The mechanism of CD8+ CD45RClow regulatory T cell in rat liver transplantation nature tolerance model

Abstract

Objective To explore the mechanism of CD8+ CD45RClow regulatory T cells and its related cytokines function during the tolerance process of orthotopic liver transplantation in rats. Methods The male Brown Norway rats were selected as the donor, the Lewis rats were the recipients, the allogenic orthotopic liver transplantation model was established by the double cuff method. Experiment animals were divided into early transplantation group (10 rats), tolerance group (10 rats), sham group. Liver function were detected. The tolerance recipients were detected by hematoxylin and eosin (HE) staining. The Luminex used to detect of cytokine and the flow cytometry were used to analyze the changes of subsets of lymphocytes in the peripheral blood/graft and draining lymph node. Results 70% of recipients in operation group could be induced natural immune tolerance. The levels of aspartate aminotransferase (AST) in tolerance group were [(456±54) U/ml] vs. those of sham group [(460±151) U/ml], (P>0.05); the levels of alanine aminotransferase (ALT) in tolerance group were [(122±35) U/ml] vs. those of sham group [(121±46) U/ml, P>0.05]. The expression of CD8+ CD45RClow T cells in tolerance group were increased than in short term group; in grafts it was up regulated in tolerance group than in sham group, and it was no significance between sham group and tolerance group in lymph node around graft. The expression of pDC in short term group are significantly increased compared with sham group. The interferon (IFN)-γ was increased in short term group, return to normal level in tolerance group. interleukin (IL)-10 in grafts milieu were dramatically increased, keep in high level in tolerance group. Conclusion In the tolerance recipients of rat orthotopic liver transplantation model, CD8+ CD45RClow regulatory T cells were significantly increased and aggregated in the peripheral blood and liver. The inhibitory cytokines IL-10 was important to maintain the long-term graft tolerance. Key words: Regulatory T cell; Liver transplantation; Immune tolerance; Interleukin-10; Dendritic cell