [3H]-thymidine assay.</jats:p>
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<jats:title>Conclusion:</jats:title>
<jats:p>The active specific immunization strategy was realized to monitor the antileukemic immune response measured with radioactive and nonradioactive assay system.</jats:p>
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<jats:title>Disclosures:</jats:title>
<jats:p>No relevant conflicts of interest to declare.</jats:p>
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