Secondary failure of plasma therapy in factor H deficiency.

We report a patient with homozygous factor H deficiency leading to permanent alternate complement activation and early onset of the hemolytic uremic syndrome. He was successfully treated with weekly infusions of fresh frozen plasma over 4 years, displaying normal blood pressure while only treated with an angiotensin converting enzyme (ACE) inhibitor, a steady level of haptoglobin, low-range proteinuria and normal creatinine clearance. By the end of the fourth year of treatment, he dramatically developed a relapse of hemolytic and uremic syndrome, displaying undetectable haptoglobin, nephrotic range proteinuria and progressive renal failure. Despite a ten-fold increase in the dosage of plasma infusion through daily plasma exchange, haptoglobin remained undetectable while circulating antigenic factor H levels reached 22-24% (normal values 65-140%). Three months following the biological onset of the relapse, a bilateral nephrectomy was performed owing to uncontrolled hypertension and rapidly progressive renal failure. The molecular mechanism of plasma resistance remained unclear while antifactor H antibodies were not detected in the plasma. We suggest that protracted administration of exogenous factor H might not be a long-term strategy in homozygous factor H deficiency.