In T-DLBCL, higher proportions of PD-1 expressing CTLs and CD4+ TILs have been shown to correlate with significantly longer survival while a subpopulation of FoxP3+T-bet+ double-positive Tregs has been identified to have a significant adverse effect on outcome (Figure 2B) [23,24,120]. Here, PDCD1 is linked to diffuse large B-cell lymphoma.