Prolongation of the Rat Composite Tissue Allograft Survival by the Combination of Tolerogenic Immature Dendritic Cells and Short-Term Treatment With FK506

ObjectivePrevention of rejection in composite tissue allotransplantation without continuous immunosuppression is of paramount importance in the field of transplantation. Recently dendritic cells (DCs) have gained considerable attention as antigen-presenting cells that are also capable of tolerance induction. This study assessed the effect of interleukin (IL)-10–supplemented, alloantigen-pulsed immature tolerogenic DC to increase survival of orthotopic hind limb transplantations in rats.Materials and MethodsHind limbs from Sprague-Dawley (SD) hosts were transplanted to Fischer 344 (F344) rats. Peripheral blood mononuclear cells (PBMC) isolated from F344 were cultured to generate immature DCs (imDCs); IL-10 was added for tolerogenic DC induction. Flow cytometric analysis were performed to characterize the DC phenotype. IL-10-imDCs cocultured with donor mononuclear cells for 24 hours were reinjected into recipients subcutaneously 1 day before transplantation. Recipient animals were divided into 4 groups, each comprising 6 rats (n = 6): group I (untreated controls), group II (IL-10-imDCs alone), group III (FK-506 [Tacrolimus, 2 mg/kg] for 2 weeks postoperative), and group IV (recipient origin IL-10-imDCs combined with FK-506 for 2 weeks postoperative). Observation of graft appearance, cytokine production assays, and confocal immunofluorescence were performed at postoperative 1 week.ResultsThe combination of IL-10–treated imDCs and FK-506 produced a significantly prolonged median allograft survival (46.7 days) compared with groups I (4.7), II (5.3), or III (26.3). Splenocytes isolated from rats treated with IL-10-imDCs plus and FK-506 produced significant amounts of IL-10 and IL-4 cytokines upon alloantigen stimulation, as confirmed using ELISPOT and ELISA.ConclusionsWe demonstrated that IL-10–treated imDCs induced T-cell hyporesponsiveness, skewing the immune response to Th2 elements, resulting in long-term survival of composite tissue allografts.