(1695) When Donor Cells Attack: Case Report on Passenger Lymphocyte Syndrome Posttransplant

Introduction: Passenger lymphocyte syndrome (PLS) is a rare complication of solid organ transplantation, occurring when donor B lymphocytes produce antibodies against the recipient's red blood cells, causing a minor ABO mismatch. PLS typically presents as sudden-onset anemia within three weeks post-transplant. The true incidence of PLS is unknown due to its often-subclinical presentation and other potential anemia causes in transplant recipients. The acute onset of anemia, especially when infections and thrombosis are ruled out, should prompt consideration of PLS. Management is generally supportive, though severe cases may require corticosteroids.

Description: A 36-year-old male with blood type A+ and a history of cirrhosis secondary to autoimmune hepatitis presented with decompensated chronic liver disease, jaundice, ascites, and febrile episodes. Suspected spontaneous bacterial peritonitis was treated with cephalosporins. Laboratory tests showed leukocytosis, lactic acidosis, transaminitis, thrombocytopenia, and a prolonged coagulation panel. An abdominal CT revealed advanced portal hypertension. Despite negative cultures, he underwent a successful orthotopic liver transplant from an O+ donor due to a high MELD-Na score. Post-transplant, was discharged on prednisone, mycophenolate, and tacrolimus with a hemoglobin level of 8.1 g/dL.

One week later, he experienced dizziness and malaise with a hemoglobin level of 3.8 g/dL and was admitted with hypovolemic shock. Imaging showed no bleeding foci. Elevated LDH, indirect bilirubin, reticulocyte count, and a positive direct Coombs test, along with normal coagulation parameters and platelet levels, led to a diagnosis of minor ABO incompatibility. Donor lymphocytes from the liver caused hemolysis, treated with steroids, resulting in a full recovery.

Discussion: This case underscores the importance of considering PLS in post-transplant patients with unexplained anemia. Although rare, PLS can cause significant complications if not promptly recognized. Management primarily involves supportive care and using ABO-compatible blood products. The lack of standardized screening protocols for PLS highlights the need for developing such protocols to enhance early detection and management.