Increased ratios of these Tregs over effector T cells <i>in vivo</i> following vaccination of T1D patients with tolerogenic DCs pulsed with islet autoantigen correlated with increased islet-specific immune regulation ex vivo.<h4>Discussion</h4>Our results define a population of induced Tregs <i>in vitro</i> and <i>in vivo</i> that is marked by elevated CD27 expression. This evidence concerns the gene CD27 and type 1 diabetes mellitus.