High-dose ATG followed by short-term rapamycin treatment failed to promote early operational tolerance to LT. AR correlates with expansion of memory-type CD8(+) T cells and increased levels of IFN-γ and IL-17 in mixed lymphocyte reaction and in the graft. This suggests that resistance and preferential expansion of effector memory T-cell in lymphopenic environment could represent the major barrier for establishment of tolerance to LT in approaches using T-cell-depleting induction.
Better tools for predicting the risk of death while awaiting transplantation are urgently needed because organ shortage is increasing the numbers on transplantation waiting lists. The aminopyrine breath test (ABT), model for endstage liver disease (MELD), and Child-Pugh (C-P) score were compared as predictors of this risk in 137 cirrhotic candidates for liver transplantation. Eighty-three were transplanted within 3 months of registration, 35 others survived, 13 died before transplantation, and 6 were removed from the list. By univariate analysis, the continuous variables significantly associated with death while awaiting transplantation were: history of infected ascites, C-P score, ABT, and international normalized ratio or prothrombin time. Receiver operating characteristic curves for quantitative variables showed that the area under the curve was greatest for ABT (0.858 * 0.067). By Youden curve analysis, the best cut-off points for identifying cirrhotic patients at high risk of death while on the waiting list were: > 10, > 16, and <0.7% for the C-P score, MELD score, and ABT, respectively. These results show that ABT is as good as the MELD and C-P scores, or better, as a predictor of death among cirrhotic patients awaiting liver transplantation.
We designed a pilot trial in cadaveric liver transplantation to determine whether induction with antithymocyte globulins (ATG) and sirolimus would allow immunosuppression withdrawal. Patients received ATG 3.75 mg/kg per day from day 1 to 5 after transplantation followed by sirolimus for 4 to 6 months. We monitored interleukin (IL)-7 serum levels, interferon (IFN)-gamma, and IL-2 mRNA accumulation in mixed leukocyte reaction and intragraft IFN-gamma mRNA expression. In the first three patients, immunosuppression discontinuation was followed by reversible acute rejection occurring on days 280, 246, and 163 posttransplantation, corresponding to days 140, 40, and 39 after drug withdrawal, respectively. At the time of rejection, blood CD8+ T-cells counts had returned to or above pretransplant levels in two of three patients, whereas CD4+ T-cell count remained low. IL-7 serum levels rose in all three patients in the first months after transplantation and IFN-gamma mRNA accumulated in mixed leukocyte reaction between recipient T cells and donor spleen cells at the time of rejection. High levels of IFN-gamma mRNA were consistently detected in liver biopsy performed at the time of rejection. In conclusion, lymphopenia-induced IL-7 production after induction with ATG and sirolimus might lead to emergence of IFN-gamma-secreting CD8+ T-cells responsible for acute rejection after immunosuppression withdrawal.
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