CD4 and type 1 diabetes mellitus: Using NSG mice administered human spleen mononuclear cells, Hu et al. showed that a combination of IL-2 and rapamycin expanded CD4+Foxp3+ Tregs, suppressed the function of effector cells in vivo, and thus extended human islet allograft survival, offering a promising way to promote islet transplantation for T1DM therapy 158.