OBJECTIVETo observe the effects of NBD-peptide pretreatment of the donor dendritic cells in immune tolerance induction in mouse allograft recipients and investigate the mechanisms.

METHODSBALB/c mouse DCs pretreated with NBD-peptide (NBD-Peptide-DC) were injected into the recipient C57BL/6 mice 7 days before transplantation. Cervical heterotopic heart transplantation model was established using the cuff technique and the cardiac allograft survival time was observed. Pathological analysis were performed to examine the graft injection and the responsiveness of the recipient spleen T cell to the donor alloantigen was determined by mixed lymphocyte reaction (MLR). The serum levels of cytokines were determined using ELISA.

RESULTSThe cardiac allograft survival time in the NBD-Peptide-DC-treated group (21.83-/+3.54 days) was significantly longer than that in the Day9-DC group (13.33-/+2.58 days) and PBS-treated group (6.66-/+1.21 days) (P<0.01), with also significantly lower pathological grade for graft rejection (P<0.01). The donor-derived NBD-Peptide-DCs induced alloantigen-specific T-cell hyporesponsiveness. In the NBD-Peptide-DC-treated group, the serum levels of IL-12 and IFN-gamma decreased significantly (P<0.01), but the levels of IL-4 and IL-10 increased significantly (P<0.01).

CONCLUSIONInjection of donor-derived NBD-Peptide-DCs can leads to donor-specific tolerance in the transplant recipients, and the induction of recipient T-cell hyporesponsiveness and polarization of Th2 response may play important roles in immune tolerance to cardiac allografts.