The tale of cytokines and the -cell is a long story, starting with in vitro discovery in 1984, evolving via descriptive and phenomenological studies to detailed mapping of the signalling pathways, gene- and protein expression patterns, molecular and biochemical effector mechanisms to in vivo studies in spontaneously diabetic and transgenic animal models. Only very recently have steps been taken to translate the accumulating compelling preclinical data into clinical trials. The aim of this chapter is to present an overview of early and recent key observations from our own groups as well as other laboratories that serve to illuminate the road from concept to clinical translation.