Reversible renal failure in a patient with the hypereosinophilia syndrome during therapy with alpha interferon

Human recombinant interferon (IFN)-alpha (α)-2b was given to a 57- year-old man with hypereosinophilia syndrome refractory to prednisone and hydroxyurea. One year later, he developed progressive renal failure and nephrotic-range proteinuria. Percutaneous kidney biopsy showed focal and segmental glomerular and mesangial sclerosis, chronic interstitial nephritis, and focal tubular necrosis. Discontinuation of cytokine therapy led to marked improvement in renal function and significant reduction in proteinuria. The potential role of IFN-α as the cause of renal failure and nephrotic-range proteinuria is discussed. The spectrum of renal disease attributed to IFN-α and the proposed pathogenic mechanisms are reviewed.