Angiotensin Type 1 Receptor Antibody Positivity in a Pediatric Liver Transplant Patient With Antibody-Mediated Rejection: A Case Report.

BACKGROUND: Antibody-mediated rejection (AMR) in pediatric liver transplantation (LT) is uncommon and poorly understood. While human leukocyte antigen (HLA) antibodies are usually implicated in AMR, non-HLA antibodies have also been reported. METHODS: We describe a 7-year-old female with non-HLA AMR in the setting of positive angiotensin type 1 receptor (AT1R) antibodies. RESULTS: She was diagnosed with acute T-cell mediated rejection (TCMR) 6 months post-LT which was treated with intravenous methylprednisolone (IVMP) but had minimal response. A repeat biopsy revealed features of AMR including C4d staining and capillaritis, but donor-specific antibodies (DSAs) were negative. However, AT1R antibodies were elevated at 21 U/mL. She received antithymocyte globulin (ATG) and was started on losartan to block AT1R antibodies, with excellent response. CONCLUSION: While the recognition and mechanisms of AMR in pediatric LT are in its infancy, this case highlights the importance of considering non-HLA antibodies as potential mediators of AMR. Children who fail to respond to TCMR treatment should be evaluated for AMR by obtaining DSAs, C4d staining on biopsy, and non-HLA antibodies.