IL2 and type 1 diabetes mellitus: This “on-demand” mechanism provides a dual advantage: it furnishes the infused Tregs with a potent, externally regulatable proliferative and survival signal, directly compensating for the intrinsic IL-2 response defect in T1D patient Tregs; and it grants clinicians precise control over the magnitude and timing of Treg expansion in vivo by managing the administration of the CISC activator, thereby substantially widening the therapeutic safety window and avoiding the non-specific activation of other immune cells associated with conventional IL-2 therapy.