Trogocytosis as a Cellular method for Identification of Antigen specific T cells in Adoptive Cellular Therapy 2265839

Abstract Introduction Our group previously demonstrated that our polyclonal adoptive cellular therapy platform significantly increased overall survival in mice in brain cancer models. The T cells transferred into our mice are cocultured with tumor specific RNA primed dendritic cells. Although this method is successful at isolating and expanding activated and antigen specific T cells, not all of the cells being transferred are tumor specific. We have designed a cellular method for identifying T cells that are antigen specific by harnessing the power of trogocytosis, the process of transferring membrane fragments from antigen presenting cells to lymphocytes. Methods We generate primary T cells from mice splenocytes and coculture them with electroporated bone marrow derived dendritic cells. These cells are then stained and sorted with flow cytometry based on their dye uptake to separate into a trog+ and a trog- population. We phenotyped these T cells using flow cytometry to assess activation status, proliferation status, and cytotoxic markers. We analyzed tumor-specific T cell activation using a restimulation challenge and measuring IFNy with an Elisa kit. PCR microarray analysis was done to assess differences in gene expression between the trog+ and trog- cells Results We observed that there were changes in the phenotype between the trog+ and trog- populations. The trog+ cells expressed much higher levels of IFNy expression levels compared to the trog- cells when challenged with the tumor it was primed against. PCR microarray showed significant upregulation of multiple activation, proliferation, differentiation, and polarization markers in the trog+ group. Conclusion Our results indicate this assay has the ability to generate activated, antigen specific T cells. These isolated T cells have the potential to increase the efficacy of our ACT treatment as well as becoming a discovery platform for the identification of personalized tumor mutations thus enhancing future strategies of targeted cellular cancer treatments. Funding Source NA Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)