Eculizumab in Anti-Factor H Antibodies Associated With Atypical Hemolytic Uremic Syndrome

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening multi-systemic condition often leading to end-stage renal failure. It results from an increased activation of the alternative pathway of the complement system due to mutations of genes coding for inhibitors of this pathway or from autoantibodies directed against them. Eculizumab is a monoclonal antibody directed against complement component C5 and inhibiting the activation of the effector limb of the complement system. Its efficacy has already been demonstrated in aHUS. The present article reports for the first time the use of eculizumab in a patient presenting with aHUS associated with circulating anti-complement Factor H autoantibodies and complicated by cardiac and neurologic symptoms. Our observation highlights the efficacy of eculizumab in this form of aHUS not only on renal symptoms but also on the extrarenal symptoms. It also suggests that eculizumab should be used very promptly after aHUS presentation to prevent life-threatening complications and to reduce the risk of chronic disabilities. To obtain a complete inhibition of the effector limb activation, the advised dosage must be respected. After this initial therapy in the autoimmune aHUS form, a long-term immunosuppressive treatment should be considered, to prevent relapses by reducing anti-complement Factor H autoantibody plasma levels.