Favorable Outcome After ABO-Incompatible Living Donor Liver Transplant With High-Titer Isoagglutinin Rebound: A Case Report.

ABO-incompatible living donor liver transplantation is an important option to expand the donor pool but carries a higher risk of antibody-mediated rejection. Elevated preoperative isoagglutinin titers and postoperative rebound are major concerns, although their clinical significance remains uncertain. Here, we report a 66-year-old woman with hepatitis B-related cirrhosis and hepatocellular carcinoma who underwent ABO-incompatible living donor liver transplant with a right lobe graft (760 g; graft-to-recipient weight ratio of 1.13) donated by her daughter (blood type B → O). Preoperative anti-B immunoglobulin G and immunoglobulin M titers were 1:1024 and 1:32, respectively. After 11 plasma exchange sessions, titers decreased to immunoglobulin G 1:32 and immunoglobulin M 1:2 on the day of transplant. Splenectomy was not performed. Postoperatively, antibody titers rebounded (peak immunoglobulin G 1:128, immunoglobulin M 1:4) but gradually declined, whereas liver function tests, tacrolimus levels, and inflammatory markers remained stable during 2 years of follow-up. No antibody-mediated rejection, graft dysfunction, or infectious complications were observed. This case suggests that rebound of anti-ABO isoagglutinin titers after ABO-incompatible living donor liver transplant does not inevitably lead to antibody-mediated rejection or graft failure. Clinical and biochemical indicators may provide more reliable guidance than antibody titers alone. The findings support individualized decision-making and underscore the need for standardized treatment strategies in ABO-incompatible living donor liver transplantation.