Prope tolerance after pediatric liver transplantation

pT, under mono- and infratherapeutic calcineurin inhibition, may constitute an optimal condition combining graft acceptance with low IS load and minimal IS-related toxicity. We reviewed 171 pediatric (<15.0 yr) survivors beyond one yr after LT, transplanted between April 1999 and June 2007 under tacrolimus-based regimens (median follow-up post-LT: 6.0 yr, range: 0.8-9.5 yr). Their current status regarding IS therapy was analyzed and correlated with initial immunoprophylaxis. pT was defined as tacrolimus monotherapy, with mean trough blood levels <4 ng/mL during the preceding year of follow-up, combined with normal liver function tests. The 66 children transplanted before April 2001 received a standard tacrolimus-steroid regimen. Beyond April 2001, 105 patients received steroid-free tacrolimus-basiliximab or tacrolimus-daclizumab immunoprophylaxis. In the latter group, 43 (41%) never experienced any acute rejection episode and never received steroids. In the long term, a total of 79 recipients (47%) developed pT (n = 73) or IS-free operational tolerance (n = 6), 27 of them belonging to the 43 steroid-free patients (63%). In contrast, only 52/128 (41%) children treated with steroids subsequently developed prope/operational tolerance (p = 0.012). Steroid-free tacrolimus-based IS seems to promote long-term graft acceptance under minimal/no IS. These results constitute the first evidence that minimization of IS, including steroid avoidance, might be tolerogenic in the long term after pediatric LT.