Granulocyte/macrophage colony-stimulating factor-stimulated hepatic dendritic cell progenitors prolong pancreatic islet allograft survival

Abstract

Liver-derived dendritic cell (DC) progenitors propagated in liquid culture in granulocyte/macrophage colony-stimulating factor exhibit low levels both of cell surface MHC class II antigens and of counter-receptors for CTLA-4/CD28. They fail to stimulate allogeneic T cells in mixed leukocyte cultures. To evaluate their in vivo functional significance, we determined their influence on survival of pancreatic islet allografts. Cultured B10.BR (H2k;I-E+) mouse liver-derived DC progenitors were injected (2 x 10(6) i.v.) into streptozotocin-diabetic B10 (H2b; I-E-) recipients 7 days before transplantation of pancreatic islets (700 IEq/mouse) from the same donor strain. No immunosuppressive agents were administered. Mean islet allograft survival time was prolonged from 15.3 days (in animals pretreated with syngeneic cells) to 30.3 days (P < 0.001) in mice pretreated with the donor-derived liver cells. In 20% of these animals, islet allograft survival exceeded 60 days. These data suggest that liver-derived DC progenitors may contribute both to the inherent tolerogenicity of the mouse liver and to its capacity to protect other allografts of the same donor strain from rejection.

Figure 1

FACSCAN immunophenotypic profile of GM-CSF-stimulated B10.BR mouse liver-derived cells with DC characteristics released from cell aggregates (culture day 8) and examined using rat, hamster, or mouse mAbs. Note the absence of lymphoid cell markers and the low level of MHC class II (I-E^k) expression. The result is representative of 6 separate experiments.

Figure 2

Influence of cultured B10.BR liver DC progenitors on B10.BR pancreatic islet allograft survival in B10 mice. Cultured liver (L)- or spleen (S)-derived cells (2×10⁶) were injected intravenously 2 days after the recipient animals were made diabetic with an intraperitoneal injection of streptozotocin (200 mg/kg). The animals were maintained on Insulin, as described in Materials and Methods (1–2 IU i.p. daily), until pancreatic islet transplantation. Pancreatic islets (700 IEq/mouse) were placed beneath the left renal capsule 7 days after the injection of cultured GM-CSF-stimulated liver DC progenitors or spleen-derived DC.