Induced pluripotent stem (iPS) cells possess tremendous therapeutic potential in the fields of both regenerative medicine and immune therapy. We have started an activity to apply iPS technology to mouse and human immunology research and therapeutic development. On a collaborative basis with individual research activities in IMS, the core facility for iPS research is engaged in developing efficient protocols to reprogram various lymphocytes and induce differentiation of iPS cells into lymphoid lineage cells. This activity is partly supported by JST.

This year, the facility established iPS cells from mature cytotoxic T cells specific for the melanoma epitope MART-1. JKF6 cells are long-term cultured tumor infiltrating lymphocytes that were originally derived from a melanoma patient and have been maintained at the Surgery Branch of the National Cancer Institute. JKF6 cells are specific for the complex of MART-1-peptide and HLA-A*02:01, and can be visualized as MART-1-tetramer+ cells by flow cytometry. These MART-1-specific T cells were transduced with Yamanaka factors, after which they established clones that form colonies with human ESC-like morphology (Vizcardo R., et al., 2013). When co-cultured with OP9/DLL1 cells, the MART-1-iPS cells efficiently generated CD8+ T cells, and more than 90% of these cells were specific for the original MART-1 epitope. Stimulation of these CD8+ T cells with HLA-A*02:01-expressing cells pulsed with MART-1-peptide resulted in the secretion of IFNγ. The present study thus provides a novel method for cloning and expanding functional CD8+ T cells specific for a given antigen, which can potentially be applied for immune cell therapy against cancer.