Characterization of Stimulated γδ T Cells: Phenotypic Analysis and Implications for Allogeneic Cellular Immunotherapy

Due to their anti-tumor activity and non-major histocompatibility complex (MHC) binding T cell receptor, γδ T cells are suitable candidates for allogeneic cellular immunotherapy in cancer. Recently, we developed a new protocol called Ko-Op for stimulation of γδ T cells (specifically Vy9Vδ2 T cells) that generates a cell product consisting mainly of γδ T cells with preserved anti-tumor activity targeted for clinical-grade application. In this study, we investigated the phenotype of stimulated γδ T cells and correlated this with results of functional assays to obtain a deeper understanding of the characteristics of stimulated γδ T cells. Additionally, an intensive analysis of surface molecules of unstimulated and stimulated γδ T cells is presented. Since heterogeneous results regarding the response to therapy with γδ T cells observed in earlier clinical trials could be a consequence of various extents of γδ T cell adhesion and migration ability, we addressed surface molecules associated with cellular activity and adhesion and migration functions as well. By investigating correlations between the phenotype of unstimulated γδ T cells and cellular cytotoxicity, as well as the degranulation ability of stimulated γδ T cells, we could draw conclusions about optimal donors for further allogeneic cellular therapies. Finally, we demonstrated that the phenotype varies over the time of culture and is clearly modifiable by changing the stimulation protocol.