DPP4 and mature T-cell and NK-cell non-Hodgkin lymphoma: The level of CD26-positive cells from the PTCL sample were 50-70% following co-culturing with CD8 2/3G control cells while co-culturing with CD26 2/3G CAR-T-cells reduced the level of CD26-positive cells to 1-2% (Figure 6A).