*Purpose: Preformed donor-specific antibodies (DSA) are considered as a risk factor after solid organ transplantation. Strong DSA is associated with high mortality and increased risk of antibody mediated rejection (AMR) after liver transplantation (LT). The purpose of this study was to check the prophylactic effect by rituximab desensitization against AMR to preformed DSA positive LT recipients.

*Methods: Between October 2014 and November 2018, a total of 97 LTs were performed. Eleven cases (11.3%) were identified with positive preformed DSA during the preoperative evaluations. A single dose of 500mg rituximab was given preoperatively to 10 recipients with positive DSA except one cadaveric LT recipient whose DSA results arrived postoperatively. No preoperative immunosuppressive agents were given. Postoperative immunosuppression consisted of triple regimens; tacrolimus, steroid, and mycophenolate mofetil. Postoperative DSA levels were checked, and liver biopsies were collected to rule out antibody mediated rejection (AMR).

*Results: All recipients survived (follow up period: 1-51 months). HLA class type of 10 recipients with positive preformed DSA were “class-I only” 3 patients, “class-II only” 4 patients, and “both class-I and II” 3 patients. Those DSA positive patients received LTs from living donors (LDLT, n=8) and deceased donors (DDLT, n=2). Rituximab was given to the LDLT recipients 1-21 (median 12) days before LDLT, and to the DDLT recipients just before DDLT. DSA were checked at 1, 3, 6, 12, 24, 36, and 48 months after each LT. MFI levels of DSA gradually declined in class-II, but rapidly disappeared in class-I. However, during the long follow-up, two patients developed de novo DSA without affecting liver function test. Liver biopsies obtained from “class-II only” DSA recipients early postoperative periods demonstrated positive C4d staining, but no signs of AMR. Those biopsies from late-postoperative periods turned negative C4d staining, indicating that accommodation of preformed DSA was achieved by rituximab desensitization without causing AMR. In contrast, “class-I only” or both “class-I and II” recipients demonstrated negative C4d staining, even early postoperative periods.

*Conclusions: Ten cases of LTs with preformed DSA were successfully managed by the rituximab desensitization. Further studies are required because the mechanism of DSA to AMR in LTs remains unclear, especially the difference between class-I and class-II DSA and de novo DSA formation.

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