Successful living kidney transplantation in a T-cell flow cytometry crossmatch-positive patient with atypical hemolytic uremic syndrome treated with an anti-C5 antibody: a case report.

Atypical hemolytic uremic syndrome (aHUS) is an intravascular hemolytic disorder caused by complement dysregulation. A 41-year-old female patient with end-stage kidney disease and a history of glomerulonephritis had been receiving frequent blood transfusions for anemia and thrombocytopenia with hemolytic findings. She came to our hospital for a living donor kidney transplant from her mother, and a preoperative evaluation revealed ABO incompatibility and strong positivity in the T-cell flow cytometry crossmatch (FCXM) due to broad anti-HLA antibodies sensitized by previous blood transfusions. Since her clinical course and genetic testing led to the diagnosis of aHUS, treatment with eculizumab was started prior to kidney transplantation. She received desensitization therapy with intravenous immunoglobulin, plasma exchange, and rituximab along with regular eculizumab treatment, and then underwent living donor kidney transplantation. She achieved stable renal function without developing antibody-mediated rejection (ABMR) or the recurrence of thrombotic microangiopathy (TMA). Kidney graft biopsies 3 months and 1 year after transplantation showed no ABMR or TMA, with stable renal function. We herein report a positive FCXM case with aHUS that safely underwent living donor kidney transplantation without ABMR or the recurrence of TMA by starting eculizumab and desensitization therapy before surgery.