Ex vivo expansion of tumor specific lymphocytes with IL-15 and IL-21 for adoptive immunotherapy in melanoma

Although T Central Memory cells have been described as the most effective T-cell subtype against tumor growth, little is known about the requirements needed for their optimal ex vivo generation. Hence, our goal is to establish a protocol that will lead to consistent ex vivo generation of lymphocytes skewed toward a Central Memory phenotype. Antigen-specific T-cell lines were generated by ex vivo stimulation with Class-I and Class-II melanoma peptide pulsed Dendritic Cells in the presence of either IL-2 or IL-15 plus IL-21. Tumor specific lymphocytes of both Central Memory and effector characteristics were consistently generated from healthy donors and melanoma patients. IL15/IL21 cultures result in a cell population with a lower proportion of CD4+CD25highFoxP3+ regulatory cells and higher number of CD8+ and CD56+ cells, and consequently render a higher yield of cells with a greater cytolytic activity and IFN-γ production against melanoma cell lines.