Early detection and rapid isolation of leukemia-reactive donor T cells for adoptive transfer using the IFN-γ secretion assay

Purpose: The poor immunogenicity of most leukemias and the lack of specificity of the donor T cells limit the in vivo effectiveness of conventional donor lymphocyte infusions in many patients suffering from persistent or recurrent leukemia after allogeneic stem cell transplantation. These limitations may be overcome by the adoptive transfer of in vitro generated leukemia-reactive T cells. Although the potential clinical efficacy of this approach has been shown previously, lack of reproducibility of the procedure and the inability to show persistence and survival of the transferred T cells hampered further clinical application. The purpose of this study was to develop a new, broadly applicable strategy for the efficient generation and isolation of leukemia-reactive T cells with a better probability to survive and expand in vivo. Experimental Design: Myeloid and B-cell leukemias were modified into professional immunogenic antigen-presenting cells, and used to stimulate HLA-matched donor T cells. After two stimulations, responding donor T cells were isolated based on their secretion of IFN-gamma and tested for their capacity to recognize and kill the primary leukemia. Results: Using one universal stimulation and isolation protocol for various forms of leukemia, T-cell populations containing high frequencies of leukemia-reactive T cells could reproducibly be generated and early isolated under mild stimulatory conditions. Isolated T cells still had high proliferative potential and their reactivity seemed to be restricted to cells of the patient's hematopoiesis. Conclusion: We here show a new robust procedure for the generation and isolation of leukemiare-active T cells for adoptive transfer.