BACKGROUND: We previously showed that pretreatment with intratracheal delivery (ITD) of alloantigen induced prolonged cardiac allograft survival and generated regulatory T cells (Tregs) in mice. In this study, we examined the role of splenic dendritic cells (DCs) in the ITD model.METHODS: CBA mice were treated with ITD from C57BL/10 splenocytes and 7 days later received transplantation of C57BL/10 hearts. In adoptive transfer studies, splenic DCs from ITD-treated mice were transferred into na?ve CBA recipients that received C57BL/10 hearts immediately after the transfer. In addition, to determine the role of splenic DCs isolated from ITD-treated mice, the cells were incubated under stimulation with lipopolysaccharide (LPS).RESULTS: ITD-treated CBA recipients had markedly prolonged allograft survival (median survival time [MST], 67 days) while na?ve recipients rejected allografts acutely (MST, 8 days). In adoptive transfer studies, CBA recipients of the transfer of splenic DCs from ITD-treated mice had prolonged allograft survival (MST, 85 days), while CBA recipients of the transfer of splenic DCs from na?ve mice did not have prolonged allograft survival (MST, 8 days). In another transfer study, CBA recipients of the transfer of splenic CD8á+ DCs from ITD-treated mice had prolonged allograft survival (MST, 79 days), while those receiving splenic CD8á- DCs from ITD-treated mice did not have prolonged allograft survival (MST, 8 days). In vitro studies showed that ITD-treated splenic DCs produced more IL-10 and less IL-12 than na?ve splenic DCs under stimulation with LPS.CONCLUSIONS: ITD pretreatment induces regulatory DCs, which produce high amounts of IL-10 resulting in the prolongation of graft survival in our model.
Adoptive Transfer Animals