Antibody-mediated rejection (AMR) is a major complication after ABO-incompatible liver transplantation (ABOi-LT). Serum B cell counts and serum anti-ABO antibody titers are the main factors monitored to prevent AMR, and a desensitization protocol has been developed to overcome this problem. According to the 2016 Banff Working Group on Liver Allograft Criteria, the diagnosis of acute AMR requires the positive serum donor specific antibody (DSA). Clinical significance of histological findings of AMR in the absence of DSA is unclear. Here, we present the case of allograft injury like acute AMR under the absence of DSA after ABOi LDLT with the low titers of anti-ABO antibody and depleted serum CD19+ B cells.
A 57-year-old man (blood type, O+) who suffered from hepatitis B virus cirrhosis with hepatocellular carcinoma. The patient received rituximab (300 mg/m2) 3 weeks before transplantation and then underwent three sessions of plasmapheresis. Pre-operative donor-specific antibody (DSA) and cross-matching were negative (donor blood type A+). The titers of anti-ABO antibodies decreased to 1:8 from 1:256, and serum CD19+ B cells were depleted before the operation. During improvement of liver function, acute AMR was observed in protocol biopsy on postoperative day 7; the CD19+ count was 0%, and anti-ABO antibody titers were 1:2. Despite treatment with three sessions of plasmapheresis and intravenous immunoglobulin (0.8 g/kg), the inflammatory reaction expanded. Histological findings were improved after steroid pulse therapy.
Although, clinical significance of DSA (-) AMR is unclear, it has been shown that the treatment improves histopathologic changes in this case. In ABOi liver transplantation, investigations for immediate histologic allograft injury similar to acute AMR might be needed to know its clinical significance.