Allogeneic T-cell apoptosis induced by interleukin-10-modified dendritic cells: a mechanism of prolongation of intestine allograft survival?

BACKGROUND: Genetic modification of donor dendritic cells (DC) is a potential therapy for allograft rejection. We hypothesized that in vitro interleukin-10 (IL)-10-transfected DC (DC-IL-10) may induce allogeneic T-cell apoptosis, resulting in prolonged allograft survival rat small intestine. METHODS: Myeloid DC from Wistar-Furth rats (RT-1u) were propagated with rrGM-CSFand rrIL-4,then genetically modified to express the hIL-10 gene. Secretion of IL-10 was quantitated by enzyme-linked immunosorbent assay (ELISA). Allogeneic T cells from Lewis (LEW; RT-1(l)) at proliferative responses were determined by MTT assay in primary mixed leukocyte reactions. We then used a combination of DNA agarose gel electrophoresis, acridine orange staining, and Annexin V/propridium iodide assays to examine apoptosis of allogeneic T cells exposed to DC-IL-10. Then 5 x 10(6) donor-derived DC-IL-10 or untransduced DC were injected intravenously 7 days before small intestine transplantation (WF-->LEW). RESULTS: DC-IL-10 showed pronounced impairment of T-cell allostimulatory activity. Apoptotic T cells were detected in the DC-IL-10 group. Flow cytometry counting at 72 hours showed 45.1% apoptotic T cells in response to DC-IL-10, whereas the untransduced group did not undergo significant apoptosis (P < .01). DC-IL-10 pretreated recipients showed moderate prolongation of allograft survival compared with controls (20.7 +/- 6.0 days vs 7.5 +/- 2.2 days, P < .01). CONCLUSIONS: DC-IL-10 induced allogeneic T-cell hyporesponsiveness in vitro, possibly due to apoptosis. DC-IL-10 pretreated recipients displayed prolonged intestinal allograft survival rates.