Similar to the in vitro results in the MLR (Fig. 6b), IL-1β secretion was inducedin the GVHD model (Fig. 6c), while deficiency of NLRP3, Caspase-1 or β2M reduced IL-1β induction (Fig. 6c), indicating that the MLR CTLs activate NLRP3 inflammasome in APCs for IL-1β maturation and secretion in vivo. Here, IL1B is linked to graft versus host disease.