Objective: To explore the roles of CD4+ CD25+ and CD8+ CD28- T regulatory cells in spontaneous tolerance of inbred rats orthotopic liver Transplantation.
Methods: The orthotopic liver transplantation models of spontaneous tolerance were established between BN (donor) and LEW (recipient) inbred rats whose survival time was more than 120 days, The expression of CD8+ CD28- T and CD4+ CD25+ T cells in PBMC and spleen were determined by flow cytometry. CD8+ CD28- T and CD4+ CD25+ T cells were sorted by immunomagnetic beads. The expressions of CD25, CD28, CD152 and CD45RO on CD8+ CD28- T and CD4+ CD25+ T regulatory cells were also determined by flow cytometry.
Results: Compared with control groups, the proportion of CD8+ CD28- T regulatory cells in spontaneous models was significantly increased in peripheral blood mononuclear cells (PBMC) and spleen [PBMC (30.2+/-5.8)% vs (16.4+/-6.1)%; Spleen (23.7+/-7.2)% vs(13.4+/-5.5)% P<0.01]. CD4+ CD25+ T regulatory cells had no change; CD11b was expressed on CD8+ CD28- T regulatory cells in both control groups and tolerance groups, and CD25, CD152 (CTL-4) were not expressed on CD8+ CD28- T regulatory cells. The expression of CD45RO on CD8+ CD28- T regulatory cells was 76.1% in control groups and more than 90% in tolerance groups; CD11b, CD152 (CTL-4) and CD45RO were expressed on CD4+ CD25+ T regulatory cells in both control groups and tolerance groups.
Conclusion: The roles of CD8+ CD28- T cells were more important than CD4+ CD25+ T cells in spontaneous tolerance of rat liver transplantation. the different expressions of CD152 showed the functions of CD8+ CD28- and CD4+ CD25+ T cells were different. The different expressions of CD45RO suggested CD8+ CD28- T regulatory cells was changed before and after liver transplantation.