Immune Thrombocytopenic Purpura Due to Passenger Donor Lymphocytes in Liver Transplantation

Introduction: Thrombocytopenia is a frequent complication following solid organ transplant but previous reports suggest that the incidence of immune mediated thrombocytopenic purpura (ITP) following liver transplantation is low (0.7%). Although the mechanisms involved in post transplant thrombocytopenia are complex, the presence of alloantibody derived from passenger donor lymphocytes should be considered when severe thrombocytopenia is identified.

Case presentation: Our case is a 58-year-old gentleman who underwent liver transplantation for end stage cirrhosis and hepatocellular carcinoma. His baseline pre-transplant platelet count was low at 83 ×10⁹/L, but he postoperatively worsened to a platelet count of 5×10⁹/L with bleeding sequelae. The liver donor was a 71-year-old previously healthy man who presented with severe thrombocytopenia (platelet count of 3 ×10⁹/L) and hemorrhagic stroke, but no evidence of hematological pathology on bone marrow examination. As the donor history of presumptive ITP was known to the service, antiplatelet antibody assays on both the donor and recipient were performed using the ELISA based GTI-PAK12 kit (GTI Diagnostics, Waukesha, WI). Although there were no detectable antiplatelet antibodies in the organ recipient’s pre-transplant specimens, the immediate post-transplant specimen demonstrated reactivity in all three GPIIb/IIIa wells, corresponding to a stronger but identical reaction pattern in the organ donor. This suggested that the reactivity and subsequent worsening of the thrombocytopenia were secondary to antibodies produced by passenger donor lymphocytes in the transplanted liver. The transplant recipient was treated with corticosteroids, intravenous immune globulin and platelet transfusion with a return to his baseline platelet count and cessation of bleeding symptomatology five days later. Repeat platelet antibody testing in the organ recipient five weeks post-transplant revealed no detectable antiplatelet antibody reactivity, indicating lack of engraftment of the passenger donor lymphocytes.

Conclusion: Passenger donor lymphocytes producing antiplatelet antibodies may be a contributing factor in post-transplant thrombocytopenia. Close monitoring and high clinical suspicion should be present when there is a history of immune/idiopathic thrombocytopenia in the organ donor.