LAUSR

There are some reported cases of liver transplant between identical twins with no immunosuppressants because of their matched HLA. However, there is no mention of donor-specific antibodies (DSA). Here, we report a rare case of living donor liver transplant (LDLT) between identical twins, mimicking DSA positivity, on a low-dose immunosuppression protocol. A 57-year-old man with acute liver failure underwent LDLT using the right lobe from his identical twin. Their blood types were identical on HLA matching. However, the preoperative DSA test results were positive for class II antibodies. This was supposed to be due to the relatively large amount of blood transfusion before testing: a total of 580 units of fresh frozen plasma for plasma exchange. The presence of class II antibodies for DSA positivity was the result of the passive immunity from transfusion, and this result could not be ignored, given the risk of rejection. Therefore, we arranged low-dose postoperative immunosuppressants using tacrolimus at a quarter dose and no mycophenolate mofetil. The postoperative course was uneventful. A few months after LDLT, the patient's DSA level was negative for class II antibodies, thus confirming our preoperative hypothesis of DSA as the result of transfusion. Currently, 6 months after LDLT, he is free from immunosuppressive medication with good liver function. When administering relatively large doses of fresh frozen plasma by repeated plasma exchange before LDLT, even between identical twins, it is important to consider that the DSA test could be positive and that immunosuppressive treatment should be performed carefully.