http://www.ncbi.nlm.nih.gov/pubmed/27302659

Feng S, Demetris AJ, Spain KM, Kanaparthi S, Burrell BE, Ekong UD, Alonso EM, Rosenthal P, Turka LA, Ikle D, Tchao NK. Hepatology. 2016 Jun 15. doi: 10.1002/hep.28681. [Epub ahead of print]

Abstract
Pediatric liver transplant recipients arguably have the most to gain and the most to lose from discontinuing immunosuppression (IS). While IS undoubtedly exerts a cumulative toll, there is concern that insufficient or no IS may contribute to allograft deterioration. Twelve pediatric recipients of parental living donor liver grafts, identified as operationally tolerant through complete IS withdrawal (WISP-R; NCT00320606) were followed for a total of five years (one year of IS withdrawal and four years off IS) with serial liver tests, auto- and allo-antibody assessments. Liver biopsies were performed two and four years off IS and, at these time points, immunoglobulin G (IgG) subclass and C1q binding activity for donor specific antibodies (DSAs) were determined. There were no cases of chronic rejection, graft loss, or death. Allografts did not exhibit progressive increase in inflammation or fibrosis. Smooth muscle actin (SMA) expression by stellate cells and CD34 expression by liver sinusoidal endothelial cells (LSECs) remained stable, consistent with the absence of progressive graft injury. Three subjects never exhibited DSA. However, three subjects showed intermittent de novo Class I DSA, four subjects showed persistent de novo Class II DSA and five subjects showed persistent pre-existing Class II DSA. Class II DSA was predominantly against donor DQ antigens, often of high mean fluorescence intensity (MFI), rarely of the IgG3 subclass, and often capable of binding C1q.

CONCLUSION:
Operationally tolerant pediatric liver transplant recipients maintain generally stable allograft histology in spite of apparently active humoral allo-immune responses. The absence of increased inflammation or progressive fibrosis suggests that a subset of liver allografts seem resistant to the chronic injury that is characteristic of antibody-mediated damage. This article is protected by copyright. All rights reserved.
© 2016 by the American Association for the Study of Liver Diseases.

KEYWORDS:
Allograft fibrosis; Donor specific antibody; Immunosuppression withdrawal; Liver transplantation; Tolerance