| Research Abstract |
Pretransplant DST significantly prolonged rat hepatic allograft survival. Immunostaining revealed OX76^+/OX-62^+ cells in the splenic red pulp of animals receiving pretransplant DST and in the white pulp of untreated animals after transplantation. The ratio of splenic CD45RC^-OX62^+ cells to CD45RC^+ OX62^+ cells in DST recipients was significantly higher than in untreated animals. CD62L, CD80, and CD86 were lower on CD45RC^-OX62^+ than CD45RC^+OX62^+ cells. RT-PCR revealed that sorted CD45RC^-OX62^+ cells expressed interleukin (IL)-4 and IL-10. In contrast, sorted CD45RC^+OX62^+ cells expressed only IL-2 and IFN-γ. Thus, the two phenotypes of CD45RC^+OX62^+ and CD45RC^-OX62^+ cells are likely DC1 and DC2, respectively. DC maturation is accompanied by a large increase in expression of MHC class II and costimulatory molecules (CD80 and CD86). The layer of marginal zone macrophages is the splenic analog of HEV, forming the port of entry for lymphocytes into the white pulp of the spleen. HEV express several L-selectin ligands including CD34, GlyCAM-1, and MAdCAM-1 The homing receptor CD62L was less abundant on CD45RC^-OX62^+ cells compared to CD45RC^+OX62^+ cells, as were the maturation markers CD80 and CD86. In addition, CCR7 expression on CD45RC^+OX62^+ cells was significantly greater than CD45RC^-OX62^+ cells. While, the cell surface expression of CCR5 on CD45RC^-OX62^+ cells was significantly greater than CD45RC^+OX62^+ cells. These results suggest that CD45RC^+OX62^+ cells and CD45RC^-OX62^+ cells are mature and immature DC, respectively.
|
