Objective: The use of donor-derived immature dendritic cells (imDC) has become a promising approach to induce immune tolerance or immune hyporesponsiveness. However, donor-derived imDC needs to be harvested for a few days and transfused into the recipient in 5-10 days before transplantation, which is practically impossible in a clinical setting where donor organs are mainly harvested from cadavers. Moreover, donor-derived imDC might be cleared by allogeneic reaction offsetting induced immune tolerance or immune hyporesponsiveness. In our study, we further explored the underlying mechanism of immune hyporesponsiveness induced by donor-antigen-unloaded recipient-derived imDC by transfusing these imDC into rats in 1 day before liver transplantation. This paper is to study the mechanism of immune hyporesponsiveness induced by donor-antigen-unloaded recipient-derived imDC and its protection of liver grafts in rats. Methods: 40 SD rats (donor) and 40 male Wistar rats (recipient) were randomly divided into 4 groups: control, cyclosporine A(CsA), mature DC (mDC), and imDC; with 10 SD rats and 10 Wistar rats for each group. Animal models of acute graft rejection were established with these rats. Corresponding treatments were given before or after transplantation. In the control group, Wistar rats received no treatment other than liver transplantation. In the CsA group, Wistar rats underwent liver transplantation plus CsA treatment (10 mg/kg·d) in the starting day 2 after transplantation. For the mDC group, recipient-derived mDC(1×106/rat) were infused intravenously via the dorsal vein of the penis to recipient rats. For the imDC group, imDC (1×106/rat) were injected into recipient rats via the dorsal vein of the penis. In each group, 5 recipients were executed at 10 days after transplantation; the remaining five recipients were kept for the observation of survival time. Blood samples were collected for the measurement of ALT and TBIL; IL-2, IFN-γ, IL-4 and IL-10 and levels were measured with double-antibody sandwich ELISA. Liver tissue was harvested for HE staining and the observation of histological features. Acute rejection was evaluated with Banff classification. Expression levels of Fas-L/Fas in the grafts were detected by immunohistochemical staining; and western blot was used to detect the expression level of Scurfin. Results: The median survival times (MST) of the liver allografts in the CsA and imDC group were significantly longer than those in the control or mDC group (P