Immunotolerance of liver allotransplantation induced by intrathymic inoculation of donor soluble liver specific antigen

Abstract

Aim: To study the effects of liver specific antigen (LSA) on the immunoreaction of liver allotransplantation and its significance.

Methods: Orthotopic liver transplantation was used in this study. Group I: syngeneic control (Wistar-to-Wistar); Group II: acute rejection (SD-to-Wistar). Group III: acute rejection treated by intramuscular injection of cyclosporine A (CsA) (SD-to-Wistar+CsA). Group IV: Intrathymic inoculation of SD rat LSA one week before transplantation (LSA+SD-to-Wistar). The common situation and survival time, rejection grades, NF-kappaB activity of splenocytes and intragraft cytokine gene expression were observed to analyze the acute rejection severity and immune state of animals.

Results: The common situation of Wistar-to-Wistar group was very good after the transplantation and no signs of rejection were found. Recipients of SD-to-Wistar group lost body weight progressively. All died within 9 to 13 days after transplantation with the median survival time of 10.7+/-0.51 days. It was an optimal control for acute rejection. The common situation of SD-to-Wistar+CsA group was bad during CsA medication but only with mild rejection. As for LSA+SD-to-Wistar group, 5 of 6 recipients survived for a long time and common situation was remarkably better than that of SD-to-Wistar group and SD-to-Wistar+CsA group. Its rejection grades were significantly lower than that of SD-to-Wistar group (P=0.026). Furthermore, no significant discrepancies of rejection were found between SD-to-Wistar group and LSA+SD-to-Wistar group at day7 and day12 (P=0.067). NF-kappaB activity, IFN-gamma and IL-2mRNA expression were significantly inhibited in LSA+SD-to-Wistar group compared with that of SD-to-Wistar group (P<0.05).

Conclusion: LSA is an important transplantation antigen which involves in the immunorejection of liver transplantation directly. We reported for the first time that intrathymic inoculation of LSA can induce immnotolerance of liver allotransplantation and grafts can survive for a long time thereby, thus leading to a novel way to liver transplantation immunotolerance.

Figure 1

Rejection grades of grafted liver in different groups. Data were expressed as mean ± SD. I, Wistar-Wistar group; II, SD-Wistar group; III, SD-Wistar + CsA group; IV, LSA + SD-Wistar group; Rejection grades of group IV were significantly lower than that in group II at all but day 1 time point. No sig-nificant discrepancies were found between group IV and group III on day 7 and day 12 time points. ^aP < 0.05 vs group II, ^bP > 0.05 vs group III.

Figure 2

The kinetic change of intragraft IL-2mRNA expres-sion in different groups. I, Wistar-Wistar group; II, SD-Wistar group; III, SD-Wistar + CsA group; IV, LSA + SD-Wistar group; IL-2mRNA expression of group IV were significantly lower than that in group II at all time point (P < 0.05).

Figure 3

The kinetic change of Intragraft IFN-γ mRNA ex-pression in different groups. I, Wistar-Wistar group; II, SD-Wistar group; III, SD-Wistar + CsA group; IV, LSA + SD-Wistar group; IL-2mRNA expression of group IV were significantly lower than that in group II at all time point (P < 0.05).

Figure 4

EMSA specific competitive inhibition. Lane 1, nega-tive control; Lane 2, positive control; Lane 3, specific competition; Lane 4, non-specific competition; Lane 5, mutant competition.

Figure 5

NF-κB activity of splenocytes at different time points after the transplantation. A, Wistar-Wistar group; B, SD-Wistar group; C, SD-Wistar + CsA group; D, LSA + SD-Wistar group; E, the kinetic change of NF-κB activity. NF-κB activity of group IV were significantly lower than that in group II at all time point (P < 0. 05).