TIL expansion with high dose IL-2 or low dose IL-2 with anti-CD3/anti-CD28 stimulation provides different quality of TIL-expanded T cell clones

Tumor infiltrating lymphocytes (TILs) are cells that are present inside the tumor environment, of which include T cells, B cells and natural killer (NK) cells. At present, TILs are used for immunotherapy in various cancers. Knowledge on adoptive transfer of TILs in ovarian cancer is still limited, especially regarding TIL expansion methods. Therefore, the aim of our study was to compare the quality of T cell clones between two expansion methods for ovarian cancer TILs. We show that TILs stimulated with the mitogenic stimulation method (low dose IL-2 with anti-human CD3/CD28) and the standard stimulation method (high dose IL-2 only) both increased total number of T cells. TCR repertoire analyses revealed different TCR repertoire patterns between TIL-expanded T cells that were stimulated with the standard stimulation method (high dose IL-2 only) and the mitogenic stimulation method (low dose IL-2 with anti-human CD3/CD28). Regardless, when TILs were expanded using the standard stimulation method (high dose IL-2 only), the predominant T cell receptor beta variable (TRBV) chains that were used in both TIL-expanded clones of the CD4+ and CD8+ subpopulations were similar. In addition, there were also TIL-expanded CD4+ and CD8+ T cell clones that were dominant in only one or the other subpopulations. These results reveal the bias in TIL quality after being stimulated with different protocols. Further studies are required to understand the selection of TIL expansion, in order for a more efficacy adoptive transfer treatment.