Figure 7. Anti-tumor activities of Naïve:Memory CD3⁺CD8⁺ CTL subsets generated by stimulation with a cocktail of XBP1 UN_185-193 (I S P W I L A V L), XBP1 SP_223-231 (V Y P E G P S S L), CD138_265-273 (I F A V C L V G F) and CS1_240-248 (L F V L G L F L W) peptides.

Upon the stimulation of CD3⁺ T cells from HLA-A24⁺ donors (N=5) with the HLA-A24-specific multipeptide, the Naïve:Memory CD8⁺ CTL subsets were evaluated for their anti-tumor activities against multiple myeloma cells. Functionally, the central memory CD8⁺ CTL subset demonstrated the highest anti-myeloma activities, as evidenced by perforin/IFN-γ/IL-2 production and 41BB upregulation in response to HLA-A24⁺ KMS11 myeloma cells (Figure 7A). The high levels of anti-tumor activities was observed consistently by the memory CD8⁺ T cells in the HLA-A24 multipeptide-specific CTL generated (Figure 7B). Within the multipeptide-specific CTL, the central memory cells subset expressed the highest level of immune checkpoints (Figure 7C).