BACKGROUND & AIM: Kidney grafts in simultaneous liver-kidney (SLK) recipients are considered to be immunologically protected due to hepatic tolerance, although recent studies have alternatively shown that kidney rejection may occur in up to 20% of SLK recipients. Here we analyzed histocompatibility factors that may be responsible for this observation.

METHODS: Retrospective single-center cohort study of SLK transplants between 01/11- 02/15. HLA-antibody data included screening for HLA antibodies (Flow-PRA), pre- and post-TX analysis of donor specific antibodies (DSA by single antigen luminex assay), and flow cytometric crossmatch (FCXM) when available. Rejection events were recorded for indication (liver, kidney) and 3-month protocol (kidney) biopsies. Patients without biopsy or histocompatibility data were excluded from analysis.

RESULTS: During the study time period, 74 SLK were performed, of which 68 had both biopsy and antibody data available. Mean age was 61.7 +/- 9.2; 57% male; 63% Caucasian; 41% HCV, 40% alcoholic cirrhosis. 36/74 had pre-formed HLA antibodies and 12/74 had pre-formed DSA . There were no appreciable difference in observed liver rejection rates in either patients who had pre TX DSA (p=0.55) or post TX DSA (p = 0.3). There was also no appreciable difference in observed kidney rejection rates in patients who had pre TX DSA (p=0.19). However, a higher rejection rate was identified in kidneys of recipients who expressed post TX DSA. Among 22 DSA+ patients, 13 had rejection while 9 did not; among 41 DSA- patients, 13 had rejection while 28 did not (p=0.035). 5 of these 26 patients experienced antibody mediated rejection (AMR).

Table 1. Breakdown of patient outcomes based on antibody and biopsy results. DSA detected means either DSA+ or FCXM+. DSA not detected means PRA- or FCXM-. P-value for pre TX was p = 0.19. P-value for post TX was 0.035.

CONCLUSIONS: Post-transplant DSA is an important determinant of kidney graft rejection in SLK recipients. This increased risk suggests the need to implement post-operative DSA monitoring and protocol biopsies to minimize rejection post-SLK, similar to strategies in kidney alone recipients.

CITATION INFORMATION: Dong R, Tambur A, Gallon L, Levitsky J. Factors Mediating Kidney Rejection in Patients of Simultaneous Liver-Kidney Transplants. Am J Transplant. 2016;16 (suppl 3).

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