Figure 1. Adoptive T cell-based immunotherapy strategies. Two teams reprogrammed antigen-specific CD8+ T cells (orange cells) using Yamanaka factors and SV40 large T antigen to produce induced pluripotent stem (iPS) cells (purple cells). When cocultured with mouse feeder cells, the iPS cells differentiated into mature, antigen-specific CD8+ T cells (blue cells). These cells could be expanded using the T cell growth factor IL-2, and the result was a source of antigen-specific T cells that showed longer telomeres, greater effector function and higher proliferating capacity than antigen-specific T cells that did not go through the iPS cell stage (orange cells).

Standard adoptive T cell-based immunotherapy involves expanding CD8+ T cells ex vivo with IL-2. The cells can be infused back into the patient to help them mount a response to a virus or cancer, but the approach has shown limited efficacy. (Figure based on Figure 1B in ref. 12.)