We first sought to investigate the regulatory effect of Flt3L combined with a short-term of low-dose Rapa treatment on allograft acute rejection. A murine cardiac allograft transplantation model was employed to address this question. As shown in Figure 1A , untreated recipients rapidly rejected their grafts (7.660.516 days) along with typical pathological features of acute rejection (Fig. 1B) . Similar pathological features were observed in recipients treated with either PBS or rGST (controls, Figure 1B ). As expected, administration of Rapa significantly increased graft mean survival time (MST) (16.962 .767 days, Fig. 1A) . Similarly, recipients treated with Flt3L doubled allograft MST (13.161.287 days, Fig. 1A ). In sharp contrast, a significant enhanced graft survival was observed in mice treated with Flt3L and low-dose of Rapa (36.4618.704 days, Fig. 1A) . Remarkably, about 20% of recipients showed long-term graft survival (MST.100 days, Fig. 1A ). In consistent with these results, a significant reduction for inflammatory infiltration was observed in the allograft sections (Fig. 1B ).