Effects of HDACi on the interactions of Tregs, APCs, and effector T cells. Epigenetic events are displayed according to each stage of T-cell maturation (boxes) and matched with corresponding HDACi effects as shown in the outer row of arrows. (Middle) Treg, APC, and T-cell interactions, cytokine production, reciprocal stimulatory and inhibitory signals, and effects of HDACi on Tregs and pro-inflammatory APC (top boxes); the suppressive effects of Tregs are not shown.